WO2025098290A1 - Downlink synchronization signal indication method, and communication apparatus - Google Patents

Abstract

A downlink synchronization signal indication method and a communication apparatus, which relate to the field of communications and can increase SSB coverage cell ranges. The method comprises: receiving a first synchronization/physical broadcast channel block (SSB), the first SSB being one SSB in an SSB burst set, the SSB burst set comprising at most K candidate SSBs selected from M candidate SSBs, the first SSB comprising first indication information, the first indication information being used for indicating an index of a candidate SSB corresponding to the first SSB, K being greater than L and K being less than or equal to M, K being an integer, L being a first threshold, M being an integer greater than 1, and L being a positive integer; according to the first indication information, determining an index of the first SSB in the SSB burst set; and according to a random access resource corresponding to the index of the first SSB in the SSB burst set, initiating a random access.

Description

Downlink synchronization signal indication method and communication device

This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on November 10, 2023, with application number 202311498386.9 and application name “Downlink synchronization signal indication method and communication device”, all contents of which are incorporated by reference in this application.

Technical Field

The present application relates to the field of communications, and in particular to a downlink synchronization signal indication method and a communication device.

Background Art

When a terminal device accesses the network, it achieves time and frequency synchronization with the network device by acquiring the synchronization signal (SS)/physical broadcast channel (PBCH) block (SS/PBCH block, SSB). In one half frame, the network device sends multiple SSBs in a beam scanning manner. Multiple SSBs constitute an SSB burst set. Each SSB in the SSB burst set covers different directions of the cell, and each SSB has an SSB index value (index). The SSB actually sent by the network device, that is, the SSB in the SSB burst set, is selected from the candidate SSB set. Each candidate SSB in the candidate SSB set also corresponds to an index. The network device can indicate which candidate SSBs in the candidate SSB set are sent as actual SSBs and which candidate SSBs are not sent in the form of a bitmap. For cells with a frequency less than 3 gigahertz (GHz), the demodulation reference signal (DMRS) of the PBCH can also be used to indicate the index of the candidate SSB corresponding to the SSB actually sent.

For cells with frequencies less than 3 GHz, an SSB burst set includes a maximum of 4 SSBs, that is, the network equipment supports SSB transmission in a maximum of 4 directions. Even in the shared frequency band scenario, if the subcarrier space (SCS) is small, such as SCS is 15 or 30 kilo hertz (KHz), the network equipment supports SSB transmission in a maximum of 2 directions.

However, in a satellite communication scenario, since a satellite covers a very large area, adopting the above implementation method will result in limited cell coverage.

Summary of the invention

The embodiments of the present application provide a downlink synchronization signal indication method and a communication device, which can increase the cell range covered by SSB.

In order to achieve the above objectives, this application adopts the following technical solutions:

In a first aspect, a downlink synchronization signal indication method is provided, which can be executed by a terminal device, or by a component of the terminal device, such as a processor, a chip, or a chip system of the terminal device, or can be implemented by a logic module or software that can implement all or part of the terminal device. The method includes: receiving a first synchronization/physical broadcast channel block SSB. The first SSB is an SSB in an SSB burst set, and the SSB burst set includes at most K candidate SSBs selected from M candidate SSBs. The first SSB includes first indication information, and the first indication information is used to indicate the index of the candidate SSB corresponding to the first SSB, K is greater than L and K is less than or equal to M, K is an integer, L is a first threshold, M is an integer greater than 1, and L is a positive integer. Determine the index of the first SSB in the SSB burst set according to the first indication information. Initiate random access according to the random access resource corresponding to the index of the first SSB in the SSB burst set.

Based on this method, the maximum number of SSBs actually sent is expanded to be consistent with the number of candidate SSBs, so that the direction/index of the SSB actually sent can be expanded to the maximum index of the candidate SSB, that is, the direction/index of the SSB actually sent increases, thereby increasing the coverage range of the cell, and further reducing the cell data in the satellite coverage area, reducing the complexity of network equipment scheduling, and reducing the switching frequency of terminal equipment and improving the success rate of terminal equipment accessing the cell.

In a possible design scheme, the method provided in the embodiment of the present application may further include: receiving second indication information, wherein the second indication information is used to indicate whether the maximum number of SSBs contained in the SSB burst set is L or K. Thus, the terminal device can determine whether to use the extended SSB indication method to interpret the received SSB or the unextended SSB indication method to interpret the received SSB according to the third indication information sent by the network device, so that the terminal device can accurately obtain the corresponding random access resource and initiate random access.

In one possible design scheme, when the communication frequency band is the first communication frequency band, the maximum number of SSBs included in the SSB burst set is K. For example, the first communication frequency band is a satellite communication frequency band, and the extended SSB indication method is used by default in this frequency band. The terminal device can interpret the received SSB based on the extended SSB indication method to determine the random access resource to initiate random access. Correspondingly, when the communication frequency band is the second communication frequency band, the maximum number of SSBs included in the SSB burst set is L. If the second communication frequency band is a terrestrial communication frequency band, the non-extended SSB indication method is used by default in this frequency band. The terminal device can interpret the received SSB based on the non-extended SSB indication method to determine the random access resource to initiate random access.

In a possible design solution, the method provided in the embodiment of the present application may further include: receiving third indication information. The indication information is used to indicate the positions of the X candidate SSBs sent among the M candidate SSBs, where X is greater than or equal to 1 and less than or equal to K, and X is an integer. Thus, the terminal device can learn the positions of the candidate SSBs sent by the network device according to the third indication information.

In one possible design scheme, the third indication information may be a bit map including M bits.

In a possible design scheme, the third indication information may be a pattern index for indicating the positions of the X candidate SSBs among the M candidate SSBs. Thus, the terminal device may be pre-configured with different candidate SSB transmission bitmaps, such as stored in the form of a table, and different candidate SSB transmission bitmaps are used to indicate the situation where different numbers and/or different positions of the M candidate SSBs are transmitted, and each candidate SSB transmission bitmap corresponds to an index, and the third indication information indicates the index of the candidate SSB transmission bitmap of the transmission status of the current candidate SSB, which can reduce the bit overhead.

In a possible design, M candidate SSBs are divided into S candidate SSB groups according to indexes, and the third indication information is specifically used to indicate that candidate SSBs in N candidate SSB groups among the S candidate SSB groups are sent, where the N candidate SSB groups include X candidate SSBs, and N is an integer greater than 0 and less than or equal to S. Thus, the candidate SSBs are grouped, and the third indication information indicates the sending status of each candidate SSB group, which can reduce bit overhead.

In a possible design scheme, the method provided in the embodiment of the present application may further include: receiving fourth indication information. The fourth indication information is used to indicate the number X of candidate SSBs sent among the M candidate SSBs, the X candidate SSBs are candidate SSBs at X fixed positions among the M candidate SSBs, X is greater than or equal to 1 and less than or equal to K, and X is an integer. For example, the X candidate SSBs are candidate SSBs with indexes of 0 to X-1 among the M candidate SSBs, or candidate SSBs with indexes of M-1-X to M-1, and there is no limitation on this. Therefore, the terminal device only needs to determine the number of candidate SSBs currently being sent through the fourth indication information to reduce bit overhead.

In one possible design, M candidate SSBs are divided into S candidate SSB groups, and the method provided in the embodiment of the present application may further include the following steps: receiving fifth indication information. The fifth indication information is used to indicate the number of candidate SSBs sent in each candidate SSB group in the S candidate SSB groups. In this design, the candidate SSBs sent in each candidate SSB group may also be located at a fixed position, so that the terminal device can determine the number and position of the candidate SSBs currently being sent based on the fifth indication information.

In a second aspect, a downlink synchronization signal indication method is provided, which can be executed by a network device, or by a component of the network device, such as a processor, chip, or chip system of the network device, or can be implemented by a logic module or software that can implement all or part of the network device. The method includes: determining a first synchronization/physical broadcast channel block SSB. The first SSB is an SSB in an SSB burst set, and the SSB burst set includes at most K candidate SSBs selected from M candidate SSBs, K is greater than L and K is less than or equal to M, K is an integer, L is a first threshold, M is an integer greater than 1, and L is a positive integer. Send the first SSB. The first SSB includes first indication information, and the first indication information is used to indicate the index of the candidate SSB corresponding to the first SSB, and the index of the candidate SSB corresponding to the first SSB is used to determine the index of the first SSB in the SSB burst set.

In a possible design scheme, the method provided in the embodiment of the present application may further include: sending second indication information. The second indication information is used to indicate whether the maximum number of SSBs included in the SSB burst set is L or K.

In a possible design scheme, when the communication frequency band is the first communication frequency band, the maximum number of SSBs included in the SSB burst set is K.

In a possible design, when the communication frequency band is the first communication frequency band, third indication information is sent. The third indication information is used to indicate the positions of X candidate SSBs sent among the M candidate SSBs, where X is greater than or equal to 1 and less than or equal to K, and X is an integer.

In one possible design scheme, the third indication information may be a bit map including M bits.

In a possible design scheme, the third indication information may be a pattern index used to indicate the positions of the X candidate SSBs among the M candidate SSBs.

In one possible design scheme, M candidate SSBs are divided into S candidate SSB groups, and the third indication information is specifically used to indicate that candidate SSBs in N candidate SSB groups among the S candidate SSB groups are sent, and the N candidate SSB groups include X candidate SSBs.

In a possible design scheme, the method provided in the embodiment of the present application may further include: sending fourth indication information. The fourth indication information is used to indicate the number X of candidate SSBs sent among the M candidate SSBs, the X candidate SSBs are candidate SSBs at X fixed positions among the M candidate SSBs, X is greater than or equal to 1 and less than or equal to K, and X is an integer.

In a possible design scheme, M candidate SSBs are divided into S candidate SSB groups, and the method provided in the embodiment of the present application may further include: sending fifth indication information. The fifth indication information is used to indicate the number of candidate SSBs sent in each candidate SSB group in the S candidate SSB groups.

In combination with the first aspect or the second aspect, in a possible design scheme, the first threshold may be determined according to the communication frequency band and the subcarrier spacing. That is, based on different communication frequency bands and subcarrier spacings, the number of SSBs that can be sent in the non-extended SSB indication mode may be determined. Maximum quantity.

In combination with the first aspect or the second aspect, in a possible design scheme, the subcarrier spacing is 15KHz or 30KHz, and in the case of a non-shared frequency band: if the communication frequency band is less than or equal to 3GHz, L=4; if the communication frequency band is greater than 3GHz and less than or equal to 6GHz, L=8.

In combination with the first aspect or the second aspect, in a possible design scheme, in the case of a shared frequency band: if the subcarrier spacing is 15 KHz, then L=2; if the subcarrier spacing is 30 KHz, then L=4.

In combination with the first aspect or the second aspect, in a possible design scheme, the index of the first SSB in the SSB burst set is greater than or equal to 0 and less than or equal to M-1, and the index of the first SSB in the SSB burst set corresponds to the index of a candidate SSB.

In combination with the first aspect or the second aspect, in a possible design scheme, the index of the first SSB in the SSB burst set is the same as the index of the candidate SSB corresponding to the first SSB.

In combination with the first aspect or the second aspect, in a possible design scheme, the index of the first SSB in the SSB burst set is greater than or equal to 0 and less than or equal to K-1, K is the maximum number of candidate SSBs that do not have a quasi-co-location relationship, and the index of the first SSB corresponds to the index of at least one candidate SSB. That is, K can be a parameter Under this design, the index of one or more candidate SSBs can correspond to the index of an SSB in the SSB burst set. Thus, the terminal device can receive candidate SSBs with different indexes in the same direction. If the random access resources and the candidate indexes correspond one-to-one, the terminal device can obtain more random access resources and achieve non-uniform random access resource allocation.

In combination with the first aspect or the second aspect, in a possible design scheme, the index of the first SSB in the SSB burst set can be determined based on the first indication information and K.

In combination with the first aspect or the second aspect, in a possible design scheme, when the maximum number of SSBs included in the SSB burst set is K, the bits occupied by the first indication information include a first bit and a second bit, the first bit is multiplexed to indicate the bits occupied by the information that the Type0-physical downlink control channel PDCCH and the SSB have the same subcarrier spacing, and the second bit is multiplexed to indicate the bits occupied by the information that the resource block boundary of the SSB satisfies an even or odd number of subcarriers. Thus, by multiplexing the bits occupied by the existing information, the bit indication overhead can be reduced.

Among them, the relevant description of the technical effects achieved by the method described in the second aspect can refer to the technical effects described in the method described in the first aspect, and no further details are given.

In a third aspect, a communication device is provided for implementing the above-mentioned various methods. The communication device may be the terminal device in the above-mentioned first aspect or the network device in the above-mentioned second aspect, or a device including the above-mentioned terminal device or network device, or a device included in the above-mentioned terminal device or network device, such as a chip. The communication device includes corresponding modules, units, or means for implementing the methods described in the above-mentioned first aspect or second aspect, and the modules, units, or means may be implemented by hardware, software, or by executing corresponding software implementations by hardware. The hardware or software includes one or more modules or units corresponding to the above-mentioned functions.

In some possible designs, the communication device includes: a processing module and a transceiver module. The transceiver module is used to indicate the transceiver function of the communication device. The processing module is used to perform functions of the communication device other than the transceiver function.

In a possible design, the transceiver module may include a receiving module and a sending module, wherein the sending module is used to implement the sending function of the communication device described in the third aspect, and the receiving module is used to implement the receiving function of the communication device described in the third aspect.

In a possible design scheme, the communication device described in the third aspect may further include a storage module, which stores a program or instruction. When the processing module executes the program or instruction, the communication device described in the third aspect can execute the method described in the first aspect or the second aspect.

In a fourth aspect, a communication device is provided (for example, the communication device may be a chip or a chip system). The communication device includes: a processor, configured to implement the functions involved in the first aspect or the second aspect.

In a possible design, the communication device may further include a memory, the memory being used to store necessary program instructions and data. A processor is coupled to the memory, the processor being used to execute a computer program or instruction stored in the memory, so that the communication device executes the method described in the first aspect or the second aspect.

In a possible design solution, the communication device described in the fourth aspect may further include a transceiver. The transceiver may be a transceiver circuit or an interface circuit. The transceiver may be used for the communication device described in the fourth aspect to communicate with other communication devices.

In one possible design, the processor may be integrated with the memory.

In some possible designs, when the device is a chip system, it can be composed of a chip or include a chip and other discrete devices.

In a fifth aspect, a communication device is provided, the communication device comprising a processor and an interface circuit, the interface circuit being used to receive a signal from another communication device other than the communication device and transmit it to the processor or to send a signal from the processor to another communication device other than the communication device. The processor is configured to implement the method described in the first aspect or the second aspect through a logic circuit or by executing code instructions.

In a sixth aspect, a communication device is provided, which may be a terminal device, or a module or unit (e.g., a chip, or a chip system, or a circuit) in a terminal device that corresponds to the method/operation/step/action described in the first aspect, or may be used in combination with a terminal device. The communication device may be a network device, or a module or unit (e.g., a chip, or a chip system, or a circuit) in a network device that corresponds to the method/operation/step/action described in the second aspect, or may be used in combination with a network device.

It can be understood that when the communication device provided in any one of the fourth aspect or the sixth aspect is a chip, the above-mentioned sending action/function can be understood as output, and the above-mentioned receiving action/function can be understood as input.

In a seventh aspect, a computer-readable storage medium is provided, in which a computer program or instruction is stored. When the computer-readable storage medium is run on a communication device, the communication device can execute the method described in the first aspect or the second aspect.

In an eighth aspect, a computer program product comprising instructions is provided, including computer program codes, which, when executed on a communication device, enable the communication device to execute the method described in the first or second aspect above.

In a ninth aspect, a communication system is provided, comprising a communication device (such as a terminal device) for implementing the method described in the first aspect above, and a communication device (such as a network device) for implementing the method described in the second aspect above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of a SSB;

FIG2 is a schematic diagram of a SSB transmission scenario;

FIG3 is a schematic diagram of the architecture of a communication system provided in an embodiment of the present application;

FIG4 is a schematic diagram of a flow chart of a downlink synchronization signal indication method provided in an embodiment of the present application;

FIG5 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application;

FIG6 is a schematic diagram of the structure of another communication device provided in an embodiment of the present application.

DETAILED DESCRIPTION

The embodiments of the present application will present various aspects, embodiments or features around a system that may include multiple devices, components, modules, etc. It should be understood and appreciated that each system may include additional devices, components, modules, etc., and/or may not include all devices, components, modules, etc. discussed in conjunction with the figures. In addition, combinations of these schemes may also be used.

The technical solutions of the embodiments of the present application can be applied to various communication systems, such as wireless fidelity (Wi-Fi) systems, vehicle to everything (V2X) communication systems, device-to-device (D2D) communication systems, Internet of Vehicles communication systems, 4th generation (4G) mobile communication systems such as long term evolution (LTE) systems, worldwide interoperability for microwave access (WiMAX) communication systems, 5th generation (5G) mobile communication systems such as new radio (NR) systems, and future communication systems.

The following introduces the communication system and applicable network elements involved in the embodiments of the present application, as well as related terms.

1. SSB

Exemplarily, FIG1 shows a schematic diagram of the structure of the time-frequency resource structure of an SSB. As shown in FIG1, an SSB is composed of a primary synchronization signal (PSS), a secondary synchronization signal (SSS) and a physical broadcast channel PBCH. An SSB occupies 4 orthogonal frequency division multiplexing (OFDM) symbols in the time domain and 240 subcarriers in the frequency domain, that is, 20 physical resource blocks (PRBs).

The time-frequency resources used for PSS, SSS, PBCH and demodulation reference signal (DMRS) in SSB are shown in Table 1, where: It is the physical cell ID (PCI).

Table 1

As shown in Figure 1 and Table 1, PSS is located in the middle 127 subcarriers of the 240 subcarriers of symbol 0, SSS is located in the middle 127 subcarriers of the 240 subcarriers of symbol 2. In order to protect PSS and SSS, different zero-set subcarriers are respectively arranged at both ends thereof. PBCH is located in symbols 1, 3, and 2, wherein PBCH occupies all subcarriers from 0 to 239 in symbols 1 and 3, and PBCH occupies all subcarriers except the subcarriers occupied by SSS and the zero-set subcarriers for protecting SSS in symbol 2. DMRS is located in symbols 1 and 3 and in the middle of PBCH. There are 60 DMRS in each symbol, each DMRS is separated by 4 subcarriers, and the subcarrier position offset is v.

In a half frame in the time domain, that is, within 5 milliseconds (ms), multiple SSBs are defined. The multiple SSBs are located at different time domain positions but at the same frequency domain position. The multiple SSBs constitute an SSB burst set (SSB burst set). Each SSB in an SSB burst set corresponds to an SSB index value (SSB index), and each SSB is sent in different directions through different beams at different times, which can achieve the purpose of covering cells in different directions. An SSB burst set in the entire half frame can be repeatedly sent periodically. This period can be called an SSB burst period or an SSB burst set period. In the cell search phase, the SSB burst period defaults to 20ms, but it can also be configured or reconfigured to other values. In addition, the PBCH in the SSB carries the master information block (MIB), and the update period of the MIB is 80ms.

When accessing the network, the terminal device can complete time and frequency synchronization with the network device based on the PSS and SSS in the received SSB, obtain PCI, and then obtain broadcast information based on PBCH, such as MIB and timing-related information from the physical layer.

As shown in Figure 2, the SSB burst set sent in the first half of a 10ms frame includes 8 SSBs, namely SSB0 to SSB7. The network device sends 8 SSBs in different directions through different beams, and each SSB sent has a corresponding random access resource. The terminal device within the coverage of the network device can initiate access on the random access resource corresponding to the SSB with the strongest received signal. For example, if the SSB1 signal received by terminal device 1 is the strongest, terminal device 1 can initiate random access on the random access resource corresponding to SSB1. If the SSB7 signal received by terminal device 2 is the strongest, terminal device 2 can initiate random access on the random access resource corresponding to SSB7. Accordingly, the network device can determine in which beam direction the terminal device initiates access by receiving the random access signal.

Different NR frequency bands can support different maximum numbers of SSBs sent in a half frame, that is, the maximum number of SSBs included in an SSB burst set is different. For example, for the 3-6GHz frequency band, NR supports up to 8 SSBs; for frequency bands below 3GHz, NR supports up to 4 SSBs; for frequency bands above 6GHz, NR supports up to 64 SSBs. Usually, the maximum number of SSBs included in an SSB burst set is expressed as L.

For communication frequency bands below 3 GHz, such as L=4, the index of the SSB received by the terminal device can be obtained from the DMRS pilot (i_SSB) of the PBCH channel; for frequency bands above 3 GHz, the index of the SSB received by the terminal device, the lower 3 bits can be obtained from the DMRS pilot signal of the PBCH channel, and the upper 3 bits can be obtained from the PBCH payload information.

Regarding the time domain position of sending SSB and the number of SSBs, the 3rd generation partnership Project (3GPP) standard protocol defines five SSB modes according to the position of the synchronization grid, namely case A to case E. The following takes case A and case C as examples for shared frequency bands and non-shared frequency bands respectively. The time domain position of sending SSB is determined according to the SSB 5ms half radio frame, the number of candidate SSBs and the first symbol index position are determined according to the subcarrier spacing of the SSB.

In non-shared frequency bands, the number of candidate SSBs is the same as the maximum number of SSBs that can be transmitted (i.e., the maximum number of SSBs in an SSB burst set). The number of candidate SSBs and the first symbol index position are determined according to the subcarrier spacing of the SSB. The index of the first OFDM symbol of the candidate SSB is as follows:

For SCS of 15KHz, caseA: {2,8}+14n; where n=0,1 for a communication frequency band less than or equal to 3GHz; and n=0,1,2,3 for a communication frequency band greater than 3GHz and less than or equal to 6GHz.

For SCS of 30KHz, case C: {2,8}+14n;

Among them, frequency division duplexing (FDD): for communication frequency bands less than or equal to 3 GHz, n = 0, 1; for communication frequency bands greater than 3 GHz and less than or equal to 6 GHz, n = 0, 1, 2, 3;

Time division duplexing (TDD): For communication frequency bands less than or equal to 2.4 GHz, n=0,1; for communication frequency bands greater than 2.4 GHz and less than or equal to 6 GHz, n=0,1,2,3.

From the above, it can be seen that for the communication frequency band less than or equal to 3 GHz, the subcarrier spacing SCS is 15 kilohertz (KHz) or 30 KHz, and L=4; for the communication frequency band greater than 3 GHz and less than or equal to 6 GHz, the SCS is 15 KHz or 30 KHz, and L=8.

In this scenario, the index of the actually transmitted SSB in the SSB burst set is the index of the candidate SSB. 4 bits are used to support up to 4 SSB transmissions, or 8 bits are used to support up to 8 SSB transmissions. If a bit is 0, the candidate SSB at the position corresponding to the bit with the value of 0 is not transmitted; if a bit is 1, the candidate SSB at the position corresponding to the bit with the value of 1 is transmitted.

From this, we can see that in the non-shared frequency band scenario, for the communication frequency band below 3 GHz, the SCS is 15 KHz or 30 KHz, the number of candidate SSBs is at most 4, and it also supports at most 4 beams of coverage, and the supported coverage is limited.

In the shared frequency band scenario, the number of candidate SSBs and the first symbol index position are determined according to the subcarrier spacing of the SSB, as follows:

For the index of the first OFDM symbol of the candidate SSB:

For SCS of 15KHz, caseA: {2,8}+14n, n=0,1,2,3,4;

For SCS of 30KHz, case C: {2,8}+14n, n＝0,1,2,3,4,5,6,7,8,9.

It can be seen that when the SCS is 15KHz, the network device supports 10 candidate SSBs; when the SCS is 30KHz, the network device supports 20 candidate SSBs. The SSB actually sent can be selected from the 10 or 20 candidate SSBs, that is, the number of supported candidate SSBs increases, and the index of the actual SSB can be calculated from the index of the candidate SSB.

For the calculation of the index of the SSB actually sent, according to formula (1) Or according to formula (2) To obtain, among which is the index of the candidate SSB corresponding to the SSB actually transmitted. Formula (1) indicates that the index of the candidate SSB is directly determined based on the DMRS. The parameter of formula (2) is Indicates that the index of the candidate SSB needs to be combined with the PBCH payload and According to formula (1) or (2), the index of the SSB actually sent will not exceed In addition, the SSBs actually sent will not have the same SSB index.

In this scenario, the number of SSBs actually sent does not exceed is the maximum number of candidate SSBs that do not have a quasi-colocation (QCL) relationship, for different subcarrier spacings, The values of are shown in Table 2 below:

Table 2

From Table 2, we can see that for SCS of 15KHz, The maximum is 2; for SCS it is 30KHz, The maximum is 8. That is, in the shared frequency band scenario, for communication frequency bands below 3 GHz, although the number of supported candidate SSBs increases, the number of SSBs supported for transmission is still small, and the supported coverage is limited.

2. Satellite Communications

Satellite communications have their own unique advantages over ground communications, such as providing a wider coverage area; satellite base stations are not easily damaged by natural disasters or external forces. If satellite communications are introduced into 5G communications in the future, it can provide communication services for areas that cannot be covered by ground communication networks, such as oceans and forests; enhance the reliability of 5G communications, such as ensuring that airplanes, trains, and users on these transportations receive better communication services; provide more data transmission resources for 5G communications and increase the network speed. Therefore, supporting communications with both the ground and satellites at the same time is an inevitable trend for future 5G communications, which has relatively large benefits in terms of wide coverage, reliability, multiple connections, and high throughput.

In satellite communication scenarios, a satellite covers a very large area. For non-shared frequency bands and low-frequency scenarios, the number of candidate SSBs and the number of SSBs sent are at most 4 or 8. If the coverage of a cell is limited to only 4 or 8 SSB beam directions, then a satellite will include a lot of cells. This increases the complexity of network-side scheduling. At the same time, due to the satellite's altitude, the terminal device may quickly switch from one cell to another, increasing the frequency of cell switching for the terminal device.

Although the shared spectrum technology increases the number of candidate SSBs to 20, the actual number of SSBs that can be transmitted will not exceed 8 at most, and will not exceed 2 when the subcarrier spacing is relatively small. There is also the problem of limited cell coverage.

Therefore, in satellite communication scenarios, how to improve cell coverage during downlink synchronization has become an urgent problem to be solved.

In order to better understand the embodiments of the present application, the following explanations are made before introducing the embodiments of the present application.

First, in the embodiments of the present application, "used for indication" may include being used for direct indication and being used for indirect indication. When describing that a certain "indication information" is used to indicate A, it may include that the indication information directly indicates A or indirectly indicates A, but it does not mean that the indication information must carry A.

The information indicated by the indication information is called the information to be indicated. In the specific implementation process, there are many ways to indicate the information to be indicated, such as but not limited to, directly indicating the information to be indicated, such as the information to be indicated itself or the index of the information to be indicated. The information to be indicated can also be indirectly indicated by indicating other information, where the other information is associated with the information to be indicated. Only a part of the information to be indicated is indicated, while the other parts of the information to be indicated are known or agreed in advance. For example, the indication of specific information can also be achieved by using the arrangement order of each information agreed in advance (such as protocol regulations), thereby reducing the indication overhead to a certain extent. At the same time, the common parts of each information can also be identified and indicated uniformly, so as to reduce the indication overhead caused by indicating the same information separately.

In addition, the specific indication method may also be various existing indication methods, such as but not limited to the above-mentioned indication methods and various combinations thereof. The specific details of the various indication methods can refer to the prior art and will not be repeated herein. As can be seen from the above, for example, when it is necessary to indicate multiple information of the same type, different indication methods may be used for different information. In the specific implementation process, the desired indication method can be selected according to specific needs. The embodiment of the present application does not limit the selected indication method. In this way, the indication method involved in the embodiment of the present application should be understood to cover various methods that can enable the party to be indicated to obtain the information to be indicated.

The information to be indicated can be sent as a whole, or divided into multiple sub-information and sent separately, and the sending period and/or sending time of these sub-information can be the same or different. The specific sending method is not limited in this application. Among them, the sending period and/or sending time of these sub-information can be pre-defined, for example, pre-defined according to the protocol, or configured by the transmitting device by sending configuration information to the terminal device. Among them, the configuration information can include, for example but not limited to, one or a combination of at least two of radio resource control (radio resource control, RRC) signaling, media access control (media access control, MAC) layer signaling and physical layer signaling. Among them, MAC layer signaling, for example, includes MAC-control element (control element, CE); physical (physical, PHY) layer signaling, for example, includes downlink control information (downlink control information, DCI).

Second, in the embodiments of the present application, the first, second and various digital numbers are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application. For example, to distinguish different indication information. For another example, the first indication information and the second indication information are only used to distinguish different areas, and their order is not limited. Those skilled in the art can understand that the words "first", "second" and the like do not limit the quantity and execution order, and the words "first", "second" and the like do not necessarily limit them to be different.

Third, in the embodiments of the present application, descriptions such as "when...", "in the case of...", "if" and "if" all mean that under certain objective circumstances, the device (such as a terminal device or a network device) will make corresponding processing, which does not limit the time, and does not require the device (such as a terminal device or a network device) to have a judgment action when implementing it, nor does it mean that there are other limitations.

Meanwhile, in the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a concrete manner for ease of understanding.

Finally, the network architecture and business scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. Ordinary technicians in this field can know that with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

To facilitate understanding of the embodiments of the present application, a communication system applicable to the embodiments of the present application is first described in detail using the communication system shown in Figure 3 as an example.

As shown in Figure 3, the communication system includes a network device and a plurality of terminal devices communicating with the network device. Optionally, the communication system may also include a core network device communicating with the network device.

Among them, the core network device referred to in the embodiment of the present application is a device deployed in the core network to provide services for terminal devices. In systems using different wireless access technologies, the names of core network devices with similar wireless communication functions may be different. For example, when the communication method of the embodiment of the present application is applied to a 5G system, the core network device may be an access and mobility management function (AMF) network element, a session management function (SMF) network element, a user plane function (UPF) network element, etc. Among them, the UPF network element processes user plane data. The AMF network element and the SMF network element process control plane signaling. When the precoding method of the embodiment of the present application is applied to an LTE system, the core network device may be a mobility management entity (MME). For the convenience of description only, in the embodiment of the present application, the above-mentioned devices that can provide services for terminal devices are collectively referred to as core network devices.

In the embodiments of the present application, the network device may also be referred to as an access network (radio access network, RAN) node, access network device, RAN entity or access node, etc., which is located on the network side of the above-mentioned communication system to help terminal devices achieve wireless access, and has a device with wireless transceiver function or a chip or chip system that can be set in the device. The network device includes but is not limited to: base station (base station), evolved base station (evolved NodeB, eNodeB), access point (access point, AP), transmission reception point (transmission reception point, TRP), next generation base station (next generationNodeB, gNB), base station in future mobile communication system, or access node in Wi-Fi system, etc. The network device can be a macro base station, a micro base station or an indoor station, a relay node or a donor node, an open wireless access network A wireless controller in an open radio access network (ORAN) or centralized radio access network (CRAN) scenario. Optionally, the RAN node may also be a server, a wearable device, a vehicle or an on-board device, etc. For example, the access network device in the V2X technology may be a road side unit (RSU). All or part of the functions of the network device in this application may also be implemented by software functions running on hardware, or by virtualization functions instantiated on a platform (such as a cloud platform). The network device in this application may also be a logical node, a logical module or software that can implement all or part of the functions of the network device.

In another possible scenario, multiple RAN nodes collaborate to assist terminal devices in achieving wireless access, and different RAN nodes implement part of the functions of the base station. For example, the RAN node can be a central unit (CU), a distributed unit (DU), a CU-control plane (CP), a CU-user plane (UP), or a radio unit (RU). The CU and DU can be set separately, or can also be included in the same network element, such as a baseband unit (BBU). The RU can be included in a radio frequency device or a radio frequency unit, such as a remote radio unit (RRU), an active antenna unit (AAU), or a remote radio head (RRH).

In different systems, CU (or CU-CP and CU-UP), DU or RU may also have different names, but those skilled in the art can understand their meanings. For example, in the ORAN system, CU may also be called O-CU (open CU), DU may also be called O-DU, CU-CP may also be called O-CU-CP, CU-UP may also be called O-CU-UP, and RU may also be called O-RU. For the convenience of description, CU, CU-CP, CU-UP, DU and RU are described as examples in this application. Any unit of CU (or CU-CP, CU-UP), DU and RU in this application may be implemented by a software module, a hardware module, or a combination of a software module and a hardware module.

As mentioned above, all or part of the functional modules of the network equipment can be deployed on an airborne platform or satellite, or other forms of communication equipment deployed in the sky. Accordingly, the network equipment can refer to an airborne platform, satellite, or other similar equipment that connects the terminal equipment to the network equipment. The airborne platform can include at least one of the following: a satellite, a drone, or a hot air balloon.

The embodiment of the present application does not limit the form of the network device. The device for realizing the function of the network device can be a network device; or it can be a device that can support the network device to realize the function, such as a chip system. The device can be installed in the network device or used in combination with the network device.

In the embodiment of the present application, the terminal device is a terminal that accesses the above-mentioned communication system and has a wireless transceiver function or a chip or chip system that can be set in the terminal. The terminal device can also be called user equipment (UE), user device, access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device. The terminal device in the embodiment of the present application can be a mobile phone, a tablet computer (Pad), a computer with a wireless transceiver function, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self-driving, a wireless terminal in remote medical, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city, a wireless terminal in smart home, a vehicle-mounted terminal, an RSU with terminal function, etc. The terminal device of the present application may also be a vehicle-mounted module, vehicle-mounted module, vehicle-mounted component, vehicle-mounted chip or vehicle-mounted unit that is built into the vehicle as one or more components or units. The vehicle can implement the method provided by the present application through the built-in vehicle-mounted module, vehicle-mounted module, vehicle-mounted component, vehicle-mounted chip or vehicle-mounted unit.

The embodiments of the present application do not limit the device form of the terminal device. The device for realizing the function of the terminal device can be the terminal device; it can also be a device that can support the terminal device to realize the function, such as a chip system. The device can be installed in the terminal device or used in combination with the terminal device. In the embodiments of the present application, the chip system can be composed of chips, or it can include chips and other discrete devices.

In the system architecture shown in FIG3, the system also includes a ground gateway and a data network (DN). Here, the interface for the terminal device to communicate with the access network device may be an air interface or a Uu port. The interface for the access network device to communicate with the ground gateway may be an NG interface. The interface for the ground gateway to communicate with the core network device may be an NG interface. The core network device may be connected only to the ground gateway, in which case the access network device may be connected to the core network device through the ground gateway, as shown in FIG3. The core network device may be connected to more than one ground gateway, in which case the access network device may be connected to the core network device through any one of more than one ground gateways (not shown in FIG3). The core network device (such as a UPF network element) may communicate with entities or network elements in the DN through an interface (such as an N6 interface).

It should be noted that the above only lists the communication methods between some network elements. Other network elements can also communicate through certain connection methods, which will not be repeated here in the embodiments of the present application.

It should be pointed out that the solutions in the embodiments of the present application can also be applied to other communication systems, and the corresponding names can also be replaced by the names of corresponding functions in other communication systems.

The downlink synchronization signal indication method provided in the embodiment of the present application will be specifically described below in conjunction with Figure 4.

Exemplarily, FIG4 is a flow chart of a downlink synchronization signal indication method provided in an embodiment of the present application. The downlink synchronization signal indication method is described by taking the communication between the network device and the terminal device shown in FIG3 as an example. Of course, the subject that executes the terminal device action in the method can also be a device/module in the terminal device, such as a chip, processor, processing unit, etc. in the terminal device; the subject that executes the network device action in the method can also be a device/module in the network device, such as a chip, processor, processing unit, etc. in the network device, and the embodiment of the present application does not specifically limit this.

As shown in FIG4 , the downlink synchronization signal indication method includes:

S401. The network device determines the first SSB.

Among them, the first SSB is an SSB in the SSB burst set. The SSB burst set contains all SSBs that need to be sent by the network device in one beam scan. The network device sends different SSBs in the SSB burst set through different beams in different directions at different times within one half frame. One SSB in the SSB burst set corresponds to one direction, and multiple SSBs do not overlap in direction.

In an embodiment of the present application, the SSB in the SSB burst set is selected from M candidate SSBs, and the SSB burst set includes at most K candidate SSBs selected from the M candidate SSBs, that is, the SSB burst set contains at most K SSBs, and the K SSBs are K candidate SSBs selected from the M candidate SSBs, K is greater than L and K is less than or equal to M, K is an integer, L is a first threshold, M is an integer greater than 1, and L is a positive integer.

The first threshold L is related to the communication frequency band and the subcarrier spacing SCS. Based on different communication frequency bands and SCSs, the value of the first threshold L is different. In some embodiments, the first threshold L can be determined based on the communication frequency band and the subcarrier spacing SCS.

The following describes the first threshold value in different scenarios using the SSB mode as case A and case C:

In a non-shared frequency band and the SCS is 15KHz or 30KHz, if the communication frequency band is less than or equal to 3GHz, that is, f≤3GHz, then L=4; if the communication frequency band is greater than 3GHz and less than or equal to 6GHz, that is, 3GHz＜f≤6GHz, then L=8.

In the shared frequency band, if the SCS is 15KHz, then L = 2; if the SCS is 30KHz, then L = 4. For the shared frequency band scenario, the size of the shared communication frequency band varies based on different regulations and scenario requirements, and there is no limitation on this.

K is less than or equal to L, which is the SSB transmission method described in 3GPP technical specification (TS) 38.213. In the embodiment of the present application, the maximum number of SSBs that can be actually transmitted is enhanced, and the corresponding number of indexes of SSBs transmitted is also increased, and the directions covered are increased.

Each of the M candidate SSBs corresponds to an index, and the index of each candidate SSB can be understood as the index of the candidate SSB in the candidate SSB set, and the candidate SSB set includes M candidate SSBs. In the embodiment of the present application, the indexes of the M candidate SSBs are numbered consecutively starting from 0, that is, the indexes of the M candidate SSBs are 0 to M-1.

In some embodiments, based on different communication frequency bands and subcarrier spacings, the value of the number M of candidate SSBs is different. In an embodiment of the present application, for non-shared frequency band scenarios, in order to enhance the actual maximum number of SSBs that can be sent, the number M of candidate SSBs is also enhanced accordingly, and the enhanced number M of candidate SSBs can reach the number of candidate SSBs in the shared frequency band scenario or more, without limitation. In the following examples, the number of candidate SSBs can be applicable to shared frequency band and non-shared frequency band scenarios. For example, the SSB mode is case A: SCS is 15KHz, M=10; the SSB mode is case C: SCS is 30KHz, M=20.

In some possible situations, the indexes of the M candidate SSBs may also be numbered consecutively starting from 1, without limitation. In addition, in the embodiment of the present application, the index of the candidate SSB may also be referred to as a candidate index, without limitation.

The number of SSBs actually included in the SSB burst set, that is, the number of SSBs actually sent by the network device in one beam scan, is represented by X, which does not exceed the maximum number of SSBs included in the SSB burst set, that is, K, that is, X is greater than 0 and X is less than or equal to K, and X is an integer. The X SSBs in the SSB burst set are the X candidate SSBs selected by the network device from the M candidate SSBs. In other words, the X candidate SSBs selected by the network device from the M candidate SSBs are the X SSBs actually sent, that is, X candidate SSBs among the M candidate SSBs are sent, and the first SSB is any one of the X candidate SSBs.

In a specific example 1, for SCS of 15KHz, L=2, M=K=10, X=8, the indexes of the 10 candidate SSBs are 0 to 9. It can be seen that the number of candidate SSBs is 10, and the network device can send all 10 candidate SSBs at most, that is, the SSB burst set can include a maximum of 10 SSBs, which is the same as the number of candidate SSBs, but the number of candidate SSBs actually sent is less than the maximum number of SSBs that can be sent, that is, the network device selects 8 candidate SSBs from the 10 candidate SSBs for transmission, and the 8 SSBs are sent in 8 different directions.

In a specific example 2, for SCS of 30KHz, M=20, K=16, X=14, the indexes of the 20 candidate SSBs are 0 to 19. It can be seen that the number of candidate SSBs is 20, and the network device can select at most 16 candidate SSBs from the 20 candidate SSBs to send, that is, the SSB burst set can include at most 16 SSBs, and the number of candidate SSBs actually sent is less than the maximum number of SSBs that can be sent, that is, the network device selects 14 candidate SSBs from the 20 candidate SSBs for sending, and the 14 candidate SSBs are sent in 14 different directions.

For each SSB in the SSB burst set, such as the first SSB, it also has a corresponding index in the SSB burst set. The index in the burst set may also be referred to as the index of the SSB, the actual index of the SSB, the actual transmission index of the SSB, etc., without limitation. The index of an SSB in the SSB burst set also corresponds to a transmission direction, and different indexes correspond to different transmission directions. Moreover, the index of each SSB is associated with a random access resource. An SSB may correspond to one or more random access channel occasions (RACH occasions, ROs), and multiple ROs may correspond to one or more SSBs. ROs may be time-frequency resources used for random access of terminal devices.

For one RO, the network device can allocate multiple random access preambles to the terminal device for random access. The value range of the preamble index is associated with the index of the SSB received by the terminal device, and the index of the SSB is associated with the RO. Therefore, for each SSB in the SSB burst set, the network device can map different random access resources for each SSB according to the index of the SSB, so that the terminal device can initiate random access. In other words, the terminal device can determine the resource for initiating random access based on the index of the received SSB in the SSB burst set.

S402: The network device sends a first SSB. Correspondingly, the terminal device receives the first SSB.

Among them, the first SSB includes first indication information, the first indication information is used to indicate the index of the candidate SSB corresponding to the first SSB, and the index of the candidate SSB corresponding to the first SSB is used to determine the index of the first SSB in the SSB burst set.

In a possible implementation, the first indication information may include information for indicating a DMRS sequence and information for indicating a PBCH load. For example, if M=10, the information for indicating a DMRS sequence is 3 bits, and the information for indicating a PBCH load is 1 bit; for another example, if M=20, the information for indicating a DMRS sequence is 3 bits, and the information for indicating a PBCH load is 2 bits.

In another possible implementation, the bits occupied by the first indication information include a first bit and a second bit. The first bit is multiplexed to indicate the bits occupied by the information that the Type0-physical downlink control channel (PDCCH) and the SSB subcarrier spacing are the same, and the second bit is multiplexed to indicate the bits occupied by the information that the resource block boundary of the SSB satisfies an even number or an odd number of subcarriers.

In this implementation, the subcarrier spacing relationship between Type0-PDCCH and SSB and the information that the resource block boundary of SSB satisfies an even number of subcarriers or an odd number of subcarriers can be agreed upon in advance, such as by a protocol agreement; and the 1 bit originally used to indicate that the subcarrier spacing between Type0-PDCCH and SSB is the same and the 1 bit originally used to indicate that the resource block boundary of SSB satisfies an even number of subcarriers or an odd number of subcarriers are used to indicate the index of the candidate SSB corresponding to the first SSB.

For example, M=20, the bits occupied by the first indication information include a first bit, a second bit, and bits occupied by information used to indicate a DMRS sequence, wherein the first bit is 1 bit, the second bit is 1 bit, the first bit and the second bit are 2 bits located at a high position, the bits occupied by the information used to indicate the DMRS sequence are 3 bits, and the first indication information indicates the indexes of 20 candidate SSBs through 5 bits, such as 00000~10011 is used to indicate indexes 0~19, and the remaining indexes 20~31 indicated by 10100~11111 can be used as reserved indexes.

In an embodiment of the present application, the first bit and the second bit may also be 2 bits located in the low order, and the remaining high-order bits are used to indicate the index of the candidate SSB. The bits occupied by the information indicating the DMRS sequence or the bits occupied by the information indicating the PBCH load may be used. The number of bits used is related to the number M of candidate SSBs, and there is no limitation on this.

In an embodiment of the present application, the network device sends X SSBs in the SSB burst set in different directions at different times through different beams within one half frame in the form of beam scanning. The first SSB is the SSB with the strongest signal received by the terminal device among the X SSBs sent. After receiving the first SSB, the terminal device parses the first SSB, obtains the first indication information, and determines the index of the candidate SSB corresponding to the first SSB according to the first indication information, that is, the first SSB is which candidate SSB is sent among the M candidate SSBs. For details, please refer to the relevant description in S403 below, which will not be repeated here.

Continuing to refer to Example 1 above, the 8 SSBs (SSB0~SSB7) included in the SSB burst set correspond to candidate SSBs with indexes 0 to 7 respectively, and the first SSB (SSB5) is a candidate SSB with index 5. The first indication information is indicated by 4 bits, and the first indication information in the first SSB is indicated as 0101.

Continuing to refer to Example 2 above, the 14 SSBs (SSB0 to SSB14) included in the SSB burst set correspond to candidate SSBs with indexes of 0 to 4, 8 to 12, and 16 to 19 respectively, and the first SSB (SSB4) is a candidate SSB with index 4. The first indication information is indicated by 5 bits, and the first indication information in the first SSB is indicated as 00100.

In the embodiment of the present application, since the number and index of SSBs that can be sent are expanded, for the expanded SSB indication method, since the meaning of each field in the MIB message or the system information block (SIB) message may be redefined, for the terminal device, in the current working scenario, whether the SSB indication method is interpreted in an enhanced manner or a non-enhanced manner, the network device can instruct the terminal device through the indication information.

In a possible design scheme, the network device may send second indication information to the terminal device, and correspondingly, the terminal device receives the second indication information from the network device. The second indication information is used to indicate whether the maximum number of SSBs included in the SSB burst set is L or K. The second indication information can be carried in the MIB message and sent. For example, the second indication information is indicated by 1 bit in the reserved bit position in the MIB message, and the bit value is 1 for indicating that the maximum number of SSBs included in the SSB burst set is K, indicating that the current SSB transmission is enhanced; the bit value is 0 for indicating that the maximum number of SSBs included in the SSB burst set is L, indicating that the current SSB transmission is not enhanced. Alternatively, the second indication information is indicated by 1 bit in the reserved bit position in the MIB message, and the bit value is 0 for indicating that the maximum number of SSBs included in the SSB burst set is K, indicating that the current SSB transmission is enhanced; the bit value is 1 for indicating that the maximum number of SSBs included in the SSB burst set is L, indicating that the current SSB transmission is not enhanced. Thus, the terminal device can determine whether the currently received SSB is interpreted in an enhanced manner based on the second indication information.

In addition to the above-mentioned explicit indication method, in a possible design scheme, whether the extended SSB indication method is currently adopted can be determined by the communication frequency band in which the communication frequency band is located through protocol agreement or pre-configuration. If the communication frequency band is the first communication frequency band, the maximum number of SSBs contained in the SSB burst set is K, that is, the extended SSB indication method is adopted; if the communication frequency band is the second communication frequency band, the maximum number of SSBs contained in the SSB burst set is L, that is, the extended SSB indication method is adopted, and the maximum number of SSBs contained in the SSB burst set is L, that is, the non-extended SSB indication method is adopted.

For example, if the terminal device operates in a satellite communication frequency band, the network device adopts an enhanced SSB indication method by default, and accordingly, the terminal device interprets the received SSB based on the extended SSB indication method; if the terminal device operates in a terrestrial network communication frequency band, the network device adopts a non-enhanced SSB indication method by default, and accordingly, the terminal device interprets the received SSB based on the non-extended SSB indication method.

In the embodiment of the present application, the network device may also indicate the sending status of the current candidate SSB of the terminal device through indication information, such as the number and position of the candidate SSBs sent among the M candidate SSBs, which is described below in combination with three design schemes:

In a possible design scheme 1, the network device sends third indication information to the terminal device, and correspondingly, the terminal device receives the third indication information from the network device. The third indication information is used to indicate the positions of X candidate SSBs sent among the M candidate SSBs, where X is greater than or equal to 1 and less than or equal to K, and X is an integer. For example, the third indication information can be carried in a SIB message and sent.

In this design scheme, in a possible implementation 1, the third indication information may be a bit map including M bits, each bit of the M bits corresponds to a candidate SSB, and a bit value of 1 indicates that the candidate SSB at the corresponding position is sent, and a bit value of 0 indicates that the candidate SSB at the corresponding position is not sent; alternatively, a bit value of 0 indicates that the candidate SSB at the corresponding position is sent, and a bit value of 1 indicates that the candidate SSB at the corresponding position is not sent.

Continuing to refer to the above example 1, M=10, X=8, the network device selects candidate SSBs with indexes 0 to 7 from 10 candidate SSBs to send, and the third indication information is indicated by a bitmap including 10 bits, such as the third indication information is 1111111100. Thus, the terminal device can determine that 8 candidate SSBs out of 10 candidate SSBs are sent according to the third indication information, and the sent candidate SSBs are candidate SSBs with indexes 0 to 7.

Continuing to refer to the above example 2, M=20, X=14, the network device selects candidate SSBs with indexes of 0-4, 8-12 and 16-19 from 20 candidate SSBs to send, and the third indication information is indicated by a bitmap including 20 bits, such as the third indication information is 11111000111110001111. Thus, the terminal device can determine that 14 candidate SSBs out of 20 candidate SSBs are sent according to the third indication information, and the sent candidate SSBs are candidate SSBs with indexes of 0-4, 8-12 and 16-19.

In a possible implementation 2, the third indication information is a pattern index for indicating the positions of the X candidate SSBs among the M candidate SSBs. The pattern of the positions of the X candidate SSBs among the M candidate SSBs can be called a transmission bitmap of the candidate SSBs.

In this implementation 2, the network device and the terminal device may be pre-configured with different candidate SSB transmission bitmaps, which may be stored in the form of a table. Different candidate SSB transmission bitmaps are used to indicate the situation where different numbers and/or different positions of candidate SSBs are transmitted among the M candidate SSBs, and each candidate SSB transmission bitmap corresponds to an index. Thus, the network device may indicate the index of the candidate SSB transmission bitmap used to indicate the transmission status of the current candidate SSB to the terminal device, so that the terminal device can determine the number (i.e., X) and position (i.e., the index of the candidate SSB transmitted) of the candidate SSBs transmitted among the M candidate SSBs in the form of a table lookup according to the index.

In a possible implementation 3, M candidate SSBs are divided into S candidate SSB groups, and the third indication information is specifically used to indicate that candidate SSBs in N candidate SSB groups among the S candidate SSB groups are sent, and the N candidate SSB groups include X candidate SSBs, where N is an integer greater than 0 and less than or equal to S.

In the embodiment of the present application, the indexes of the candidate SSBs in the S candidate SSB groups may be continuous, and the division method of the S candidate SSB groups may be: the number of candidate SSBs in each candidate SSB group is specified or pre-configured by the protocol (such as expressed as P, where P is a positive integer), and the M candidate SSBs are divided into S groups according to the specified number of candidate SSBs in the candidate SSB group; or, the number S of candidate SSB groups is specified or pre-configured by the protocol, and the M candidate SSBs are divided into S candidate SSB groups according to the number of SSB groups, and each candidate SSB group includes P candidate SSBs. In other words, S can be determined when P is known, and P can also be determined when S is known.

In some embodiments, among the S candidate SSB groups, the number of candidate SSBs in the candidate SSB groups may be the same or different, or may be partially the same and partially different, and there is no limitation on this.

For example, M=20, which is divided into 10 candidate SSB groups according to the index, such as two candidate SSBs with indexes 0 and 1 constitute candidate SSB group 0, two candidate SSBs with indexes 2 and 3 constitute candidate SSB group 1, and so on. At this time, the third indication information can be indicated by 10 bits, each bit position indicates the transmission status of a candidate SSB, a bit value of 1 indicates that the candidate SSB in the candidate SSB group at the corresponding position is transmitted, and a bit value of 0 indicates that the candidate SSB in the candidate SSB group at the corresponding position is not transmitted, and the X candidate SSBs transmitted are the candidate SSBs contained in the N candidate SSB groups in the S candidate SSB groups.

In a possible design scheme 2, the network device may only inform the terminal device of the number of candidate SSBs sent. The positions of the candidate SSBs sent may be predefined by the protocol or agreed upon by the network device and the terminal device, and there is no limitation on this.

In this design scheme 2, the network device can send fourth indication information to the terminal device, and correspondingly, the terminal device receives the fourth indication information from the network device. The fourth indication information is used to indicate the number X of candidate SSBs sent among the M candidate SSBs, and the X candidate SSBs are candidate SSBs at X fixed positions among the M candidate SSBs. For example, M=10, X=8, then the default candidate SSBs sent are the first 8 candidate SSBs (i.e., candidate SSBs with indexes 0 to 7) or the last 8 candidate SSBs (i.e., candidate SSBs with indexes 2 to 9) among the 10 candidate SSBs, or the first 4 candidate SSBs and the last 4 candidate SSBs (i.e., candidate SSBs with indexes 0 to 3 and 6 to 9), and there is no limitation on this.

In a possible design scheme 3, when M candidate SSBs are divided into S candidate SSB groups, the network device can indicate the number of candidate SSBs sent in each candidate SSB group, and the position of the candidate SSBs sent in each candidate SSB group is predetermined by the protocol or agreed upon by the network device and the terminal device, such as the first Q (Q is a positive integer) or the last Q candidate SSBs in each candidate SSB group are sent by default. The specific description of the division method of the S candidate SSB groups can be the relevant description in implementation 3 of the above-mentioned design scheme 1, which will not be repeated here.

In this design solution 3, the network device may send fifth indication information to the terminal device, and correspondingly, the terminal device may receive the fifth indication information from the network device. The fifth indication information is used to indicate the number of candidate SSBs sent in each of the S candidate SSB groups. In some implementations, the fifth indication information may be used to indicate the number of candidate SSBs that have not been sent in each of the S candidate SSB groups.

For example, M=20, S=10, X=15, the network device selects candidate SSBs with indexes 0 to 4, 8 to 11, and 15 to 19 from the 20 candidate SSBs to send, and each of the 10 candidate SSB groups includes 2 candidate SSBs, such as the two candidate SSBs with indexes 0 and 1 constitute candidate SSB group 0, the two candidate SSBs with indexes 2 and 3 constitute candidate SSB group 1, and so on. A maximum of 2 candidate SSBs are sent for each candidate SSB group.

It can be seen that all candidate SSBs in candidate SSB group 0, candidate SSB group 1, candidate SSB group 4, candidate SSB group 5, candidate SSB group 8 and candidate SSB group 9 are sent, that is, Q=2, and one candidate SSB is sent in candidate SSB group 2, candidate SSB group 6 and candidate SSB group 7, that is, Q=1. At this time, for the sending status of the candidate SSB of each candidate SSB group, the fifth indication information can be indicated by 20 bits, and every 2 bits indicate the sending status of the candidate SSB of a candidate SSB group, such as 00 indicates that no candidate SSB of the candidate SSB group is sent, 01 indicates that 1 candidate SSB of the candidate SSB group is sent, and 10 indicates that 2 candidate SSBs of the candidate SSB group are sent. Alternatively, the fifth indication information can indicate the number of candidate SSBs that have not been sent in each candidate SSB group.

In this design scheme 3, the network device selects the candidate SSB to be sent based on the S candidate SSB groups, that is, selects the first Q (Q is a positive integer) or last Q candidate SSBs in each candidate SSB group in the S candidate SSB groups to be sent, so that the terminal device can determine the position of the X candidate SSBs to be sent in the M candidate SSBs according to the fifth indication information.

S403. The terminal device determines the index of the first SSB in the SSB burst set according to the first indication information.

After the terminal device receives the first SSB, it parses the first SSB to obtain the first indication information, and determines the index of the first SSB in the SSB burst set according to the index of the candidate SSB indicated by the first indication information.

In one possible design, the index of the first SSB in the SSB burst set is greater than or equal to 0 and less than or equal to M-1, and the index of the first SSB in the SSB burst set corresponds to the index of a candidate SSB. In other words, the index of an SSB in the SSB burst set will not correspond to the indexes of multiple candidate SSBs, or the indexes of multiple candidate SSBs will not correspond to the index of an SSB in the SSB burst set, that is, candidate SSBs with different indexes will not be sent in one direction, and there is no co-address relationship between the candidate SSBs.

In this design, the index of the first SSB in the SSB burst set is the same as the index of the candidate SSB corresponding to the first SSB. In some embodiments, the index of the first SSB in the SSB burst set is the index of the candidate SSB corresponding to the first SSB.

Continuing with Example 1 above, the indexes of the 8 SSBs (SSB0 to SSB7) in the SSB burst set are 0 to 7 respectively, where the first SSB is SSB5. Since the index of the candidate SSB corresponding to it is 5, the index of the first SSB in the SSB burst set is 5, which is the same as the index of its corresponding candidate SSB.

Continuing to refer to Example 2 above, the indexes of the 14 SSBs (SSB0 to SSB13) in the SSB burst set are 0 to 4, 8 to 12, and 16 to 19 respectively, among which the first SSB is SSB4. Since the index of the corresponding candidate SSB is 4, the index of the first SSB in the SSB burst set is 4, which is the same as the index of the corresponding candidate SSB.

It can be seen from this that if K=M=X, the index of the first SSB in the SSB burst set can be a maximum of M-1 and a minimum of 0.

In another possible design, the index of the first SSB in the SSB burst set is greater than or equal to 0 and less than or equal to K-1, K is the maximum number of candidate SSBs that do not have a quasi-co-location relationship, and the index of the first SSB corresponds to the index of at least one candidate SSB. In other words, the maximum index of an SSB in the SSB burst set is K-1, the index of an SSB in the SSB burst set may correspond to the index of one or more candidate SSBs, or the index of one or more candidate SSBs may correspond to the index of an SSB in the SSB burst set, that is, candidate SSBs with different indexes may be sent in one direction, and the candidate SSBs sent in the same direction have a co-location relationship, and an SSB burst set may support the sending of up to K SSBs in different directions, and the K SSBs in different directions do not have a co-location relationship.

Under this design scheme, the index of the first SSB in the SSB burst set is related to the first indication information and K. In some embodiments, the index of the first SSB in the SSB burst set can be determined based on the first indication information and K.

In one implementation, the following relationship is satisfied: Where i is the index of the first SSB in the SSB burst set, is the index of the candidate SSB corresponding to the first SSB, K is the maximum number of SSBs contained in the SSB burst set, and also represents the maximum number of candidate SSBs that do not have a co-location relationship, that is, K can be a parameter

Continuing with the above example 1, M=K=10, the first indication information indicates 0101. The terminal device can determine that the candidate SSB corresponding to the currently received SSB (i.e., the first SSB) has an index of 5 among the 10 candidate SSBs based on the first indication information. Then, the index of the first SSB in the SSB burst set is i=(5mod 10)=5, that is, the indices of the 8 sent SSBs in the SSB burst set are 0 to 7 respectively.

In this example, if X=10, that is, when all 10 candidate SSBs are sent, their respective indexes in the SSB burst set correspond to 0 to 9.

Continuing to refer to the above example 2, M=20, K=16, X=14, the first indication information indicates 00100, and the terminal device can determine that the index of the candidate SSB corresponding to the currently received SSB (i.e., the first SSB) in the 20 candidate SSBs is 4 according to the first indication information, and the index of the first SSB in the SSB burst set is i=(4mod 16)=4, that is, the indexes of the 14 transmitted SSBs in the SSB burst set are 0-4, 8-12, and 0-3, respectively. It can be seen that there are two SSBs with the same index in the SSB burst set, but the corresponding candidate SSBs have different indexes. The SSBs with the same index in the SSB burst set indicate that they are all sent in the same direction, and the terminal device can receive candidate SSBs with different indexes at different times in this direction.

In some embodiments, for the 20 candidate SSBs, their indices in the SSB burst set when they are sent are cycled in sequence from 0 to 15, that is, the candidate SSBs with indices 0 to 15 are sent with indices 0 to 15 in the SSB burst set, and the candidate SSBs with indices 16 to 19 are sent with indices 0 to 3 in the SSB burst set. Among them, the indexes of the candidate SSBs with indices 0 and 16 are both 0 in the SSB burst set when they are sent, the indexes of the candidate SSBs with indices 1 and 17 are both 1 in the SSB burst set when they are sent, the indexes of the candidate SSBs with indices 2 and 18 are both 2 in the SSB burst set when they are sent, and the indexes of the candidate SSBs with indices 3 and 19 are both 3 in the SSB burst set when they are sent, that is, the indexes of two candidate SSBs can correspond to the index of one SSB in the SSB burst set.

At this time, the network device can send candidate SSBs with different indexes in the same direction at different times, that is, the terminal device can receive multiple candidate SSBs with different indexes in the same direction at different times. If the random access resources and the candidate indexes correspond one-to-one, the terminal device can obtain more random access resources and achieve non-uniform random access resource allocation.

S404. The terminal device initiates random access according to the random access resources corresponding to the index of the first SSB in the SSB burst set.

Exemplarily, after the terminal device determines the index of the first SSB in the SSB burst set, it can determine the random access resource (such as RO) based on the mapping relationship between the index of the first SSB in the SSB burst set and the random access resource to initiate random access and complete network access.

If the terminal device receives multiple first SSBs in the same direction, that is, multiple first SSBs have the same index in the SSB burst set but correspond to candidate SSBs with different indexes, the terminal device can select the first SSB whose characteristics are closest to the sending/receiving data to send and receive data. The characteristics of the first SSB may include part or all of various channel information and beam sending/receiving information, etc.

Based on the downlink synchronization signal indication method shown in Figure 4, the maximum number of SSBs actually sent is expanded to be consistent with the number of candidate SSBs, so that the direction/index of the SSB actually sent can be expanded to be the same as the maximum index of the candidate SSB, that is, the direction/index of the SSB actually sent increases, thereby increasing the coverage range of the cell, and further reducing the cell data within the satellite coverage area, reducing the complexity of network equipment scheduling and the switching frequency of terminal equipment.

In the above embodiments, the methods and/or steps implemented by the network device may also be implemented by components (such as processors, chips, chip systems, circuits, logic modules, or software) that can be used in the network device; the methods and/or steps implemented by the terminal device may also be implemented by The components (such as processor, chip, chip system, circuit, logic module, or software) that can be used for the terminal device are implemented.

The above mainly introduces the scheme provided by the present application. Accordingly, the present application also provides a communication device, which is used to implement various methods in the above method embodiments. The communication device can be a network device in the above method embodiments, or a device including a network device, or a component that can be used for a network device, such as a chip or a chip system. Alternatively, the communication device can be a terminal device in the above method embodiments, or a device including a terminal device, or a component that can be used for a terminal device, such as a chip or a chip system.

In some embodiments, in order to implement the above functions, the communication device includes hardware structures and/or software modules corresponding to the execution of each function. Those skilled in the art should easily realize that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

The embodiment of the present application can divide the functional modules of the communication device according to the above method embodiment. For example, each functional module can be divided according to each function, or two or more functions can be integrated into one processing module. The above integrated module can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation.

Taking the communication device as a network device or terminal device in the above method embodiment as an example, FIG5 is a schematic diagram of the structure of a communication device provided in an embodiment of the present application. As shown in FIG5, the communication device 500 includes: a processing module 501 and a transceiver module 502. Among them, the processing module 501 is used to perform the processing function of the network device or terminal device in the above method embodiment. The transceiver module 502 is used to perform the transceiver function of the network device or terminal device in the above method embodiment.

Among them, all relevant contents of each step involved in the above method embodiment can be referred to the functional description of the corresponding functional module, and will not be repeated here.

Since the communication device 500 provided in this embodiment can execute the above method, the technical effects that can be obtained can refer to the above method embodiments and will not be repeated here.

In a possible design scheme, in the embodiment of the present application, the transceiver module 502 may include a receiving module and a sending module (not shown in FIG. 5 ). The sending module and the receiving module are used to implement the sending function and the receiving function of the communication device 500 , respectively.

In a possible design, the communication device 500 may further include a storage module (not shown in FIG. 5 ), which stores a program or instruction. When the processing module 501 executes the program or instruction, the communication device 500 may perform the function of the network device or terminal device in the method shown in FIG. 4 .

In some embodiments, the processing module 501 involved in the communication device 500 can be implemented by a processor or a processor-related circuit component, which can be a processor or a processing unit; the transceiver module 502 can be implemented by a transceiver or a transceiver-related circuit component, which can be a transceiver or a transceiver unit.

Exemplarily, FIG6 is a schematic diagram of the structure of another communication device provided in an embodiment of the present application. The communication device may be a network device or a terminal device, or may be a chip (system) or other parts or components that can be set in a network device or a terminal device. As shown in FIG6, a communication device 600 may include a processor 601. In a possible design scheme, the communication device 600 may also include a memory 602 and/or a transceiver 603. The processor 601 is coupled to the memory 602 and the transceiver 603, such as being connected via a communication bus.

The following is a detailed introduction to the various components of the communication device 600 in conjunction with FIG. 6 :

The processor 601 is the control center of the communication device 600, which can be a processor or a general term for multiple processing elements. For example, the processor 601 includes one or more central processing units (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application, such as one or more microprocessors (digital signal processors, DSP), or one or more field programmable gate arrays (field programmable gate array, FPGA).

In one possible design, the processor 601 may perform various functions of the communication device 600 by running or executing a software program stored in the memory 602 and calling data stored in the memory 602 .

In a specific implementation, as an embodiment, the processor 601 may include one or more CPUs, such as CPU0 and CPU1 shown in FIG. 6 .

In a specific implementation, as an embodiment, the communication device 600 may also include multiple processors, such as the processor 601 and the processor 604 shown in FIG6. Each of these processors may be a single-core processor or a multi-core processor. The processor here may refer to one or more devices, circuits, and/or processing cores for processing data (e.g., computer program instructions).

The memory 602 is used to store the software program for executing the solution of the present application, and the execution is controlled by the processor 601. The present method can refer to the above method embodiment, which will not be described again here.

In a possible design, the memory 602 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical disc, laser disc, optical disc, digital versatile disc, Blu-ray disc, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory 602 may be integrated with the processor 601, or may exist independently and be coupled to the processor 601 through an interface circuit (not shown in FIG. 6 ) of the communication device 600, which is not specifically limited in the embodiment of the present application.

The transceiver 603 is used for communication with other communication devices. For example, if the communication device 600 is a terminal device, the transceiver 603 can be used to communicate with an access network device, or with another terminal device. For another example, if the communication device 600 is a network device, the transceiver 603 can be used to communicate with a terminal device, or with another network device.

In a possible design, transceiver 603 may include a receiver and a transmitter (not shown separately in FIG6 ), wherein the receiver is used to implement a receiving function, and the transmitter is used to implement a sending function.

In one possible design scheme, the transceiver 603 can be integrated with the processor 601, or it can exist independently and be coupled to the processor 601 through the interface circuit of the communication device 600 (not shown in Figure 6), which is not specifically limited in the embodiment of the present application.

It should be noted that the structure of the communication device 600 shown in FIG. 6 does not constitute a limitation on the communication device, and an actual communication device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

In addition, the technical effects of the communication device 600 can refer to the technical effects of the methods described in the above method embodiments, which will not be repeated here.

The embodiment of the present application also provides a computer-readable storage medium on which a computer program or instruction is stored. When the computer program or instruction is executed by a computer, the functions of the above-mentioned method embodiment are realized.

The embodiment of the present application also provides a computer program product, which implements the functions of the above method embodiment when executed by a computer.

In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using a software program, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that contains one or more media integrated. Available media can be magnetic media (e.g., floppy disks, hard disks, tapes), optical media (e.g., DVDs), or semiconductor media (e.g., solid state drives (SSDs)), etc.

Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may be a separate object. It can exist logically, or two or more units can be integrated into one unit.

If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or access network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, and other media that can store program codes.

Although the present application is described herein in conjunction with various embodiments, in the process of implementing the claimed application, those skilled in the art may understand and implement other changes to the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "one" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in the claims. Certain measures are recorded in different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

Although the present application has been described in conjunction with specific features and embodiments thereof, it is obvious that various modifications and combinations may be made thereto without departing from the spirit and scope of the present application. Accordingly, this specification and the drawings are merely exemplary illustrations of the present application as defined by the appended claims, and are deemed to have covered any and all modifications, variations, combinations or equivalents within the scope of the present application. Obviously, those skilled in the art may make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims (31)

A downlink synchronization signal indication method, characterized by comprising: Receive a first synchronization/physical broadcast channel block SSB, where the first SSB is an SSB in an SSB burst set, where the SSB burst set includes at most K candidate SSBs selected from M candidate SSBs, and the first SSB includes first indication information, where the first indication information is used to indicate an index of the candidate SSB corresponding to the first SSB, where K is greater than L and K is less than or equal to M, where K is an integer, L is a first threshold, M is an integer greater than 1, and L is a positive integer; Determine, according to the first indication information, an index of the first SSB in the SSB burst set; Initiate random access according to the random access resources corresponding to the index of the first SSB in the SSB burst set. The method according to claim 1, characterized in that the method further comprises: Receive second indication information, where the second indication information is used to indicate whether the maximum number of SSBs included in the SSB burst set is L or K. The method according to claim 1 is characterized in that, when the communication frequency band is the first communication frequency band, the maximum number of SSBs contained in the SSB burst set is K. The method according to any one of claims 1 to 3, characterized in that the method further comprises: Receive third indication information, where the third indication information is used to indicate positions of X candidate SSBs sent among the M candidate SSBs, where X is greater than or equal to 1 and less than or equal to K, and X is an integer. The method according to claim 4 is characterized in that the third indication information is a bit map including M bits. The method according to claim 4 is characterized in that the third indication information is a pattern index used to indicate the position of the X candidate SSBs among the M candidate SSBs. The method according to claim 4 is characterized in that the M candidate SSBs are divided into S candidate SSB groups, and the third indication information is specifically used to indicate that the candidate SSBs in N candidate SSB groups among the S candidate SSB groups are sent, and the N candidate SSB groups include the X candidate SSBs, where N is an integer greater than 0 and less than or equal to S. The method according to any one of claims 1 to 3, characterized in that the method further comprises: Receive fourth indication information, where the fourth indication information is used to indicate the number X of candidate SSBs sent among the M candidate SSBs, where the X candidate SSBs are candidate SSBs at X fixed positions among the M candidate SSBs, X is greater than or equal to 1 and less than or equal to K, and X is an integer. The method according to any one of claims 1 to 3, characterized in that the M candidate SSBs are divided into S candidate SSB groups, and the method further comprises: Receive fifth indication information, where the fifth indication information is used to indicate the number of candidate SSBs sent in each of the S candidate SSB groups. A downlink synchronization signal indication method, characterized by comprising: Determine a first synchronization/physical broadcast channel block SSB, where the first SSB is an SSB in an SSB burst set, where the SSB burst set includes at most K candidate SSBs selected from M candidate SSBs, where K is greater than L and K is less than or equal to M, where K is an integer, L is a first threshold, M is an integer greater than 1, and L is a positive integer; The first SSB is sent, wherein the first SSB includes first indication information, wherein the first indication information is used to indicate an index of a candidate SSB corresponding to the first SSB, and the index of the candidate SSB corresponding to the first SSB is used to determine an index of the first SSB in the SSB burst set. The method according to claim 10, characterized in that the method further comprises: Send second indication information, where the second indication information is used to indicate whether the maximum number of SSBs included in the SSB burst set is L or K. The method according to claim 10 is characterized in that, when the communication frequency band is the first communication frequency band, the maximum number of SSBs contained in the SSB burst set is K. The method according to any one of claims 10 to 12, characterized in that the method further comprises: Send third indication information, where the third indication information is used to indicate the positions of X candidate SSBs sent among the M candidate SSBs, where X is greater than or equal to 1 and less than or equal to K, and X is an integer. The method according to claim 13 is characterized in that the third indication information is a bit map including M bits. The method according to claim 13 is characterized in that the third indication information is a pattern index used to indicate the position of the X candidate SSBs among the M candidate SSBs. The method according to claim 13, characterized in that the M candidate SSBs are divided into S candidate SSB groups, and the third indication information is specifically used to indicate that the candidate SSBs in N candidate SSB groups in the S candidate SSB groups are sent, and the N candidate SSBs are sent to the S candidate SSB groups. The selected SSB group includes the X candidate SSBs, where N is an integer greater than 0 and less than or equal to S. The method according to any one of claims 10 to 12, characterized in that the method further comprises: Send fourth indication information, where the fourth indication information is used to indicate the number X of candidate SSBs sent among the M candidate SSBs, where the X candidate SSBs are candidate SSBs at X fixed positions among the M candidate SSBs, X is greater than or equal to 1 and less than or equal to K, and X is an integer. The method according to any one of claims 10 to 12, characterized in that the M candidate SSBs are divided into S candidate SSB groups, and the method further comprises: Send fifth indication information, where the fifth indication information is used to indicate the number of candidate SSBs sent in each candidate SSB group in the S candidate SSB groups. The method according to any one of claims 1-18 is characterized in that the first threshold is determined according to the communication frequency band and the subcarrier spacing. The method according to claim 19, characterized in that the subcarrier spacing is 15KHz or 30KHz, in the case of a non-shared frequency band: If the communication frequency band is less than or equal to 3 GHz, L=4; If the communication frequency band is greater than 3 GHz and less than or equal to 6 GHz, then L=8. The method according to claim 19 is characterized in that, in the case of a shared frequency band: if the subcarrier spacing is 15KHz, L=2; if the subcarrier spacing is 30KHz, L=4. The method according to claim 20 or 21 is characterized in that the index of the first SSB in the SSB burst set is greater than or equal to 0 and less than or equal to M-1, and the index of the first SSB in the SSB burst set corresponds to the index of one of the candidate SSBs. The method according to claim 22 is characterized in that the index of the first SSB in the SSB burst set is the same as the index of the candidate SSB corresponding to the first SSB. The method according to claim 20 or 21 is characterized in that the index of the first SSB in the SSB burst set is greater than or equal to 0 and less than or equal to K-1, K is the maximum number of the candidate SSBs that do not have a quasi-co-location relationship, and the index of the first SSB corresponds to the index of at least one of the candidate SSBs. The method according to claim 24 is characterized in that the index of the first SSB in the SSB burst set is determined based on the first indication information and K. The method according to any one of claims 1-25 is characterized in that, when the maximum number of SSBs contained in the SSB burst set is K, the bits occupied by the first indication information include a first bit and a second bit, the first bit is multiplexed to indicate the bits occupied by the information that the Type0-physical downlink control channel PDCCH and the SSB have the same subcarrier spacing, and the second bit is multiplexed to indicate the bits occupied by the information that the resource block boundary of the SSB satisfies an even or odd number of subcarriers. A communication device, characterized by comprising a module for executing the method as claimed in any one of claims 1-9, 19-26 or claims 10-26. A communication device, characterized in that it comprises: a processor; the processor is used to run a computer program or instruction so that the method as claimed in any one of claims 1-9, 19-26 or claims 10-26 is implemented. A communication chip, characterized in that instructions are stored therein, and when the chip is run on a communication device, the method according to any one of claims 1-9, 19-26 or claims 10-26 is implemented. A computer-readable storage medium, characterized in that a computer program or instruction is stored in the storage medium, and when the computer program or instruction is executed by a communication device, the method as described in any one of claims 1-9, 19-26 or claims 10-26 is implemented. A computer program product, characterized in that it comprises a computer program code, and when the computer program code runs on a communication device, the communication device implements the method as claimed in any one of claims 1-9, 19-26 or claims 10-26.