阅读说明：本技术 下一代蜂窝网络中初始接入的方法和装置 (Method and apparatus for initial access in next generation cellular networks ) 是由 薛鹏 A.阿吉瓦 柳贤锡 柳炫圭 于 2018-05-02 设计创作，主要内容包括：提供了一种通信方法和系统,用于将支持超过第四代(4G)系统的更高数据速率的第五代(5G)通信系统与用于物联网(IoT)的技术相融合。该通信方法和系统可以应用于基于5G通信技术和IoT相关技术的智能服务,诸如,智能家居、智能建筑、智能城市、智能汽车、联网汽车、医疗保健、数字教育、智能零售、保障和安全服务。提供了一种终端在蜂窝网络中接收数据的方法。该方法包括从基站接收包括至少一个同步信号和广播信道的同步信号块(SS块),从广播信道中的系统信息识别SS块和资源块(RB)网格之间的偏移,并基于偏移确定资源块网格。(A communication method and system are provided for merging a fifth generation (5G) communication system that supports higher data rates than a fourth generation (4G) system with technologies for internet of things (IoT). The communication method and system can be applied to intelligent services based on 5G communication technology and IoT related technology, such as smart homes, smart buildings, smart cities, smart cars, networked cars, healthcare, digital education, smart retail, security and security services. A method of a terminal receiving data in a cellular network is provided. The method includes receiving a synchronization signal block (SS block) including at least one synchronization signal and a broadcast channel from a base station, identifying an offset between the SS block and a Resource Block (RB) grid from system information in the broadcast channel, and determining the resource block grid based on the offset.)

1. A method for a terminal receiving data in a cellular network, the method comprising:

receiving a synchronization signal block (SS block) including at least one synchronization signal and a broadcast channel from a base station;

identifying an offset between an SS block and a resource block, RB, grid from system information in a broadcast channel; and

an RB grid is determined based on the offset.

2. The method of claim 1, wherein the offset is received in a master information block over a broadcast channel.

3. The method of claim 1, wherein the offset is a 4-bit Physical Resource Block (PRB) grid offset.

4. The method of claim 1, wherein the offset is defined based on a lowest subcarrier in an SS block.

5. A method for a base station transmitting data in a cellular network, the method comprising:

determining a location of a resource block, RB, grid and a synchronization signal block, SS, block comprising at least one synchronization signal and a broadcast channel; and

the SS block is transmitted to the terminal based on the RB grid,

wherein the offset between the SS block and the RB grid is transmitted in the system information through a broadcast channel.

6. The method of claim 5, wherein the offset is transmitted in a master information block through a broadcast channel.

7. The method of claim 5, wherein the offset is a 4-bit Physical Resource Block (PRB) grid offset.

8. The method of claim 5, wherein the offset is defined based on a lowest subcarrier in an SS block.

9. A terminal for receiving data in a cellular network, the terminal comprising:

a transceiver configured to:

receiving a signal from a base station, an

Transmitting a signal to a base station; and a controller coupled with the transceiver and configured to:

the control transceiver receives a synchronization signal block SS block including at least one synchronization signal and a broadcast channel from the base station,

identifying an offset between an SS block and a resource block, RB, grid from system information in a broadcast channel, an

An RB grid is determined based on the offset.

10. The terminal of claim 9, wherein the controller is further configured to control the transceiver to receive the offset in the master information block through a broadcast channel.

11. The terminal of claim 9, wherein the offset is a 4-bit physical resource block, PRB, grid offset.

12. The terminal of claim 9, wherein the offset is defined based on a lowest subcarrier in an SS block.

13. A base station for transmitting data in a cellular network, the base station comprising:

a transceiver configured to:

receiving a signal from a terminal, an

Sending a signal to a terminal; and

a controller coupled with the transceiver and configured to:

determining a location of a resource block RB grid and a synchronization signal block SS block comprising at least one synchronization signal and a broadcast channel,

controlling the transceiver to transmit the SS blocks to the terminal based on the RB grid, an

The control transceiver transmits the offset between the SS blocks and the RB grid to the terminal in system information through a broadcast channel.

14. The base station of claim 13, wherein the controller is further configured to control the transceiver to transmit the offset in the master information block over a broadcast channel.

15. The base station of claim 13, wherein the offset is defined based on a lowest subcarrier in an SS block.

Technical Field

The present disclosure relates to a method and apparatus for receiving/transmitting data in a cellular network. More particularly, the present disclosure relates to initial access in a next generation cellular network.

Background

In order to meet the increasing demand for wireless data traffic since the deployment of fourth generation (4G) communication systems, efforts have been made to develop improved fifth generation (5G) or quasi-5G communication systems. Accordingly, a 5G or quasi-5G communication system is also referred to as an "ultra 4G network" or a "Long Term Evolution (LTE) system". The 5G wireless communication system is considered to be implemented not only in a frequency band of a lower frequency but also in a frequency band of a higher frequency (mmWave) (for example, 10GHz to 100GHz band) in order to achieve a higher data rate. In order to reduce propagation loss of radio waves and increase transmission distance, designs of 5G wireless communication systems are considering beamforming, massive multiple-input multiple-output (MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, and massive antenna technologies. Further, in the 5G communication system, development of system network improvement based on advanced small cells, a cloud Radio Access Network (RAN), an ultra-dense network, device-to-device (D2D) communication, a wireless backhaul, a mobile network, cooperative communication, coordinated multi-point (CoMP), receiving end interference cancellation, and the like is in progress. In the 5G system, hybrid Frequency Shift Keying (FSK) and Quadrature Amplitude Modulation (QAM) (FQAM) and Sliding Window Superposition Coding (SWSC) as Advanced Coding Modulation (ACM) have been developed, and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and Sparse Code Multiple Access (SCMA) as advanced access technologies.

The internet is a human-centric connected network of people that generates and consumes information, and is now evolving towards the internet of things (IoT), where distributed entities, such as things, exchange and process information without human intervention. Internet of everything (IoE) has emerged, which is the product of combining IoT technology and big data processing technology through a connection with a cloud server. With the demand of IoT implementations for technical elements such as "sensing technology", "wired/wireless communication and network infrastructure", "service interface technology", and "security technology", sensor networks, machine-to-machine (M2M) communication, Machine Type Communication (MTC), and the like have recently been studied. Such an IoT environment can provide an intelligent internet technology service that creates new value for human life by collecting and analyzing data generated between connected things. Through the fusion and integration of existing Information Technology (IT) with various industrial applications, IoT is applicable to a variety of fields including smart homes, smart buildings, smart cities, smart cars or networked cars, smart grids, healthcare, smart appliances, and advanced medical services.

In view of this, various attempts have been made to apply the 5G communication system to the IoT network. For example, techniques such as sensor network, MTC, and M2M communication may be implemented by beamforming, MIMO, and array antennas. The application of cloud RAN as the big data processing technology described above can also be considered as an example of the convergence between 5G technology and IoT technology.

In recent years, several broadband wireless technologies have been developed to meet the growing number of broadband users and to provide more and better applications and services. A second generation (2G) wireless communication system has been developed to provide voice services while ensuring mobility of users. Third generation (3G) wireless communication systems support not only voice services but also data services. 4G wireless communication systems have been developed to provide high-speed data services. However, 4G wireless communication systems lack resources to meet the increasing demand for high-speed data services. Accordingly, a 5G wireless communication system is being developed to meet the increasing demand for various services having various requirements, such as high-speed data service, ultra-reliability, low-delay application, and large-scale machine type communication. Due to the widely supported services and various performance requirements, User Equipments (UEs) are likely to have different capabilities, e.g. in terms of supported UE Bandwidth (BW). Flexible UE bandwidth support needs to be considered in the design of 5G networks, as well as flexible network access for UEs with different bandwidth capabilities.

In a 4G LTE network, flexible system bandwidths (e.g., 1.4MHz/3MHz/5MHz/10MHz/15MHz/20MHz) are supported, and channel design is primarily based on the operating system bandwidth. This gives the mandatory requirement that the UE should operate in the same bandwidth as the system, except for initial access when the UE has no information of the system bandwidth. Since the UE does not have information of a system bandwidth in initial access, a basic signal and a channel are transmitted based on a predetermined bandwidth (e.g., a minimum bandwidth supported by a network).

Fig. 1 illustrates system operation in LTE.

As shown in fig. 1, transmission of synchronization signals (e.g., Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS)) and broadcast channels (e.g., Physical Broadcast Channel (PBCH)) is fixed at the center of the system bandwidth and limited within a predetermined bandwidth accessible to all UEs. After receiving the PBCH, the UE may obtain a system bandwidth, which is indicated in a Master Information Block (MIB) carried by the PBCH. The transmission of other channels/signals occupies the full system bandwidth because the UE has access to the actual system bandwidth after obtaining the system bandwidth information.

Fig. 2 shows a flowchart for a UE to perform initial access.

Referring to fig. 2, in operation 210, a UE searches for a PSS/SSS. In operation 220, if the UE detects the PSS/SSS, the UE derives a center frequency of the system bandwidth based on the PSS/SSS and obtains a symbol/slot/frame boundary. In operation 230, the UE receives the PBCH and decodes the MIB based on the information derived and obtained in operation 220. In operation 240, the UE obtains information on a System Frame Number (SFN), a system bandwidth, etc., from the decoded MIB. In operation 250, the UE searches for a PDCCH in a system-wide bandwidth to receive system information.

Meanwhile, for a UE whose bandwidth is smaller than the system bandwidth, it is impossible for the UE to access a channel occupying the full system bandwidth. The current system has a limitation in supporting flexible access of UEs having various bandwidths.

The above information is presented merely as background information to aid in understanding the present disclosure. No determination is made as to whether any of the above is applicable as prior art to the present disclosure, nor is any assertion made.

Disclosure of Invention

Technical problem

Aspects of the present disclosure are directed to solving at least the above problems and/or disadvantages and to providing at least the advantages described below. Accordingly, it is an aspect of the present disclosure to provide a communication method and system for merging fifth generation (5G) communication systems that support higher data rates than fourth generation (4G) systems.

Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the presented embodiments.

The present disclosure provides a method and apparatus for receiving/transmitting data in a cellular network.

The present disclosure provides methods and apparatus for initial access in next generation cellular networks.

The present disclosure provides a method and apparatus for supporting flexible access of terminals having various bandwidths.

Technical scheme

According to a first aspect of the present disclosure, a method for a terminal receiving data in a cellular network is provided. The method includes receiving a synchronization signal block (SS block) including at least one synchronization signal and a broadcast channel from a base station, identifying an offset between the SS block and a Resource Block (RB) grid from system information in the broadcast channel, and determining the RB grid based on the offset.

According to a second aspect of the present disclosure, a method is provided for a base station transmitting data in a cellular network. The method includes determining a location of a Resource Block (RB) grid and a synchronization signal block (SS block) including at least one synchronization signal and a broadcast channel, and transmitting the SS block to a terminal based on the RB grid. The offset between the SS block and the RB grid is transmitted in system information through a broadcast channel.

According to a third aspect of the present disclosure, a terminal for receiving data in a cellular network is provided. The terminal includes a transceiver and a controller coupled to the transceiver. The transceiver is configured to receive signals from and transmit signals to a base station. The controller is configured to control the transceiver to receive a synchronization signal block (SS block) including at least one synchronization signal and a broadcast channel from the base station, identify an offset between the SS block and a Resource Block (RB) grid from system information in the broadcast channel, and determine the RB grid based on the offset.

According to a fourth aspect of the present disclosure, there is provided a base station for transmitting data in a cellular network. The base station includes a transceiver and a controller coupled to the transceiver. The transceiver is configured to receive signals from and transmit signals to the terminal. The controller is configured to determine a location of a Resource Block (RB) grid and a synchronization signal block (SS block) including at least one synchronization signal and a broadcast channel, control the transceiver to transmit the SS block to the terminal based on the RB grid, and control the transceiver to transmit an offset between the SS block and the RB grid to the terminal in system information through the broadcast channel.

Technical effects

Flexible access for terminals may be supported with various bandwidths.

Other aspects, advantages, and salient features of the disclosure will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses various embodiments of the disclosure.

Drawings

The above and other aspects, features and advantages of certain embodiments of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

fig. 1 illustrates system operation in Long Term Evolution (LTE);

fig. 2 shows a flowchart of a User Equipment (UE) performing initial access;

fig. 3 shows an example of a resource grid structure of an Orthogonal Frequency Division Multiplexing (OFDM) based communication system;

FIG. 4 shows an example of a same size channel grid (raster) and synchronization grid;

FIG. 5 shows another example of a channel grid and synchronization grid of the same size;

FIG. 6 shows examples of different sized channel grids and synchronization grids;

fig. 7 shows an example of an SS block including a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS)) and a Physical Broadcast Channel (PBCH);

fig. 8 shows an example of valid candidates for the center frequency of a synchronization signal block (SS block);

fig. 9 shows another example of valid candidate center frequencies for an SS block;

fig. 10 shows an example of valid candidates for the SS block center frequency;

fig. 11 shows another example of a subset of valid candidate center frequencies for an SS block;

FIG. 12 shows examples of different sized channel grids and synchronization grids;

fig. 13 shows an example of candidate center frequencies of SS blocks having different sized channel grids and synchronization grids;

fig. 14a shows an example of effective SS block candidate center frequencies for both narrowband and wideband carriers;

fig. 14b shows another example of effective SS block candidate center frequencies for both narrowband and wideband carriers;

FIG. 15 shows an example of arbitrary subcarrier level offsets between an SS block RB grid and an actual system RB grid;

FIG. 16 shows an example of misalignment between a SS block Resource Block (RB) grid and an actual system RB grid;

fig. 17 is a flow diagram of a gNB procedure to determine SS block center frequencies and indicate to a UE;

fig. 18 is a flowchart of a UE process of searching for SS block center frequencies and deriving carrier center frequencies;

fig. 19 shows an example of carrier center frequency indication in a Master Information Block (MIB);

fig. 20 shows an example of carrier center frequency indication in Remaining Minimum System Information (RMSI);

fig. 21 shows an example of Bandwidth (BW) related indication of SS block location in MIB;

fig. 22a and 22b are flow diagrams of a gNB procedure to determine SS block center frequencies and indicate to a UE;

fig. 23 is a flowchart of a UE process of searching for an SS block center frequency and deriving a carrier center frequency;

fig. 24 shows an example of a network configuring a carrier index to a UE;

FIG. 25 is a flow diagram of a UE obtaining information for multiple carriers and carriers assigned to the UE;

fig. 26, 27 and 28 show multiple SS blocks in a single carrier;

fig. 29 is a flowchart for a UE to acquire information of a plurality of SS blocks;

fig. 30 shows a plurality of SS blocks transmitted in a wideband carrier;

31a, 31b and 31c are examples of indications of RMSI control resource set (CORESET) frequency locations;

FIG. 32 shows a UE procedure for obtaining RMSI CORESET frequency resource location information;

FIG. 33 shows an example of indications of limited cases of RMSI CORESET frequency locations;

FIG. 34 shows another example of an indication of RMSI CORESET frequency location;

FIGS. 35, 36, and 37 show examples of indications of RMSI CORESET frequency locations;

fig. 38 shows an example of the RMSI CORESET position case for the same subcarrier spacing case;

fig. 39 shows an example of the RMSI CORESET position case for different subcarrier spacing cases;

fig. 40 is a block diagram of a terminal according to an embodiment of the present invention; and

fig. 41 is a block diagram of a base station in accordance with an embodiment of the present disclosure.

Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.

Detailed Description

The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the disclosure as defined by the claims and their equivalents. It includes various specific details to aid understanding, but these are to be regarded as exemplary only. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are not limited to the written meaning, but are used only by the inventors to enable a clear and consistent understanding of the disclosure. Accordingly, it will be apparent to those skilled in the art that the following descriptions of the various embodiments of the present disclosure are provided for illustration only and not for the purpose of limiting the disclosure as defined by the appended claims and their equivalents.

It is understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a "component surface" includes reference to one or more such surfaces.

The term "substantially" means that the property, parameter or value does not need to be achieved exactly, but rather that a certain amount of deviation or variation may occur without excluding the effect that the property is intended to provide, for example, such deviation or variation including tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art.

Blocks of the flowchart (or sequence diagram) and combinations of blocks in the flowchart (or sequence diagram) can be represented by computer program instructions and executed by those skilled in the art. These computer program instructions may be loaded onto a processor of a general purpose computer, special purpose computer, or a programmable data processing apparatus. When the processors execute the loaded program instructions, they create means for implementing the functions specified in the flowchart. Because the computer program instructions may be stored in a computer-readable memory that can be used in a special purpose computer or a programmable data processing apparatus, an article of manufacture that performs the function described in the flowchart may also be created. Because the computer program instructions may be loaded onto a computer or a programmable data processing apparatus, they may perform the operations of the functions described in the flowcharts when they are run as a process.

The blocks of the flowchart may correspond to modules, segments, or code containing one or more executable instructions for implementing one or more logical functions, or may correspond to portions thereof. In some cases, the functions described by the blocks may be performed in an order different than the order listed. For example, two blocks listed in sequence may run simultaneously or in reverse order.

In this specification, the terms "unit", "module", and the like may refer to a software component or a hardware component capable of performing a function or an operation, such as, for example, a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC). However, "unit" and the like are not limited to hardware or software. A unit or the like may be configured to reside in the addressable storage medium or to drive one or more processors. A unit, etc. may refer to a software component, an object-oriented software component, a class component, a task component, a procedure, a function, an attribute, a procedure, a subroutine, a program code segment, a driver, firmware, microcode, circuitry, data, a database, a data structure, a table, an array, or a variable. The functionality provided by the components and units may be combined in smaller components and units and may be combined with other components and units to form larger components and units. The components and units may be configured to drive a device or one or more processors in a secure multimedia card.

Before the detailed description, terms or definitions necessary for understanding the present disclosure are described. However, these terms should be construed in a non-limiting manner.

A "Base Station (BS)" is an entity that communicates with a User Equipment (UE), and may be referred to as a BS, a Base Transceiver Station (BTS), a Node B (NB), an evolved NB (eNB), an Access Point (AP), or a 5G NB (5 GNB).

The "UE" is an entity communicating with the BS, and may be referred to as a UE, a device, a Mobile Station (MS), a Mobile Equipment (ME), or a terminal.

A. Basic operation

Considering an Orthogonal Frequency Division Multiplexing (OFDM) based communication system, resource elements may be defined by subcarriers during an OFDM symbol duration. In the time domain, a Transmission Time Interval (TTI) consisting of a plurality of OFDM symbols may be defined. In the frequency domain, a Resource Block (RB) consisting of a plurality of OFDM subcarriers may be defined.

Fig. 3 shows an example of a resource grid structure of an OFDM based communication system.

As shown in fig. 3, the resources may be divided into TTIs in the time domain and RBs in the frequency domain. In general, an RB may be a baseline resource unit for resource mapping and scheduling in the frequency domain.

As shown in fig. 2, when a UE accesses a network, the UE first searches for synchronization signals (e.g., a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS)) to obtain time/frequency synchronization and a cell identifier (i)dentist, ID). Similar to other cellular networks, the deployment of next generation cellular systems requires consideration of channel grid requirements. For example, in Long Term Evolution (LTE), the channel grid is Δ f for all bands_{ch_raster}This means that the carrier center frequency is an integer multiple of 100 kHz. The carrier center frequency candidate may be defined as f_n＝f_o+n×Δf_{ch_raster}Is shown in which f_oIs a reference frequency in a certain frequency band, e.g. f_o0Hz and n is an integer used to derive a certain carrier center frequency fn. The carriers may be located around a certain center frequency candidate with a given carrier bandwidth.

Synchronous grid Δ f_{sync_raster}Determines the granularity with which the UE searches for synchronization signals (e.g., PSS/SSS in LTE) over the frequency range.

Fig. 4 shows an example of a channel grid and a synchronization grid of the same size.

As shown in the example of FIG. 4, if the synchronization grid is the same as the channel grid, for example, Δ f_{sync_raster}＝Δf_{ch_raster}At 100kHz, the carrier center frequency candidate is also a candidate for the center frequency of the synchronization signal. In this case (which may be the case in LTE), the center frequency of the synchronization signal may be fixed to the center frequency of the carrier. Here, a synchronization signal block (SS block) may include a PSS, an SSs, and a Physical Broadcast Channel (PBCH). When the UE is turned on, the UE synchronizes with the grid Δ f_{sync_raster}Searches for a synchronization signal from among the SS block center frequency candidates. If the UE is on a certain frequency f_nIn detecting the synchronization signal, the UE assumes f_nIs the SS block center frequency and the center frequency of the current carrier.

To allow flexible deployment, the SS block center frequency is not forced to be the same as the center frequency of the corresponding carrier.

Fig. 5 shows another example of a channel grid and a synchronization grid of the same size.

As shown in the example of FIG. 5, the carrier center frequency is f_nAnd there are multiple SS block center frequency candidates within the carrier. The SS block may be located at the center frequencyRate candidate f_mIn, f_mAnd f_nDifferent. In this case, when the UE is turned on, the UE searches for a synchronization signal from among SS block center frequency candidates. If the UE is on a certain frequency f_mIn detecting the synchronization signal, the UE cannot assume the detected frequency f_mThe same as the center frequency of the current carrier.

The size of the synchronization grid may be different in each frequency range. For example, for frequency ranges supporting wider carrier bandwidths and operating in a wider spectrum (e.g., above 6 GHz), a larger synchronization grid size may be used to reduce the search time for initial access.

Fig. 6 shows examples of different sizes of channel grids and synchronization grids.

As shown in the example of FIG. 6, the size of the synchronization grid is larger than the size of the channel grid, i.e., Δ f_{sync_raster}＞Δf_{ch_raster}. The carrier center frequency candidate may be defined as f_ch,n＝f_o+n×Δf_{ch_raster}The candidate for the center frequency of the SS block may be represented by f_sync,m＝f_o+m×Δf_{sync_raster}And (4) showing. Let Δ f_{sync_raster}＝k×Δf_{ch_raster}Where k is a predetermined positive integer representing the ratio of the synchronization trellis size to the channel trellis size, and the candidates for the SS block center frequency are k times less sparse (sparse) than the candidates for the carrier center frequency. Different values of k may be used in different frequency ranges. Similarly, the SS block center frequency may not always be aligned with the center frequency of the corresponding carrier. If the UE is on a certain frequency f_sync,mWhere a synchronization signal is detected based on the synchronization grid, the UE cannot assume the detected frequency f_sync,mThe same as the center frequency of the current carrier.

Thus, in contrast to conventional cellular systems, the UE needs to be informed where the SS block center frequency is and where the actual carrier center frequency is located. Then, based on the system bandwidth information, the UE may obtain the actual frequency resources occupied by the carrier in the frequency band.

Fig. 7 shows an example of an SS block including PSS, SSS, and PBCH.

Referring to fig. 7 showing an example of an SS block, it has two types of synchronization signals; PSS and SSS and one broadcast channel PBCH. The PSS, SSS, and PBCH may be transmitted within the SS block in a Time Division Multiplexing (TDM) manner. A New radio-PBCH (NR-PBCH) is a non-scheduled broadcast channel that carries at least a part of minimum system information (master information block, MIB)) and a periodicity predetermined according to a carrier frequency range. In the example of fig. 7, in one OFDM symbol, PSS is transmitted in 144 subcarriers, as is SSS. During two OFDM symbols, PBCH is transmitted in 288 subcarriers. For a given frequency band, SS blocks may be transmitted based on a default subcarrier spacing in a predetermined time and frequency resource. The UE may be able to identify an OFDM symbol index, a slot index in a radio frame, and a radio frame number from the SS block. Some other remaining minimum system information (e.g., represented by RMSI or system information block 1 (SIB 1)) may be scheduled by the control channel and sent in the data channel.

B. Determining SS block center frequency

Assuming that the base station (for next generation cellular networks, represented by the gNB) decides the carrier center frequency and carrier bandwidth within the frequency range, there may be multiple SS block center frequency candidates that the UE can search based on the synchronization grid size. Based on a predetermined rule or condition, there may be one or more valid SS block center frequency candidates that are valid for transmission of an SS block in a given carrier. The rules or conditions are predetermined and known to both the gNB and the UE. The number of valid SS block center frequency candidates may be determined by considering a carrier Bandwidth (BW), a carrier center frequency and a channel grid size, and a synchronization grid size. The gNB may select a valid SS block center frequency candidate for transmitting SS blocks in the carrier. To enable the UE to obtain information of carrier center frequencies and/or other relevant information, the gNB may need to send an additional indication if there are multiple valid SS block center frequency candidates. Different methods may be considered to determine valid SS block center frequency candidates.

Case where the channel grid and the synchronization grid are the same size

In case the channel grid and the synchronization grid are of the same size, i.e. Δ f_{sync_raster}＝Δf_{ch_raster}The following method of determining valid SS block center frequency candidates may be considered.

Method 1: in a given carrier, there is one valid SS block center frequency candidate that has a predetermined relationship to the center frequency of the carrier. For example, the SS block center frequency may be the same as the center frequency of the carrier. After the gNB determines the center frequency of the carrier, e.g., f_nThe center frequency of the carrier is by default the center frequency used for transmitting the SS block. This is the situation shown in fig. 4 above. In this case, no indication on the location of the SS block and the carrier center frequency is needed, since the location of the SS block and the carrier center frequency can be derived by the UE based on a predetermined relationship.

Method 2: there is more than one valid SS block center frequency candidate in a given carrier. There are some predetermined limits on the valid SS block center frequency candidates in the carrier.