SSB transmission method, apparatus and system, and storage medium

Abstract

The present application relates to the technical field of communications, and provides an SSB transmission method, apparatus and system, and a storage medium. In the solution, one transmission period (for example, 80 ms) comprises a plurality of synchronization periods (for example, 20 ms). A new SSB is defined on the basis of the transmission period, and the new SSB only comprises a PSS and an SSS. A legacy SSB is transmitted by means of a beam in one synchronization period of each transmission period, and the new SSB is transmitted by means of a beam in each of the other synchronization periods. The position or number of a first synchronization period in different transmission periods is adjusted on the basis of a traffic to be transmitted of a first beam. Because the legacy SSB comprises a complete PBCH and the new SSB does not comprise a PBCH, the data volume of the new SSB is smaller than that of the legacy SSB, thereby reducing resource overheads. By dynamically adjusting the position or number of the first synchronization period in different transmission periods, the problem of limited transmission caused by a plurality of beams transmitting legacy SSBs at the same time and position can be solved, so that a terminal device can search for and camp on a cell on the basis of legacy and new SSBs.

Description

SSB transmission method, device, system and storage medium

[0001] The present application claims priority from the Chinese patent application No. 202411366614.1 filed on September 27, 2024, and entitled "SSB transmission method, device, system and storage medium", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the field of communication technology, in particular to a SSB transmission method, device, system and storage medium. BACKGROUND

[0003] In a traditional synchronization signal block (SSB) transmission scheme, a base station usually transmits SSBs at a period of 20 ms on at least one SSB candidate position among four specified SSB candidate positions.

[0004] When a satellite deployment of the communication protocol LEO600km Set1-1 FR1 assumption is adopted, the satellite needs to extend the transmission period of SSBs to 80 ms to be able to send at least one SSB on each of the 1058 beams. However, when a terminal device searches for a satellite cell, it searches for SSBs on each frequency point by default at a period of 20 ms. If the satellite transmits SSBs on a beam at a period of 80 ms on a certain frequency point, the terminal device may miss the beam or take a long time to search for the cell because it does not search for SSBs on the beam within 20 ms, or the terminal device cannot search for the cell or takes a long time to search for the cell because the transmission of the satellite is limited due to the transmission of SSBs on multiple beams at the same candidate position. SUMMARY

[0005] The present application provides a SSB transmission method, device, system and storage medium to solve the problem that a terminal device cannot search for a cell.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a SSB transmission method. The method can be applied to a network device. The method can include: transmitting a first SSB (which can be referred to as a legacy SSB) through a first beam in a first synchronization period of each transmission period, and transmitting a second SSB (which can be referred to as a new SSB) through the first beam in a second synchronization period of each transmission period, except for the first synchronization period. Wherein, the position or number of the first synchronization period in different transmission periods is adjusted based on the to-be-transmitted service of the first beam, the first SSB can include PSS, SSS and PBCH, and the second SSB can include PSS and SSS. The first transmission period and the second transmission period are two different transmission periods.

[0008] In this scheme, the network device transmits a legacy SSB through a certain beam in a synchronization period (such as 20 ms) of each transmission period (such as 80 ms), and transmits a new SSB through the beam in each other synchronization period. If a terminal device searches for a new SSB, it can be preliminarily determined to be within the coverage of the beam, and continue to search for a legacy SSB on the same beam, and camp on a cell based on the legacy SSB. Since the legacy SSB includes complete PBCH, and the new SSB does not include PBCH (such as not including complete PBCH or not including part of the data of PBCH), the amount of data carried by the new SSB is less than the amount of data carried by the legacy SSB, reducing resource overhead and improving the success rate of terminal devices searching for a cell. On the one hand, when the network device transmits SSB signals through multiple beams, since the network device can dynamically adjust the position of the first synchronization period in each transmission period based on the to-be-transmitted service of the first beam, it can solve the problem that multiple beams transmit legacy SSBs at the same time, which limits transmission, so that the terminal device can search and camp on a cell based on the legacy SSB and the new SSB. On the other hand, the network device can dynamically adjust the number of first synchronization periods in each transmission period based on the to-be-transmitted service of the first beam, such as reducing the number of first synchronization periods when the to-be-transmitted services of multiple beams compete for resources, thereby avoiding the problem that transmitting SSBs at the same candidate position limits transmission and makes it impossible to search for a cell. For example, when the resource competition of multiple beams is not intense, the number of first synchronization periods is increased to transmit more legacy SSBs, thereby shortening the time to search for a cell.

[0009] In a possible implementation, the period length of the transmission period and the synchronization period can be determined according to network configuration, or determined according to the indication of the terminal device to the network device, or predefined. For example, the transmission period is 80 ms, and the synchronization period is 20 ms.

[0010] In a possible implementation, each transmission period can include N synchronization periods, each of the N synchronization periods has equal length, the first synchronization period is at least one of the N synchronization periods, the second synchronization period is a synchronization period other than the first synchronization period in the N synchronization periods, each first synchronization period is used for transmitting a first SSB, each second synchronization period is used for transmitting a second SSB, and N is an integer greater than or equal to 2. As an example, the value of N can be determined according to network configuration, for example, the network device can determine the value of N according to the total number of satellite coverage beams, the number of beams transmitted simultaneously by the satellite, and other parameters.

[0011] In a possible implementation, the PBCH of the first SSB can include a PBCH DMRS and PBCH data. The second SSB can also include a PBCH DMRS, and the second SSB can not include PBCH data; or the second SSB can not include a PBCH DMRS and PBCH data. The PBCH DMRS in the second SSB can be a complete PBCH DMRS (in this case, the PBCH DMRS of the second SSB is the same as the PBCH DMRS of the first SSB), or a partial PBCH DMRS (in this case, the PBCH DMRS of the second SSB is the same as part of the PBCH DMRS of the second SSB), such as a PBCH DMRS on part of OFDM symbols or part of REs. Whether the second SSB includes a PBCH DMRS, and whether the PBCH DMRS in the second SSB is a complete PBCH DMRS or a partial PBCH DMRS, can be determined according to network configuration, or determined according to an indication of the terminal device to the network device, or predefined. In this scheme, the amount of data carried by the second SSB is reduced relative to the first SSB, which optimizes the resource overhead of the SSB.

[0012] In a possible implementation, the PBCH DMRS of the first SSB is used for demodulating the PBCH data. If the second SSB includes the PBCH DMRS, the PBCH DMRS of the second SSB is used for measuring whether the SSB exists or the signal quality of the SSB. In this scheme, when both the legacy SSB and the new SSB include the PBCH DMRS, the main functions of the PBCH DMRS of the legacy SSB and the PBCH DMRS of the new SSB are not the same. Specifically, because the legacy SSB includes the PBCH data, the PBCH DMRS of the legacy SSB is mainly used for demodulating the PBCH data, that is, the PBCH DMRS of the legacy SSB can be used not only for measuring whether the SSB exists or the signal quality of the SSB, but also for demodulating the PBCH data; and because the new SSB does not include the PBCH data, the PBCH DMRS of the new SSB can only be used for measuring whether the SSB exists or the signal quality of the SSB.

[0013] In a possible implementation, the second SSB can include the PBCH DMRS, each transmission period can include a first number of synchronization periods, and each synchronization period in each transmission period has a first length; or the second SSB can not include the PBCH DMRS, each transmission period can include a second number of synchronization periods, and each synchronization period in each transmission period has a second length. The first number is greater than the second number, and the first length is equal to the second length. In this scheme, when the new SSB includes the PBCH DMRS, the RE corresponding to the PBCH DMRS is not 0, and transmitting the PBCH DMRS increases the resource overhead of the new SSB and the transmission power, which reduces the number of SSBs transmitted by the network device through the beam in one synchronization period, and causes the length of the transmission period to increase, that is, the number of synchronization periods (that is, the first number) included in one transmission period increases. When the new SSB does not include the PBCH DMRS, the RE corresponding to the PBCH DMRS is a free RE, and not carrying the PBCH DMRS in the new SSB reduces the resource overhead of the new SSB and the transmission power, which increases the number of SSBs transmitted by the network device through the beam in one synchronization period, and causes the length of the transmission period to decrease, that is, the number of synchronization periods (that is, the second number) included in one transmission period decreases.

[0014] In a possible implementation, the first SSB is in a first candidate position of a first synchronization period, and the second SSB is in a second candidate position of a second synchronization period. The first candidate position and the second candidate position are associated with each other. As an example, the association between the first candidate position and the second candidate position can include that the indexes of the first candidate position and the second candidate position are the same. As another example, the association between the first candidate position and the second candidate position can include that the indexes of the first candidate position and the second candidate position conform to a preset rule. In this scheme, when the terminal device searches for a new SSB in the second candidate position of a synchronization period, the terminal device can determine the association between the first candidate position and the second candidate position according to a predefined rule or a rule configured by the network device, and perform SSB search on the first candidate position in a subsequent synchronization period at the first frequency point based on the association between the first candidate position and the second candidate position, until a legacy SSB is searched for in the first candidate position of a synchronization period. Since there is an association between the index of the first candidate position and the index of the second candidate position, the terminal device only needs to search for the candidate positions and skips some symbols, without searching for the entire synchronization period, thereby reducing the power consumption of the terminal device.

[0015] In a possible implementation, the PSS of the first SSB is offset from the start symbol of the first candidate position by 0 OFDM symbol. The PSS of the second SSB is offset from the start symbol of the second candidate position by 0 or at least one OFDM symbol. In this scheme, the network device can adjust the number of OFDM symbols by which the PSS is offset from the start symbol of the candidate position in each synchronization period according to factors such as the transmission power, the number of beams, and the to-be-transmitted service. For example, when the transmission power of the network device is limited, the network device can set the number of OFDM symbols by which the PSS is offset from the start symbol of the candidate position to 1 for some beams, and set the number of OFDM symbols by which the PSS is offset from the start symbol of the candidate position to 0 for other beams, so that the network device can transmit more beams in one synchronization period.

[0016] In a possible implementation, the number of OFDM symbols by which the PSS of the second SSB is offset from the start symbol of the second candidate position is determined according to at least one of a PCID, a SFN, and a HF.

[0017] In a possible implementation, in one transmission period, the number of OFDM symbols of the starting symbol offset of the PSS in each synchronization period from the candidate position is determined according to network configuration, or determined according to the indication of the terminal device to the network device, or predefined; or, in one transmission period, the starting symbol offsets of the PSS in all synchronization periods from the candidate position are arranged in a first sequence in order, and the first sequence is specified in the protocol. For example, if one transmission period includes one first synchronization period and three second synchronization periods. Then the first sequence can be 0000, 0001, 0101, 1010, 1001, 1100 or 1111, etc. Wherein, the number 0 represents that the PSS of the SSB is offset by 0 OFDM symbol from the starting symbol of the second candidate position, and the number 1 represents that the PSS of the SSB is offset by 0 OFDM symbol from the starting symbol of the second candidate position.

[0018] In a possible implementation, the SSS of the first SSB is offset by 2 OFDM symbols from the PSS; and the SSS of the second SSB is offset by 2 OFDM symbols from the PSS.

[0019] In a possible implementation, the PCID carried by the PSS and the SSS of the first SSB is the same as the PCID carried by the PSS and the SSS of the second SSB; or, the PCID carried by the PSS and the SSS of the first SSB is different from the PCID carried by the PSS and the SSS of the second SSB.

[0020] In a possible implementation, in different synchronization periods of the same transmission period, the PCID carried by the PSS and the SSS of any two second SSBs is the same; or, in different synchronization periods of the same transmission period, the PCID carried by the PSS and the SSS of any two second SSBs is different.

[0021] In a possible implementation, the PCID carried by the first SSB is determined according to the PCID carried by the second SSB and the number of synchronization periods between the first SSB and the second SSB. In this scheme, when the PCID carried by the PSS and the SSS of the traditional SSB is different from the PCID carried by the PSS and the SSS of the new SSB, since the terminal device can calculate the number of synchronization periods between the new SSB and the traditional SSB based on the PCID carried by the new SSB signal #i and the PCID carried by the new SSB signal #(i-1), the terminal device can skip the detection of the SSB in some synchronization periods and directly detect the traditional SSB, thereby reducing the power consumption of the terminal device.

[0022] In a possible implementation, the first SSB is transmitted by the first beam in the first synchronization period of each transmission period, and the second SSB is transmitted by the first beam in the second synchronization period of each transmission period except the first synchronization period, which can include: the first SSB is transmitted by the first beam in the first synchronization period of the first transmission period, and the second SSB is transmitted by the first beam in each second synchronization period of the first transmission period except the first synchronization period; the third SSB is transmitted by the second beam in the third synchronization period of the first transmission period, and the fourth SSB is transmitted by the second beam in each fourth synchronization period of the first transmission period except the third synchronization period. The first synchronization period and the third synchronization period have the same position in the first transmission period, the third SSB can include a PSS, an SSS, and a PBCH, and the fourth SSB can include a PSS and an SSS. Further, the method can further include: the first SSB is transmitted by the first beam in the first synchronization period of the second transmission period, and the second SSB is transmitted by the first beam in each second synchronization period of the second transmission period except the first synchronization period; the third SSB is transmitted by the second beam in the third synchronization period of the second transmission period, and the fourth SSB is transmitted by the second beam in each fourth synchronization period of the second transmission period except the third synchronization period. The first synchronization period and the third synchronization period have different positions in the second transmission period.

[0023] In this scheme, in a communication system such as satellite communication, limited by the transmission power, the network device usually uses beamforming to obtain the beamforming gain, and uses multiple beams to realize the signal coverage of a region. In this case, the network device can need to transmit multiple SSBs through multiple beams at the same candidate position in a transmission period. At this moment, if the service type of the to-be-transmitted service of a certain beam in the multiple beams is a preset type and / or the data amount of the to-be-transmitted service is relatively large, the to-be-transmitted service will occupy a large amount of resources, and the transmission of multiple SSBs at the same candidate position is limited. In order to avoid such problems: the network device can adjust the relative position of the first synchronization period in different transmission periods or adjust the relative position of the second synchronization period in different transmission periods according to whether the service type of the to-be-transmitted service is a preset type and / or the data amount of the to-be-transmitted service.

[0024] In a second aspect, the present application provides a SSB transmission method. The method can be applied to a terminal device. The method can include: searching for SSBs at a first frequency point; and camping on a cell based on a first SSB and a second SSB. The first SSB includes a PSS, an SSS, and a PBCH, and the second SSB includes a PSS and an SSS. For example, the terminal device can search for SSBs at the first frequency point according to a synchronization period; if a second SSB is searched for within a second synchronization period, the terminal device continues to search for SSBs at the first frequency point according to the synchronization period; and if a first SSB is searched for within a first synchronization period, the terminal device camps on a cell based on the first SSB.

[0025] In this scheme, the network device transmits a legacy SSB through a certain beam in one synchronization period (e.g., 20 ms) of each transmission period (e.g., 80 ms), and transmits a new SSB through the beam in each other synchronization period. In this way, when the terminal device determines that a SSB is searched for based on the PSS and the SSS of the new SSB, the terminal device can continue to search for other SSBs on the same beam, directly search for a legacy SSB including a PSS, an SSS, and a PBCH, and camp on a cell based on the legacy SSB, thereby avoiding the problem that the terminal device cannot search for any cell within one transmission period.

[0026] In a possible implementation, the PBCH of the first SSB can include a PBCH DMRS and PBCH data. The second SSB can further include a PBCH DMRS, and the second SSB can not include PBCH data; or the second SSB can not include a PBCH DMRS and PBCH data. The PBCH DMRS in the second SSB can be a complete PBCH DMRS or a partial PBCH DMRS, such as a PBCH DMRS on partial OFDM symbols or partial REs.

[0027] In a possible implementation, the PBCH DMRS of the first SSB is used for demodulating the PBCH data. If the second SSB includes a PBCH DMRS, the PBCH DMRS of the second SSB is used for measuring whether there is a SSB or the signal quality of the SSB.

[0028] In a possible implementation, the first SSB is at a first candidate position of a synchronization period, and the second SSB is at a second candidate position of a second synchronization period. The first candidate position and the second candidate position are associated.

[0029] In a possible implementation, before camping on the cell based on the searched first SSB and the second SSB, the method further includes: searching for the second SSB at a second candidate position in one synchronization period; and searching for the first SSB at a first candidate position in another synchronization period based on an association relationship between the first candidate position and the second candidate position. For example, the second SSB is searched at the second candidate position in one synchronization period; the first candidate position in the synchronization period is searched for the SSB based on the association relationship between the first candidate position and the second candidate position; and the first SSB is searched at the first candidate position in another synchronization period. In this solution, the network device can adjust the number of OFDM symbols of the starting symbol offset of the PSS from the candidate position in each synchronization period according to factors such as the transmission power, the number of beams, and the to-be-transmitted service. For example, when the transmission power of the network device is limited, the network device can set the number of OFDM symbols of the starting symbol offset of the PSS from the candidate position to 1 for some beams, and set the number of OFDM symbols of the starting symbol offset of the PSS from the candidate position to 0 for other beams, so that the network device can transmit more beams in one synchronization period.

[0030] In a possible implementation, before camping on the cell based on the searched first SSB and the second SSB, the method further includes: searching for a first second SSB in a first synchronization period; continuing to search for the SSB at the first frequency point; searching for a second second SSB in a second synchronization period; determining the number of synchronization periods between the second second synchronization period and the first SSB based on a PCID of the second second SSB and a PCID of the first second SSB; and searching for the first SSB at the first frequency point based on the number of synchronization periods between the second second synchronization period and the first SSB. In this solution, when the PCIDs carried by the PSS and the SSS of the traditional SSB are different from the PCIDs carried by the PSS and the SSS of the new SSB, the terminal device can calculate the number of synchronization periods between the new SSB and the traditional SSB based on the PCID carried by the new SSB signal #i and the PCID carried by the new SSB signal #(i-1), so that the terminal device can skip the detection of the SSB in some synchronization periods and directly detect the traditional SSB, thereby reducing the power consumption of the terminal device.

[0031] In a third aspect, a communication apparatus is provided. The communication apparatus can include a processor, a communication interface, and a memory coupled to the processor and the communication interface. The memory stores instructions that, when executed by the processor, cause the communication apparatus to perform the method in any one of the first aspect or the second aspect.

[0032] In a fourth aspect, the present application provides a network device, which can include one or more processors and a memory. The memory is coupled to the one or more processors, and the memory is configured to store computer program codes, which can include computer instructions. The one or more processors invoke the computer instructions to cause the network device to perform the method according to any one of the first aspect.

[0033] In a fifth aspect, the present application provides a terminal device, which can include one or more processors and a memory. The memory is coupled to the one or more processors, and the memory is configured to store computer program codes, which can include computer instructions. The one or more processors invoke the computer instructions to cause the terminal device to perform the method according to any one of the second aspect.

[0034] In a sixth aspect, the present application provides a communication system, which can include a network device and a terminal device. The network device is configured to perform the SSB transmission method according to any one of the first aspect, and the terminal device is configured to perform the SSB transmission method according to any one of the second aspect.

[0035] In a seventh aspect, the present application provides a computer readable storage medium, which stores a computer program. When the computer program is run on a network device, the network device performs the SSB transmission method according to any one of the first aspect. When the computer program is run on a terminal device, the terminal device performs the SSB transmission method according to any one of the second aspect.

[0036] In an eighth aspect, the present application provides a chip, which is coupled to a memory. The chip is configured to read and execute a computer program stored in the memory, so as to implement the SSB transmission method according to any one of the first aspect or the second aspect.

[0037] In a ninth aspect, the present application provides a computer program product. When the computer program is run on a network device, the network device performs the SSB transmission method according to any one of the first aspect. When the computer program is run on a terminal device, the terminal device performs the SSB transmission method according to any one of the second aspect.

[0038] It can be understood that the beneficial effects of the third aspect to the ninth aspect described above can be referred to the related description of the first aspect or the second aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0039] FIG. 1 is a schematic diagram of a satellite communication architecture according to an embodiment of the present application;

[0040] FIG. 2 is a schematic diagram of SSB beam scanning according to an embodiment of the present application;

[0041] FIG. 3 is a schematic diagram of a time domain location of an SSB according to an embodiment of the present application;

[0042] FIG. 4 is a schematic diagram of a time-frequency domain structure of a conventional SSB according to an embodiment of the present application;

[0043] FIG. 5 is a schematic diagram of a case where a period of searching for an SSB by a UE is different from a period of transmitting an SSB by a satellite according to an embodiment of the present application;

[0044] FIG. 6 is a schematic diagram of a time-frequency domain structure of a new SSB according to an embodiment of the present application;

[0045] FIG. 7 is a schematic diagram of another time-frequency domain structure of a new SSB according to an embodiment of the present application;

[0046] FIG. 8 is a schematic diagram of another time-frequency domain structure of a new SSB according to an embodiment of the present application;

[0047] FIG. 9 is a schematic diagram of another time-frequency domain structure of a new SSB according to an embodiment of the present application;

[0048] FIG. 10 is a schematic diagram of a hardware structure of a communication apparatus according to an embodiment of the present application;

[0049] FIG. 11 is a schematic diagram of a flow of a method of transmitting an SSB according to an embodiment of the present application;

[0050] FIG. 12 is a schematic diagram of transmitting an SSB in each synchronization period of a transmission period according to an embodiment of the present application;

[0051] FIG. 13 is a schematic diagram of transmitting an SSB in different transmission periods according to an embodiment of the present application;

[0052] FIG. 14 is a schematic diagram of a case where a relative position of a first synchronization period in different transmission periods is the same according to an embodiment of the present application;

[0053] FIG. 15 is a schematic diagram of a case where a relative position of a first synchronization period in different transmission periods is different according to an embodiment of the present application;

[0054] FIG. 16 is a schematic diagram of a relative position of a first synchronization period in different transmission periods according to an embodiment of the present application;

[0055] FIG. 17 is a schematic diagram of a case where a number of first synchronization periods in different transmission periods is different according to an embodiment of the present application;

[0056] FIG. 18 is a schematic diagram of a case where an index of a first candidate position and an index of a second candidate position are the same according to an embodiment of the present application;

[0057] FIG. 19 is a schematic diagram of a case where an index of a first candidate position and an index of a second candidate position are different according to an embodiment of the present application;

[0058] FIG. 20 is a schematic diagram of time offset of a conventional SSB according to an embodiment of the present application;

[0059] FIG. 21 is a schematic diagram of time offset of a new SSB according to an embodiment of the present application;

[0060] FIG. 22 is a schematic diagram of time offset of another new SSB according to an embodiment of the present application;

[0061] FIG. 23 is a schematic diagram of time offset of multiple new SSBs according to an embodiment of the present application;

[0062] FIG. 24 is a schematic diagram of time offset of another multiple new SSBs according to an embodiment of the present application;

[0063] FIG. 25 is a schematic diagram of time offset of another multiple new SSBs according to an embodiment of the present application;

[0064] FIG. 26 is a schematic diagram of a conventional SSB and a new SSB carrying PCID according to an embodiment of the present application. DETAILED DESCRIPTION

[0065] The terms "first" and "second" and the like in the description of the present application and in the claims of the present application are used for distinguishing between similar objects, or for distinguishing between the same object for different claims and are not necessarily used to describe a specific sequential order. Furthermore, the terms "comprises", "comprising", "includes", "including" and the like means "including, but not limited to" and indicate the presence of what is mentioned but not to the exclusion of other matters. For example, a process, method, object, or apparatus that comprises a list of steps or elements is not necessarily limited to the listed steps or elements but can include other steps or elements not expressly listed or inherent to such process, method, object, or apparatus. In the present application, "multiple" includes two or more. In the present application, the words "example" and "for example" are used to mean serving as an instance or illustration. In addition, the network architecture and service scenarios described in the present application are for more clearly illustrating the technical solutions of the present application, and do not constitute a limitation to the technical solutions provided by the present application. Those skilled in the art can know that, with the evolution of network architecture and the appearance of new service scenarios, the technical solutions provided by the present application are also applicable to similar technical problems.

[0066] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

[0067] Satellite communication refers to communication between radio communication stations on the earth using a satellite as a relay. Generally, a satellite communication system is composed of a satellite and a ground station. Compared with ground cellular communication, satellite communication has the characteristics of long communication distance, large coverage area, wide communication frequency band, etc., and can provide users with communication services anytime and anywhere, so satellite communication has broad development prospects, especially in international and domestic communication, emergency rescue, etc., and has unique advantages.

[0068] Exemplarily, FIG. 1 is a schematic diagram of a satellite communication architecture provided by an embodiment of the present application. A satellite normally working around the earth as a base station (or the satellite transmits user signals to a ground station) realizes wide area coverage in an independent or inter-satellite cooperative manner. Taking uplink transmission as an example, a terminal device 01 sends data or signaling to a satellite 02, the satellite 02 forwards the data or signaling to a ground station 03, and the ground station 03 routes the data or signaling to an Internet 05 through a routing device 04.

[0069] In a ground cellular communication system, a terminal device needs to be able to communicate normally, and the first step of accessing a cell is to complete cell search, which includes a series of synchronization processes. In the cell search and synchronization process, the terminal device can achieve frequency and symbol synchronization with the cell, obtain the starting position of the downlink (DL) frame, determine the number of the cell to reside in, and decode the necessary system information. Cell search and initial synchronization both depend on downlink broadcast messages. The broadcast messages contain synchronization signals and basic system messages, and the base station must periodically send the broadcast messages when it is in working state, so that the terminal device can find the cell it belongs to at any time. Generally, the broadcast messages have fixed transmission period and occupied bandwidth. Sending broadcast messages will cause the inherent time-frequency resource and power consumption of the working state base station. For example, in the 5th generation (5G) new radio (NR) system, downlink synchronization is achieved by searching the synchronization signal in the SSB, decoding the system message in the physical broadcast channel (PBCH) and physical downlink shared channel (PDSCH), the main purpose is to realize symbol synchronization, frame synchronization and frequency synchronization, and to obtain the physical cell number and system message, etc. The NR system covers the entire cell by beam scanning, the base station transmits a narrow beam to cover a specific direction at a certain moment, and transmits a narrow beam to cover another direction at the next moment, until the entire cell is scanned. Each beam is configured with an SSB to enable the terminal device to achieve downlink synchronization. Each SSB is composed of 240 consecutive subcarriers in the frequency domain.

[0070] Similar to the terrestrial cellular communication system, for satellite communication system, due to the limited transmission power of the satellite, beam forming is usually used to obtain the beam forming gain to ensure the signal strength reaching the ground, and at the same time, the signal coverage of a region is realized by using multiple beams. Since the angle covered by each beam is limited, the satellite covers the entire service range by beam sweeping.

[0071] Exemplarily, FIG. 2 is a schematic diagram of SSB beam sweeping provided by an embodiment of the present application. As shown in (a) of FIG. 2, a plurality of SSBs (such as SSB0 to SS7) form an SSB burst set. As shown in (b) of FIG. 2, the SSB burst set is periodically transmitted. A region usually needs to transmit a plurality of SSBs to complete a beam sweep to make the synchronization signal cover the entire service range of the region, and the SSBs required to complete a beam sweep form an SSB burst set.

[0072] At present, there are six time domain transmission periods of the SSB burst set: 5ms, 10ms, 20ms, 40ms, 80ms, and 160ms. Generally, the terminal device defaults to a transmission period of 20 milliseconds when performing initial cell search. In the subsequent process, the period of the SSB burst set can be configured in the signaling ServingCellConfigCommon, and it is stipulated that the beams in the SSB burst set are transmitted within the first 5ms of the period. For the time domain distribution of the SSBs in the SSB burst set, as shown in Table 1 below, the communication protocol R15 stipulates five time domain patterns: Case A, Case B, Case C, Case D, and Case E.

[0073] Table 1

[0074] When beam forming is used, the sensor array is used to direct the transmission of the signal, and a large transmission power is not required, so the transmission power of the satellite can be reduced to a certain extent. However, even if beam forming is used, when the number of beams of a region is very large, the satellite still cannot simultaneously transmit signals on all beams due to the limited transmission power. Taking the satellite deployment assumed by the communication protocol LEO600km Set1-1 FR1 as an example, as shown in Table 2, the satellite realizes ground coverage through 1058 beams, but the number of beams that can be simultaneously transmitted by the satellite is only 106.

[0075] Table 2

[0076] The SSB is a downlink reference signal necessary for a terminal device to access a network. In initial cell search, a base station will usually send an SSB in at least one of the four SSB candidate positions specified in a 20 ms cycle.

[0077] Exemplarily, FIG. 3 shows a schematic diagram of a time-domain position of an SSB. As shown in FIG. 3, one cycle corresponds to two frames, such as SFN0 and SFN1, and each frame has a length of 10 ms; one frame includes two half-frames, such as SFN0 includes HF0 and HF1, and each half-frame has a length of 10 ms; one half-frame includes five slots, such as HF0 includes slot0, slot1, slot2, slot3 and slot4, and each slot has a length of 1 ms; and each slot includes 14 symbols, such as slot0 includes symbol0-symbol13 and slot1 includes symbol14-symbol27. Among them, slot0 and slot1 specify four candidate positions: SSB0, SSB1, SSB2 and SSB3. Each candidate position occupies four symbols. SSB0 is at the index s = 2 of the starting symbol of HF0. SSB1 is at the index s = 8 of the starting symbol of HF0. SSB2 is at the index s = 16 of the starting symbol of HF0. SSB3 is at the index s = 22 of the starting symbol of HF0. In this way, the base station can send an SSB in at least one of the SSB candidate positions SSB0, SSB1, SSB2 and SSB3 in a 20 ms cycle.

[0078] Taking a satellite deployment assuming the communication protocol LEO 600km Set1-1 FR1 as an example. When the satellite sends an SSB in the four SSB candidate positions as shown in FIG. 3 in a 20 ms cycle, the maximum number of beam data sent simultaneously in a 20 ms cycle is 106*4 = 424. If ground coverage is to be achieved through 1058 beams, at least 1058 ÷ 424 ≈ 3 20 ms cycles are needed. Since there are six time-domain transmission cycles for an SSB burst set: 5 ms, 10 ms, 20 ms, 40 ms, 80 ms and 160 ms, the satellite needs to expand the transmission cycle of the SSB to 80 ms to be able to send at least one SSB on each of the 1058 beams.

[0079] In a conventional SSB structure, the SSB includes a synchronization signal and a broadcast signal. Among them, the synchronization signal includes a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). The broadcast signal includes PBCH data and a PBCH demodulation reference signal (DMRS). That is, the conventional SSB is composed of the three parts of PSS, SSS and PBCH.

[0080] For example, FIG. 4 shows a schematic diagram of the time-frequency domain structure of a conventional SSB. As shown in FIG. 4, in the time-frequency domain structure of the conventional SSB, 4 orthogonal frequency division multiplexing (OFDM) symbols numbered 0-3 are occupied in the time domain; and 20 physical resource blocks (PRBs), i.e., 240 subcarriers numbered 0-239, are occupied in the frequency domain. Among them, the PSS and the SSS are located in symbol 0 and symbol 2, respectively, and each occupies 127 resource elements (REs) in the frequency domain, while the other idle REs in symbol 0 and symbol 2 are set to 0. The PBCH data and the DMRS signal are located in symbol 1, symbol 2 and symbol 3, and the upper and lower ends of the SSS in symbol 2 are respectively spaced apart from the PBCH by 9 REs and 8 REs. By leaving a certain guard interval between the SSS and the PBCH, inter-subcarrier interference can be suppressed. The PBCH DMRS is located in the middle of the PBCH, and there are 60 PBCH DMRS in each of symbol 0 and symbol 3. In addition, the RE density of the PBCH DMRS is 1 / 4. The first RE position occupied by the PBCH DMRS is offset, and can take 0, 1, 2 or 3, a total of 4 values, which to some extent reduces the co-frequency interference of the PBCH DMRS signals between different cells.

[0081] The PSS and the SSS are mainly used for time domain synchronization, frequency domain synchronization and obtaining a cell ID in the downlink synchronization process. In the NR system, there are 1008 unique physical cell identifiers (PCIs), and each physical cell identifier NID cell N^{cell}_{ID}NID cell is determined by the combination of the PSS sequence ID and the SSS sequence ID.

[0082] The PBCH is the first channel that needs to be decoded by the terminal device after the primary synchronization signal and secondary synchronization signal detection is completed. The PBCH DMRS is used to measure whether there is an SSB or the signal quality of the SSB, and to demodulate the PBCH data. The PBCH data includes a master information block (MIB) and other additional timing related PBCH payload bits, a total of 56 bits.

[0083] In order to realize downlink synchronization, the terminal device needs to obtain the frequency point of the access carrier by searching and detecting the SSB. In order to reduce the complexity of the search, the terminal device can search for the SSB according to a certain frequency interval specified by the protocol, which is called a synchronization raster. Specifically, the terminal device can first search for the PSS to complete OFDM symbol boundary synchronization, coarse frequency synchronization, and obtain the cell identifier NID(2)N^{(2)}_{ID}NID(2); after detecting the primary synchronization signal, NID(2)N^{(2)}_{ID}NID(2) is used to detect the SSS to obtain the remaining information of the cell ID, i.e. NID(1)N^{(1)}_{ID}NID(1), at the same time, the SSS is used as the demodulation signal of the PBCH, and the PBCH is decoded, and the terminal starts to receive the physical broadcast channel. On the PBCH, the MIB message is received, and the terminal device obtains the system frame number and the half-frame indication, thereby completing the radio frame timing and the half-frame timing, at the same time, the terminal device determines the time slot and the symbol in which the current synchronization signal is located through the SSB Index in the PBCH DMRS and the pattern mode of the SSB burst set used by the current frequency band, thereby completing the time slot timing (i.e. time synchronization).

[0084] When a terminal device (such as a legacy UE) searches for a satellite cell, it searches for SSBs one frequency point at a time with a period of 20 ms by default. When the terminal device searches for a satellite cell on a frequency point, if it does not search for any satellite cell within 20 ms, it will jump to search for a satellite cell on the next frequency point. If a satellite transmits SSBs on a beam with a period of 80 ms on a certain frequency point, the UE is very likely to miss the beam because it does not search for SSBs on the beam within 20 ms and jumps to search for SSBs on other frequency points. As shown in FIG. 5, the satellite transmits SSB0 on beam 1 with a period of 80 ms on frequency point 3 at a candidate position of frame number SFN1. Within a period of 20 ms corresponding to frame numbers SFN0 and SFN1, the terminal device searches for a satellite cell on frequency point 1. Since the frequency points are inconsistent, the terminal device continues to search for SSBs one frequency point at a time on frequency point 1, frequency point 2, frequency point 3, and so on within other periods of 20 ms. In this way, even if the UE is indeed in a satellite cell covered by beam 1, the UE is likely to search for no cell or take a longer time to search for a cell because the period (20 ms) at which the UE searches for SSBs is less than the period (80 ms) at which the satellite transmits SSBs.

[0085] To solve the problem that the terminal device searches for no cell or takes a longer time to search for a cell because the period at which the terminal device searches for SSBs is less than the period at which the satellite transmits SSBs, so that the satellite can transmit SSBs of all beams within a period of 20 ms, the present application proposes the following solution: increasing the number of candidate positions of SSBs within a period of 20 ms. Taking a satellite deployment assuming the communication protocol LEO600km Set1-1 FR1 as an example. If it is desired to achieve ground coverage through 1058 beams within a period of 20 ms, 1058 ÷ 106 ≈ 10 candidate positions are needed. In this way, the number of candidate positions within a period of 20 ms is increased from the original 4 candidate positions to 10 candidate positions, so that the satellite can transmit SSBs of 1058 beams within a period of 20 ms. However, the biggest problem of this approach is that the resource overhead of SSBs is too large, reaching 10*4 / (20*14) = 14.3%, where 10 represents the number of candidate positions after the increase, 4 represents the number of candidate positions before the increase, 20 represents the period length (in ms), and 14 represents the number of symbols contained in one time slot.

[0086] In view of the above problems, the present application provides an SSB transmission method. In this scheme, a longer transmission period (such as 80 ms) includes multiple shorter synchronization periods (such as 20 ms). A new SSB is defined based on the transmission period (such as 80 ms), and compared with the traditional SSB including PSS, SSS and PBCH, the new SSB only includes PSS and SSS. The network device transmits the traditional SSB through a certain beam in one synchronization period (such as 20 ms) of each transmission period (such as 80 ms), and transmits the new SSB through the beam in every other synchronization period. On the one hand, when the terminal device determines to search for the SSB based on the PSS and SSS of the new SSB, it can continue to search for other SSBs on the same beam, directly search for the traditional SSB including PSS, SSS and PBCH, and camp on the cell based on the traditional SSB, thereby avoiding the problem that the terminal device cannot search for any cell in a transmission period. On the other hand, since the traditional SSB includes complete PBCH, the new SSB does not include PBCH (such as not including complete PBCH or not including part of the data of PBCH), so the data amount of the new SSB is less than that of the traditional SSB, thereby reducing resource overhead.

[0087] In order to understand the SSB transmission method provided by the present application, the time-frequency domain structure of the new SSB is introduced below.

[0088] With reference to the description of the above embodiments, the traditional SSB (also referred to as the first SSB) includes PSS, SSS and PBCH, the PBCH of the traditional SSB includes PBCH DMRS and PBCH data, and the SSS of the traditional SSB is offset by 2 OFDM symbols from the PSS. Based on the traditional SSB, the present application defines a new SSB (also referred to as the second SSB), which includes PSS and SSS, and the SSS of the new SSB is offset by 2 OFDM symbols from the PSS.

[0089] In some embodiments, the new SSB does not include PBCH DMRS and PBCH data.

[0090] Exemplarily, FIG. 6 shows a schematic diagram of a time-frequency domain structure of a new SSB. As shown in FIG. 6, in the time-frequency domain structure of the new SSB, 4 OFDM symbols numbered 0-3 are occupied in the time domain; and 20 PRBs, i.e., 240 subcarriers numbered 0-239, are occupied in the frequency domain. Among them, the PSS and the SSS are located in symbol 0 and symbol 2 respectively, and each occupies 127 REs in the frequency domain, while the other idle REs in symbol 0 and symbol 2, and the idle REs in symbol 1 and symbol 3 are set to 0. Among them, the PSS and the SSS are mainly used for time domain synchronization, frequency domain synchronization and obtaining a cell ID in the downlink synchronization process. When the network device sends the new SSB, the terminal device can first search for the PSS to complete the OFDM symbol boundary synchronization, the coarse frequency synchronization and obtain the cell identification NID(2)NID(2). After detecting the primary synchronization signal, the terminal device detects the SSS to obtain the remaining information of the cell ID, i.e., NID(1)NID(1), by using NID(2)NID(2). The terminal device can complete the rough energy detection based on the PSS and the SSS to measure whether there is an SSB. Since the new SSB does not include the PBCH DMRS and the PBCH data, the terminal device cannot demodulate the PBCH data based on the PBCH DMRS. In this case, the terminal device can continue to search for an SSB (i.e., a traditional SSB) including the PSS, the SSS and the PBCH at the same frequency point. It can be understood that if the traditional SSB is continuously sent in each synchronization period, it will cause a large overhead. By not carrying the PBCH DMRS and the PBCH data in the new SSB, the resource overhead and the transmission power can be reduced.

[0091] In some other embodiments, the new SSB includes the PBCH DMRS, but does not include the PBCH data. The PBCH DMRS of the new SSB is used to measure whether there is an SSB or the signal quality of the SSB, but cannot be used to demodulate the PBCH data.

[0092] Exemplarily, FIG. 7 shows a schematic diagram of another time-frequency domain structure of a new SSB. As shown in FIG. 7, in the time-frequency domain structure of the new SSB, 4 OFDM symbols numbered 0-3 are occupied in the time domain; and 20 PRBs, i.e., 240 subcarriers numbered 0-239, are occupied in the frequency domain. Among them, the PSS and the SSS are located in symbol 0 and symbol 2 respectively, and each occupies 127 REs in the frequency domain, while the other idle REs in symbol 0 and symbol 2 are set to 0. The PBCH is located in symbol 1, symbol 2 and symbol 3, and is separated from the upper and lower ends of the SSS in symbol 2 by 9 REs and 8 REs respectively. By leaving a certain guard interval between the SSS and the PBCH, the inter-subcarrier interference can be suppressed. The PBCH includes the PBCH DMRS but does not include the PBCH data, and the idle REs in symbol 1, symbol 2 and symbol 3 are set to 0. The RE density of the PBCH DMRS is 1 / 4. The first RE position occupied by the PBCH DMRS is offset, and can take 0, 1, 2 or 3 values in total, which reduces the PBCH DMRS signal co-frequency interference between different cells to some extent. Among them, the PSS and the SSS are mainly used for time domain synchronization, frequency domain synchronization and obtaining a cell ID in the downlink synchronization process, and the PBCH DMRS is used for measuring whether there is an SSB or measuring the signal quality of the SSB. When the network device sends a new SSB, the terminal device can first search for the PSS to complete the OFDM symbol boundary synchronization, the coarse frequency synchronization and obtain the cell identification NID(2)N^{(2)}_{ID}NID(2). After detecting the primary synchronization signal, the NID(2)N^{(2)}_{ID}NID(2) is used to detect the SSS to obtain the remaining information of the cell ID, i.e., NID(1)N^{(1)}_{ID}NID(1). The terminal device can complete the rough energy detection based on the PSS and the SSS to measure whether there is an SSB. Then, the terminal device can measure the signal quality of the SSB based on the PBCH DMRS, but since the new SSB does not include the PBCH data, the PBCH data cannot be demodulated based on the PBCH DMRS. When the signal quality of the SSB is measured to be good, the terminal device can continue to search for an SSB (i.e., a traditional SSB) including the PSS, the SSS and the PBCH at the same frequency point. It can be understood that if the traditional SSB is continuously sent in each synchronization period, the cost will be large, and by not carrying the PBCH data in the new SSB, the resource cost and the transmission power can be reduced.

[0093] In the description of the above embodiments, the new SSB can or can not include a PBCH DMRS. The PBCH DMRS in the new SSB can be a complete PBCH DMRS or a partial PBCH DMRS, such as a PBCH DMRS on partial OFDM symbols or partial REs. Whether the new SSB includes a PBCH DMRS and whether the PBCH DMRS in the new SSB is a complete PBCH DMRS or a partial PBCH DMRS can be determined according to network configuration, or according to an indication of the terminal device to the network device, or be predefined. For example, in some scenarios with high requirements for cell measurement accuracy, the network is configured to include a PBCH DMRS in the new SSB; in other scenarios with low requirements for cell measurement accuracy, the network is configured to not include a PBCH DMRS in the new SSB.

[0094] It should be noted that the time-frequency domain structures shown in FIGS. 6 and 7 do not limit the time-frequency structure of the new SSB. In other embodiments, the time-frequency structure of the new SSB can be adjusted according to network configuration, including but not limited to: increasing or decreasing the number of OFDM symbols occupied in the time domain, increasing or decreasing the number of PRBs occupied in the frequency domain, adjusting the relative positions of PSS and SSS in the time domain, adjusting the relative positions of PSS and SSS in the frequency domain, adjusting the number of OFDM symbols between PSS and SSS. For example, with respect to FIG. 6, as shown in FIG. 8, the number of OFDM symbols occupied by the new SSB in the time domain is reduced from 4 to 3, numbered 0-2, and PSS and SSS are located in symbol 0 and symbol 2, respectively. For another example, with respect to FIG. 7, as shown in FIG. 9, the number of OFDM symbols occupied by the new SSB in the time domain is increased from 4 to 5, numbered 0-4, and PSS and SSS are located in symbol 0 and symbol 2, respectively.

[0095] The SSB transmission method provided by the embodiments of the present application can be applied to a communication system, which can be a satellite communication system, a non-terrestrial network (NTN) communication system, a high altitude platform station (HAPS), or other possible communication systems, etc., which are not limited by the embodiments of the present application. The communication system can include a network device and one or more terminal devices connected to the network device. The network device and the terminal device can perform uplink (UL) data and downlink (DL) data transmission.

[0096] The network device is a device capable of communicating with the terminal device. In some embodiments, the network device can be an access network device, which can also be referred to as a radio access network (RAN) device, and is a device that provides wireless communication functions for the terminal device. For example, the access network device can be a satellite or a UAS platform. As an example, the satellite or UAS platform can perform signal forwarding, has the functions of radio frequency filtering, frequency conversion and amplification, and the payload repeated waveform signal is unchanged, i.e., works in a transparent forwarding mode; as another example, the satellite or UAS platform has all or part of the functions of a base station, has the functions of radio frequency filtering, frequency conversion and amplification, and demodulation / decoding, switching and / or routing, encoding or modulation, i.e., works in a regenerative mode. For another example, the access network device can also be a base station, which can be a generation nodeB (gNB) in 5G, an evolved nodeB (eNB or eNodeB) in LTE, a radio network controller (RNC), a nodeB (NB), a home controller (BSC), a base station transceiver station (BTS), a home base station (such as a home nodeB or a home evolved nodeB), a baseband unit (BBU), a transmitting and receiving point (TRP), a transmitting point (TP), a mobile switching center, and the like. For yet another example, the access network device can also be a radio controller in a cloud radio access network (CRAN) scenario, a centralized unit (CU), and / or a distributed unit (DU), or the network device can be a relay station, an access point, a vehicle-mounted device, a terminal device, a wearable device, and a device in future mobile networks, and the like.

[0097] The terminal device is a device with wireless transceiving function. The terminal device can be a mobile terminal device or a non-mobile terminal device. For example, the terminal device can be a UE, a subscriber unit, a subscriber station, a mobile station, a mobile station, a remote station, a remote terminal, a mobile device, a terminal, an access terminal, a user terminal, a wireless communication device, a user agent or a user equipment. The access terminal can be a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL), a personal digital assistant (PDA), a handheld device with wireless communication function, a computer device or other processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal device in a future evolved public land mobile network (PLMN), and the like, which are not limited in the embodiments of the present application.

[0098] In a specific implementation, the network device or the terminal device can have the components shown in FIG. 10.

[0099] Exemplarily, FIG. 10 is a schematic diagram of a hardware structure of a communication apparatus provided by an embodiment of the present application. As shown in FIG. 10, the communication apparatus 100 includes at least one processor 101, a communication line 102 and at least one communication interface 103. Further, the communication apparatus 100 can also include a memory 104. The processor 101, the memory 104 and the communication interface 103 can be connected through the communication line 102. In the embodiments of the present application, at least one can be one, two, three or more, which are not limited in the embodiments of the present application.

[0100] The processor 101 can be a central processing unit (CPU), a network processor (NP), or a combination of CPU and NP. The processor 101 can further include a hardware chip. The hardware chip can be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The PLD can be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof. The processor can also be any other processing means having processing function, such as a circuit, a device, or a software module, etc.

[0101] The communication line 102 can include a path for transmitting information between components included in the communication apparatus.

[0102] The communication interface 103 can be used for communication with other devices or communication networks (such as satellite communication, Ethernet, radio access network (RAN), wireless local area networks (WLAN), etc.). The communication interface 103 can be a module, a circuit, a transceiver, or any means capable of realizing communication.

[0103] The memory 104 can be a read-only memory (ROM) or other type of static storage device that can store static information and / or instructions, or a random access memory (RAM), or other type of dynamic storage device that can store information and / or instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disk storage, a magnetic disk storage or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0104] In a possible design, the memory 104 can exist independently of the processor 101, that is, the memory 104 can be a memory external to the processor 101, and the memory 104 can be connected to the processor 101 through the communication line 102, for storing instructions or program codes. When the processor 101 invokes and executes the instructions or program codes stored in the memory 104, the SSB transmission method provided in embodiments of the present application can be implemented. In another possible design, the memory 104 can also be integrated with the processor 101, that is, the memory 104 can be an internal memory of the processor 101, for example, the memory 104 can be a cache, and can be used to temporarily store some data and / or instruction information, and the like.

[0105] As a possible implementation, the processor 101 can include one or more CPUs, for example, the CPU0 and the CPU1 in FIG. 10. As another possible implementation, the communication apparatus 100 can include multiple processors, for example, the processor 101 and the processor 107 in FIG. 10. As still another possible implementation, the communication apparatus 100 can further include the output device 105 and the input device 106. For example, the input device 106 can be a keyboard, a mouse, a microphone, a joystick, or the like, and the output device 105 can be a display screen, a speaker, or the like.

[0106] It should be noted that the communication apparatus 100 can be a general-purpose device or a special-purpose device. For example, the communication apparatus 100 can be a satellite, a UAS, a mobile phone, a desktop computer, a laptop computer, a network server, a tablet computer, an embedded device, a chip system, or a device having a similar structure as shown in FIG. 10. The embodiments of the present application do not limit the type of the communication apparatus 100.

[0107] The SSB transmission method provided in embodiments of the present application is described below. In the following method embodiments, each device mentioned can have the components shown in FIG. 10, and will not be described again.

[0108] FIG. 11 is a flow diagram of an SSB transmission method provided in an embodiment of the present application.

[0109] As shown in FIG. 11, the method can include the following S11 to S16.

[0110] S11, a network device sends a legacy SSB (also referred to as a first SSB) through a first beam in a first synchronization period of each transmission period, and sends a new SSB (also referred to as a second SSB) through the first beam in a second synchronization period of each transmission period, the second synchronization period being different from the first synchronization period.

[0111] The first beam is any one of the beams covered by the network device, that is, for any one of the beams covered by the network device, the network device can transmit the SSB according to the SSB transmission method provided in the embodiments of the present application.

[0112] The embodiments of the present application define two types of SSBs: a traditional SSB and a new SSB. The traditional SSB can include a PSS, an SSS, and a PBCH, and the PBCH of the traditional SSB can include a PBCH DMRS and PBCH data. The new SSB includes a PSS and an SSS. As an example, the new SSB can also include a PBCH DMRS, but the new SSB does not include PBCH data. As another example, the new SSB does not include a PBCH DMRS and PBCH data. Whether the new SSB includes a PBCH DMRS can be determined according to network configuration, or determined according to an indication of the terminal device to the network device, or predefined. It should be noted that when the traditional SSB and the new SSB both include a PBCH DMRS, the main functions of the PBCH DMRS of the traditional SSB and the PBCH DMRS of the new SSB are not the same. Specifically, since the traditional SSB includes PBCH data, the PBCH DMRS of the traditional SSB is mainly used for demodulating the PBCH data, that is, the PBCH DMRS of the traditional SSB can not only be used for measuring whether there is an SSB or the signal quality of the SSB, but also be used for demodulating the PBCH data; and since the new SSB does not include PBCH data, the PBCH DMRS of the new SSB can only be used for measuring whether there is an SSB or the signal quality of the SSB. For the implementation of the traditional SSB and the new SSB, reference can be made to the specific description of the above embodiments, which will not be described here.

[0113] The embodiments of the present application define two cycles: a transmission cycle and a synchronization cycle. Each transmission cycle includes N synchronization cycles, the length of each synchronization cycle in the N synchronization cycles is equal, and N is an integer greater than or equal to 2. The transmission cycle is also referred to as a broadcast cycle, an SSB cycle, or a full cycle, etc., and is a relatively long cycle. As an example, the value of N can be determined according to network configuration, or determined according to the indication of the terminal device to the network device, or predefined, such as the network configuration can determine N according to the total number of satellite coverage beams, the number of beams simultaneously transmitted by the satellite, etc. The synchronization cycle is a relatively short cycle, such as 5ms, 10ms, 20ms, 40ms, 80ms, or 160ms, etc. In the embodiments of the present application, one synchronization cycle is used to transmit at least one SSB, and one transmission cycle is used to transmit at least N SSBs. Whether a traditional SSB or a new SSB is transmitted in a certain synchronization cycle can be determined according to network configuration, or determined according to the indication of the terminal device to the network device, or predefined. The first synchronization cycle is at least one synchronization cycle in the N synchronization cycles, and the second synchronization cycle is the other synchronization cycle in the N synchronization cycles except the first synchronization cycle. Each first synchronization cycle can be used to send at least one traditional SSB, and each second synchronization cycle can be used to send at least one new SSB. It should be noted that the specific name and cycle length of the transmission cycle and the synchronization cycle are not limited in the embodiments of the present application, and can be adjusted according to actual use requirements.

[0114] Exemplarily, FIG. 12 shows a schematic diagram of transmitting SSBs in each synchronization cycle of a transmission cycle. As shown in FIG. 12, 1 transmission cycle is 80ms, and 1 synchronization cycle is 20ms. In the 1st synchronization cycle of the 1 transmission cycle, the network device transmits a new SSB through one beam (which can be referred to as a first beam); in the 2nd synchronization cycle of the 1 transmission cycle, the network device transmits a traditional SSB through the beam; in the 3rd synchronization cycle of the 1 transmission cycle, the network device transmits a new SSB through the beam; and in the 4th synchronization cycle of the 1 transmission cycle, the network device transmits a new SSB through the beam. That is, 1 transmission cycle includes 1 first synchronization cycle and 3 second synchronization cycles, and the network device transmits 1 traditional SSB and 3 new SSBs in the transmission cycle.

[0115] In some embodiments, when the new SSB includes the PBCH DMRS, each transmission cycle includes a first number of synchronization cycles, and the length of each synchronization cycle in each transmission cycle is a first length; when the new SSB does not include the PBCH DMRS, each transmission cycle includes a second number of synchronization cycles, and the length of each synchronization cycle in each transmission cycle is a second length. Wherein, the first number is greater than the second number, and the first length is equal to the second length.

[0116] Exemplarily, FIG. 13 shows a schematic diagram of transmitting SSBs in different transmission periods.

[0117] As shown in (a) of FIG. 13, when the new SSB includes the PBCH DMRS, 1 transmission period can be 80 ms, and 1 synchronization period can be 20 ms. It can be understood that when the new SSB includes the PBCH DMRS, the RE corresponding to the PBCH DMRS is not 0, and transmitting the PBCH DMRS increases the resource overhead of the new SSB and the transmission power, which reduces the number of SSBs simultaneously transmitted by the network device through the beam in one synchronization period, and increases the length of the transmission period, i.e., the number (i.e., the first number) of synchronization periods included in 1 transmission period increases.

[0118] As shown in (b) of FIG. 13, when the new SSB does not include the PBCH DMRS, 1 transmission period can be 40 ms, and 1 synchronization period can be 20 ms. It can be understood that when the new SSB does not include the PBCH DMRS, the RE corresponding to the PBCH DMRS is originally an idle RE, and not carrying the PBCH DMRS in the new SSB reduces the resource overhead of the new SSB and the transmission power, which increases the number of SSBs simultaneously transmitted by the network device through the beam in one synchronization period, and shortens the length of the transmission period, i.e., the number (i.e., the second number) of synchronization periods included in 1 transmission period decreases.

[0119] In some embodiments, the relative positions of the first synchronization period in different transmission periods are the same or different. For example, the position of the first synchronization period in the first transmission period is the same as or different from the position of the first synchronization period in the second transmission period. The first transmission period and the second transmission period are two different transmission periods.

[0120] It should be noted that the above-mentioned "relative position" refers to the time offset between the starting time of the first synchronization period and the starting time of the transmission period in which the first synchronization period is located.

[0121] Exemplarily, FIG. 14 shows a schematic diagram in which the relative positions of the first synchronization period in different transmission periods are the same. As shown in FIG. 14, 1 transmission period is 80 ms, and 1 synchronization period is 20 ms. For the 1st transmission period: the network device transmits a legacy SSB through a beam in the 2nd synchronization period; the network device transmits a new SSB through a beam in the 1st synchronization period, the 3rd synchronization period, and the 4th synchronization period, respectively. For the 2nd transmission period: the network device transmits a legacy SSB through a beam in the 2nd synchronization period; the network device transmits a new SSB through a beam in the 1st synchronization period, the 3rd synchronization period, and the 4th synchronization period, respectively. Whether it is the 1st transmission period or the 2nd transmission period, the time offset between the start time of the synchronization period (i.e., the first synchronization period) for transmitting the legacy SSB and the start time of the transmission period in which the first synchronization period is located is 20 ms. That is, the relative positions of the first synchronization period in different transmission periods are the same.

[0122] Exemplarily, FIG. 15 shows a schematic diagram in which the relative positions of the first synchronization period in different transmission periods are different. As shown in FIG. 15, 1 transmission period is 80 ms, and 1 synchronization period is 20 ms. For the 1st transmission period: the network device transmits a legacy SSB through a beam in the 2nd synchronization period; the network device transmits a new SSB through a beam in the 1st synchronization period, the 3rd synchronization period, and the 4th synchronization period, respectively. For the 2nd transmission period: the network device transmits a legacy SSB through a beam in the 1st synchronization period; the network device transmits a new SSB through a beam in the 2nd synchronization period, the 3rd synchronization period, and the 4th synchronization period, respectively. Since the time offset between the start time of the synchronization period (i.e., the first synchronization period) for transmitting the legacy SSB and the start time of the 1st transmission period is 20 ms, and the time offset between the start time of the synchronization period (i.e., the first synchronization period) for transmitting the legacy SSB and the start time of the 1st transmission period is 0 ms, the relative positions of the first synchronization period in different transmission periods are different.

[0123] With the above embodiment, in a communication system such as satellite communication, due to the limitation of transmission power, the network device usually uses beamforming to obtain beamforming gain and uses multiple beams to realize signal coverage of a region. In this case, the network device may need to transmit multiple SSBs through multiple beams at the same candidate position in a transmission period. At this moment, if the service type of the to-be-transmitted service of a certain beam in the multiple beams is a preset type and / or the data amount of the to-be-transmitted service is relatively large, the to-be-transmitted service will occupy a large amount of resources, and transmission at the same candidate position will be limited. In order to avoid such problems, the network device can adjust the relative position of the first synchronization period in different transmission periods or adjust the relative position of the second synchronization period in different transmission periods according to whether the service type of the to-be-transmitted service is a preset type and / or the data amount of the to-be-transmitted service.

[0124] For ease of understanding, the specific implementation of the network device adjusting the relative position of the first synchronization period in different transmission periods or adjusting the relative position of the second synchronization period in different transmission periods according to whether the service type of the to-be-transmitted service is a preset type and / or the data amount of the to-be-transmitted service will be described below by taking FIG. 16 as an example.

[0125] As shown in FIG. 16, one transmission period is 80 ms, and one synchronization period is 20 ms.

[0126] For the first transmission period, if the data amount of the to-be-transmitted service of beam 1 (referred to as the first beam) or beam 2 (referred to as the second beam) is small, and does not cause resource occupation to the traditional SSB transmission, the network device can execute the following transmission strategy: in the second synchronization period (referred to as the first synchronization period) of the first transmission period, a traditional SSB (referred to as the first SSB) is transmitted through the first beam; in the first synchronization period, the third synchronization period, and the fourth synchronization period (referred to as the second synchronization period) of the first transmission period, a new SSB (referred to as the second SSB) is transmitted through the first beam; in the second synchronization period (referred to as the third synchronization period) of the first transmission period, a traditional SSB (referred to as the third SSB) is transmitted through the second beam; and in the first synchronization period, the third synchronization period, and the fourth synchronization period (referred to as the fourth synchronization period) of the first transmission period, a new SSB (referred to as the fourth SSB) is transmitted through the second beam. In this case, the first synchronization period and the third synchronization period have the same position in the first transmission period.

[0127] For the second transmission period, if the traffic data volume of the traffic to be transmitted by beam 1 (referred to as a first beam) or beam 2 (referred to as a second beam) is large, resource occupation of the traditional SSB transmission is caused, and then the network device can perform the following transmission strategy: in the first synchronization period (referred to as a first synchronization period) of the second transmission period, a traditional SSB (referred to as a first SSB) is transmitted through beam 1; in the second synchronization period, the third synchronization period, and the fourth synchronization period (referred to as a second synchronization period) of the first transmission period, a new SSB (referred to as a second SSB) is transmitted through beam 1 respectively; in the second synchronization period (referred to as a third synchronization period) of the second transmission period, a traditional SSB (referred to as a third SSB) is transmitted through beam 2; in the first synchronization period, the third synchronization period, and the fourth synchronization period (referred to as a fourth synchronization period) of the first transmission period, a new SSB (referred to as a fourth SSB) is transmitted through beam 2 respectively. In this case, the first synchronization period and the third synchronization period are located in different positions in the first transmission period.

[0128] In some embodiments, the number of first synchronization periods in different transmission periods is the same or different. For example, the number of first synchronization periods in the first transmission period is the same as or different from the number of first synchronization periods in the second transmission period. Wherein, the first transmission period and the second transmission period are two different transmission periods.

[0129] As a more common application scenario, the number of first synchronization periods in different transmission periods is fixed. For example, as shown in FIG. 14, each transmission period includes one first synchronization period, and the first synchronization period is located in the second synchronization period of each transmission period. For another example, as shown in FIG. 15, each transmission period includes one first synchronization period, and the first synchronization period is located in the second synchronization period of the first transmission period and the first synchronization period of the second transmission period respectively.

[0130] As a more special application scenario, for some reasons, the network device no longer provides network coverage through some beams. Before ending the network coverage, the network device needs to indicate to the terminal device in the coverage range which frequency to search for new beam coverage, so that the terminal device can search for SSBs at these frequencies according to the indication of the network device. In order to make these terminal devices migrate to the new cell as soon as possible, the network device can change the SSB transmission scheme and increase the number of traditional SSBs transmitted in each transmission period. After a period of time, the terminal device may have migrated to the new cell, and the network device can restore the original SSB transmission scheme and reduce the number of traditional SSBs transmitted in the transmission period to reduce resource overhead.

[0131] Exemplarily, FIG. 17 shows a schematic diagram of different numbers of first synchronization periods in different transmission periods. As shown in FIG. 17, in the 1st transmission period, the network device transmits SSBs according to the original SSB transmission scheme, at this moment, 1 transmission period includes 1 first synchronization period, that is, one transmission period transmits one traditional SSB. Before the coverage of this beam ends, such as in 2 first synchronization periods, the network device can change the SSB transmission scheme, increase the number of traditional SSBs transmitted in each transmission period, such as from 1 traditional SSB to 4 traditional SSBs. It can be understood that by increasing the number of traditional SSBs transmitted in the transmission period, the speed of the terminal device searching for the cell can be improved, so that the terminal device can be migrated to the new cell as soon as possible.

[0132] S12, the terminal device searches for SSBs according to a synchronization period at the first frequency point.

[0133] It should be noted that the "synchronization period" in S12 is equal in length to the "synchronization period" in S11. In addition, the application does not limit the order of S11 and S12. The terminal device can search for SSBs at the frequency point by frequency point according to the synchronization period, such as searching for SSBs at the frequency point by frequency point in the order from low to high, or searching for SSBs at the frequency point by frequency point in the order from high to low. In the process of searching for SSBs at the first frequency point according to the synchronization period, the terminal device may search for SSBs in one synchronization period, or may not search for SSBs.

[0134] As a possible scenario, the terminal device is not located in the coverage range of the first beam, that is, the frequency point of the first beam is not the first frequency point. If the terminal device does not search for any SSB in one synchronization period, it jumps to the next frequency point (such as the second frequency point) different from the first frequency point, and searches for SSBs at the second frequency point according to the synchronization period.

[0135] As another possible scenario, the terminal device is located in the coverage range of the first beam, that is, the frequency point of the first beam is the first frequency point. The terminal device searches for SSBs at the first frequency point, and the search result is any one of the following: the searched SSB can be a new SSB (that is, S13 is performed below), or a traditional SSB (that is, S15 is performed below).

[0136] S13, the terminal device searches for a new SSB in one synchronization period.

[0137] The above-mentioned new SSB can include PSS and SSS. As an example, the new SSB can not include PBCH DMRS and PBCH data. As another example, the new SSB can also include PBCH DMRS, but does not include PBCH data.

[0138] For some terminal devices with low requirements on measurement accuracy, when the terminal device searches a new SSB which does not include PBCH DMRS and PBCH data, the terminal device can complete rough energy detection based on PSS and SSS of the new SSB to determine that there is an SSB, but the terminal device cannot demodulate PBCH data based on PBCH DMRS. In this case, the terminal device can perform the following S14 to continue searching a traditional SSB including PSS, SSS and PBCH at the same frequency point.

[0139] For some terminal devices with high requirements on measurement accuracy, when the terminal device searches a new SSB including PBCH DMRS but not including PBCH data, the terminal device can measure the signal quality of the SSB based on PBCH DMRS, but cannot demodulate PBCH data based on PBCH DMRS because the new SSB does not include PBCH data. When the signal quality of the SSB is measured to be good, the terminal device can perform the following S14 to continue searching a traditional SSB including PSS, SSS and PBCH at the same frequency point.

[0140] It can be understood that if the traditional SSB is continuously sent in each synchronization period, it will cause large overhead, and by not carrying PBCH DMRS and PBCH data in the new SSB or not carrying PBCH data in the new SSB, the resource overhead can be reduced.

[0141] S14, continue searching SSB at the first frequency point according to a synchronization period.

[0142] The terminal device can continue to search SSB at the first frequency point according to a synchronization period. In the next synchronization period, the terminal device can search a traditional SSB (i.e., perform the following S15); or the terminal device can search a new SSB (i.e., return to perform the above S13) until a traditional SSB is searched (i.e., perform the following S15).

[0143] S15, the terminal device searches a traditional SSB in a synchronization period.

[0144] The traditional SSB can include PSS, SSS and PBCH.

[0145] The PBCH of the traditional SSB can include PBCH DMRS and PBCH data.

[0146] S16, the terminal device camps on a cell based on the traditional SSB.

[0147] Exemplarily, the terminal device can first search for the PSS, complete OFDM symbol boundary synchronization, coarse frequency synchronization, and obtain the cell identifier 2NID(2)N^{(2)}_{ID}NID(2); after detecting the primary synchronization signal, the NID(2)N^{(2)}_{ID}NID(2) is used to detect the SSS to obtain the remaining information of the cell ID, that is, NID(1)N^{(1)}_{ID}NID(1), and at the same time, the SSS is used as the demodulation signal of the PBCH, and the PBCH is decoded, and the terminal starts to receive the physical broadcast channel. On the PBCH, the MIB message is received, and the terminal device obtains the system frame number and the half-frame indication, thereby completing the wireless frame timing and the half-frame timing, and at the same time, the terminal device determines the time slot and the symbol in which the current synchronization signal is located through the SSB Index in the PBCH DMRS and the pattern mode of the SSB burst set used by the current frequency band, thereby completing the time slot timing.

[0148] In the SSB transmission method provided in the application, a new SSB is defined on the basis of a transmission period (such as 80 ms), and the new SSB includes PSS and SSS compared with the traditional SSB including PSS, SSS and PBCH. The network device transmits the traditional SSB through a certain beam in one synchronization period (such as 20 ms) of each transmission period (such as 80 ms), and transmits the new SSB through the beam in each other synchronization period. On the one hand, when the terminal device determines that the SSB is searched based on the PSS and the SSS of the new SSB, it can continue to search for other SSBs on the same beam, directly search for the traditional SSB including PSS, SSS and PBCH, and camp on the cell based on the traditional SSB, thereby avoiding the problem that the terminal device cannot search for any cell in a transmission period. On the other hand, since the traditional SSB includes complete PBCH, the new SSB does not include PBCH (such as not including complete PBCH or not including part of the data of PBCH), so the amount of data carried by the new SSB is less than the amount of data carried by the traditional SSB, thereby reducing resource overhead.

[0149] The above embodiments introduce the flow of the SSB transmission method. In the following three embodiments, the specific implementation modes of the traditional SSB and the new SSB in the process of implementing the SSB transmission method provided in the application are exemplarily introduced.

[0150] Embodiment one,

[0151] According to the description of the above embodiment, in order to solve the problem that the terminal device cannot search for any cell or needs to spend a longer time to search for a cell due to the period of the terminal device searching for the SSB being less than the period of the satellite sending the SSB, so that the satellite can send the SSB of all beams in a 20 ms period, the application proposes that in each synchronization period (such as 20 ms) in each transmission period (such as 80 ms), the first beam sends a traditional SSB, and in each other synchronization period, the beam sends a new SSB. Since in the traditional SSB transmission scheme, the SSB needs a 20 ms period to be sent at least at one SSB candidate position in the specified 4 SSB candidate positions, when the new SSB is defined on the basis of the transmission period (such as 80 ms), the problem of how to set the candidate positions of the traditional SSB and the new SSB in each transmission period is involved.

[0152] To this end, the application proposes the following scheme: for a certain beam, in each transmission period, the traditional SSB is at a first candidate position in a first synchronization period, and the new SSB is at a second candidate position in a second synchronization period, and the first candidate position and the second candidate position are associated.

[0153] The above-mentioned "association between the first candidate position and the second candidate position" can mean that there is an association relationship between the index of the first candidate position and the index of the second candidate position. The association relationship can be predefined or configured by the network device through an instruction. The association relationship specifically includes the following two meanings:

[0154] The first meaning is that the index of the first candidate position is the same as the index of the second candidate position.

[0155] When the index of the first candidate position is the same as the index of the second candidate position, the index of the first candidate position and the index of the second candidate position can be a candidate position specified by a relevant protocol, or a candidate position determined according to network configuration.

[0156] As an example, the index of the first candidate position and the index of the second candidate position can be the index of the starting symbol of the SSB, which is used to indicate the relative position of the starting symbol of the SSB in a synchronization period.

[0157] Exemplarily, FIG. 18 shows a schematic diagram in which the indexes of the first candidate position and the second candidate position are the same. As shown in FIG. 18, one transmission period includes four synchronization periods. Each synchronization period includes two frames, each frame includes two half-frames, each half-frame includes five time slots, and each time slot includes fourteen symbols. The terminal device transmits one legacy SSB at the first candidate position of the third synchronization period (referred to as the first synchronization period), and transmits one new SSB at the second candidate position of the first synchronization period, the second synchronization period, and the fourth synchronization period (referred to as the second synchronization period) respectively. The index of the second candidate position of the first synchronization period, the index of the second candidate position of the second synchronization period, the index of the first candidate position of the third synchronization period, and the index of the second candidate position of the fourth synchronization period are all s = 8. That is, the indexes of the candidate positions of the synchronization periods in one transmission period are the same.

[0158] In a second meaning, the indexes of the first candidate position and the second candidate position are different, but the indexes of the first candidate position and the second candidate position comply with a preset rule.

[0159] As an example, the preset rule can be that the indexes of the candidate positions of the synchronization periods in one transmission period increase in ascending order or decrease in descending order.

[0160] Exemplarily, FIG. 19 shows a schematic diagram in which the indexes of the first candidate position and the second candidate position are different. As shown in FIG. 19, one transmission period includes four synchronization periods. Each synchronization period includes two frames, each frame includes two half-frames, each half-frame includes five time slots, and each time slot includes fourteen symbols. The terminal device transmits one legacy SSB at the first candidate position of the third synchronization period (referred to as the first synchronization period), and transmits one new SSB at the second candidate position of the first synchronization period, the second synchronization period, and the fourth synchronization period (referred to as the second synchronization period) respectively. The index of the second candidate position of the first synchronization period is s = 4, the index of the second candidate position of the second synchronization period is s = 6, the index of the first candidate position of the third synchronization period is s = 8, and the index of the second candidate position of the fourth synchronization period is s = 10. That is, the indexes of the candidate positions of the synchronization periods in one transmission period increase by 2 in ascending order.

[0161] In the foregoing scheme, when the terminal device searches for a new SSB at the second candidate position in a synchronization period, the terminal device can determine the association relationship between the first candidate position and the second candidate position according to a predefined rule or a rule configured by the network device, and perform SSB search on the first candidate position in a subsequent synchronization period at the first frequency point based on the association relationship between the first candidate position and the second candidate position, until a conventional SSB is searched for at the first candidate position in a certain synchronization period. Since there is an association relationship between the index of the first candidate position and the index of the second candidate position, the terminal device only searches for the candidate position, skips some symbols, and does not need to search for the entire synchronization period, thereby reducing the power consumption of the terminal device.

[0162] It should be noted that the foregoing embodiments are described by taking the indexes of the first candidate position and the second candidate position being the same or the indexes of the first candidate position and the second candidate position conforming to a preset rule as examples, which do not limit the present application. In other embodiments, the indexes of the first candidate position and the second candidate position can be randomly configured by the network device, and in this case, the terminal device needs to search for all positions in the transmission period without distinction.

[0163] Embodiment two,

[0164] On the basis of the first candidate position and the second candidate position provided in Embodiment one, the present embodiment further proposes a concept of time offset. The time offset refers to the number of OFDM symbols by which the PSS of the SSB is offset from the starting symbol of the candidate position. Here, the SSB includes a conventional SSB and a new SSB.

[0165] For a conventional SSB:

[0166] The conventional SSB is transmitted at the first candidate position in the first synchronization period, and the PSS of the conventional SSB is offset by 0 OFDM symbol from the starting symbol of the first candidate position, that is, the PSS of the conventional SSB is the same as the starting symbol of the first candidate position.

[0167] Exemplarily, FIG. 20 shows a schematic diagram of the time offset of the conventional SSB. As shown in FIG. 20, in the first synchronization period, the symbol at the position of the PSS of the conventional SSB and the starting symbol of the first candidate position are both s=8, that is, the PSS of the conventional SSB is offset by 0 OFDM symbol from the starting symbol of the first candidate position.

[0168] For a new SSB:

[0169] The PSS of the new SSB is offset by 0 OFDM symbols from the starting symbol of the second candidate position, i.e., the PSS of the new SSB is the same as the starting symbol of the second candidate position. Alternatively, the PSS of the new SSB is offset by 1 or more OFDM symbols from the starting symbol of the second candidate position, i.e., the PSS of the new SSB is 1 symbol different from the starting symbol of the second candidate position.

[0170] Exemplarily, FIG. 21 shows a schematic diagram of time offset of a new SSB. As shown in FIG. 21, in the second synchronization period, the symbol where the PSS of the new SSB is located and the starting symbol of the second candidate position are both s = 8, i.e., the PSS of the new SSB is offset by 0 OFDM symbols from the starting symbol of the second candidate position.

[0171] Exemplarily, FIG. 22 shows another schematic diagram of time offset of a new SSB. As shown in FIG. 22, in the second synchronization period, the symbol where the PSS of the new SSB is located is s = 9 and the starting symbol of the second candidate position is s = 8, i.e., the PSS of the new SSB is offset by 1 OFDM symbol from the starting symbol of the second candidate position.

[0172] In some embodiments, when one transmission period includes multiple new SSBs, the time offset of different new SSBs is the same, or the time offset of different new SSBs is different.

[0173] Exemplarily, FIG. 23 shows a schematic diagram of time offset of multiple new SSBs. As shown in FIG. 23, one transmission period includes 1 first synchronization period and 3 second synchronization periods. In any second synchronization period, the PSS of the new SSB is offset by 0 OFDM symbols from the starting symbol of the second candidate position, i.e., the time offset of different new SSBs is the same.

[0174] Exemplarily, FIG. 24 shows another schematic diagram of time offset of multiple new SSBs. As shown in FIG. 24, one transmission period includes 1 first synchronization period and 3 second synchronization periods. In any second synchronization period, the PSS of the new SSB is offset by 1 OFDM symbol from the starting symbol of the second candidate position, i.e., the time offset of different new SSBs is the same.

[0175] Exemplarily, FIG. 25 shows a schematic diagram of time offsets of a plurality of new SSBs. As shown in FIG. 25, one transmission cycle includes 1 first synchronization cycle and 3 second synchronization cycles. In the 1st second synchronization cycle, the PSS of the new SSB is offset from the starting symbol of the second candidate location by 0 OFDM symbols; in the 2nd second synchronization cycle, the PSS of the new SSB is offset from the starting symbol of the second candidate location by 1 OFDM symbol; in the 3rd second synchronization cycle, the PSS of the new SSB is offset from the starting symbol of the second candidate location by 1 OFDM symbol. That is, the time offsets of different new SSBs are different.

[0176] In some embodiments, the number of OFDM symbols by which the PSS of the new SSB is offset from the starting symbol of the second candidate location can be determined according to at least one of a physical cell identifier (PCID), a system frame number (SFN), and a half frame number (HF).

[0177] Example 1: time offset = PCID mod 2, mod is a modulo operator.

[0178] Example 2: Or, where N is 2 (i.e., the number of radio frames corresponding to a 20 ms period), k offset may be configured by a radio resource control (RRC) protocol, by a network device, or by a network side.

[0179] Example 3: time offset = HF, or, time offset = HF + k offset , k offset may be configured by a protocol or by a network device.

[0180] Example 4: where N is 2 (i.e., the number of radio frames corresponding to a 20 ms period), k offset may be configured by a protocol or by a network side.

[0181] Example 5: where N is 2 (i.e., the number of radio frames corresponding to a 20 ms period), k offset may be configured by a protocol or by a network side.

[0182] Example 6: where N is 2 (i.e., the number of radio frames corresponding to a 20 ms period), k offset may be configured by a protocol or by a network side.

[0183] Example 7: wherein N is 2 (i.e., the number of radio frames corresponding to a 20 ms period), k offset The number of OFDM symbols can be agreed by protocol or configured by the network side.

[0184] In some embodiments, in one transmission period, the number of OFDM symbols by which the starting symbol of the PSS in each synchronization period is offset from the candidate position is determined according to network configuration, or determined according to indication of the terminal device to the network device, or predefined.

[0185] Exemplarily, if one transmission period includes 1 first synchronization period and 3 second synchronization periods. Then the first sequence can be 0000, 0001, 0101, 1010, 1001, 1100 or 1111, etc. Wherein, the number 0 represents that the PSS of the SSB is offset by 0 OFDM symbols from the starting symbol of the second candidate position, and the number 1 represents that the PSS of the SSB is offset by 0 OFDM symbols from the starting symbol of the second candidate position.

[0186] In the above scheme, the network device can adjust the number of OFDM symbols by which the starting symbol of the PSS in each synchronization period is offset from the candidate position according to factors such as transmission power, number of beams, and to-be-transmitted service. For example, when the transmission power of the network device is limited, the network device can set the number of OFDM symbols by which the PSS on some beams is offset from the starting symbol of the candidate position to 1, and set the number of OFDM symbols by which the PSS on other beams is offset from the starting symbol of the candidate position to 0, so that the network device can transmit more beams in one synchronization period.

[0187] Embodiment three,

[0188] In the embodiments of the present application, the PSS and SSS of the traditional SSB can carry the PCID, and the PSS and SSS of the new SSB can also carry the PCID. The PCID is necessary information for decoding the PBCH, and after the terminal device decodes the PBCH based on the PCID, the MIB can be obtained.

[0189] In some embodiments, the PCID carried by the PSS and SSS of the traditional SSB is the same as the PCID carried by the PSS and SSS of the new SSB. In other embodiments, the PCID carried by the PSS and SSS of the traditional SSB is different from the PCID carried by the PSS and SSS of the new SSB.

[0190] As an example, when the PCID carried by the PSS and SSS of the legacy SSB is different from the PCID carried by the PSS and SSS of the new SSB, the PCID carried by the legacy SSB can be determined according to the PCID carried by the new SSB and the number of synchronization periods between the legacy SSB and the new SSB.

[0191] For example, PCID carried by new SSB signal #i - PCID carried by new SSB signal #(i-1) = the number of synchronization periods between the new SSB signal #i and the legacy SSB. Wherein, new SSB signal #i represents the i-th new SSB signal, and new SSB signal #(i-1) represents the (i-1)-th new SSB signal.

[0192] Exemplarily, FIG. 26 shows a schematic diagram of PCIDs carried by the legacy SSB and the new SSB. As shown in FIG. 26, in each transmission period, the PCID shows a periodic change rule. For example, in each transmission period, the PCIDs carried by the SSBs are 206, 207, 207 and 204 in chronological order. The terminal device can detect the PCID carried by the SSB in any synchronization period in any transmission period, which can include the following scenarios:

[0193] Scenario 1: the terminal device detects new SSB #(i-1) in the first synchronization period of the second transmission period, and decodes the PCID carried by the SSB to be 206. The terminal device continues to detect the SSB, and detects new SSB #i in the second synchronization period of the second transmission period, and decodes the PCID carried by the SSB to be 207. In this way, the terminal device can determine that there is 1 synchronization period between the new SSB signal #i and the legacy SSB based on PCID = 206 and PCID = 207, and directly detect the legacy SSB in the third transmission period of the second transmission period to camp on the cell.

[0194] Scenario 2: the terminal device detects new SSB #(i-1) in the fourth synchronization period of the first transmission period, and decodes the PCID carried by the SSB to be 204. The terminal device continues to detect the SSB, and detects new SSB #i in the first synchronization period of the second transmission period, and decodes the PCID carried by the SSB to be 206. In this way, the terminal device can determine that there are 2 synchronization periods between the new SSB signal #i and the legacy SSB based on PCID = 204 and PCID = 206, and directly detect the legacy SSB in the third transmission period of the second transmission period to camp on the cell.

[0195] Scenario 3: The terminal device detects a new SSB # (i-1) in the second synchronization period of the second transmission period, decodes the PCID = 207 carried by the SSB. The terminal device continues to detect the SSB, and directly detects a traditional SSB in the third synchronization period of the second transmission period, and camps on the cell.

[0196] Scenario 4: The terminal device directly detects a traditional SSB in the third synchronization period of the second transmission period, and camps on the cell.

[0197] In the above scenarios 3 and 4, if the terminal device searches for a first new SSB in the first synchronization period, the terminal device can continue to search for the SSB in the first frequency point according to the synchronization period; if a second new SSB is searched in the second synchronization period, the number of synchronization periods between the second second synchronization period and the traditional SSB can be determined according to the PCID of the second new SSB and the PCID of the first new SSB; and then the traditional SSB is searched in the first frequency point according to the number of synchronization periods between the second second synchronization period and the traditional SSB. In this process, since the terminal device can calculate the number of synchronization periods between the new SSB and the traditional SSB based on the PCID carried by the new SSB signal # i and the PCID carried by the new SSB signal # (i-1), the terminal device can skip the detection of the SSB in some synchronization periods and directly detect the traditional SSB, thereby reducing the power consumption of the terminal device.

[0198] It can be understood that when the number of synchronization periods included in a transmission period is greater, the probability of the terminal device calculating the number of synchronization periods between the new SSB and the traditional SSB based on the PCID carried by the new SSB signal # i and the PCID carried by the new SSB signal # (i-1) is higher, and the power consumption reduction effect of the terminal device is more obvious.

[0199] The embodiments of the present application also provide a computer readable storage medium, which stores instructions, when the instructions are run on a computer, the computer executes part or all steps of any one of the methods in the above aspects.

[0200] The embodiments of the present application also provide a computer program product including instructions, when the computer runs the instructions of the computer program product, the computer executes part or all steps of any one of the methods in the above aspects.

[0201] The embodiments of the present application also provide a chip or a chip system, which can include a processor. The chip can also include a memory (or a storage module) and / or a transceiver (or a communication module), or be coupled with the memory (or the storage module) and / or the transceiver (or the communication module), wherein the transceiver (or the communication module) can be used to support the chip to perform wired and / or wireless communication, and the memory (or the storage module) can be used to store a program, and the processor invoking the program can be used to implement the operations performed by the terminal device or the network device in the above method embodiments, any possible implementation manner of the method embodiments. The chip system can include the above chip, or include the above chip and other discrete devices, such as the memory (or the storage module) and / or the transceiver (or the communication module).

[0202] The device provided by the embodiments of the present application can be implemented by software, hardware, firmware or any combination thereof, in whole or in part. When implemented by software, it can be implemented in the form of a computer program product, in whole or in part. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, the processes or functions according to the embodiments of the present application are generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another, for example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode. 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. integrated with one or more available media. The available media can be magnetic media (such as floppy disk, hard disk, magnetic tape), optical media (such as high-density digital video disc (digital video disc, DVD)) or semiconductor media (such as SSD) and the like.

[0203] It should be understood that the term "and / or" herein is only used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after it.

[0204] It should be understood that the size of the sequence number of the above processes does not mean the order of execution in the embodiments of the present application. The execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0205] Those skilled in the art can appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0206] Those skilled in the art can clearly understand that, for the convenience and brevity of the description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0207] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of units is only a logical function division, and actual implementation can have another division manner. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, device or unit, and can be electrical, mechanical or other forms.

[0208] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e. they can be located in one place or distributed on multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0209] In addition, the functional units in each embodiment of the present application can be integrated into one processing unit, or each unit can exist physically, or two or more units can be integrated into one unit.

[0210] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

A method of SSB transmission, characterized in that, The method comprises: transmitting a first SSB through a first beam in a first synchronization period of each transmission period, and transmitting a second SSB through the first beam in a second synchronization period of each transmission period except the first synchronization period; wherein a position or a number of the first synchronization period in different transmission periods is adjusted based on to-be-transmitted service of the first beam, the first SSB comprises a PSS, an SSS and a PBCH, and the second SSB comprises a PSS and an SSS. The method of claim 1, wherein Each transmission period comprises N synchronization periods, a length of each synchronization period in the N synchronization periods is equal, the first synchronization period is at least one synchronization period in the N synchronization periods, the second synchronization period is a synchronization period in the N synchronization periods except the first synchronization period, each first synchronization period is used for transmitting one first SSB, each second synchronization period is used for transmitting one second SSB, and N is an integer greater than or equal to 2. The method according to claim 1 or 2, wherein the PBCH of the first SSB comprises a PBCH DMRS and PBCH data; the second SSB further comprises a PBCH DMRS, and the second SSB does not comprise PBCH data; or the second SSB does not comprise a PBCH DMRS and PBCH data. The method according to claim 3, wherein the PBCH DMRS of the first SSB is used for demodulating PBCH data; if the second SSB comprises a PBCH DMRS, the PBCH DMRS of the second SSB is used for measuring whether there is an SSB or a signal quality of an SSB. The method according to claim 3, wherein whether the second SSB comprises a PBCH DMRS is determined according to network configuration, or determined according to an indication of a terminal device to a network device, or predefined. The method according to any one of claims 2 to 5, characterized in that a number of synchronization periods comprised in each transmission period is determined according to network configuration, or determined according to an indication of a terminal device to a network device, or predefined. The method according to any one of claims 1 to 6, wherein the first SSB is in a first candidate position of the first synchronization period; the second SSB is in a second candidate position of the second synchronization period; wherein the first candidate position and the second candidate position are associated. The method of claim 7, wherein The first candidate position and the second candidate position are associated, including that indexes of the first candidate position and the second candidate position are the same. The method according to claim 7, wherein a PSS of the first SSB is offset from a starting symbol of the first candidate position by 0 OFDM symbol; a PSS of the second SSB is offset from a starting symbol of the second candidate position by 0 or at least one OFDM symbol. The method of claim 9, wherein A number of OFDM symbols by which the PSS of the second SSB is offset from the starting symbol of the second candidate position is determined according to at least one of a PCID, a SFN and a HF. The method according to claim 8 or 9, wherein The number of OFDM symbols of the starting symbol offset of the PSS in each synchronization period in a transmission period is determined according to network configuration, or determined according to indication of the terminal device to the network device, or predefined; Or, in a transmission period, the starting symbol offsets of the PSS in all synchronization periods form a first sequence in order, and the first sequence is specified by a protocol. The method according to any one of claims 1 to 11, characterized in that, The SSS of the first SSB is offset from the PSS by 2 OFDM symbols. The SSS of the second SSB is offset from the PSS by 2 OFDM symbols. The method according to any one of claims 1 to 12, characterized in that The PCIDs carried by the PSS and the SSS of the first SSB are different from the PCIDs carried by the PSS and the SSS of the second SSB. The method of claim 13, wherein In different synchronization periods of the same transmission period, the PCIDs carried by the PSS and the SSS of any two second SSBs are the same; or, in different synchronization periods of the same transmission period, the PCIDs carried by the PSS and the SSS of any two second SSBs are different. The method of claim 14, wherein The PCID carried by the first SSB is determined according to the PCID carried by the second SSB and the number of synchronization periods between the first SSB and the second SSB. A method of SSB transmission, characterized in that, The method comprises: searching for SSBs at a first frequency point; camping on a cell based on the searched first SSB and second SSB. The first SSB comprises a PSS, an SSS and a PBCH, and the second SSB comprises a PSS and an SSS. The method according to claim 16, characterized in that, The PBCH of the first SSB comprises a PBCH DMRS and PBCH data. The second SSB further comprises a PBCH DMRS, and the second SSB does not comprise PBCH data; or, the second SSB does not comprise a PBCH DMRS and PBCH data. The method according to claim 17, characterized in that, The PBCH DMRS of the first SSB is used for demodulating PBCH data. If the second SSB comprises a PBCH DMRS, the PBCH DMRS of the second SSB is used for measuring whether there is an SSB or the signal quality of an SSB. The method according to any one of claims 16 to 18, characterized in that, The first SSB is in a first candidate position of a synchronization period. The second SSB is in a second candidate position of a second synchronization period. The first candidate position and the second candidate position are associated. The method of claim 19, wherein Before the camping on the cell based on the searched first SSB and second SSB, the method further comprises: searching for a second SSB at the second candidate position of one of the synchronization periods; based on the association between the first candidate position and the second candidate position, searching for the first SSB at the first candidate position of another of the synchronization periods. The method according to any one of claims 16 to 20, characterized in that Before the camping on the cell based on the searched first SSB and second SSB, the method further comprises: searching for a first second SSB in a first synchronization period; continuously searching for the SSB at the first frequency point; searching for a second second SSB in a second synchronization period; determining a number of synchronization periods between the second second synchronization period and the first SSB according to a PCID of the second second SSB and a PCID of the first second SSB; searching for the first SSB at the first frequency point according to the number of synchronization periods between the second second synchronization period and the first SSB. A communication device, characterized by The communication apparatus includes a processor, a communication interface, and a memory coupled to the processor and the communication interface; The memory stores instructions, and the processor executes the instructions to cause the communication apparatus to perform the SSB transmission method in any one of claims 1 to 15 or to cause the communication apparatus to perform the SSB transmission method in any one of claims 16 to 21. A communication system characterized by The communication system includes a network device and a terminal device; The network device is configured to perform the SSB transmission method in any one of claims 1 to 15, and the terminal device is configured to perform the SSB transmission method in any one of claims 16 to 21. A computer-readable storage medium, characterized by The computer readable storage medium stores a computer program; when the computer program runs on the network device, the network device performs the SSB transmission method in any one of claims 1 to 15; or when the computer program runs on the terminal device, the terminal device performs the SSB transmission method in any one of claims 16 to 21.

Images