阅读说明：本技术 两步随机接入信道配置 (Two-step random access channel configuration ) 是由 曹一卿 雷静 郑瑞明 于 2020-05-14 设计创作，主要内容包括：描述了用于无线通信的方法、系统和设备。无线设备可接收用于两步随机接入信道规程的第一随机接入消息的配置。无线设备可至少部分地基于该配置和无线设备的速度来选择用于传送第一随机接入消息的副载波间隔和解调参考信号出现次数。无线设备可使用副载波间隔和解调参考信号出现次数来传送两步随机接入信道规程的第一随机接入消息。(Methods, systems, and devices for wireless communication are described. The wireless device may receive a configuration of a first random access message for a two-step random access channel procedure. The wireless device may select a subcarrier spacing and a number of occurrences of demodulation reference signals for transmitting the first random access message based at least in part on the configuration and a speed of the wireless device. The wireless device may transmit a first random access message of a two-step random access channel procedure using a subcarrier spacing and a number of occurrences of a demodulation reference signal.)

1. A method for wireless communications at a wireless device, comprising:

receiving a configuration of a first random access message for a two-step random access channel procedure;

selecting a subcarrier spacing and a number of occurrences of demodulation reference signals for transmitting the first random access message based at least in part on the configuration and a speed of the wireless device; and

transmitting the first random access message of the two-step random access channel procedure using the subcarrier spacing and the number of occurrences of demodulation reference signals.

2. The method of claim 1, wherein the configuration comprises a combined set for the subcarrier spacing and the number of occurrences of demodulation reference signals.

3. The method of claim 2, wherein the selecting comprises:

selecting a configuration identifier corresponding to a combination in a combination set for the subcarrier spacing and the number of occurrences of the demodulation reference signal.

4. The method of claim 1, wherein the configuration comprises a first parameter for the subcarrier spacing and a second parameter for the number of occurrences of the demodulation reference signal.

5. The method of claim 4, wherein the selecting comprises:

independently selecting the subcarrier spacing based at least in part on the first parameter and the number of occurrences of the demodulation reference signal based at least in part on the second parameter.

6. The method of claim 1, further comprising:

selecting the subcarrier spacing and the number of demodulation reference signal occurrences based at least in part on a velocity of the wireless device exceeding a threshold.

7. The method of claim 1, further comprising:

transmitting an indication of the selected subcarrier spacing and the number of occurrences of the demodulation reference signal.

8. The method of claim 7, wherein the indication is included in a Physical Uplink Shared Channel (PUSCH) of the first random access message, in uplink control information on a physical uplink control channel, or both.

9. The method of claim 7, wherein the indication comprises a first parameter for the selected subcarrier spacing and a second parameter for the number of occurrences of the demodulation reference signal.

10. The method of claim 7, wherein the indication comprises a configuration identification indicating the subcarrier spacing and the number of occurrences of the demodulation reference signal.

11. The method of claim 7, wherein the indication comprises a sequence, frequency location information, or both for demodulation reference signals corresponding to the number of occurrences of the demodulation reference signal.

12. The method of claim 1, wherein the configuration is received in a system information message.

13. The method of claim 12, further comprising:

transmitting a request for the system information message, wherein the system information message is received based at least in part on the request.

14. The method of claim 1, further comprising:

determining that a velocity of the wireless device is below a threshold; and

registering with another cell based at least in part on the determination.

15. The method of claim 1, wherein the number of occurrences of the demodulation reference signal comprises occurrences of the pre-loaded demodulation reference signal and at least one additional demodulation reference signal.

16. The method of claim 15, wherein the at least one additional demodulation reference signal uses the same sequence, frequency position, or both, or uses a different sequence, frequency position, or both, than the pre-loaded demodulation reference signal.

17. The method of claim 1, wherein the wireless device is a User Equipment (UE) or a relay node.

18. A method for wireless communication, comprising:

transmitting a configuration of a first random access message for a two-step random access channel procedure to a first wireless device; and

receiving the first random access message of the two-step random access channel procedure using a subcarrier spacing and a number of occurrences of demodulation reference signals, wherein the subcarrier spacing and the number of occurrences of demodulation reference signals are based at least in part on the configuration and a speed of the first wireless device.

19. The method of claim 18, wherein the configuration comprises a combined set for the subcarrier spacing and the number of occurrences of demodulation reference signals.

20. The method of claim 18, wherein the configuration comprises a first parameter for the subcarrier spacing and a second parameter for the number of occurrences of the demodulation reference signal.

21. The method of claim 18, wherein the subcarrier spacing and the number of demodulation reference signal occurrences is based at least in part on a velocity of the first wireless device exceeding a threshold.

22. The method of claim 18, further comprising:

receiving an indication of the selected subcarrier spacing and the number of occurrences of the demodulation reference signal.

23. The method of claim 22, wherein the indication is received in a Physical Uplink Shared Channel (PUSCH) of the first random access message, in uplink control information on a physical uplink control channel, or both.

24. The method of claim 22, wherein the indication comprises a first parameter for the selected subcarrier spacing and a second parameter for the number of occurrences of the demodulation reference signal.

25. The method of claim 22, wherein the indication comprises a configuration identification indicating the subcarrier spacing and the number of occurrences of the demodulation reference signal.

26. The method of claim 22, wherein the indication comprises a sequence, frequency location information, or both for demodulation reference signals corresponding to the number of occurrences of the demodulation reference signal.

27. The method of claim 18, wherein the configuration is transmitted in a system information message.

28. The method of claim 18, wherein the first wireless device is a User Equipment (UE) or a relay node.

29. An apparatus for wireless communications at a wireless device, comprising:

a processor;

a memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

receiving a configuration of a first random access message for a two-step random access channel procedure;

selecting a subcarrier spacing and a number of occurrences of demodulation reference signals for transmitting the first random access message based at least in part on the configuration and a speed of the wireless device; and

transmitting the first random access message of the two-step random access channel procedure using the subcarrier spacing and the number of occurrences of demodulation reference signals.

30. An apparatus for wireless communication, comprising:

a processor;

a memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

transmitting a configuration of a first random access message for a two-step random access channel procedure to a first wireless device; and

receiving the first random access message of the two-step random access channel procedure using a subcarrier spacing and a number of occurrences of demodulation reference signals, wherein the subcarrier spacing and the number of occurrences of demodulation reference signals are based at least in part on the configuration and a speed of the first wireless device.

Background

The following relates generally to wireless communications and more particularly to two-step random access channel configuration.

Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be able to support communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include fourth generation (4G) systems, such as Long Term Evolution (LTE) systems, LTE-advanced (LTE-a) systems, or LTE-a Pro systems, and fifth generation (5G) systems that may be referred to as New Radio (NR) systems. These systems may employ various techniques, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM). A wireless multiple-access communication system may include several base stations or network access nodes, each supporting communication for multiple communication devices simultaneously, which may otherwise be referred to as User Equipment (UE).

Some wireless communication systems may support random access channel procedures when wireless devices travel at high speeds. The common techniques for high speed random access channel procedures may have some drawbacks and may be improved.

SUMMARY

The described technology relates to an improved method, system, device or apparatus supporting a two-step random access channel configuration. Some wireless communication systems may support a two-step random access channel procedure and communication when a device is traveling at high speeds. For example, a User Equipment (UE) may transmit a first random access message to a base station and receive a second random access response, after which a random access channel procedure is completed and the UE has an established Radio Resource Control (RRC) connection with the base station. The techniques described herein may support configurations that use an additional demodulation reference signal (DMRS) occurrence and a larger subcarrier spacing for a first random access message when the first random access message is transmitted in a high speed scenario. The base station may transmit a configuration of a first random access message for a two-step random access channel procedure to the UE. The configuration may include an indicator or possible values of a subcarrier spacing and a DMRS occurrence number of a first random access message for a two-step random access channel procedure.

The UE may select a subcarrier spacing and a number of DMRS occurrences for the first random access message based on the configuration. In a first example, the UE may select a subcarrier spacing and a number of DMRS occurrences based on the speed of the UE. For example, there may be different speed thresholds corresponding to different configurations or subcarrier spacing and number of DMRS occurrences. In some examples, some cells may support or configure high speed configurations. For example, a cell may only support configurations used in high speed situations. In some cases, the UE may indicate to the base station the selected subcarrier spacing and the number of DMRS occurrences. In some cases, the indication may be transmitted (e.g., via piggybacking) on an uplink shared channel.

A method of wireless communication at a wireless device is described. The method can comprise the following steps: receiving a configuration of a first random access message for a two-step random access channel procedure; selecting a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and a speed of the wireless device; and transmitting a first random access message of the two-step random access channel procedure using the subcarrier spacing and the DMRS occurrence number.

An apparatus for wireless communication at a wireless device is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to: receiving a configuration of a first random access message for a two-step random access channel procedure; selecting a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and a speed of the wireless device; and transmitting a first random access message of the two-step random access channel procedure using the subcarrier spacing and the DMRS occurrence number.

Another apparatus for wireless communication at a wireless device is described. The apparatus may include means for: receiving a configuration of a first random access message for a two-step random access channel procedure; selecting a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and a speed of the wireless device; and transmitting a first random access message of the two-step random access channel procedure using the subcarrier spacing and the DMRS occurrence number.

A non-transitory computer-readable medium storing code for wireless communication at a wireless device is described. The code may include instructions executable by a processor for: receiving a configuration of a first random access message for a two-step random access channel procedure; selecting a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and a speed of the wireless device; and transmitting a first random access message of the two-step random access channel procedure using the subcarrier spacing and the DMRS occurrence number.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the configuration includes a combined set for subcarrier spacing and DMRS occurrence number.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the selection may include operations, features, apparatuses, or instructions for: selecting a configuration identity corresponding to a combination in a combination set for a subcarrier spacing and a DMRS occurrence number.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the configuration includes a first parameter for subcarrier spacing and a second parameter for a number of DMRS occurrences.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the selection may include operations, features, means, or instructions for: independently selecting a subcarrier spacing based on the first parameter and selecting a DMRS occurrence number based on the second parameter.

Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions to: the subcarrier spacing and the number of DMRS occurrences are selected based on the speed of the wireless device exceeding a threshold.

Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions to: transmitting an indication of the selected subcarrier spacing and the number of DMRS occurrences.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication may be included in a PUSCH of the first random access message.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication may be transmitted in uplink control information on a physical uplink control channel.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication includes a first parameter for the selected subcarrier spacing and a second parameter for the number of DMRS occurrences.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication includes a configuration identification indicating a subcarrier spacing and a number of DMRS occurrences.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication includes a sequence, frequency location information, or both, for a DMRS corresponding to a number of occurrences of the DMRS.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the configuration may be received in a system information message.

Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions to: a request for a system information message is transmitted, wherein the system information message is receivable based on the request.

Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions to: the method may include determining that a velocity of the wireless device may be below a threshold, and registering with another cell based on the determination.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the DMRS number of occurrences includes occurrences of the piggybacked DMRS and the at least one additional DMRS.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the at least one additional DMRS uses the same sequence, frequency location, or both as the piggybacked DMRS.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the at least one additional DMRS uses a different sequence, frequency location, or both than the piggybacked DMRS.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the wireless device may be a UE or a relay node.

A method of wireless communication is described. The method can comprise the following steps: transmitting a configuration of a first random access message for a two-step random access channel procedure to a first wireless device; and receiving a first random access message of a two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences, wherein the subcarrier spacing and the number of DMRS occurrences are based on the configuration and the speed of the first wireless device.

An apparatus for wireless communication is described. The apparatus may include a processor, a memory in electronic communication with the processor, and instructions stored in the memory. The instructions are executable by the processor to cause the apparatus to: transmitting a configuration of a first random access message for a two-step random access channel procedure to a first wireless device; and receiving a first random access message of a two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences, wherein the subcarrier spacing and the number of DMRS occurrences are based on the configuration and the speed of the first wireless device.

Another apparatus for wireless communication is described. The apparatus may include means for: transmitting a configuration of a first random access message for a two-step random access channel procedure to a first wireless device; and receiving a first random access message of a two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences, wherein the subcarrier spacing and the number of DMRS occurrences are based on the configuration and the speed of the first wireless device.

A non-transitory computer-readable medium storing code for wireless communication is described. The code may include instructions executable by a processor for: transmitting a configuration of a first random access message for a two-step random access channel procedure to a first wireless device; and receiving a first random access message of a two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences, wherein the subcarrier spacing and the number of DMRS occurrences are based on the configuration and the speed of the first wireless device.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the configuration includes a combined set for subcarrier spacing and DMRS occurrence number.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the configuration includes a first parameter for subcarrier spacing and a second parameter for a number of DMRS occurrences.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the subcarrier spacing and the number of DMRS occurrences may be based on a velocity of the first wireless device exceeding a threshold.

Some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein may further include operations, features, apparatuses, or instructions to: an indication of the selected subcarrier spacing and the number of DMRS occurrences is received.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication may be received in a PUSCH of the first random access message.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication may be received in uplink control information on a physical uplink control channel.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication includes a first parameter for the selected subcarrier spacing and a second parameter for the number of DMRS occurrences.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication includes a configuration identification indicating a subcarrier spacing and a number of DMRS occurrences.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the indication includes a sequence, frequency location information, or both, for a DMRS corresponding to a number of occurrences of the DMRS.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the configuration may be transmitted in a system information message.

In some examples of the methods, apparatuses (devices), and non-transitory computer-readable media described herein, the first wireless device may be a UE or a relay node.

Brief Description of Drawings

Fig. 1 illustrates an example of a system for wireless communication supporting a two-step random access channel configuration in accordance with aspects of the present disclosure.

Fig. 2 illustrates an example of a wireless communication system supporting a two-step random access channel configuration in accordance with aspects of the present disclosure.

Fig. 3 illustrates an example of a process flow to support two-step random access channel configuration in accordance with aspects of the present disclosure.

Fig. 4 and 5 show block diagrams of devices supporting a two-step random access channel configuration according to aspects of the present disclosure.

Fig. 6 illustrates a block diagram of a communication manager supporting a two-step random access channel configuration, in accordance with aspects of the present disclosure.

Fig. 7 shows a diagram of a system including a device supporting a two-step random access channel configuration, in accordance with aspects of the present disclosure.

Fig. 8 and 9 show block diagrams of devices supporting two-step random access channel configuration according to aspects of the present disclosure.

Fig. 10 illustrates a block diagram of a communication manager supporting a two-step random access channel configuration in accordance with aspects of the present disclosure.

Fig. 11 shows a diagram of a system including a device supporting a two-step random access channel configuration, in accordance with aspects of the present disclosure.

Fig. 12 to 15 show flowcharts explaining a method of supporting two-step random access channel configuration according to aspects of the present disclosure.

Detailed Description

Some wireless communication systems may support a two-step random access channel procedure and communication when a device is traveling at high speeds. For a two-step random access channel procedure, a User Equipment (UE) may transmit a first random access message to a base station and receive a second random access response. Upon receiving the random access response, the random access channel procedure is complete and the UE has a Radio Resource Control (RRC) connection established with the base station. The two-step random access channel procedure may establish an RRC connection between the UE and the base station with less signaling and in a shorter amount of time than some other random access channel procedures, especially in the contention-based radio frequency spectrum band, because the device may first perform a Clear Channel Assessment (CCA) to gain control of the contention-based resource. To provide these advantages over other random access procedures, a two-step random access channel procedure may be robust to interference and other problems. However, some configurations for the two-step random access channel procedure may support only a single demodulation reference signal (DMRS) occurrence for the first random access message. In some high speed scenarios, a single DMRS may not provide a sufficiently robust first random access message for a reliable two-step random access channel procedure.

Accordingly, the wireless communication system described herein may support a configuration for the first random access message that may use an additional DMRS occurrence and a larger subcarrier spacing. The base station may transmit a configuration of a first random access message for a two-step random access channel procedure to the UE. The configuration may include an indicator or possible values of a subcarrier spacing and a DMRS occurrence number of a first random access message for a two-step random access channel procedure. In a first example, the configuration may include a combination of subcarrier spacing and DMRS occurrence. In a second example, the configuration may include two separate parameters for subcarrier spacing and number of DMRSs.

The UE may select a subcarrier spacing and a number of DMRS occurrences for the first random access message based on the configuration. In a first example, the UE may select a subcarrier spacing and a number of DMRS occurrences based on the speed of the UE. For example, there may be different speed thresholds corresponding to different configurations or subcarrier spacing and number of DMRS occurrences. If the UE detects that the moving speed of the UE is higher than the speed threshold value, the UE can select corresponding configuration or corresponding subcarrier intervals and corresponding DMRS occurrence times. In some examples, some cells may only support or configure high speed configurations. For example, a cell may only support configurations used in high speed situations.

Once the UE selects the subcarrier spacing and the number of DMRS occurrences, the UE may generate a first random access message for a two-step random access channel procedure. In some cases, the UE may indicate to the base station the selected subcarrier spacing and the number of DMRS occurrences. Blind detection of subcarrier spacing and DMRS occurrence times may increase complexity at the receiving side. Thus, in some cases, the UE may transmit an indication to reduce complexity at the receiving side. In some cases, the indication may be transmitted (e.g., via piggybacking) on a Physical Uplink Shared Channel (PUSCH).

Aspects of the present disclosure are initially described in the context of a wireless communication system. Aspects of the present disclosure are further illustrated and described by and with reference to apparatus diagrams, system diagrams, and flow charts related to a two-step random access channel configuration.

Fig. 1 illustrates an example of a wireless communication system 100 supporting a two-step random access channel configuration in accordance with aspects of the present disclosure. The wireless communication system 100 includes base stations 105, UEs 115, and a core network 130. In some examples, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an LTE-advanced (LTE-a) network, an LTE-a Pro network, or a New Radio (NR) network. In some cases, wireless communication system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low cost and low complexity devices.

The base station 105 may communicate wirelessly with the UE115 via one or more base station antennas. The base stations 105 described herein may include or may be referred to by those skilled in the art as base transceiver stations, radio base stations, access points, radio transceivers, node bs, evolved node bs (enbs), next generation node bs or gigabit node bs (any of which may be referred to as gnbs), home node bs, home evolved node bs, or some other suitable terminology. The wireless communication system 100 may include different types of base stations 105 (e.g., macro cell base stations or small cell base stations). The UEs 115 described herein may be capable of communicating with various types of base stations 105 and network equipment, including macro enbs, small cell enbs, gbbs, relay base stations, and so forth.

Each base station 105 may be associated with a particular geographic coverage area 110, supporting communication with various UEs 115 in that particular geographic coverage area 110. Each base station 105 may provide communication coverage for a respective physical coverage area 110 via a communication link 125, and the communication link 125 between the base station 105 and the UE115 may utilize one or more carriers. The communication links 125 shown in the wireless communication system 100 may include uplink transmissions from the UEs 115 to the base stations 105 or downlink transmissions from the base stations 105 to the UEs 115. Downlink transmissions may also be referred to as forward link transmissions, and uplink transmissions may also be referred to as reverse link transmissions.

The geographic coverage area 110 of a base station 105 can be divided into sectors that form a portion of the geographic coverage area 110, and each sector can be associated with a cell. For example, each base station 105 may provide communication coverage for a macro cell, a small cell, a hot spot, or other type of cell, or various combinations thereof. In some examples, the base stations 105 may be mobile and thus provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, and the overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station 105 or different base stations 105. The wireless communication system 100 may include, for example, a heterogeneous LTE/LTE-A/LTE-A Pro or NR network in which different types of base stations 105 provide coverage for various geographic coverage areas 110.

The term "cell" refers to a logical communication entity for communicating with a base station 105 (e.g., on a carrier) and may be associated with an identifier to distinguish between neighboring cells (e.g., Physical Cell Identifier (PCID), Virtual Cell Identifier (VCID)) operating via the same or different carriers. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., Machine Type Communication (MTC), narrowband internet of things (NB-IoT), enhanced mobile broadband (eMBB), or others) that may provide access for different types of devices. In some cases, the term "cell" may refer to a portion (e.g., a sector) of geographic coverage area 110 over which a logical entity operates.

The UEs 115 may be dispersed throughout the wireless communication system 100, and each UE115 may be stationary or mobile. A UE115 may also be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where a "device" may also be referred to as a unit, station, terminal, or client. The UE115 may also be a personal electronic device, such as a cellular telephone, a Personal Digital Assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some examples, the UE115 may also refer to a Wireless Local Loop (WLL) station, an internet of things (IoT) device, an internet of everything (IoE) device, or an MTC device, among others, which may be implemented in various items such as appliances, vehicles, meters, and so forth.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices and may provide automated communication between machines (e.g., communication via machine-to-machine (M2M)). M2M communication or MTC may refer to data communication techniques that allow devices to communicate with each other or with the base station 105 without human intervention. In some examples, M2M communications or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay the information to a central server or application that may utilize the information or present the information to a person interacting with the program or application. Some UEs 115 may be designed to collect information or implement automated behavior of a machine. Examples of applications for MTC devices include: smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, field survival monitoring, weather and geographic event monitoring, queue management and tracking, remote security sensing, physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ a reduced power consumption mode of operation, such as half-duplex communications (e.g., a mode that supports unidirectional communication via transmission or reception but does not simultaneously transmit and receive). In some examples, half-duplex communication may be performed with a reduced peak rate. Other power saving techniques for the UE115 include entering a power saving "deep sleep" mode when not engaged in active communication, or operating on a limited bandwidth (e.g., according to narrowband communication). In some cases, the UE115 may be designed to support critical functions (e.g., mission critical functions), and the wireless communication system 100 may be configured to provide ultra-reliable communication for these functions.

In some cases, the UE115 may also be able to communicate directly with other UEs 115 (e.g., using peer-to-peer (P2P) or device-to-device (D2D) protocols). One or more UEs of the group of UEs 115 communicating with D2D may be within the geographic coverage area 110 of the base station 105. The other UEs 115 in the group may be outside the geographic coverage area 110 of the base station 105 or otherwise unable to receive transmissions from the base station 105. In some cases, groups of UEs 115 communicating via D2D may utilize a one-to-many (1: M) system, where each UE115 transmits to every other UE115 in the group. In some cases, the base station 105 facilitates scheduling of resources for D2D communication. In other cases, D2D communication is performed between UEs 115 without involving base stations 105.

The base stations 105 may communicate with the core network 130 and with each other. For example, the base stations 105 may interface with the core network 130 over backhaul links 132 (e.g., via S1, N2, N3, or other interfaces). The base stations 105 may communicate with each other over backhaul links 134 (e.g., via X2, Xn, or other interfaces) directly (e.g., directly between base stations 105) or indirectly (e.g., via the core network 130).

The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an Evolved Packet Core (EPC) that may include at least one Mobility Management Entity (MME), at least one serving gateway (S-GW), and at least one Packet Data Network (PDN) gateway (P-GW). The MME may manage non-access stratum (e.g., control plane) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the EPC. User IP packets may be communicated through the S-GW, which may itself be connected to the P-GW. The P-GW may provide IP address allocation as well as other functions. The P-GW may be connected to network operator IP services. The operator IP services may include access to the internet, intranets, IP Multimedia Subsystem (IMS), or Packet Switched (PS) streaming services.

At least some network devices, such as base stations 105, may include subcomponents, such as access network entities, which may be examples of Access Node Controllers (ANCs). Each access network entity may communicate with UEs 115 through a number of other access network transport entities, which may be referred to as radio heads, intelligent radio heads, or transmission/reception points (TRPs). In some configurations, the various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., base station 105).

Wireless communication system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the 300MHz to 3GHz region is referred to as an Ultra High Frequency (UHF) region or a decimeter band because the wavelengths range from about 1 decimeter to 1 meter long. UHF waves can be blocked or redirected by building and environmental features. However, these waves may penetrate a variety of structures sufficiently for a macro cell to provide service to a UE115 located indoors. UHF-wave transmission can be associated with smaller antennas and shorter ranges (e.g., less than 100km) than transmission using smaller and longer waves of the High Frequency (HF) or Very High Frequency (VHF) portions of the spectrum below 300 MHz.

The wireless communication system 100 may also operate in the ultra-high frequency (SHF) region using a frequency band from 3GHz to 30GHz, also referred to as a centimeter frequency band. The SHF region includes frequency bands (such as the 5GHz industrial, scientific, and medical (ISM) frequency bands) that may be opportunistically used by devices that may be able to tolerate interference from other users.

The wireless communication system 100 may also operate in the Extremely High Frequency (EHF) region of the spectrum (e.g., from 30GHz to 300GHz), which is also referred to as the millimeter-band. In some examples, the wireless communication system 100 may support millimeter wave (mmW) communication between the UE115 and the base station 105, and EHF antennas of respective devices may be even smaller and more closely spaced than UHF antennas. In some cases, this may facilitate the use of antenna arrays within the UE 115. However, propagation of EHF transmissions may experience even greater atmospheric attenuation and shorter ranges than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions using one or more different frequency regions, and the frequency band usage designated across these frequency regions may differ by country or regulatory agency.

In some cases, the wireless communication system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communication system 100 may employ Licensed Assisted Access (LAA), LTE unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band, such as the 5GHz ISM band. When operating in the unlicensed radio frequency spectrum band, wireless devices, such as base stations 105 and UEs 115, may employ a Listen Before Talk (LBT) procedure to ensure that frequency channels are clear before transmitting data. In some cases, operation in the unlicensed band may be based on a carrier aggregation configuration (e.g., LAA) in coordination with component carriers operating in the licensed band. Operations in the unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer transmissions, or a combination of these. Duplexing in the unlicensed spectrum may be based on Frequency Division Duplexing (FDD), Time Division Duplexing (TDD), or a combination of both.

In some examples, a base station 105 or UE115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. For example, the wireless communication system 100 may use a transmission scheme between a transmitting device (e.g., base station 105) equipped with multiple antennas and a receiving device (e.g., UE 115) equipped with one or more antennas. MIMO communication may employ multipath signal propagation to increase spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. For example, a transmitting device may transmit multiple signals via different antennas or different combinations of antennas. Also, the receiving device may receive multiple signals via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO), in which multiple spatial layers are transmitted to the same receiver device; and multi-user MIMO (MU-MIMO), in which a plurality of spatial layers are transmitted to a plurality of devices.

Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting or receiving device (e.g., base station 105 or UE 115) to shape or steer an antenna beam (e.g., a transmit beam or a receive beam) along a spatial path between the transmitting and receiving devices. Beamforming may be achieved by combining signals communicated via antenna elements of an antenna array such that signals propagating in a particular orientation relative to the antenna array undergo constructive interference while other signals undergo destructive interference. The adjustment to the signals communicated via the antenna elements may include the transmitting or receiving device applying a particular amplitude and phase shift to the signals carried via each antenna element associated with the device. The adjustment associated with each antenna element may be defined by a set of beamforming weights associated with a particular orientation (e.g., relative to an antenna array of a transmitting device or a receiving device, or relative to some other orientation).

In one example, the base station 105 may use multiple antennas or antenna arrays for beamforming operations for directional communication with the UEs 115. For example, some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted multiple times in different directions by the base station 105, which may include a signal being transmitted according to different sets of beamforming weights associated with different transmission directions. Transmissions in different beam directions may be used (e.g., by the base station 105 or a receiving device, such as UE 115) to identify beam directions used by the base station 105 for subsequent transmission and/or reception.

Some signals, such as data signals associated with a particular recipient device, may be transmitted by the base station 105 in a single beam direction (e.g., a direction associated with the recipient device, such as the UE 115). In some examples, a beam direction associated with transmission along a single beam direction may be determined based at least in part on signals transmitted in different beam directions. For example, the UE115 may receive one or more signals transmitted by the base station 105 in different directions, and the UE115 may report an indication to the base station 105 of the signal for which it is received at the highest signal quality or other acceptable signal quality. Although the techniques are described with reference to signals transmitted by the base station 105 in one or more directions, the UE115 may use similar techniques for transmitting signals multiple times in different directions (e.g., to identify beam directions used by the UE115 for subsequent transmission or reception) or for transmitting signals in a single direction (e.g., for transmitting data to a receiving device).

A receiving device (e.g., UE115, which may be an example of a mmW receiving device) may attempt multiple receive beams when receiving various signals from base station 105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a recipient device may attempt multiple receive directions by: receiving via different antenna sub-arrays, processing received signals according to different antenna sub-arrays, receiving according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of an antenna array, or processing received signals according to different sets of receive beamforming weights applied to signals received at multiple antenna elements of an antenna array, either of which may be referred to as "listening" according to different receive beams or receive directions. In some examples, the receiving device may use a single receive beam to receive along a single beam direction (e.g., when receiving a data signal). The single receive beam may be aligned in a beam direction determined based at least in part on listening from different receive beam directions (e.g., a beam direction determined to have the highest signal strength, highest signal-to-noise ratio, or other acceptable signal quality based at least in part on listening from multiple beam directions).

In some cases, the antennas of a base station 105 or UE115 may be located within one or more antenna arrays that may support MIMO operation or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly (such as an antenna tower). In some cases, the antennas or antenna arrays associated with the base station 105 may be located at different geographic locations. The base station 105 may have an antenna array with a number of rows and columns of antenna ports that the base station 105 may use to support beamforming for communications with the UEs 115. Likewise, the UE115 may have one or more antenna arrays that may support various MIMO or beamforming operations.

In some cases, the wireless communication system 100 may be a packet-based network operating according to a layered protocol stack. In the user plane, communication of the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. The Radio Link Control (RLC) layer may perform packet segmentation and reassembly to communicate on logical channels. The Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use hybrid automatic repeat request (HARQ) to provide retransmission by the MAC layer, thereby improving link efficiency. In the control plane, a Radio Resource Control (RRC) protocol layer may provide for establishment, configuration, and maintenance of RRC connections of radio bearers supporting user plane data between the UE115 and the base station 105 or core network 130. At the physical layer, transport channels may be mapped to physical channels.

In some cases, the UE115 and the base station 105 may support retransmission of data to increase the likelihood that the data is successfully received. HARQ feedback is a technique that increases the likelihood that data will be correctly received on the communication link 125. HARQ may include a combination of error detection (e.g., using Cyclic Redundancy Check (CRC)), Forward Error Correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ may improve throughput of the MAC layer in poor radio conditions (e.g., signal-to-noise conditions). In some cases, a wireless device may support simultaneous slot HARQ feedback, where the device may provide HARQ feedback in a particular slot for data received in a previous symbol in that slot. In other cases, the device may provide HARQ feedback in subsequent time slots or according to some other time interval.

The time interval in LTE or NR may be in a basic unit of time (which may for example refer to the sampling period T)_s1/30,720,000 seconds). The time intervals of the communication resources may be organized according to radio frames each having a duration of 10 milliseconds (ms), where the frame period may be expressed as T_f＝307,200T_s. The radio frame may be composed ofSystem Frame Numbers (SFN) around 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9, and each subframe may have a duration of 1 ms. A subframe may be further divided into 2 slots, each having a duration of 0.5ms, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix preceding each symbol period). Each symbol period may contain 2048 sample periods, excluding the cyclic prefix. In some cases, a subframe may be the smallest scheduling unit of the wireless communication system 100 and may be referred to as a Transmission Time Interval (TTI). In other cases, the minimum scheduling unit of the wireless communication system 100 may be shorter than a subframe or may be dynamically selected (e.g., in a burst of shortened tti (sTTI) or in a selected component carrier using sTTI).

In some wireless communication systems, a slot may be further divided into a plurality of mini-slots containing one or more symbols. In some examples, a symbol of a mini-slot or a mini-slot may be a minimum scheduling unit. For example, each symbol may vary in duration depending on the subcarrier spacing or operating frequency band. Further, some wireless communication systems may implement timeslot aggregation, where multiple timeslots or mini-timeslots are aggregated together and used for communication between the UE115 and the base station 105.

The term "carrier" refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communications over the communication link 125. For example, the carrier of the communication link 125 may comprise a portion of a radio frequency spectrum band operating according to a physical layer channel for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. The carriers may be associated with predefined frequency channels (e.g., evolved universal mobile telecommunications system terrestrial radio access (E-UTRA) absolute radio frequency channel numbers (EARFCNs)) and may be located according to a channel grid for discovery by UEs 115. The carriers may be downlink or uplink (e.g., in FDD mode), or configured to carry downlink and uplink communications (e.g., in TDD mode). In some examples, a signal waveform transmitted on a carrier may include multiple subcarriers (e.g., using multicarrier modulation (MCM) techniques such as Orthogonal Frequency Division Multiplexing (OFDM) or discrete fourier transform spread OFDM (DFT-S-OFDM)).

The organization of the carriers may be different for different radio access technologies (e.g., LTE-A, LTE-A Pro, NR). For example, communications on a carrier may be organized according to TTIs or slots, each of which may include user data as well as control information or signaling supporting decoding of the user data. The carrier may also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc.) and control signaling that coordinates operation of the carrier. In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling that coordinates the operation of other carriers.

The physical channels may be multiplexed on the carriers according to various techniques. The physical control channels and physical data channels may be multiplexed on the downlink carrier using, for example, Time Division Multiplexing (TDM) techniques, Frequency Division Multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. In some examples, control information transmitted in the physical control channel may be distributed in a cascaded manner between different control regions (e.g., between a common control region or common search space and one or more UE-specific control regions or UE-specific search spaces).

A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples, the carrier bandwidth may be referred to as a carrier or "system bandwidth" of the wireless communication system 100. For example, the carrier bandwidth may be one of several predetermined bandwidths (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80MHz) of a carrier of a particular radio access technology. In some examples, each served UE115 may be configured to operate over part or all of the carrier bandwidth. In other examples, some UEs 115 may be configured for operation using a narrowband protocol type associated with a predefined portion or range within a carrier (e.g., a set of subcarriers or RBs) (e.g., "in-band" deployment of narrowband protocol types).

In a system employing MCM technology, a resource element may include one symbol period (e.g., the duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme). Thus, the more resource elements the UE115 receives and the higher the order of the modulation scheme, the higher the data rate of the UE115 may be. In a MIMO system, wireless communication resources may refer to a combination of radio frequency spectrum resources, time resources, and spatial resources (e.g., spatial layers), and using multiple spatial layers may further improve the data rate of communication with the UE 115.

Devices of the wireless communication system 100 (e.g., base stations 105 or UEs 115) may have a hardware configuration that supports communication over a particular carrier bandwidth or may be configurable to support communication over one carrier bandwidth of a set of carrier bandwidths. In some examples, the wireless communication system 100 may include a base station 105 and/or a UE115 that supports simultaneous communication via carriers associated with more than one different carrier bandwidth.

The wireless communication system 100 may support communication with UEs 115 over multiple cells or carriers, a feature that may be referred to as carrier aggregation or multi-carrier operation. The UE115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both FDD and TDD component carriers.

In some cases, the wireless communication system 100 may utilize an enhanced component carrier (eCC). An eCC may be characterized by one or more characteristics including a wider carrier or frequency channel bandwidth, a shorter symbol duration, a shorter TTI duration, or a modified control channel configuration. In some cases, an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have suboptimal or non-ideal backhaul links). An eCC may also be configured for use in unlicensed spectrum or shared spectrum (e.g., where more than one operator is allowed to use the spectrum). An eCC characterized by a wide carrier bandwidth may include one or more segments that may be utilized by UEs 115 that are unable to monitor the entire carrier bandwidth or are otherwise configured to use a limited carrier bandwidth (e.g., to conserve power).

In some cases, an eCC may utilize a different symbol duration than other component carriers, which may include using a reduced symbol duration compared to the symbol duration of the other component carriers. Shorter symbol durations may be associated with increased spacing between adjacent subcarriers. Devices utilizing an eCC, such as UE115 or base station 105, may transmit a wideband signal (e.g., according to a frequency channel or carrier bandwidth of 20, 40, 60, 80MHz, etc.) with a reduced symbol duration (e.g., 16.67 microseconds). A TTI in an eCC may include one or more symbol periods. In some cases, the TTI duration (i.e., the number of symbol periods in a TTI) may be variable.

The wireless communication system 100 may be an NR system that may utilize any combination of licensed, shared, and unlicensed spectrum bands, etc. Flexibility in eCC symbol duration and subcarrier spacing may allow eCC to be used across multiple spectra. In some examples, NR sharing spectrum may improve spectrum utilization and spectral efficiency, particularly through dynamic vertical (e.g., across frequency domains) and horizontal (e.g., across time domains) sharing of resources.

The wireless communication system 100 may support a two-step random access channel procedure and communication when devices travel at high speeds. In some cases, the UE115 and the base station 105, or other wireless devices described herein (such as a relay device or relay node), may support a two-step random access channel procedure that uses the presence of an additional DMRS and a larger subcarrier spacing for a first random access message when the first random access message is transmitted in a high-speed scenario. The base station 105 may transmit a configuration of a first random access message to the UE115 for a two-step random access channel procedure. The configuration may include an indicator or possible values of a subcarrier spacing and a DMRS occurrence number of a first random access message for a two-step random access channel procedure.

The UE115 may select a subcarrier spacing and a number of DMRS occurrences for the first random access message based on the configuration. In a first example, the UE115 may select a subcarrier spacing and a number of DMRS occurrences based on the speed of the UE 115. For example, there may be different speed thresholds corresponding to different configurations or subcarrier spacing and number of DMRS occurrences. In some examples, some cells may only support or configure high speed configurations. For example, a cell may only support configurations used in high speed situations. In some cases, the UE115 may indicate to the base station 105 the selected subcarrier spacing and the number of DMRS occurrences. In some cases, the indication may be transmitted (e.g., via piggybacking) on an uplink shared channel.

Fig. 2 illustrates an example of a wireless communication system 200 that supports a two-step random access channel configuration in accordance with aspects of the present disclosure. In some examples, the wireless communication system 200 may implement aspects of the wireless communication system 100. The wireless communication system 200 may include a base station 105-a and a base station 105-b, each of which may be an example of a base station 105 as described herein. The wireless communication system 200 may also include a UE 115-a and a UE 115-b, each of which may be an example of a UE115 as described herein.

The wireless communication system 200 may be an example of a wireless communication system supporting high speed vehicles or high speed devices. For example, the UE 115-a and the UE 115-b may travel on the high speed vehicle 230. In other examples, the UE 115-a and the UE 115-b may travel at high speeds based on other conditions. In some cases, the high speed vehicle 230 may include the relay device 205. In some examples, the relay device 205 may be an example of a UE115 or include aspects of a UE 115. For example, the relay device 205 may act as a UE115 when communicating with the base station 105. In some cases, the relay device 205 may act as a base station 105 when communicating with the UE 115. For example, the relay device 205 may receive information from the base station 105 for one or more UEs 115 on a high speed vehicle. The relay device 205 may then transmit (e.g., relay) the received information to the corresponding UE 115. In some examples, relay device 205 may be an example of a node of an integrated access and backhaul network (IAB), such as an IAB relay node.

In some examples, the UE115 may have direct communication with the base station 105. For example, the UE 115-a may receive downlink transmissions from the base station 105-a on a downlink carrier 210-c and transmit uplink transmissions to the base station 105-a on an uplink carrier 215-c. Alternatively, in some cases, the UE 115-a may communicate with the base station 105-a through the relay device 205 via the communication link 235. In some cases, the UE115 described herein may support both direct communication with the base station 105 and communication with the base station 105 via the relay device 205.

The base stations 105 may each transmit to the relay device 205 on a downlink carrier 210, and the relay device 205 may transmit to each of the base stations 105 on an uplink carrier 215. For example, the relay device 205 may receive downlink transmissions from the base station 105-a on a downlink carrier 210-a and transmit uplink transmissions to the base station 105-a on an uplink carrier 215-a.

The relay device 205 may transmit to the UE115 on a downlink carrier 220, while the UE115 may transmit to the relay device 205 on an uplink carrier 225. For example, the UE 115-b may transmit to the relay device 205 on the uplink carrier 225-a, and the relay device 205 may transmit to the UE 115-b on the downlink carrier 220-a. In some cases, the communication link 260 between the relay device 205 and the UE115 may also include uplink and downlink carriers.

The wireless communication system 200 may support a two-step random access channel procedure. For example, instead of a four-step random access procedure, the UE115 may transmit a first random access message (e.g., message a or MsgA) and receive a second random access message (e.g., message B or random access response). The first random access message may include a preamble and an uplink shared channel transmission (e.g., a Physical Uplink Shared Channel (PUSCH) transmission).

Upon receiving the second random access message, the two-step random access channel procedure may be completed and the UE115 may have an RRC connection established with the base station 105. In contrast, for other random access channel procedures (e.g., four-step random access channel procedures), the UE115 may transmit a random access preamble, receive a random access response, transmit an RRC connection request, and then receive an RRC connection setup. Thus, a two-step random access channel procedure may establish an RRC connection between the UE115 and the base station 105 with less signaling and in a shorter amount of time. In some cases, the two-step random access channel procedure may result in significant latency reduction in the contention-based radio frequency spectrum band, as devices performing the two-step random access channel procedure may perform fewer Clear Channel Assessments (CCAs) to gain control of the contention-based resources.

To provide these advantages over the four-step random access procedure, the two-step random access channel procedure may be robust to interference and other problems. For example, the PUSCH transmission of the first random access message may be more robust than the third random access message (e.g., PUSCH or RRC connection request) of the four-step random access channel procedure. In some cases, a wireless device performing a four-step random access channel procedure may exchange or determine some timing or synchronization information via the first two random access messages (e.g., random access preamble and random access response of the four-step random access channel procedure) of the four-step random access channel procedure.

Some configurations of two-step random access channel procedures may support only a single DMRS occurrence. For example, the PUSCH of the first random access message of the two-step random access channel procedure may be configured with only a single-port DMRS. In some high speed scenarios, such as UE115 and relay device 205 on a high speed vehicle 230, a single DMRS may not provide a sufficiently robust first random access message for a reliable two-step random access channel procedure. Without a sufficiently reliable and robust first random access message, some of the advantages of the two-step random access channel procedure described above may be lost.

The wireless devices of the wireless communication system 200 may implement techniques to increase the robustness of the two-step random access channel procedure. For example, the wireless communication system 200 may support a configuration for a first random access message (e.g., MsgA) that may occur using an additional DMRS and a larger PUSCH or DMRS subcarrier spacing. In general, techniques are described herein for configuring a UE115 (e.g., UE 115-a, UE 115-b, or relay device 205) with additional DMRS occurrences and SCS. Some techniques for the UE115 to select DMRS occurrences and SCS are described herein. Also described herein are some techniques for the UE115 to report the selected DMRS occurrences and SCS. The additional DMRSs may use the same or different sequences as the pre-loaded or preloaded DMRSs. The additional DMRS may also have or use the same or different frequency location as the pre-loaded or preloaded DMRS.

In an example, the base station 105 may transmit a configuration 240 of a first random access message to the UE115 for a two-step random access channel procedure. The configuration 240 may include an indicator or possible values of the subcarrier spacing and the number of DMRS occurrences of the first random access message for the two-step random access channel procedure. In the illustrated example, the base station 105-a may transmit the configuration 240 to the relay device 205.

The configuration 240 may be transmitted in a system information message. In some cases, the UE115 may be pre-configured with information associated with the configuration 240, and the information may be stored in memory at the device. The configuration may be transmitted from the base station 105 to the UE115 or broadcast as needed. For example, UE115 may transmit a request for a system information message. The base station 105 may receive the request and transmit the configuration 240 in a system information message based on receiving the request. Alternatively, in some cases, the configuration 240 may be broadcast. For example, the base station 105 may periodically broadcast the configuration 240 in a system information message.

In a first example, configuration 240 may include a combination of subcarrier spacing and DMRS occurrences. For example, configuration 240 may include a set of possible combinations or configurations for subcarrier spacing and DMRS. In a first example, the subcarrier spacing and DMRS times may be jointly indicated or bundled together. For example, a first configuration of configurations 240 may include a 30KHz subcarrier spacing and a single DMRS occurrence. For example, the first configuration may not include any additional DMRS occurrences, i.e., only include the piggybacked or preloaded DMRS. The second configuration may include a 60KHz subcarrier spacing and a single DMRS occurrence. The second configuration may use a larger subcarrier spacing without any additional DMRS being present. A third configuration may include a 60kHz subcarrier spacing and two DMRS occurrences. For example, the third configuration may include a preloaded DMRS occurrence and one additional DMRS occurrence. A fourth configuration may include a 60kHz subcarrier spacing and three DMRS occurrences, corresponding to one preloaded DMRS and two additional DMRS.

In a second example, configuration 240 may include two separate parameters for subcarrier spacing and DMRS times. For example, a first parameter of the configuration 240 may indicate a subcarrier spacing for a first random access message, and a second parameter of the configuration 240 may indicate a DMRS occurrence number. In some cases, the configuration 240 may indicate a range of subcarrier spacings or a number of different subcarrier spacings and a range of DMRS occurrences or a number of different DMRS occurrences. In a second example, the subcarrier spacing and DMRS number may be individually or separately indicated.

The UE115 may select a subcarrier spacing and a DMRS number for the first random access message based on the configuration 240. In a first example, the UE115 may select a subcarrier spacing and a number of DMRS occurrences based on the speed of the UE 115. For example, there may be different speed thresholds corresponding to different configurations or subcarrier spacing and number of DMRS occurrences. If the UE115 detects that its own mobility speed is faster than the speed threshold, the UE115 may select a corresponding configuration (e.g., as described in the first example above) or a corresponding subcarrier spacing and a corresponding number of DMRS occurrences (e.g., as described in the second example above).

For example, a high speed vehicle, and thus the relay device 205 and the UE115, may travel at a speed below the first threshold. For a first configuration example, the UE115 may detect its speed and select a subcarrier spacing and DMRS number based on the first configuration. For example, at low speed, the UE115 may use a first configuration without an additional DMRS and a low subcarrier spacing. The UE115 may use the second configuration if the UE115 is traveling at a speed above the first threshold and below the second threshold, as described above. The UE115 may use the third configuration if the UE115 is traveling at a speed above the second threshold but below a third threshold. Alternatively, if the UE115 is traveling at a speed that exceeds the third threshold, the UE115 may use a fourth configuration. In some cases, the higher the speed of the UE115, the higher the subcarrier spacing, the higher the number of DMRS occurrences, or both. When the speed of the UE115 changes, the UE115 may detect the speed change and select a different configuration based on the new speed of the UE 115.

The UE115 may similarly individually select the subcarrier spacing and the number of DMRS occurrences based on the speed of the UE 115. For example, below a first threshold, the UE115 may use a subcarrier spacing of 15, 30, or 60, but only occur using one DMRS (e.g., one of the pre-carriers). At speeds between the first and second thresholds, the UE115 may use a subcarrier spacing of 30kHz or 60 kHz. At this speed, the UE115 may use only the pre-loaded DMRS, or may optionally use one additional DMRS. At speeds between the second and third thresholds, the UE115 may use a subcarrier spacing of 30KHz or 60 KHz. The UE115 may use the pre-loaded DMRS presence and one or two additional DMRSs. When the speed exceeds a third threshold, the UE115 may use a subcarrier spacing of 60KHz, a pre-loaded DMRS, and one or two additional DMRSs. Accordingly, the subcarrier spacing and the number of DMRS occurrences may increase with the speed of the UE.

In some examples, some cells may only support or configure high speed configurations. For example, a cell may be deployed to serve only high speed UEs (e.g., relay devices 205 on high speed vehicles 230) with antennas and beam patterns configured to provide enhanced communication in high speed scenarios. For example, the cell may support only the third and fourth configurations, which may be used to improve robustness in high speed situations. Additionally or alternatively, a cell may support only high subcarrier spacing (e.g., 60KHz instead of 15KHz or 30KHz) and use additional DMRSs. If the UE115 detects that it is in a low speed mode (e.g., traveling at low speed) and the high speed configuration is not appropriate, the UE115 may register or reselect to another cell configured for lower speed.

For example, base station 105-a may provide a cell configured for high speed UEs 115, while base station 105-b may provide a cell configured for lower speed UEs 115. If the relay device 205 detects that it is traveling at a low speed that is not suitable for the high speed configuration of the cell of the base station 105-a, the relay device 205 may reselect or attach to the cell provided by the base station 105-b. Similarly, if the UE115 is attached to a cell configured for lower UE speeds, the UE115 may reselect to a cell configured for high speed UEs if the speed of the UE115 increases.

Once the UE115 selects the subcarrier spacing and the number of DMRS occurrences, the UE115 may generate a first random access message for a two-step random access channel procedure. The UE115 may generate the first random access message using the selected subcarrier spacing and using the selected number of additional DMRS times. The UE115 may then transmit a first random access message to the base station 105. For example, the relay device 205 may generate the first random access message 245 and transmit the first random access message 245 to the base station 105-a on the uplink carrier 215-a. In another example, the UE 115-a may perform a similar technique to generate and transmit a first random access message to the base station 105-a on the uplink carrier 215-c. Alternatively, in some cases, the UE 115-a may generate and transmit a first random access message to the relay device 205 over the communication link 235.

The UE115 may indicate to the base station 105 the selected subcarrier spacing and the number of DMRS occurrences. Blind detection of subcarrier spacing and DMRS occurrence times can increase complexity at the receiver. Thus, in some cases, the UE115 may transmit the indication 250 to reduce complexity at the receiver. The indication 250 may be, for example, an example of uplink control information or transmitted in uplink control information. The UE115 may report the configuration along with the PUSCH in uplink control information. In some cases, uplink control information (e.g., indication 250) may be transmitted with the PUSCH (e.g., piggybacked on a PUSCH transmission), or the uplink control information may be transmitted separately. In some cases, the uplink control information may indicate a configuration number (e.g., corresponding to the first example above), or the uplink control information may indicate a specific subcarrier spacing and the number of additional DMRS times (e.g., corresponding to the second example above). If the additional DMRS uses a different sequence than the pre-loaded DMRS, the uplink control information may include an indication of the sequence (e.g., may include an exact sequence). The uplink control information may include frequency location information of the additional DMRS if the additional DMRS uses a different frequency location than the piggybacked DMRS.

The first random access message 245 generated using the additional DMRS may be more reliable and robust for high speed scenarios. Thus, a receiving device (e.g., base station 105-a in the illustrated example) may have an increased likelihood of receiving and successfully decoding the first random access message 245. Subsequently, the base station 105-a may transmit a second random access message (e.g., random access response) to the relay device 205 to complete the two-step random access channel procedure.

Fig. 3 illustrates an example of a process flow 300 for supporting a two-step random access channel configuration in accordance with aspects of the present disclosure. In some examples, the process flow 300 may implement aspects of the wireless communication system 100. Process flow 300 may include UE 115-c and base station 105-c. The UE 115-c may be an example of a UE115 as described herein or a relay device 205 as described with reference to fig. 2. In some cases, UE 115-c may be referred to as a wireless device. The base station 105-c may be a base station 105 as described herein or may also be an example of a relay device 205 as described with reference to fig. 2.

At 305, the base station 105-c may transmit a configuration of a first random access message to the UE 115-c for a two-step random access channel procedure. In some cases, the configuration may include a combined set for subcarrier spacing and DMRS occurrence number. For example, the subcarrier spacing and the number of DMRS occurrences may be bundled together into a number of different options or configurations. In some cases, the configuration may include a first parameter for subcarrier spacing and a second parameter for a number of DMRS occurrences. For example, the subcarrier spacing and the number of DMRS occurrences may be independently or individually indicated.

In some cases, at 310, the UE 115-c may detect its speed. For example, the UE 115-c may travel at a high speed (e.g., on a high speed train or another high speed vehicle). At 315, the UE 115-c may select a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and the speed of the UE 115-c. The UE 115-c may select a subcarrier spacing and a number of DMRS occurrences based on a velocity of the wireless device exceeding a threshold. For example, as described with reference to fig. 2, the UE 115-c may travel at a speed that exceeds a threshold or falls between two thresholds. In some cases, the UE 115-c may select a configuration identity corresponding to a combination in the set of combinations for subcarrier spacing and DMRS occurrence. Alternatively, in some cases, the UE 115-c may independently select a subcarrier spacing based on the first parameter and a number of DMRS occurrences based on the second parameter.

In some examples, the UE 115-c may transmit an indication of the selected subcarrier spacing and the number of DMRS occurrences. In some examples, the indication may be transmitted in a PUSCH of the first random access message. For example, UE 115-c may transmit the indication in uplink control information of PUSCH piggybacked to the first random access message. In some examples, the UE 115-c may indicate which combination of the different sets of combinations to select. Alternatively, in some examples, the UE 115-c may individually indicate values for the subcarrier spacing and the number of DMRS occurrences.

At 325, the UE 115-c may transmit a first random access message for a two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences. In some cases, the number of DMRS occurrences includes occurrences of the pre-loaded DMRS and the at least one additional DMRS.

Fig. 4 shows a block diagram 400 of an apparatus 405 supporting a two-step random access channel configuration in accordance with aspects of the present disclosure. The device 405 may be an example of aspects of a UE115 as described herein. The device 405 may include a receiver 410, a communication manager 415, and a transmitter 420. The device 405 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

The receiver 410 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to a two-step random access channel configuration, etc.). The information may be passed to other components of the device 405. The receiver 410 may be an example of aspects of the transceiver 720 described with reference to fig. 7. The receiver 410 may utilize a single antenna or a set of antennas.

The communication manager 415 may receive a configuration of a first random access message for a two-step random access channel procedure; selecting a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and a speed of the wireless device; and transmitting a first random access message of the two-step random access channel procedure using the subcarrier spacing and the DMRS occurrence number. The communication manager 415 may be an example of aspects of the communication manager 710 described herein.

The communication manager 415 or subcomponents thereof may be implemented in hardware, code executed by a processor (e.g., software or firmware), or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 415 or its subcomponents may be performed by a general purpose processor, a DSP, an Application Specific Integrated Circuit (ASIC), an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in this disclosure.

The communication manager 415, or subcomponents thereof, may be physically located at various locations, including being distributed such that portions of functionality are implemented by one or more physical components at different physical locations. In some examples, the communication manager 415 or subcomponents thereof may be separate and distinct components in accordance with various aspects of the present disclosure. In some examples, the communication manager 415 or subcomponents thereof may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof, in accordance with various aspects of the present disclosure.

Transmitter 420 may transmit signals generated by other components of device 405. In some examples, the transmitter 420 may be co-located with the receiver 410 in a transceiver module. For example, the transmitter 420 may be an example of aspects of the transceiver 720 described with reference to fig. 7. The transmitter 420 may utilize a single antenna or a set of antennas.

The actions performed by the UE communications manager 415 as described herein may be implemented to achieve one or more potential advantages. One implementation may allow the UE115 to reduce latency and improve reliability by avoiding having to retransmit the first random access message of a two-step random access channel procedure. In contrast, by implementing the techniques described herein, the first random access message may be made more robust, which may improve the reliability and likelihood of successful reception (e.g., at the recipient device) of the first random access message. These techniques may enable the UE115 to achieve the advantages of a two-step random access channel procedure over other random access channel procedures (e.g., a four-step random access channel procedure) by providing timely RRC connection with fewer transmissions. This may correspond to the UE115 performing fewer CCA procedures (e.g., LBT procedures), with each additional CCA procedure having a likelihood that the UE115 does not gain control of the transmission medium, thereby further delaying completion of the random access channel procedure. In the case where the PUSCH (e.g., the third message) of the four-step random access channel procedure may have some timing information or timing synchronization based on the first and second messages, the techniques described herein may allow the two-step random access channel procedure to compensate for the lack of timing information by increasing the robustness of the first random access message of the two-step random access channel procedure.

Fig. 5 illustrates a block diagram 500 of a device 505 supporting a two-step random access channel configuration in accordance with aspects of the present disclosure. The device 505 may be an example of aspects of the device 405 or UE115 as described herein. The device 505 may include a receiver 510, a communication manager 515, and a transmitter 535. The device 505 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

The receiver 510 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to a two-step random access channel configuration, etc.). Information may be passed to other components of device 505. The receiver 510 may be an example of aspects of the transceiver 720 described with reference to fig. 7. Receiver 510 may utilize a single antenna or a set of antennas.

The communication manager 515 may be an example of aspects of the communication manager 415 as described herein. The communication manager 515 may include a configuration receiving component 520, a selecting component 525, and a first random access messaging component 530. The communication manager 515 may be an example of aspects of the communication manager 710 described herein.

Configuration receiving component 520 may receive a configuration of a first random access message for a two-step random access channel procedure.

Selection component 525 may select a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and the speed of the wireless device.

The first random access message transmitting component 530 may transmit the first random access message of the two-step random access channel procedure using the subcarrier spacing and the DMRS occurrence number.

The transmitter 535 may transmit signals generated by other components of the device 505. In some examples, the transmitter 535 may be co-located with the receiver 510 in a transceiver module. For example, the transmitter 535 may be an example of aspects of the transceiver 720 described with reference to fig. 7. The transmitter 535 may utilize a single antenna or a set of antennas.

Based on configuring the first random access message with the two-step random access channel procedure with the additional DMRS occurring, the processor of the UE115 (e.g., controlling the receiver 510, transmitter 535, or transceiver 720 as described with reference to fig. 7) may efficiently improve the robustness of the first random access message. By improving the reliability of the first random access message, the processor may establish an RRC connection with the base station faster, perform fewer CCA procedures, and generate fewer retransmissions of the first random access message. This may result in the processor being able to enter a low power state faster or to use less processing power to establish the RRC connection. Further, the processor of the UE115 may transmit an indication of the number of occurrences of the selected additional DMRS and the selected subcarrier spacing. This may help the receiving side (e.g., base station 105) to determine which subcarrier spacing and how many DMRS occurrences were selected to generate the first random access message of the two-step random access channel procedure so that the receiving side does not have to blindly detect these parameters. This may also result in improved performance at the receiving device.

Fig. 6 illustrates a block diagram 600 of a communication manager 605 supporting a two-step random access channel configuration in accordance with aspects of the present disclosure. The communication manager 605 may be an example of aspects of the communication manager 415, the communication manager 515, or the communication manager 710 described herein. The communication manager 605 may include a configuration receiving component 610, a selecting component 615, a first random access messaging component 620, a selection indicating component 625, and a cell registering component 630. Each of these modules may communicate with each other directly or indirectly (e.g., via one or more buses).

Configuration receiving component 610 can receive a configuration of a first random access message for a two-step random access channel procedure. In some examples, configuration receiving component 610 can transmit a request for a system information message, wherein the system information message is received based on the request. In some examples, the system information message is broadcast. In some cases, the configuration includes a combined set for subcarrier spacing and DMRS occurrence number. In some cases, the configuration includes a first parameter for subcarrier spacing and a second parameter for a number of DMRS occurrences. In some cases, the configuration is received in a system information message.

In some cases, the number of DMRS occurrences includes occurrences of the pre-loaded DMRS and the at least one additional DMRS. In some cases, the at least one additional DMRS uses the same sequence, frequency location, or both as the pre-loaded DMRS. In some cases, the at least one additional DMRS uses a different sequence, frequency location, or both than the pre-loaded DMRS. In some cases, the wireless device is a UE or a relay node.

Selection component 615 can select a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and the speed of the wireless device. In some cases, selecting component 615 may select a configuration identification corresponding to a combination in the set of combinations for subcarrier spacing and DMRS occurrence.

In some examples, selecting component 615 may independently select a subcarrier spacing based on the first parameter and a number of DMRS occurrences based on the second parameter. In some examples, selecting component 615 may select a subcarrier spacing and a number of DMRS occurrences based on a velocity of the wireless device exceeding a threshold.

The first random access message transmitting component 620 may transmit the first random access message of the two-step random access channel procedure using the subcarrier spacing and the DMRS occurrence number.

Selection indication component 625 may transmit an indication of the selected subcarrier spacing and the number of DMRS occurrences. In some cases, the indication is included in a PUSCH of the first random access message. In some cases, the indication is transmitted in uplink control information on a physical uplink control channel. In some cases, the indication includes a first parameter for the selected subcarrier spacing and a second parameter for a number of DMRS occurrences.

In some cases, the indication includes a configuration identification indicating a subcarrier spacing and a number of DMRS occurrences. In some cases, the indication includes a sequence, frequency location information, or both, for the DMRS corresponding to the number of DMRS occurrences.

Cell registration component 630 can determine that the velocity of the wireless device is below a threshold. In some examples, cell registering component 630 may register with another cell based on the determination.

Fig. 7 shows a diagram of a system 700 including a device 705 that supports a two-step random access channel configuration, in accordance with aspects of the present disclosure. Device 705 may be an example of device 405, device 505, or UE115 or include components of device 705, device 805, or UE115 as described herein. Device 705 may include components for two-way voice and data communications, including components for transmitting and receiving communications, including a communications manager 710, an I/O controller 715, a transceiver 720, an antenna 725, memory 730, and a processor 740. These components may be in electronic communication via one or more buses, such as bus 745.

The communication manager 710 may receive a configuration of a first random access message for a two-step random access channel procedure; selecting a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and a speed of the wireless device; and transmitting a first random access message of the two-step random access channel procedure using the subcarrier spacing and the DMRS occurrence number.

I/O controller 715 may manage input and output signals for device 705. I/O controller 715 may also manage peripheral devices that are not integrated into device 705. In some cases, I/O controller 715 may represent a physical connection or port to an external peripheral device. In some cases, I/O controller 715 may utilize an operating system, such as Or another known operating system. In other cases, I/O controller 715 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some cases, I/O controller 715 may be implemented as part of a processor. In some cases, a user may interact with device 705 via I/O controller 715 or via hardware components controlled by I/O controller 715.

The transceiver 720 may communicate bi-directionally via one or more antennas, wired or wireless links, as described above. For example, the transceiver 720 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 720 may also include a modem to modulate packets and provide the modulated packets to an antenna for transmission, as well as to demodulate packets received from the antenna.

In some cases, the wireless device may include a single antenna 725. However, in some cases, the device may have more than one antenna 725, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

Memory 730 may include RAM and ROM. The memory 730 may store computer-readable, computer-executable code 735 comprising instructions that, when executed, cause the processor to perform various functions described herein. In some cases, memory 730 may contain, among other things, a BIOS that may control basic hardware or software operations, such as interaction with peripheral components or devices.

Processor 740 may include intelligent hardware devices (e.g., general-purpose processors, DSPs, CPUs, microcontrollers, ASICs, FPGAs, programmable logic devices, discrete gate or transistor logic components, discrete hardware components, or any combinations thereof). In some cases, processor 740 may be configured to operate the memory array using a memory controller. In other cases, the memory controller may be integrated into processor 740. Processor 740 may be configured to execute computer-readable instructions stored in a memory (e.g., memory 730) to cause apparatus 705 to perform various functions (e.g., functions or tasks to support a two-step random access channel configuration).

Code 735 may include instructions for implementing aspects of the present disclosure, including instructions for supporting wireless communications. Code 735 may be stored in a non-transitory computer-readable medium, such as system memory or other type of memory. In some cases, code 735 may not be directly executable by processor 740, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

Fig. 8 illustrates a block diagram 800 of an apparatus 805 that supports a two-step random access channel configuration in accordance with aspects of the present disclosure. The device 805 may be an example of aspects of a base station 105 as described herein. The device 805 may include a receiver 810, a communication manager 815, and a transmitter 820. The device 805 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

Receiver 810 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to a two-step random access channel configuration, etc.). Information may be passed to other components of device 805. The receiver 810 may be an example of aspects of the transceiver 1120 described with reference to fig. 11. Receiver 810 can utilize a single antenna or a set of antennas.

The communication manager 815 may transmit a configuration of a first random access message for a two-step random access channel procedure to the first wireless device; and receiving a first random access message of a two-step random access channel procedure using a subcarrier spacing and a number of DMRs occurrences, wherein the subcarrier spacing and the number of DMRs occurrences are based on the configuration and the speed of the first wireless device. The communication manager 815 may be an example of aspects of the communication manager 1110 described herein.

The communication manager 815 or its subcomponents may be implemented in hardware, code executed by a processor (e.g., software or firmware), or any combination thereof. If implemented in code executed by a processor, the functions of the communication manager 815 or its subcomponents may be performed by a general purpose processor, a DSP, an Application Specific Integrated Circuit (ASIC), an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in this disclosure.

The communication manager 815, or subcomponents thereof, may be physically located at various locations, including being distributed such that portions of the functionality are implemented by one or more physical components at different physical locations. In some examples, the communication manager 815, or subcomponents thereof, may be separate and distinct components in accordance with various aspects of the present disclosure. In some examples, according to various aspects of the present disclosure, the communication manager 815, or subcomponents thereof, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof.

The transmitter 820 may transmit signals generated by other components of the device 805. In some examples, the transmitter 820 may be co-located with the receiver 810 in a transceiver module. For example, the transmitter 820 may be an example of aspects of the transceiver 1120 described with reference to fig. 11. The transmitter 820 may utilize a single antenna or a set of antennas.

Fig. 9 illustrates a block diagram 900 of a device 905 supporting a two-step random access channel configuration in accordance with aspects of the present disclosure. The device 905 may be an example of aspects of the device 805 or the base station 105 as described herein. The device 905 may include a receiver 910, a communication manager 915, and a transmitter 930. The device 905 may also include a processor. Each of these components may be in communication with each other (e.g., via one or more buses).

Receiver 910 can receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to a two-step random access channel configuration, etc.). Information may be passed to other components of device 905. The receiver 910 may be an example of aspects of the transceiver 1120 described with reference to fig. 11. Receiver 910 can utilize a single antenna or a set of antennas.

The communication manager 915 may be an example of aspects of the communication manager 815 as described herein. The communication manager 915 may include a configuration transmitting component 920 and a first random access message receiving component 925. The communication manager 915 may be an example of aspects of the communication manager 1110 described herein.

A configuration transmitting component 920 may transmit a configuration of a first random access message for a two-step random access channel procedure to a first wireless device.

The first random access message receiving component 925 may receive the first random access message of the two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences based on the configuration and the speed of the first wireless device.

Transmitter 930 may transmit signals generated by other components of device 905. In some examples, the transmitter 930 may be co-located with the receiver 910 in a transceiver module. For example, the transmitter 930 may be an example of aspects of the transceiver 1120 described with reference to fig. 11. Transmitter 930 may utilize a single antenna or a set of antennas.

Fig. 10 illustrates a block diagram 1000 of a communication manager 1005 supporting a two-step random access channel configuration in accordance with aspects of the present disclosure. The communication manager 1005 may be an example of aspects of the communication manager 815, the communication manager 915, or the communication manager 1110 described herein. The communication manager 1005 may include a configuration transmitting component 1010, a first random access message receiving component 1015, and an indication receiving component 1020. Each of these modules may communicate with each other directly or indirectly (e.g., via one or more buses).

Configuration transmitting component 1010 may transmit a configuration of a first random access message for a two-step random access channel procedure to a first wireless device. In some cases, the configuration includes a combined set for subcarrier spacing and DMRS occurrence number. In some cases, the configuration includes a first parameter for subcarrier spacing and a second parameter for a number of DMRS occurrences. In some cases, the configuration is communicated in a system information message. In some cases, the first wireless device is a UE or a relay node.

First random access message receiving component 1015 may receive a first random access message for a two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences that are based on the configuration and the speed of the first wireless device. In some cases, the subcarrier spacing and the number of DMRS occurrences are based on a velocity of the first wireless device exceeding a threshold.

Indication receiving component 1020 may receive an indication of the selected subcarrier spacing and the number of DMRS occurrences. In some cases, the indication is received in a PUSCH of the first random access message. In some cases, the indication is received in uplink control information on a physical uplink control channel.

In some cases, the indication includes a first parameter for the selected subcarrier spacing and a second parameter for a number of DMRS occurrences. In some cases, the indication includes a configuration identification indicating a subcarrier spacing and a number of DMRS occurrences. In some cases, the indication includes a sequence, frequency location information, or both, for the DMRS corresponding to the number of DMRS occurrences.

Fig. 11 shows a diagram of a system 1100 including a device 1105 supporting a two-step random access channel configuration, in accordance with aspects of the present disclosure. The device 1105 may be an example of or include the device 805, the device 905, or the base station 105 as described herein. The device 1105 may include components for two-way voice and data communications including components for transmitting and receiving communications including a communications manager 1110, a network communications manager 1115, a transceiver 1120, an antenna 1125, a memory 1130, a processor 1140, and an inter-station communications manager 1145. These components may be in electronic communication via one or more buses, such as bus 1150.

The communication manager 1110 may transmit a configuration of a first random access message for a two-step random access channel procedure to the first wireless device; and receiving a first random access message of a two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences, wherein the subcarrier spacing and the number of DMRS occurrences are based on the configuration and the speed of the first wireless device.

The network communication manager 1115 may manage communications with the core network (e.g., via one or more wired backhaul links). For example, the network communication manager 1115 may manage the delivery of data communications for client devices (such as one or more UEs 115).

The transceiver 1120 may communicate bi-directionally via one or more antennas, wired or wireless links, as described above. For example, the transceiver 1120 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1120 may also include a modem to modulate packets and provide the modulated packets to an antenna for transmission, as well as demodulate packets received from the antenna.

In some cases, the wireless device may include a single antenna 1125. However, in some cases, the device may have more than one antenna 1125, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory 1130 may include RAM, ROM, or a combination thereof. The memory 1130 may store computer readable code 1135 comprising instructions that, when executed by a processor (e.g., processor 1140), cause the device to perform various functions described herein. In some cases, memory 1130 may contain, among other things, a BIOS that may control basic hardware or software operations, such as interaction with peripheral components or devices.

Processor 1140 may comprise an intelligent hardware device (e.g., a general purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, discrete gate or transistor logic components, discrete hardware components, or any combination thereof). In some cases, processor 1140 may be configured to operate a memory array using a memory controller. In some cases, a memory controller may be integrated into processor 1140. Processor 1140 may be configured to execute computer readable instructions stored in a memory (e.g., memory 1130) to cause apparatus 1105 to perform various functions (e.g., functions or tasks to support a two-step random access channel configuration).

The inter-station communication manager 1145 may manage communications with other base stations 105 and may include a controller or scheduler to control communications with UEs 115 in cooperation with the other base stations 105. For example, the inter-station communication manager 1145 may coordinate scheduling of transmissions to the UEs 115 for various interference mitigation techniques, such as beamforming or joint transmission. In some examples, the inter-station communication manager 1145 may provide an X2 interface within LTE/LTE-a wireless communication network technology to provide communication between base stations 105.

Code 1135 may include instructions for implementing aspects of the present disclosure, including instructions for supporting wireless communications. Code 1135 may be stored in a non-transitory computer-readable medium, such as a system memory or other type of memory. In some cases, code 1135 may not be directly executable by processor 1140, but may cause a computer (e.g., when compiled and executed) to perform the functions described herein.

Fig. 12 shows a flow diagram illustrating a method 1200 of supporting two-step random access channel configuration in accordance with aspects of the present disclosure. The operations of method 1200 may be implemented by a UE115 or components thereof as described herein. For example, the operations of method 1200 may be performed by a communication manager as described with reference to fig. 4-7. In some examples, the UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

At 1205, the UE may receive a configuration of a first random access message for a two-step random access channel procedure. The operations of 1205 may be performed according to the methods described herein. In some examples, aspects of the operations of 1205 may be performed by a configuration receiving component as described with reference to fig. 4-7.

At 1210, the UE may select a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and the speed of the wireless device. 1210 may be performed according to the methods described herein. In some examples, aspects of the operations of 1210 may be performed by a selection component as described with reference to fig. 4-7.

At 1215, the UE may transmit a first random access message for a two-step random access channel procedure using a subcarrier spacing and a DMRS occurrence number. The operations of 1215 may be performed in accordance with the methods described herein. In some examples, aspects of the operations of 1215 may be performed by a first random access messaging component as described with reference to fig. 4-7.

Fig. 13 shows a flow diagram illustrating a method 1300 of supporting two-step random access channel configuration according to aspects of the present disclosure. The operations of method 1300 may be implemented by UE115 or components thereof as described herein. For example, the operations of method 1300 may be performed by a communication manager as described with reference to fig. 4-7. In some examples, the UE may execute a set of instructions to control the functional elements of the UE to perform the functions described below. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the functions described below.

At 1305, the UE may receive a configuration of a first random access message for a two-step random access channel procedure. 1305 may be performed in accordance with the methods described herein. In some examples, aspects of the operations of 1305 may be performed by a configuration receiving component as described with reference to fig. 4-7.

At 1310, the UE may select a subcarrier spacing and a number of DMRS occurrences for transmitting the first random access message based on the configuration and the speed of the wireless device. 1310 may be performed according to the methods described herein. In some examples, aspects of the operations of 1310 may be performed by a selection component as described with reference to fig. 4-7.

At 1315, the UE may transmit a first random access message for a two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences. 1315 may be performed according to the methods described herein. In some examples, aspects of the operations of 1315 may be performed by the first random access messaging component as described with reference to fig. 4-7.

At 1320, the UE may transmit an indication of the selected subcarrier spacing and the number of DMRS occurrences. 1320 may be performed in accordance with the methods described herein. In some examples, aspects of the operations of 1320 may be performed by a selection indication component as described with reference to fig. 4-7.

Fig. 14 shows a flow diagram illustrating a method 1400 of supporting two-step random access channel configuration according to aspects of the present disclosure. The operations of the method 1400 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of method 1400 may be performed by a communication manager as described with reference to fig. 8-11. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, the base station may use dedicated hardware to perform aspects of the functions described below.

At 1405, the base station may transmit a configuration of a first random access message to the first wireless device for a two-step random access channel procedure. 1405 may be performed according to the methods described herein. In some examples, aspects of the operations of 1405 may be performed by a configuration transfer component as described with reference to fig. 8-11.

At 1410, the base station may receive a first random access message for a two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences based on the configuration and a speed of the first wireless device. 1410 may be performed according to the methods described herein. In some examples, aspects of the operations of 1410 may be performed by a first random access message receiving component as described with reference to fig. 8-11.

Fig. 15 shows a flow diagram illustrating a method 1500 of supporting two-step random access channel configuration in accordance with aspects of the present disclosure. The operations of method 1500 may be implemented by a base station 105 or components thereof as described herein. For example, the operations of method 1500 may be performed by a communication manager as described with reference to fig. 8-11. In some examples, a base station may execute a set of instructions to control the functional elements of the base station to perform the functions described below. Additionally or alternatively, the base station may use dedicated hardware to perform aspects of the functions described below.

At 1505, the base station may transmit a configuration of a first random access message to the first wireless device for a two-step random access channel procedure. 1505 may be performed in accordance with the methods described herein. In some examples, aspects of the operations of 1505 may be performed by a configuration transfer component as described with reference to fig. 8-11.

At 1510, the base station may receive a first random access message for a two-step random access channel procedure using a subcarrier spacing and a number of DMRS occurrences, wherein the subcarrier spacing and the number of DMRS occurrences are based on the configuration and the speed of the first wireless device. 1510 may be performed according to the methods described herein. In some examples, aspects of the operations of 1510 may be performed by a first random access message receiving component as described with reference to fig. 8-11.

At 1515, the base station may receive an indication of the selected subcarrier spacing and the number of DMRS occurrences. 1515 the operations may be performed in accordance with the methods described herein. In some examples, aspects of the operations of 1515 may be performed by the indication receiving component as described with reference to fig. 8-11.

It should be noted that the methods described herein describe possible implementations, and that the operations and steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more methods may be combined.

Example 1: a method for wireless communications at a wireless device, comprising: receiving a configuration of a first random access message for a two-step random access channel procedure; selecting a subcarrier spacing and a number of occurrences of demodulation reference signals for transmitting the first random access message based at least in part on the configuration and a speed of the wireless device; and transmitting a first random access message of the two-step random access channel procedure using the subcarrier spacing and the number of occurrences of the demodulation reference signal.

Example 2: the method of embodiment 1 wherein the configuration comprises a combined set of subcarrier spacing and number of occurrences of demodulation reference signals.

Example 3: the method of embodiment 2, wherein the selecting comprises: a configuration identifier corresponding to a combination in a combination set for a subcarrier spacing and a number of occurrences of demodulation reference signals is selected.

Example 4: the method of any of embodiments 1 through 3, wherein the configuration comprises a first parameter for subcarrier spacing and a second parameter for a number of occurrences of demodulation reference signals.

Example 5: the method of embodiment 4, wherein the selecting comprises: independently selecting a subcarrier spacing based at least in part on the first parameter and selecting a number of demodulation reference signal occurrences based at least in part on the second parameter.

Example 6: the method of any of embodiments 1-5, further comprising: the subcarrier spacing and the number of DMRS occurrences are selected based at least in part on a velocity of the wireless device exceeding a threshold.

Example 7: the method of any of embodiments 1-6, further comprising: an indication of the selected subcarrier spacing and the number of occurrences of demodulation reference signals is transmitted.

Example 8: the method of embodiment 7, wherein the indication is included in a Physical Uplink Shared Channel (PUSCH) of the first random access message.

Example 9: the method of embodiment 7 wherein the indication is transmitted in uplink control information on a physical uplink control channel.

Example 10: the method of embodiment 7 wherein the indication comprises a first parameter for the selected subcarrier spacing and a second parameter for the number of occurrences of the demodulation reference signal.

Example 11: the method of embodiment 7 wherein the indication comprises a configuration indicator indicating a subcarrier spacing and a number of occurrences of demodulation reference signals.

Example 12: the method of embodiment 7, wherein the indication comprises a sequence, frequency location information, or both for the demodulation reference signal corresponding to the number of occurrences of the demodulation reference signal.

Example 13: the method of any of embodiments 1-12, wherein the configuration is received in a system information message.

Example 14: the method of embodiment 13, further comprising: transmitting a request for a system information message, wherein the system information message is received based at least in part on the request.

Example 15: the method of any of embodiments 1-14, further comprising: determining that a velocity of the wireless device is below a threshold; and register with another cell based at least in part on the determination.

Example 16: the method of any of embodiments 1 through 15, wherein the number of occurrences of the demodulation reference signal comprises occurrences of the pre-loaded demodulation reference signal and at least one additional demodulation reference signal.

Example 17: the method of embodiment 16, wherein the at least one additional demodulation reference signal uses the same sequence, frequency location, or both as the piggybacked demodulation reference signal.

Example 18: the method of embodiment 16, wherein the at least one additional demodulation reference signal uses a different sequence, frequency location, or both than the on-load demodulation reference signal.

Example 19: the method of any of embodiments 1 through 18, wherein the wireless device is a User Equipment (UE) or a relay node.

Example 20: a method for wireless communication, comprising: transmitting a configuration of a first random access message for a two-step random access channel procedure to a first wireless device; and receiving a first random access message of a two-step random access channel procedure using a subcarrier spacing and a number of occurrences of demodulation reference signals, wherein the subcarrier spacing and the number of occurrences of demodulation reference signals are based at least in part on the configuration and a speed of the first wireless device.

Example 21: the method of embodiment 20 wherein the configuration comprises a combined set of subcarrier spacing and number of occurrences of demodulation reference signals.

Example 22: the method of any of embodiments 20 through 21, wherein the configuration comprises a first parameter for subcarrier spacing and a second parameter for a number of occurrences of a demodulation reference signal.

Example 23: the method of any of embodiments 20-22, wherein the subcarrier spacing and the number of occurrences of demodulation reference signals are based at least in part on a velocity of the first wireless device exceeding a threshold.

Example 24: the method of any of embodiments 20-23, further comprising: an indication of the selected subcarrier spacing and the number of occurrences of demodulation reference signals is received.

Example 25: the method of embodiment 24 wherein the indication is received in a Physical Uplink Shared Channel (PUSCH) of the first random access message.

Example 26: the method of embodiment 24 wherein the indication is received in uplink control information on a physical uplink control channel.

Example 27: the method of embodiment 24 wherein the indication comprises a first parameter for the selected subcarrier spacing and a second parameter for the number of occurrences of the demodulation reference signal.

Example 28: the method of embodiment 24 wherein the indication comprises a configuration indicator indicating a subcarrier spacing and a number of occurrences of demodulation reference signals.

Example 29: the method of embodiment 24, wherein the indication comprises a sequence, frequency location information, or both for the demodulation reference signal corresponding to the number of occurrences of the demodulation reference signal.

Example 30: the method as in any one of embodiments 20-29, wherein the configuration is transmitted in a system information message.

Example 31: the method of any of embodiments 20-30, wherein the first wireless device is a User Equipment (UE) or a relay node.

Example 32: an apparatus comprising at least one means for performing the method of any of embodiments 1-19.

Example 33: an apparatus comprising at least one means for performing the method of any of embodiments 20-31.

Example 34: an apparatus for wireless communication, comprising: a processor; a memory in electronic communication with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method as in any of embodiments 1 to 19.

Example 35: an apparatus for wireless communication, comprising: a processor; a memory in electronic communication with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method as in any of embodiments 20 to 31.

Example 36: a non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform a method as in any one of embodiments 1-19.

Example 37: a non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to perform the method of any of embodiments 21 to 31.

The techniques described herein may be used for various wireless communication systems such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and others. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000, IS-95 and IS-856 standards. The IS-2000 version may be generally referred to as CDMA 20001X, 1X, etc. IS-856(TIA-856) IS commonly referred to as CDMA 20001 xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes wideband CDMA (wcdma) and other variants of CDMA. TDMA systems may implement radio technologies such as global system for mobile communications (GSM).

The OFDMA system may implement radio technologies such as Ultra Mobile Broadband (UMB), evolved UTRA (E-UTRA), Institute of Electrical and Electronics Engineers (IEEE)802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). LTE, LTE-A and LTE-A Pro are versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE-A, LTE-A Pro, NR, and GSM are described in literature from an organization named "third Generation partnership project" (3 GPP). CDMA2000 and UMB are described in documents from an organization named "third generation partnership project 2" (3GPP 2). The techniques described herein may be used for both the systems and radio technologies mentioned herein and for other systems and radio technologies. Although aspects of the LTE, LTE-A, LTE-A Pro or NR system may be described for exemplary purposes and LTE, LTE-A, LTE-A Pro or NR terminology may be used in much of the description, the techniques described herein may also be applied to applications other than LTE, LTE-A, LTE-A Pro or NR applications.

A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscriptions with the network provider. A small cell may be associated with a lower power base station (as compared to a macro cell), and the small cell may operate in the same or a different (e.g., licensed, unlicensed, etc.) frequency band than the macro cell. According to various examples, a small cell may include a picocell, a femtocell, and a microcell. A picocell, for example, may cover a small geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A femtocell may also cover a smaller geographic area (e.g., a residence) and may provide restricted access by UEs associated with the femtocell (e.g., UEs in a Closed Subscriber Group (CSG), UEs of users in the residence, etc.). The eNB for a macro cell may be referred to as a macro eNB. An eNB for a small cell may be referred to as a small cell eNB, pico eNB, femto eNB, or home eNB. An eNB may support one or more (e.g., two, three, four, etc.) cells and may also support communication using one or more component carriers.

The wireless communication systems described herein may support synchronous or asynchronous operation. For synchronous operation, the base stations may have similar frame timing, and transmissions from different base stations may be approximately aligned in time. For asynchronous operation, each base station may have different frame timing, and transmissions from different base stations may not be aligned in time. The techniques described herein may be used for synchronous or asynchronous operations.

Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection with the disclosure herein may be implemented or performed with a general purpose processor, a DSP, an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration).

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and the following claims. For example, due to the nature of software, the functions described herein may be implemented using software executed by a processor, hardware, firmware, hard-wired, or any combination thereof. Features that implement functions may also be physically located at various locations, including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. Non-transitory storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, a non-transitory computer-readable medium may include Random Access Memory (RAM), Read Only Memory (ROM), electrically erasable programmable ROM (eeprom), flash memory, Compact Disc (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk (disk) and disc (disc), as used herein, includes CD, laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

As used herein, including in the claims, "or" as used in a list of items (e.g., a list of items accompanied by a phrase such as "at least one of" or "one or more of") indicates an inclusive list, such that, for example, a list of at least one of A, B or C means a or B or C or AB or AC or BC or ABC (i.e., a and B and C). Also, as used herein, the phrase "based on" should not be read as referring to a closed condition set. For example, an exemplary step described as "based on condition a" may be based on both condition a and condition B without departing from the scope of the present disclosure. In other words, the phrase "based on," as used herein, should be interpreted in the same manner as the phrase "based, at least in part, on.

In the drawings, similar components or features may have the same reference numerals. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description may apply to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.

The illustrations set forth herein in connection with the figures describe example configurations and are not intended to represent all examples that may be implemented or fall within the scope of the claims. The term "exemplary" as used herein means "serving as an example, instance, or illustration," and does not mean "preferred" or "advantageous over other examples. The detailed description includes specific details to provide an understanding of the described technology. However, the techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

The description herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.