阅读说明：本技术 经由相移或者频移的信号修改 (Signal modification via phase or frequency shift ) 是由 X·F·王 A·里科阿尔瓦里尼奥 于 2018-05-09 设计创作，主要内容包括：一种无线通信的示例方法包括：由第一无线通信设备对副本中的符号组的集合应用与小区相关联的加扰序列。所述方法还包括：由所述第一无线通信设备在所述加扰序列被应用于符号组的所述集合之后,向与所述小区相关联的第二无线通信设备发送符号组的所述集合。另一种无线通信的示例方法包括：由第一无线通信设备对副本中的符号组的集合应用与小区相关联的频移。所述方法还包括：由所述第一无线通信设备在所述频移被应用于符号组的所述集合之后,向与所述小区相关联的第二无线通信设备发送符号组的所述集合。(An example method of wireless communication includes: a scrambling sequence associated with the cell is applied by the first wireless communication device to the set of symbol groups in the replica. The method further comprises the following steps: transmitting, by the first wireless communication device, the set of symbol groups to a second wireless communication device associated with the cell after the scrambling sequence is applied to the set of symbol groups. Another example method of wireless communication includes: applying, by the first wireless communication device, a frequency shift associated with the cell to the set of symbol groups in the replica. The method further comprises the following steps: transmitting, by the first wireless communication device, the set of symbol groups to a second wireless communication device associated with the cell after the frequency shift is applied to the set of symbol groups.)

1. A method of wireless communication, comprising:

applying, by the first wireless communication device, a scrambling sequence associated with the cell to the set of symbol groups in the replica; and

transmitting, by the first wireless communication device, the set of symbol groups to a second wireless communication device associated with the cell after the applying the scrambling sequence to the set of symbol groups.

2. The method of claim 1, wherein the set of symbol groups comprises four symbol groups.

3. The method of claim 1, wherein the scrambling sequence is cell-dependent.

4. The method of claim 3, wherein different copies in the cell have the same predefined scrambling sequence or have different predefined scrambling sequences.

5. The method of claim 1, wherein the scrambling sequence comprises entries having constant absolute values.

6. The method of claim 1, wherein the applying the scrambling sequence results in an amplitude of the set of symbol groups remaining unchanged.

7. The method of claim 1, wherein the applying the scrambling sequence comprises: applying a phase shift to one or more of the set of symbol groups.

8. The method of claim 1, wherein the scrambling sequence has four defined values.

9. The method of claim 1, further comprising:

receiving, by the first wireless communication device, a cell ID of the cell; and

determining, by the first wireless communication device, the scrambling sequence based on the cell ID.

10. The method of claim 9, wherein the scrambling sequence defines a set of values.

11. The method of claim 10, wherein the applying the scrambling sequence comprises: rotating a first symbol group of the set of symbol groups by a first value listed in the set of values.

12. The method of claim 11, wherein the applying the scrambling sequence comprises: rotating a second symbol group of the set of symbol groups by a second value listed in the set of values.

13. The method of claim 1, comprising:

applying, by the first wireless communication device, a frequency shift associated with the cell to the set of symbols in the replica, wherein the transmitting comprises: transmitting the set of symbol groups after the applying the frequency shift.

14. The method of claim 1, wherein different cells use different scrambling sequences.

15. The method of claim 1, wherein each symbol group comprises a set of symbols, each symbol being a single tone transmission.

16. A system for wireless communication, comprising:

a scrambler that applies a scrambling sequence associated with a cell to a set of symbol groups in a replica; and

a transceiver that transmits the set of symbol groups to a first wireless communication device associated with the cell after the scrambling sequence is applied to the set of symbol groups.

17. The system of claim 16, further comprising:

a second wireless communication device comprising the scrambler and the transceiver.

18. An apparatus for wireless communication, comprising:

means for applying a scrambling sequence associated with the cell to a set of symbol groups in the replica; and

means for transmitting the set of symbol groups after the scrambling sequence is applied to the set of symbol groups.

19. A computer-readable medium having program code recorded thereon, the program code comprising:

code for causing the first wireless communication device to apply a scrambling sequence associated with the cell to the set of symbol groups in the replica; and

code for causing the first wireless communication device to transmit the set of symbol groups to a second wireless communication device associated with the cell after the scrambling sequence is applied to the set of symbol groups.

20. A method of wireless communication, comprising:

applying, by the first wireless communication device, a frequency shift associated with the cell to the set of symbol groups in the replica; and

transmitting, by the first wireless communication device, the set of symbol groups to a second wireless communication device associated with the cell after the frequency shift is applied to the set of symbol groups.

21. The method of claim 20, further comprising:

applying, by the first wireless communication device, a scrambling sequence associated with the cell to the set of symbols in the replica, wherein the transmitting further comprises: transmitting the set of symbol groups to the second wireless communication device after applying the scrambling sequence to the set of symbols.

22. A system for wireless communication, comprising:

a frequency shifter to apply a frequency shift associated with the cell to a set of symbol groups in the replica; and

a transceiver that transmits the set of symbol groups to a first wireless communication device associated with the cell after the frequency shift is applied to the set of symbol groups.

23. The system of claim 22 wherein NPRACH signal comprises a set of the symbol groups.

24. The system of claim 23, further comprising:

a second wireless communication device comprising the frequency shifter and the transceiver.

25. An apparatus for wireless communication, comprising:

means for applying a frequency shift associated with the cell to a set of symbol groups in the replica; and

means for transmitting the set of symbol groups to a first wireless communication device associated with the cell after the frequency shift is applied to the set of symbol groups.

26. A computer-readable medium having program code recorded thereon, the program code comprising:

code for causing the first wireless communication device to apply a frequency shift associated with the cell to a set of symbol groups in the replica; and

code for causing the first wireless communication device to transmit the set of symbol groups to a second wireless communication device associated with the cell after the frequency shift is applied to the set of symbol groups.

27. A method of wireless communication, comprising:

detecting one or more phase shifts between groups of symbols;

determining whether a difference of the two or more phase shifts matches a set of expected phase shift values associated with the cell;

detecting a signal comprising the set of symbols in response to a determination that the difference of two or more phase shifts matches the set of expected phase shift values; and

ignoring the signal comprising the set of symbols in response to a determination that the difference of two or more phase shifts does not match the set of expected phase shift values.

28. A method of wireless communication, comprising:

detecting a frequency shift between groups of symbols;

determining whether a difference of the two or more frequency shifts matches a set of expected frequency shift values associated with the cell;

detecting a signal comprising the group of symbols in response to a determination that the difference of two or more frequency shifts matches an expected set of frequency shift values; and

disregarding the signal comprising the group of symbols in response to a determination that the difference in two or more detected frequency shifts does not match the set of expected frequency shift values.

Technical Field

The present application relates to wireless communication systems, and more particularly, to reducing cell interference by modifying signals via phase or frequency shifting.

Background

A wireless communication network may include multiple Base Stations (BSs) that may support communication for multiple User Equipments (UEs). In recent years, advances in electronics, information, sensing, and application technologies have evolved the internet from a human-oriented network in which people create and consume information to the internet of things (IoT) in which distributed elements exchange and process information. Accordingly, the demand for serving IoT-type wireless data traffic is increasing. For example, smart wireless gauges and wireless sensors may be installed throughout a building in various areas. The smart meter may send meter readings to the utility at some time period (e.g., hourly, daily, or weekly). The sensor may send the sensing measurements to the server at time periods that may be based on the sensing events. IoT application packets are typically small in size, e.g., in tens of bytes to about 100 bytes.

Narrowband IoT (NB-IoT) is an emerging cellular technology that provides coverage for a large number of low-throughput, low-cost devices with low device power consumption in delay tolerant applications. New single tone signals with frequency hopping have been designed for NB-IoT physical random access channel (NPRACH).

Disclosure of Invention

The following presents a simplified summary of some aspects of the disclosure in order to provide a basic understanding of the discussed technology. This summary is not an extensive overview of all contemplated features of the disclosure, and is intended to neither identify key or critical elements of all aspects of the disclosure, nor delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in a summary form as a prelude to the more detailed description that is presented later.

For example, in an aspect of the disclosure, a method of wireless communication includes: a scrambling sequence associated with the cell is applied by the first wireless communication device to the set of symbol groups in the replica. The method further comprises the following steps: transmitting, by the first wireless communication device, the set of symbol groups to a second wireless communication device associated with the cell after the applying the scrambling sequence to the set of symbol groups.

A system for wireless communication includes a scrambler that applies a scrambling sequence associated with a cell to a set of symbol groups in a replica. The system also includes a transceiver that transmits the set of symbol groups to a first wireless communication device associated with the cell after the scrambling sequence is applied to the set of symbol groups.

In a further aspect of the disclosure, an apparatus for wireless communication comprises: means for applying a scrambling sequence associated with the cell to the set of symbol groups in the replica. The device further comprises: means for transmitting the set of symbol groups after the scrambling sequence is applied to the set of symbol groups.

In a further aspect of the present disclosure, a computer readable medium having program code recorded thereon, the program code comprising: code for causing the first wireless communication device to apply a scrambling sequence associated with the cell to the set of symbol groups in the replica; and code for causing the first wireless communication device to transmit the set of symbol groups to a second wireless communication device associated with the cell after the scrambling sequence is applied to the set of symbol groups.

In a further aspect of the disclosure, a method of wireless communication includes: applying, by the first wireless communication device, a frequency shift associated with the cell to the set of symbol groups in the replica. The method further comprises the following steps: transmitting, by the first wireless communication device, the set of symbol groups to a second wireless communication device associated with the cell after the frequency shift is applied to the set of symbol groups.

In a further aspect of the disclosure, a system for wireless communication includes: a frequency shifter to apply a frequency shift associated with the cell to the set of symbol groups in the replica. The system further comprises: a transceiver that transmits the set of symbol groups to a first wireless communication device associated with the cell after the frequency shift is applied to the set of symbol groups.

In a further aspect of the disclosure, an apparatus for wireless communication comprises: means for applying a frequency shift associated with the cell to the set of symbol groups in the replica. The device further comprises: means for transmitting the set of symbol groups to a first wireless communication device associated with the cell after the applying the frequency shift.

In a further aspect of the present disclosure, a computer readable medium having program code recorded thereon, the program code comprising: code for causing the first wireless communication device to apply a frequency shift associated with the cell to a set of symbol groups in the replica; and code for causing the first wireless communication device to transmit the set of symbol groups to a second wireless communication device associated with the cell after the frequency shift is applied to the set of symbol groups.

In a further aspect of the disclosure, a method of wireless communication includes: a phase shift between the groups of symbols is detected. The method further comprises the following steps: it is determined whether the difference of the two or more phase shifts matches the set of expected phase shift values. The method further comprises the following steps: in response to a determination that the difference between one or more phase shifts matches an expected set of phase shift values, a signal comprising the set of symbols is detected. The method further comprises the following steps: ignoring the signal comprising the set of symbols in response to a determination that the one or more phase shifts do not match the set of expected phase shift values.

In a further aspect of the disclosure, a method of wireless communication includes: a frequency shift between groups of symbols is detected. The method further comprises the following steps: it is determined whether the difference of the two or more frequency shifts matches an expected set of frequency shift values. The method further comprises the following steps: detecting a signal comprising the group of symbols in response to a determination that the difference of two or more frequency shifts matches an expected set of frequency shift values. The method further comprises the following steps: ignoring the signal comprising the group of symbols in response to a determination that the one or more frequency shifts do not match the set of expected frequency shift values.

Other aspects, features and embodiments of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific, exemplary embodiments of the invention in conjunction with the accompanying figures. Although features of the present invention may be discussed below with respect to particular embodiments and figures, all embodiments of the present invention may include one or more of the advantageous features discussed herein. In other words, although one or more embodiments may be discussed as having particular advantageous features, one or more of such features may also be used in accordance with the various embodiments of the invention discussed herein. In a similar manner, although example embodiments may be discussed below as apparatus, system, or method embodiments, it should be understood that such example embodiments may be implemented with various apparatus, systems, and methods.

Drawings

Fig. 1 illustrates a wireless communication network in accordance with an embodiment of the present disclosure.

Fig. 2 shows an NPRACH signal comprising four copies.

Fig. 3 is a block diagram of an example User Equipment (UE) that scrambles a set of symbols included in a replica in accordance with an embodiment of the disclosure.

Fig. 4 is a block diagram of an exemplary Base Station (BS) detecting a phase shift in a signal in accordance with an embodiment of the present disclosure.

Fig. 5 is a block diagram of an example UE applying a frequency shift to a signal in accordance with an embodiment of the present disclosure.

Fig. 6 is a diagram of an NPRACH signal with a frequency shift-frequency grid in accordance with an embodiment of the present disclosure.

Fig. 7 is a block diagram according to an embodiment of the present disclosure.

Fig. 8 is a block diagram of an exemplary BS detecting a frequency shift in a signal in accordance with an embodiment of the present disclosure.

Fig. 9 is a flow diagram of a method of modifying a signal by scrambling a set of symbol groups in accordance with an embodiment of the present disclosure.

Fig. 10 is a flow diagram of a method of modifying a signal by applying one or more frequency shifts to a set of symbol groups in accordance with an embodiment of the present disclosure.

Detailed Description

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations by which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. It should be apparent, however, to one skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

The techniques described herein may be used for various wireless communication networks 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 FDMA (SC-FDMA), and others. The terms "network" and "system" are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc. UTRA includes wideband CDMA (wcdma) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. TDMA networks may implement radio technologies such as global system for mobile communications (GSM). An OFDMA network may implement radio technologies such as evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, flash OFDMA, and the like. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-advanced (LTE-A) are new versions of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE-A, and GSM are described in documents from an organization entitled "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 the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies such as next generation (e.g., fifth generation (5G)) networks.

Fig. 1 illustrates a wireless communication network 100 according to an embodiment of the present disclosure. The network 100 may include a plurality of UEs 102 and a plurality of BSs 104. The BS104 may comprise an evolved node b (enodeb). The BS104 may be a station that communicates with the UE102 and may also be referred to as a base transceiver station, a node B, an access point, etc.

The BS104 communicates with the UE102 as indicated by communication signal 106. The UE102 may communicate with the BS104 via an Uplink (UL) and a Downlink (DL). The downlink (or forward link) refers to the communication link from the BS104 to the UE 102. The UL (or reverse link) refers to the communication link from the UE102 to the BS 104. The BSs 104 may also communicate with each other, directly or indirectly, through wired and/or wireless connections as indicated by communication signals 108.

UEs 102 may be dispersed throughout network 100 as shown, and each UE102 may be fixed or mobile. UE102 may also be referred to as a terminal, mobile station, subscriber unit, etc. The UE102 may be a cellular phone, a smart phone, a personal digital assistant, a wireless modem, a laptop computer, a tablet computer, etc. Network 100 is one example of a network to which various aspects of the present disclosure are applicable.

Each BS104 may provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to this particular geographic coverage area of a BS and/or a BS subsystem serving this coverage area, depending on the context in which the term is used. In this regard, the BS104 may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. A macro cell typically 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 pico cell may generally cover a relatively small geographic area and may allow unrestricted access by UEs with service subscriptions with the network provider. A femto cell may also generally cover a relatively small geographic area (e.g., a home) and may provide restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG), UEs of users in the home, etc.) in addition to unrestricted access. The BS for the macro cell may be referred to as a macro BS. The BS for the pico cell may be referred to as a pico BS. The BS for the femto cell may be referred to as a femto BS or a home BS.

In the example shown in fig. 1, BSs 104a, 104b, and 104c are examples of macro BSs for covering areas 110a, 110b, and 110c, respectively. BSs 104d and 104e are examples of pico and/or femto BSs for coverage areas 110d and 110e, respectively. As should be appreciated, the BS104 may support one or more (e.g., two, three, four, etc.) cells.

Network 100 may also include relay stations. A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., a BS, a UE, etc.) and sends a transmission of data and/or other information to a downstream station (e.g., another UE, another BS, etc.). A relay station may also be a UE that relays transmissions of other UEs. A relay station may also be referred to as a relay BS, a relay UE, a relay, etc.

The network 100 may support synchronous operation or asynchronous operation. For synchronous operation, the BSs 104 may have similar frame timing and transmissions from different BSs 104 may be approximately aligned in time. For asynchronous operation, the BSs 104 may have different frame timing and transmissions from different BSs 104 may not be aligned in time.

In some implementations, network 100 uses Orthogonal Frequency Division Multiplexing (OFDM) on the downlink and single carrier frequency division multiplexing (SC-FDM) on the UL. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, and so on. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The interval between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be system bandwidth dependent. For example, K may be equal to 72, 180, 300, 600, 900, and 1200 for corresponding system bandwidths of 1.4, 3, 5, 10, 15, or 20 megahertz (MHz), respectively. The system bandwidth may also be divided into subbands. For example, one sub-band may cover 1.08MHz, and there may be 1,2, 4, 8, or 16 sub-bands for a corresponding system bandwidth of 1.4, 3, 5, 10, 15, or 20MHz, respectively.

In an embodiment, the network 100 may be an LTE network. The reference signal is a predetermined signal that facilitates communication between the BS104 and the UE 102. For example, the reference signal may have a particular pilot pattern or structure, wherein pilot tones may be positioned across an operating bandwidth or band, each at a predefined time and a predefined frequency. The control information may include resource assignments and protocol controls. The data may include protocol data and/or operational data.

In an embodiment, the UE102 may contain a USIM (universal subscriber identity module) that represents an International Mobile Subscriber Identity (IMSI) and stores corresponding authentication credentials. This IMSI is used to uniquely identify an LTE user (commonly referred to as a "user" in 3GPP terminology). The USIM may participate in the LTE user authentication protocol and generate cryptographic keys that form the basis of a key hierarchy that is then used to secure signaling and user data communications between the UE102 and the BS104 over the radio interface.

In an embodiment, the BS104 controls one or more cells and may broadcast system information associated with the network 100. Some examples of system information may include physical layer information such as cell bandwidth and frame configuration, cell access information, cell Identifiers (IDs), and neighbor cell information. The UE102 may access the network 100 by listening to the broadcast system information and request a connection or channel setup with the BS 104. For example, the UE102 may perform a random access procedure to begin communication with the BS104, and may subsequently perform a connection and/or registration procedure to register with the BS 104. After completing the connection and/or registration, the UE102 and the BS104 may enter a normal operation phase in which operational data may be exchanged. The BS104 may assign a UE ID to the UE102 for identifying the UE102 in the network 100. Data exchange between the BS104 and the UE102 during normal operation may be based on the assigned UE ID.

The UE102 downloads the system information and uses the system information to successfully communicate with the network. In an embodiment, the BS104 broadcasts system information, for example, in the form of a Master Information Block (MIB) and/or a System Information Block (SIB). The system information may include information related to cell access, channel configuration, Physical Random Access (PRACH) configuration, cell ID, and/or neighbor cell information. The UE102 may receive the cell ID of a particular cell via a SIB message or a MIB message.

The NB-IoT may include one or more NPRACH signals. Fig. 2 shows an NPRACH signal comprising four replicas 202. The number of replicas 202 may be configurable and depends on the coverage level, the distance between the UE102 and the cell, etc. In fig. 2, each copy 202 includes four symbol groups 204, and each symbol group 204 includes a cyclic prefix 206 and five consecutive symbols of the same value located at a given 3.75kHz tone. Each symbol group may be a NPRACH symbol group. The length of the cyclic prefix 206 may be 66.67 μ s for cell radii up to 10km and 266.67 μ s for cell radii up to 40 km. In some embodiments, each symbol group includes a set of symbols, each symbol being a single tone transmission.

The NPRACH signal may be repeated between each replica 202 and frequency hopping may occur between the replicas. NPRACH signals associated with different cells can be distinguished by cell-specific random frequency hopping between replicas. For a coverage level with one replica, the NPRACH signal received by cell a may be identical to the NPRACH signal received by cell B. The UE102 may hop randomly between replicas and may define random hopping per cell. In this example, the UE102 may provide cell-specific random hopping between replicas. The frequency hopping can be cell-dependent in that the UE102 can apply a formula that is a function of the cell ID to determine the frequency hopping. In an embodiment, an evolved node B may distinguish one signal intended for one cell from another via a hopping pattern because the evolved node B is aware of its own hopping pattern.

In addition to frequency hopping between copies, the UE 104 may apply frequency hopping to groups of symbols. In some embodiments, the frequency hopping between symbol groups may be defined in the specification and fixed for all of the cells. In some embodiments, frequency hopping between groups of symbols may be provided in the synchronization information. The tone frequency index may vary from one symbol group to another. For example, the hop distance from the symbol group 204a to the symbol group 204b is 1 (which may be +1 or-1) and is associated with a frequency of 3.75 kHz. The hop distance from the symbol group 204b to the symbol group 204c is 6 (which may be +6 or-6), associated with a frequency of 6x 3.75 kHz. The hop distance from the symbol group 204c to the symbol group 204d is 1 (which may be +1 or-1), associated with a frequency of 3.75 kHz. The five symbols in the symbol group 204 may be uniformly modulated by a constant value (e.g., 1). In some examples, five symbols represent sinusoidal signals having frequencies that are integer multiples of 0.75 kHz.

The positive or negative nature of the hopping distance (e.g., +1, -1, +6, or-6) may depend on the starting tone of the frequency location, which may be randomly selected by the UE 102. If the hop distance from the symbol group 204a to the symbol group 204b is +1 and the hop distance from the symbol group 204c to the symbol group 204d is +1, the phase difference between the symbol group 204a and the symbol group 204b and the phase difference between the symbol group 204c and the symbol group 204d should be identical when no frequency offset occurs because their distances in frequency remain the same. However, if the transition distance from the symbol group 204a to the symbol group 204b is +1 and the transition distance from the symbol group 204c to the symbol group 204d is-1, the phase difference between the symbol group 204a and the symbol group 204b and the phase difference between the symbol group 204c and the symbol group 204d should be conjugate to each other. Similarly, if the transition distance from the symbol group 204a to the symbol group 204b is-1 and the transition distance from the symbol group 204c to the symbol group 204d is +1, the phase difference between the symbol group 204a and the symbol group 204b and the phase difference between the symbol group 204c and the symbol group 204d should also be conjugate to each other. Additionally, if the UE102 applies a phase shift to the symbol group 204d, the previous case in which the phase differences are the same or conjugate to each other will not hold.

Under NPRACH design, random access is the same for all cells. However, random access of the UE102 to the cell may have some drawbacks. For example, the random access signal is the same for all cells, and a cell may detect an NPRACH signal intended for another cell. NB-IoT covers large geographic areas and NB-IoT NPRACH designs may suffer from spurious alarms due to inter-cell interference. For example, cell a may suffer interference from one or more random accesses intended for cell B, which may be referred to as false alarms and may cause problems. Additionally, random access may cause inter-cell interference between cell a and cell B. If cell a and cell B have NPRACH resources that overlap completely or partially in time, NPRACH signals intended for one cell may be detected by the other cell, especially when the number of replicas is small. In addition, the timing estimate for random access to cell a may be biased due to interference from one or more random access signals intended for other cells. It may be desirable to reduce false alarms and/or inter-cell interference.

Additionally, the UE may have been programmed to transmit NPRACH signals in a particular manner. The present disclosure provides techniques for "new" UEs to modify NPRACH signals and transmit these modified signals to cells so that the signals are not detected by unintended cells. It may be desirable to provide these new UEs with backward compatibility for communicating with components in the network 100 and transmitting the NPRACH signals disclosed in the present disclosure.

Fig. 3 is a block diagram of an example UE300 that scrambles a set of symbol groups included in a replica in accordance with an embodiment of the disclosure. The UE300 may be the UE102 as discussed above. As shown, UE300 may include a processor 302, a memory 304, a scrambler 308, a transceiver 310 including a modem subsystem 312 and an RF unit 314, and an antenna 316. These elements may communicate with each other, directly or indirectly, for example via one or more buses.

The processor 302 may include a Central Processing Unit (CPU), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a controller, a Field Programmable Gate Array (FPGA) device, another hardware device, a firmware device, or any combination thereof, configured to perform the operations described herein. The processor 302 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 memory 304 may include cache memory (e.g., cache memory of the processor 302), Random Access Memory (RAM), magnetoresistive RAM (mram), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, solid-state memory devices, hard drives, other forms of volatile and non-volatile memory, or a combination of different types of memory. In an embodiment, memory 304 includes a non-transitory computer-readable medium. The memory 304 may store instructions 306. The instructions 306 may include instructions that, when executed by the processor 302, cause the processor 302 to perform the operations described herein with reference to the UE in connection with embodiments of the disclosure. The instructions 306 may also be referred to as code. The terms "instructions" and "code" should be construed broadly to include any type of computer-readable statements. For example, the terms "instructions" and "code" may refer to one or more programs, routines, subroutines, functions, procedures, and the like. The "instructions" and "code" may comprise a single computer-readable statement or many computer-readable statements.

Additionally, memory 304 may store a cell ID311 that is received by UE300 and used by UE300 to apply the techniques discussed in this disclosure (e.g., for scrambling or frequency shifting). The cell ID311 may identify the cell with which the UE300 is connected and to which authentication has been performed. The cell may include its cell ID311 in the synchronization information, and the UE300 may receive the synchronization information and store the cell ID311 in the memory 304.

The scrambler 308 may be used in various aspects of the present disclosure. The scrambler 308 may reduce the occurrence of inter-cell interference and false alarms. The scrambler 308 may apply a scrambling sequence at the symbol group level. For example, the scrambler 308 may scramble a set of four symbol groups 204a, 204b, 204c, and 204d in the replica 202d by a sequence having a length of four. Scrambling may be done based on a cell ID defined by the specification or may be explicitly signaled in the system information. The use of scrambling sequences on a group of symbols by scrambler 308 may be cell specific. For example, the scrambler 308 may identify the scrambling sequence associated with the cell ID311 and apply that particular scrambler 308 sequence to the set of symbol groups. The cell ID311 may be associated with a phase shift value 309, the phase shift value 309 providing information to the scrambler 308 regarding the angle of the phase shift. If the UE300 is connected to another cell, the cell ID311 may be updated to the cell ID of the new cell and the phase shift value 309 may be updated to reflect the phase shift value of the new cell. Different cells may use different scrambling sequences. Additionally, different copies in a cell may have the same or different scrambling sequences, and different NPRACH resources may have different or the same scrambling sequences. The scrambler 308 may apply different scrambling sequences at the symbol group level.

In some embodiments, the applied sequence is associated with the network and a particular UE, and scrambler 308 applies a different scrambling sequence in different copies. The scrambling sequence may be cell-dependent (e.g., predefined based on a cell ID). After the cell is defined, a specific scrambling sequence may be defined for all copies. In the example, four copies and four scrambling sequences (e.g., 1,2,3, 4) are defined. For the cell identified by cell ID311, UE300 may use sequences 1,2,3,4 for duplicates 1,2,3, 4. In this example, for replica 1, scrambler 308 may apply scrambling sequence 1 based on cell ID 311; for copy 2, scrambler 308 may apply scrambling sequence 2 based on cell ID 311; for copy 3, scrambler 308 may apply scrambling sequence 3 based on cell ID 311; and for copy 4, scrambler 308 may apply scrambling sequence 4 based on cell ID 311. For a second cell identified by a second cell ID different from cell ID311, UE300 may use sequence 2,3,4, 1 for duplicates 1,2,3, 4. In this example, for replica 1, scrambler 308 may apply scrambling sequence 2 based on the second cell ID; for copy 2, the scrambler may apply scrambling sequence 3 based on the second cell ID; for copy 3, scrambler 308 may apply scrambling sequence 4 based on the second cell ID; and for replica 4, the scrambler may apply scrambling sequence 1 based on the second cell ID. In an example, all copies use the same sequence. For example, scrambler 308 may apply scrambling sequences 1,1 for all 4 copies.

In some embodiments, the scrambling sequence includes entries having constant absolute values. So as not to change the signal length between symbol groups so that all four symbol groups have exactly the same length. In this example, the amplitude remains unchanged, and the scrambler 308 may apply the scrambling sequence by applying a phase shift to one or more of the symbol groups, thus changing the phase between one or more of the four symbol groups. While the present disclosure may provide examples in which phase shifts are applied to four symbol groups, it should be understood that other examples provide for the application of scrambling sequences applied to more or less than four symbol groups. The terms "phase rotation" and "phase shift" may be used interchangeably.

In some examples, the phase shifted signal may be written exponentially as follows:

signal exp (j × s (n)), equation (1)

Where n ═ 1,2,3,4, s (n) denotes the phase shift of the symbol group n, and j ═ the square root of (-1). If the phase shift s (n) pi/2, the scrambler 308 shifts or rotates the signal by the phase shift value (e.g., pi/2). In an example, the scrambler 308 can apply equation (1) to the symbol set n and transmit this signal to the BS 104. In some examples, the scrambler 308 applies the scrambling sequence to the symbol groups 204a, 204b, 204c, and 204d by rotating the symbol group 204a by a first value listed in the scrambling sequence (e.g., 0), the symbol group 204b by a second value listed in the scrambling sequence (e.g., pi/2), the symbol group 204c by a third value listed in the scrambling sequence (e.g., pi), and the symbol group 204d by a fourth value listed in the scrambling sequence (e.g., 3 pi/2).

Equation (1) can be further simplified as shown in equation (2) below:

phase rotation ═ s (n), equation (2)

Wherein n is 1,2,3 is 0. In this example, s (n) has a value of zero for the first three symbols, and thus the scrambler 308 does not apply phase rotation to symbol groups 1,2, and 3 (since they are rotated by zero). Scrambler 308 may apply a phase shift rotation to symbol group 4. For example, if s (n) ═ pi/2, the scrambling sequence may take the form of [0,0,0, n/2 pi ], and the scrambler 308 rotates the last symbol group 4 at possible values of [0, pi/2, pi and 3 pi/2 ]. In an example, the scrambler 308 may apply a phase rotation given by equation (2) to the symbol set n and send this signal to the BS 104.

The application of scrambling sequences may provide a robust scheme that provides for signal reuse. The robustness of the scheme may depend on the phase shift of the angle. For example, see equation (2) with n-4, the distance is angular. In the example, four values [0, pi/2, pi and 3 pi/2 ] are defined for symbol group 4, and no phase shift is defined for the other symbol groups, and the distance between each of the possible values is pi/2, pi/2 defining the robustness of the scheme. Cell a and three other cells close to cell a may use different defined values with respect to each other due to their proximity. However, more distant cells may reuse the value used by cell a. Alternatively, if the number of defined values exceeds four, another scrambling scheme may be provided.

The memory 304 may store one or more phase shift values 309, and the phase shift values 309 may provide the UE300 with information as to how much to phase shift a signal (e.g., NPRACH signal). The phase shift value 309 may be provided in a variety of ways. In the example, a phase rotation or phase shift value 309 is defined in the specification as a function of the cell ID. In this example, four values may be defined for the phase shift value 309. If a cell ID is already assigned, it may be advantageous to provide the UE300 with a more flexible means for obtaining the phase shift value 309 for the cell. In another example, the cell provides its cell ID in the synchronization information. The synchronization information may be, for example, a SIB message or a MID message. The UE300 may synchronize with the cell and attach synchronization information (e.g., SIB or MID information) for determining the value (e.g., pi/2) of the phase shift value 309. In some examples, the phase shift value 309 is provided in the specification and also in both the synchronization information. In an example, the specification may define 32 values from 0 to 2 pi, and provide some phase shift values 309 in the synchronization information. Accordingly, the scrambler 308 may provide a mechanism for the UE300 to reduce spurious alarms and inter-cell interference within the network 100.

As shown, transceiver 310 may include a modem subsystem 312 and an RF unit 314. The transceiver 310 may be configured to bidirectionally communicate with other devices, such as the BS 104. In some examples, modem subsystem 312 may be configured to communicate with scrambler 308 and to modulate and/or encode data from memory 304 according to a scrambling scheme. RF unit 314 may be configured to process (e.g., perform analog-to-digital or digital-to-analog conversion, etc.) modulated/encoded data from modem subsystem 312 (on an outbound transmission) or a transmission originating from another source, such as UE102 or BS 104. Although shown as being integrated together in the transceiver 310, the modem subsystem 312 and the RF unit 314 may be separate devices that are coupled together at the UE300 to enable the UE300 to communicate with other devices.

RF unit 314 may provide modulated and/or processed data, such as data packets (or more generally, data messages that may contain one or more data packets and other information) to antenna 316 for transmission to one or more other devices. This may include, for example, transmission of a random access preamble, a connection request, or an NPRACH signal that has been modified by scrambler 308 in accordance with embodiments of the present disclosure. The antenna 316 may also receive data messages transmitted from other devices. The antenna 316 may provide the received data message for processing and/or demodulation at the transceiver 310. Although fig. 3 shows antenna 316 as a single antenna, antenna 316 may include multiple antennas of similar or different designs to support multiple transmission links. The RF unit 314 may configure the antenna 316.

Using the scrambling sequence techniques provided in this disclosure, a cell may be better able to distinguish which signals are intended for it and which signals are intended for another cell. At the evolved node B, a way to determine whether the NPRACH signal is intended for another cell is to detect a phase shift between symbol groups (e.g., symbol groups 1 and 2, and symbol groups 3 and 4), and to determine whether this phase shift is associated with (or assigned to) the cell. For example, cell a may be identified by cell ID311 and associated with a phase shift value 309 "pi/2". If cell a determines that the difference between symbol groups 204a and 204b is α degrees and the difference between symbol groups 204c and 204d is close to α + pi/2 degrees, cell a may determine that this received NPRACH signal is intended for that cell. In this example, cell a knows that UE102 rotates the last symbol group by a certain number of degrees (e.g., pi/2), and that the symbol group or its phase is rotated or offset as cell a expects it will be. However, if cell B is not associated with a phase shift value of "pi/2", then this NPRACH signal is not intended for cell B, and cell B will not detect this NPRACH signal or discard this copy in the timing estimation. In this example, cell B may listen for signals associated with a phase shift value of zero.

Fig. 4 is a block diagram of an exemplary BS 400 that detects phase shifts in a signal in accordance with an embodiment of the disclosure. In an example, the signal is an NPRACH signal. The BS 400 may be the BS104 as discussed above. As shown, BS 400 may include a processor 402, a memory 404, a transceiver 410 including a phase shift detector 411, a modem subsystem 412, and an RF unit 414, and an antenna 416. These elements may communicate with each other, directly or indirectly, for example via one or more buses.

The processor 402 may have various features as a dedicated type processor. For example, these may include a CPU, DSP, ASIC, controller, FPGA device, another hardware device, firmware device, or any combination thereof configured to perform the operations described herein. The processor 402 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 memory 404 may include cache memory (e.g., cache memory of the processor 402), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, a solid state memory device, one or more hard drives, an array based on memristors, other forms of volatile and non-volatile memory, or a combination of different types of memory. In some embodiments, memory 404 may include non-transitory computer-readable media. The memory 404 may store instructions 406. The instructions 406 may include instructions that, when executed by the processor 402, cause the processor 402 to perform the operations described herein. The instructions 406 may also be referred to as code, which may be broadly interpreted to include any type of computer-readable statements as discussed above with respect to FIG. 3.

Additionally, the memory 404 may store one or more expected phase shift values 407 associated with (or assigned to) the current cell and may also store the cell ID311 of the cell to which the UE300 is connected. The current cell refers to a cell to which the UE300 is connected. The expected phase shift value 407 may be configurable. Cells neighboring the current cell may store expected phase shift values that are different from the current cell to reduce confusion and inter-call interference. The memory 404 may also store a cell ID311 for the cell, the cell ID311 identifying and providing information about the cell.

As shown, transceiver 410 may include a phase shift detector 411, a modem subsystem 412, and an RF unit 414. The transceiver 410 may be configured to bidirectionally communicate with other devices, such as the UEs 102 and 302 and/or another core network element. Phase shift detector 411 may be used in various aspects of the present disclosure. The phase shift detector 411 may reduce the occurrence of inter-cell interference and false alarms. For example, phase shift detector 411 may detect phase shifts between symbol groups and determine whether a difference in these detected phase shifts is associated with or matches one or more expected phase shift values 407. In an example, phase shift detector 411 detects phase shifts between symbol groups 204a and 204b and between symbol groups 204c and 204d and determines whether a difference in these detected phase shifts matches an expected phase shift value. In response to a determination that one or more detected phase shifts match an expected set of phase shift values, phase shift detector 411 may detect a signal comprising a group of symbols. In this example, the cell is the cell for which the signal is intended. In response to a determination that the difference in one or more detected phase shifts does not match the set of expected phase shift values, phase shift detector 411 ignores the signal that includes the symbol group. In this example, the cell is not the cell for which the signal is intended.

Modem subsystem 412 may be configured to modulate and/or encode data. The RF unit 414 may be configured to process (e.g., perform analog-to-digital conversion or digital-to-analog conversion, etc.) modulated/encoded data from the modem subsystem 412 (on outbound transmissions) or transmissions originating from another source, such as the UE 102. Although shown as being integrated together in transceiver 410, modem subsystem 412 and RF unit 414 may be separate devices coupled together at BS104 to enable BS104 to communicate with other devices.

RF unit 414 may provide modulated and/or processed data, such as data packets (or more generally, data messages that may contain one or more data packets and other information) to antenna 416 for transmission to one or more other devices (e.g., UE 300). This may include, for example, the sending of information (e.g., cell ID) to complete the attachment to the network in accordance with embodiments of the disclosure. The antenna 416 may also receive data messages transmitted from other devices and provide the received data messages for processing and/or demodulation at the transceiver 410. Although fig. 4 shows antenna 416 as a single antenna, antenna 416 may include multiple antennas of similar or different designs to support multiple transmission links.

Fig. 5 is a block diagram of an example UE500 that applies a frequency shift to a signal in accordance with an embodiment of the present disclosure. In an example, the signal is an NPRACH signal. The UE500 may be the UE102 or the UE300 as discussed above. As shown, UE500 may include a processor 302, a memory 504, a frequency shifter 502, a transceiver 310 including a modem subsystem 312 and an RF unit 314, and an antenna 316. These elements may communicate with each other, directly or indirectly, for example via one or more buses. The memory 504 may store one or more frequency shift values 504.

In some embodiments, frequency shifter 502 applies one or more frequency shifts to existing NPRACH signals before transmitting them to BS 104. In the example, each symbol group 204 is a signal that is an integer multiple of 0.75kHz, and the two NPRACH signals assigned at tone k with frequency shifts of m1 x 0.75kHz and m2 x 0.75kHz are orthogonal to each other. In this example, there are five possible frequency shift values, such that NPRACH signals with different offset values are mutually orthogonal to each other. The five possible offset values may be [ -2, -1,0,1,2 ]. multidot.0.75 kHz corresponding to the tone locations in FIG. 6.

Fig. 6 is a diagram of an NPRACH signal with a frequency shift-frequency grid in accordance with an embodiment of the present disclosure. In fig. 6, the X-axis represents frequency. NPRACH tone locations 602, 604, and 606 may represent current specifications or what is currently available. For each symbol group, UE500 may select one of tone locations 602, 604, and 606 at a specified frequency and transmit their five symbols. The signal transmitted is the duration of the signal (which is one period of 0.75 kHz). The new NPRACH tone locations 604, 608, 610, 612, and 614 may represent the new NPRACH tone locations being added. Each of the new NPRACH tone locations are 0.75kHz apart from each other, and NPRACH tone locations 602, 604, and 606 and new NPRACH tone locations 604, 608, 610, 612, and 614 are frequency locations. The tone position may represent a frequency position and is based on a specification that provides five symbol durations of 3.75 kHz; these signals will be orthogonal to each other.

In an example, if the UE500 desires to transmit a symbol group using a new NPRACH tone location 604, the UE500 may shift the signal to the right by 0.75kHz, resulting in the signal being orthogonal to any signals transmitted using other tone locations. For cell B, the frequency shifter 502 may then use the new NPRACH tone location 612 placed to the right of the NPRACH tone location 604. Additionally, for another cell C, the frequency shifter 502 may use another tone location. For each of NPRACH tone locations 602, 604, and 606, five more new NPRACH tone locations at 3.75kHz/5 — 0.75kHz may be provided. Although the new NPRACH tone locations 604, 608, 610, 612, and 614 are plotted around the initial NPRACH tone location, this is not intended to be limiting and may be plotted based on other factors.

An existing UE may use a frequency shift value 504 of zero regardless of its intended cell. This zero value corresponds to the current frequency location, and existing UEs may not be able to understand anything else in terms of the frequency shift value 504. In an example of backward compatibility, the new UE500 may use one of five defined frequency shift values fd1 [ -2, -1,0,1,2] × 0.75kHz or zero (since the old UE may use zero). In another example, the new UE500 may use one of four defined frequency shift values fd2 [ -2, -1,1,2] × 0.75kHz that may be assigned to a cell depending on the cell ID of the cell. For example, the entry mod (cell _ ID,5) +1 for fd1 or the entry mod (cell _ ID,4) +1 for fd2 may be used, which may allow a frequency reuse factor of 5 or 4, i.e., 5 or 4 cells may have different frequencies for NPRACH.

If two cells are assigned different frequency shift values, the NPRACH signals of the two cells may be orthogonal to each other, depending on how they overlap or collide in time. For example, the NPRACH resource of cell a may completely collide with the NPRACH resource of cell B in both frequency and time, but this may represent a worst case. In this example, NPRACH resources occur at the same time and at the same frequency location. If this is the case, frequency shifter 502 may apply a frequency shift, and if the two cells have different frequency shift values, they will be orthogonal to each other. Accordingly, this may reduce inter-cell interference. This may not cause a big problem if NPRACH resources of cell a and cell B partially overlap in time. Although the signals will not be perfectly orthogonal, the interference may be small because the signals will be associated with different frequency locations and they only partially overlap in time.

The frequency shift value 504 may be provided in a variety of ways. In an example, the frequency shift value 504 is defined in the specification as a function of the cell ID, and thus may be fixed based on the cell ID. In this example, it may be desirable for the operator to consider the formula when assigning cell IDs to allow for efficient use of these frequency shifting techniques. In another example, the frequency shift value 504 is provided in synchronization information.

Although this disclosure may discuss NB-IoT, this disclosure is not so limited. In general, assuming that the hop distance is an integer multiple of FH Hz (which is a value) and there are M symbols (each having a duration of 1/FH) per symbol group (consecutive transmissions without frequency change), M offsets with a frequency shift of M × FH/M Hz can be created, where M is 0, … M-1.

Fig. 7 is a block diagram 700 according to an embodiment of the present disclosure. Fig. 7 includes an existing NPRACH signal generator 702 and a frequency shifter 704 that may correspond to the frequency shifter 502. An existing NPRACH signal generator 702 may be incorporated into UE500 and may generate NPRACH signals from NPRACH tone locations 602, 604, and 606. The frequency shifter 704 may take as input the cell ID 706 and one or more NPRACH tone locations 602, 604, and 606 of the cell and apply the frequency shift accordingly. Thereafter, the frequency shifter 704 may transmit the generated NPRACH signal to, for example, the BS 104. The resulting NPRACH signal may have a frequency, for example, with the new NPRACH tone location 612 shown in fig. 6.

Fig. 8 is a block diagram of an exemplary BS 800 that detects a frequency shift in a signal according to an embodiment of the disclosure. The BS 800 may be the BS104 as discussed above. As shown, BS 800 may include processor 402, memory 804, transceiver 810 including frequency shift detector 802, modem subsystem 412, and RF unit 414, and antenna 416. These elements may communicate with each other, directly or indirectly, for example via one or more buses.

Additionally, the memory 804 includes an expected frequency shift value 804 and a cell ID511 of a cell to which the UE 700 is connected. The frequency shift detector 802 may be used in various aspects of the present disclosure. For example, the frequency shift detector 802 detects frequency shifts between groups of symbols and determines whether a difference in these detected frequency shifts is associated with or matches an expected frequency shift value 804. In an example, frequency shifter 502 detects frequency shifts between groups of symbols and determines whether a difference of two or more detected frequency shifts matches an expected set of frequency shift values. Frequency shifter 502 detects a signal comprising a group of symbols in response to a determination that one or more detected frequency shifts match an expected set of frequency shift values. In response to a determination that the two or more detected frequency shifts do not match the set of expected frequency shift values, frequency shifter 502 ignores the signal that includes the symbol group.

It should be understood that although the UE300 is shown as including the scrambler 308 and the phase shift value 309, the UE300 may also include other components. For example, in some embodiments, the UE300 also includes a frequency shift 502 and one or more frequency shift values 504. In some embodiments, BS 400 also includes a frequency shift detector 802, one or more expected frequency shift values 804, and a cell ID 511. In some embodiments, immediately adjacent neighbor cells have different expected frequency shift values, and layer two neighbor cells have different scrambling sequences.

Fig. 9 is a flow diagram of a method 900 of modifying a signal by scrambling a set of symbol groups in accordance with an embodiment of the present disclosure. The steps of method 900 may be performed by a computing device (e.g., a processor, processing circuitry, and/or other suitable components) of a wireless communication device, such as UEs 102, 300, and 500. Method 900 may use similar mechanisms as described with respect to network 100. The method 900 may be better understood with reference to fig. 2. As illustrated, method 900 includes a number of enumerated steps, but embodiments of method 900 may include additional steps before, after, and between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

At step 910, the method 900 includes: a scrambling sequence associated with the cell is applied by the first wireless communication device to the set of symbol groups in the replica. At step 920, method 900 includes: transmitting, by the first wireless communication device, the set of symbol groups to a second wireless communication device associated with the cell after the scrambling sequence is applied to the set of symbol groups.

Fig. 10 is a flow diagram of a method 1000 of modifying a signal by applying one or more frequency shifts to a set of symbol groups in accordance with an embodiment of the present disclosure. The steps of method 1000 may be performed by a computing device (e.g., a processor, processing circuitry, and/or other suitable components) of a wireless communication device, such as UEs 102, 300, and 500. Method 1000 may use similar mechanisms as described with respect to network 100. The method 1000 may be better understood with reference to fig. 2. As shown, method 1000 includes a number of enumerated steps, but embodiments of method 1000 may include additional steps before, after, and in between the enumerated steps. In some embodiments, one or more of the enumerated steps may be omitted or performed in a different order.

At step 1010, the method 1000 includes: applying, by the first wireless communication device, a frequency shift associated with the cell to the set of symbol groups in the replica. At step 1020, method 1000 includes: transmitting, by the first wireless communication device, the set of symbol groups to a second wireless communication device associated with the cell after the frequency shift is applied to the set of symbol groups.

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 above may be implemented using software executed by a processor, hardware, firmware, hard wiring, or a combination of any of these. Features implementing functions may also be physically located at various locations, including being distributed such that portions of functions are implemented at different physical locations. Further, as used herein (including in the claims), "or" as used in a list of items (e.g., a list of items headed 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 [ A, B or at least one of C ] means a, or B, or C, or AB, or AC, or BC, or ABC (i.e., a and B and C).

As those skilled in the art will now appreciate, and depending on the particular application at hand, many modifications, substitutions, and variations may be made in the materials, devices, configurations, and methods of use of the apparatus of the present disclosure or to such materials, devices, configurations, and methods of use without departing from the spirit and scope thereof. In view of this, the scope of the present disclosure should not be limited to the particular embodiments shown and described herein (as they are used as only a few examples thereof), but rather should be fully commensurate with the scope of the claims appended below and their functional equivalents.