Communication method and device

Abstract

Disclosed are a communication method and device, the method comprising: a first cell can send a first SSB, the first SSB being an SSB for initial access; the first cell may also transmit a second SSB, the second SSB being an SSB for cell handover or cell reselection. By means of the method, a first cell may respectively transmit a first SSB for initial access and a second SSB for cell handover or cell reselection. Thus, when the terminal device needs to access the first cell, the first cell can send the first SSB; when the terminal equipment needs to be switched or reselected to the first cell, the first cell can send the second SSB, so that the SSB can be sent as required, the cost of sending the SSB is reduced, and the efficiency of measuring the SSB by the terminal equipment is improved.

Description

Communication method and device Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a communication method and device. Background Art

[0002] With the development of non-terrestrial networks (NTNs), satellite networks are becoming increasingly larger. For example, satellite networks have grown from 66 satellites in the Iridium constellation to 720 satellites in the OneWeb constellation, and have now expanded to the Starlink ultra-dense low-Earth orbit (LEO) constellation of over 12,000 satellites.

[0003] A single satellite can cover thousands or even tens of thousands of kilometers, while a single beam can cover tens or even thousands of meters. To support wide-area coverage, a satellite typically deploys dozens, hundreds, or even more beams. To alleviate the conflict between a single satellite's small payload and wide coverage, beam hopping can be used to achieve regional coverage. This means a satellite can deploy multiple beams to cover a wider area, but only use a smaller number of beams at any given time. Multiple beams deployed at different times can cover a wider area. For example, as shown in Figure 1, a satellite deploys 16 beams to cover a wider area, but only uses four beams at a given time. At time T1, the satellite uses beams numbered 0, 1, 4, and 5 for regional coverage; at time T2, the satellite uses beams numbered 2, 3, 6, and 7. Similarly, the satellite's coverage area (i.e., the area corresponding to the 16 beams) is served through time-sharing at T1, T2, T3, and T4.

[0004] When satellites use beam hopping to provide regional coverage, devices within the coverage area of ​​one or more beams may need to frequently switch or reselect cells. During these cell handovers or reselections, devices must measure the SSB of the target cell. Improving the efficiency of SSB measurements is a challenge.

[0005] Summary of the Invention

[0006] The present application provides a communication method and apparatus for improving the efficiency of measuring SSB.

[0007] In a first aspect, embodiments of the present application provide a communication method. The method includes: a first cell may send a first SSB, where the first SSB is an SSB used for initial access. The first cell may also send a second SSB, where the second SSB is an SSB used for cell handover or cell reselection.

[0008] Optionally, the first SSB is not used for cell switching or cell reselection, so that a terminal device receiving the first SSB will not switch or reselect to the first cell based on the first SSB. The second SSB is not used for initial access, so that a terminal device receiving the second SSB will not initially access the first cell based on the second SSB.

[0009] Through this method, the first cell can send a first SSB for initial access and a second SSB for cell handover or cell reselection. Thus, when a terminal device needs to access the first cell, the first cell can send the first SSB; when the terminal device needs to handover or reselect to the first cell, the first cell can send the second SSB. This allows SSBs to be sent on demand, reducing the overhead of SSB transmission and improving the efficiency of SSB measurement by the terminal device.

[0010] In one possible design, the first cell may send a first SSB within the first area and a second SSB within the second area. For example, the first area may be an area where the first cell sends data signals, and the second area may be included in an area where the second cell sends data signals. With this design, the first cell may send a first SSB for initial access within the first area and a second SSB for cell switching or cell reselection within the second area. In this way, in a beam hopping system, a terminal device located in the second area may measure the broadcast signal quality and perform downlink synchronization according to the second SSB before the first cell uses a beam for sending data signals to cover the second area, so that the terminal device can seamlessly reselect or switch to the first cell when the first cell uses a beam for sending data signals to cover the second area, thereby improving the efficiency of cell reselection and cell switching.

[0011] In one possible design, the first cell may further send configuration information to the second cell, where the configuration information may be used to indicate the configuration of the first cell to send the second SSB. The second cell may then send the configuration information to the terminal device in the second cell. With this design, the first cell may send a configuration to other cells (e.g., a neighboring cell of the first cell) to indicate that the first cell sends the second SSB. In this way, the terminal devices in other cells may receive the second SSB based on the configuration information, thereby avoiding blind detection of the second SSB by the terminal devices, thereby reducing the energy consumption of the terminal devices.

[0012] In one possible design, the transmission time of the first SSB and the transmission time of the second SSB do not overlap. In other words, the transmission times of the first SSB and the second SSB are time-divided. With this design, the first SSB and the second SSB do not overlap in the time domain, thereby reducing interference between the first SSB and the second SSB.

[0013] In one possible design, the transmission period of the first SSB is shorter than the transmission period of the second SSB. For example, the transmission period of the first SSB is one of the following: 5ms, 10ms, 20ms, 40ms, 80ms, or 160ms; the transmission period of the second SSB is several to several hundred seconds. With this design, the transmission period of the first SSB is shorter than the transmission period of the second SSB, thereby reducing the overhead of sending the second SSB.

[0014] In one possible design, both the first and second SSBs are NR SSBs. That is, the first and second SSBs can reuse the NR SSB pattern. This design can reuse the NR SSB pattern, improving the solution's usability and facilitating implementation.

[0015] In one possible design, the first SSB is a CD-SSB, and the second SSB is an NCD-SSB. In this case, the first SSB can reuse the NR SSB pattern, occupy the NR SSB time window, and use the NR SSB sequence number. The second SSB may not occupy the NR SSB time window and does not use the NR SSB sequence number. In this design, the second SSB does not use the NR SSB time window and sequence number, thereby expanding the number of available SSBs and improving the efficiency of cell reselection and cell handover.

[0016] In one possible design, the NCD-SSB corresponds to the resources for switching and / or the random access preamble for switching. The correspondence between the NCD-SSB and the resources for switching and / or the random access preamble for switching may be pre-set or determined by a network device (e.g., a first satellite or a network device located on the ground). Through this design, the NCD-SSB can be associated with dedicated switching resources and / or random access preambles for switching for uplink random access during group switching, thereby improving the efficiency of group switching. Moreover, through the switching resources associated with the NCD-SSB, the terminal device does not need to obtain resource configuration information for group switching, thereby reducing overhead. Through the random access preamble associated with the NCD-SSB, the conflict between the random access preamble for switching and the random access preamble for initial access can be avoided, thereby improving the success rate of group switching.

[0017] In one possible design, the first cell may send a first offset indication to the second cell, where the first offset indication is used to indicate the time offset between the transmission time of the second SSB and the transmission time of the first SSB adjacent to the second SSB. Then, the second cell may send the first offset indication to the terminal device in the second cell. With this design, the terminal device can receive the first SSB from the first cell based on the first offset indication and the time when the second SSB is received, thereby eliminating the need for the terminal device to blindly detect the first SSB and eliminating the need for the second cell to send configuration information of the first SSB to the terminal device. This can reduce the energy consumption of the terminal device and the overhead of obtaining the configuration information of the first SSB.

[0018] In one possible design, the first cell may also update the configuration for the first cell to send the second SSB, but does not update the SIB of the first cell. With this design, when the configuration for the first cell to send the second SSB is updated, the first cell does not update the SIB of the first cell, thereby reducing the overhead required to update the SIB.

[0019] In a second aspect, an embodiment of the present application provides a communication method. The method includes: after receiving a third SSB from a second cell, the terminal device may access the second cell according to the third SSB. The third SSB is an SSB used for initial access. At this time, the terminal device may be in a connected state. After receiving a second SSB from a first cell, the terminal device may send a measurement report to the second cell according to the second SSB. The second SSB is an SSB used for cell handover or cell reselection.

[0020] By using this method, a terminal device in a connected state can be switched to the first cell according to the second SSB. When all the terminal devices in the second area in the connected state are switched to the first cell by using this method, the efficiency of group switching can be improved.

[0021] In one possible design, the terminal device may further receive configuration information from the second cell and receive the second SSB from the first cell based on the configuration information. The configuration information indicates the configuration of the first cell for transmitting the second SSB. With this design, the terminal device may receive the second SSB from the first cell based on the second configuration information, thereby avoiding blind detection of the second SSB by the terminal device and reducing energy consumption of the terminal device.

[0022] In one possible design, the second SSB is NCD-SSB. The terminal device can communicate with the first cell using the resources for switching and / or the random access preamble for switching corresponding to the NCD-SSB. The correspondence between the NCD-SSB and the resources for switching and / or the random access preamble for switching can be pre-set or determined by a network device (for example, a first satellite or a network device located on the ground, etc.). Through this design, the NCD-SSB can be associated with dedicated switching resources and / or random access preambles for switching for uplink random access during group switching, thereby improving the efficiency of group switching. Moreover, through the switching resources associated with the NCD-SSB, the terminal device does not need to obtain resource configuration information for group switching, thereby reducing overhead. Through the random access preamble associated with the NCD-SSB, the conflict between the random access preamble for switching and the random access preamble for initial access can be avoided, thereby improving the success rate of group switching.

[0023] In one possible design, a terminal device may receive a handover command from a second cell, instructing the terminal device to handover to a first cell. The terminal device may then receive a first SSB from the first cell, where the first SSB is the SSB used for initial access. With this design, the terminal device may promptly receive the first SSB from the first cell after receiving the handover command from the second cell.

[0024] In one possible design, the terminal device may receive a first offset indication and receive the first SSB from the first cell based on the first offset indication and the time when the second SSB is received. The first offset indication is used to indicate the time interval between the transmission time of the second SSB and the transmission time of the first SSB adjacent to the second SSB. With this design, the terminal device may receive the first SSB from the first cell based on the first offset indication and the time when the second SSB is received, thereby eliminating the need for the terminal device to blindly detect the first SSB and eliminating the need for the second cell to send configuration information of the first SSB to the terminal device. This can reduce energy consumption of the terminal device and reduce the overhead of obtaining configuration information of the first SSB.

[0025] In one possible design, the first SSB is not used for cell switching or cell reselection, so that a terminal device receiving the first SSB does not switch or reselect to the first cell based on the first SSB. The second SSB is not used for initial access, so that a terminal device receiving the second SSB does not initially access the first cell based on the second SSB.

[0026] In one possible design, the transmission time of the first SSB and the transmission time of the second SSB do not overlap. In other words, the transmission times of the first SSB and the second SSB are time-divided. With this design, the first SSB and the second SSB do not overlap in the time domain, thereby reducing interference between the first SSB and the second SSB.

[0027] In one possible design, the transmission period of the first SSB is shorter than the transmission period of the second SSB. For example, the transmission period of the first SSB is one of the following: 5ms, 10ms, 20ms, 40ms, 80ms, or 160ms; the transmission period of the second SSB is several to several hundred seconds. With this design, the transmission period of the first SSB is shorter than the transmission period of the second SSB, thereby reducing the overhead of sending the second SSB.

[0028] In one possible design, both the first and second SSBs are NR SSBs. That is, the first and second SSBs can reuse the NR SSB pattern. This design can reuse the NR SSB pattern, improving the solution's usability and facilitating implementation.

[0029] In one possible design, the first SSB is a CD-SSB, and the second SSB is an NCD-SSB. In this case, the first SSB can reuse the NR SSB pattern, occupy the NR SSB time window, and use the NR SSB sequence number. The second SSB may not occupy the NR SSB time window and does not use the NR SSB sequence number. In this design, the second SSB does not use the NR SSB time window and sequence number, thereby expanding the number of available SSBs and improving the efficiency of cell reselection and cell handover.

[0030] In a third aspect, an embodiment of the present application provides a communication method. The method includes: a terminal device receives a second synchronization signal block SSB from a first cell, where the second SSB is an SSB used for cell switching or cell reselection. The terminal device may also receive a first offset indication, where the first offset indication is used to indicate the time offset between the transmission time of the second SSB and the transmission time of the first SSB adjacent to the second SSB, where the first SSB is an SSB used for initial access. After reselecting to the first cell based on the second SSB, the terminal device may receive the first SSB from the first cell based on the time when the second SSB was received and the first offset indication.

[0031] By using this method, a terminal device in an idle state can reselect to the first cell according to the second SSB. When all idle terminal devices in the second area reselect to the first cell using this method, the efficiency of group reselection can be improved.

[0032] In one possible design, the first SSB is not used for cell switching or cell reselection, so that a terminal device receiving the first SSB does not switch or reselect to the first cell based on the first SSB. The second SSB is not used for initial access, so that a terminal device receiving the second SSB does not initially access the first cell based on the second SSB.

[0033] In one possible design, the transmission time of the first SSB and the transmission time of the second SSB do not overlap. In other words, the transmission times of the first SSB and the second SSB are time-divided. With this design, the first SSB and the second SSB do not overlap in the time domain, thereby reducing interference between the first SSB and the second SSB.

[0034] In one possible design, the transmission period of the first SSB is shorter than the transmission period of the second SSB. For example, the transmission period of the first SSB is one of the following: 5ms, 10ms, 20ms, 40ms, 80ms, or 160ms; the transmission period of the second SSB is several to several hundred seconds. With this design, the transmission period of the first SSB is shorter than the transmission period of the second SSB, thereby reducing the overhead of sending the second SSB.

[0035] In one possible design, both the first and second SSBs are NR SSBs. That is, the first and second SSBs can reuse the NR SSB pattern. This design can reuse the NR SSB pattern, improving the solution's usability and facilitating implementation.

[0036] In one possible design, the first SSB is a CD-SSB, and the second SSB is an NCD-SSB. In this case, the first SSB can reuse the NR SSB pattern, occupy the NR SSB time window, and use the NR SSB sequence number. The second SSB may not occupy the NR SSB time window and does not use the NR SSB sequence number. In this design, the second SSB does not use the NR SSB time window and sequence number, thereby expanding the number of available SSBs and improving the efficiency of cell reselection and cell handover.

[0037] In a fourth aspect, an embodiment of the present application provides a communication device, comprising a unit for executing each step in any of the above aspects.

[0038] In a fifth aspect, an embodiment of the present application provides a communication device comprising at least one processing element and at least one storage element, wherein the at least one storage element is used to store programs and data, and the at least one processing element is used to read and execute the programs and data stored in the storage element, so that the method provided in any one of the above aspects of the present application is implemented.

[0039] In a sixth aspect, an embodiment of the present application provides a communication system, comprising: a first cell for executing the method provided in the first aspect, and a terminal device for executing the method provided in the second aspect or the third aspect.

[0040] In a seventh aspect, an embodiment of the present application further provides a computer program, which, when executed on a computer, enables the computer to execute the method provided in any of the above aspects.

[0041] In an eighth aspect, an embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a computer, the computer executes the method provided in any one of the above aspects.

[0042] In a ninth aspect, an embodiment of the present application further provides a chip, which is used to read a computer program stored in a memory and execute the method provided in any of the above aspects.

[0043] In a tenth aspect, embodiments of the present application further provide a chip system, comprising a processor configured to support a computer device in implementing the method provided in any of the above aspects. In one possible design, the chip system further comprises a memory configured to store programs and data necessary for the computer device. The chip system may be composed of a chip alone, or may include a chip and other discrete components.

[0044] The technical effects that can be achieved in any of the above-mentioned aspects 4 to 10 can refer to the description of the technical effects that can be achieved in any possible design in any of the above-mentioned aspects 1 to 3, and the repetitions will not be discussed. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG1 is a schematic diagram of a beam hopping communication process in an embodiment of the present application;

[0046] FIG2A is a schematic diagram of an application scenario of a transparent transmission mode in an embodiment of the present application;

[0047] FIG2B is a schematic diagram of an application scenario of a non-transparent transmission mode in an embodiment of the present application;

[0048] FIG3 is a schematic diagram of the architecture of a mobile communication system according to an embodiment of the present application;

[0049] FIG4 is a schematic diagram of the architecture of another mobile communication system in an embodiment of the present application;

[0050] FIG5 is a schematic diagram of a cell-defined synchronization signal block (SSB) (cell defining SSB, CD-SSB) and a non-cell defining SSB (Non-cell defining SSB, NCD-SSB) in an embodiment of the present application;

[0051] FIG6 is a flow chart of a switching method;

[0052] FIG7A is a flow chart of a communication method according to an embodiment of the present application;

[0053] FIG7B is a flow chart of a possible implementation of a communication method in an embodiment of the present application;

[0054] FIG8 is a schematic diagram of a mapping relationship between SSB and wave position in an embodiment of the present application;

[0055] FIG9 is a schematic diagram of the time domain positions of a first SSB and a second SSB in an embodiment of the present application;

[0056] FIG10 is a schematic diagram of another time domain position of a first SSB and a second SSB in an embodiment of the present application;

[0057] FIG11 is a schematic diagram of the positions of the first RO and the second RO in an embodiment of the present application;

[0058] FIG12 is a flow chart of another communication method in an embodiment of the present application;

[0059] FIG13 is a schematic diagram of the coverage area of ​​the first satellite at different times in an embodiment of the present application;

[0060] FIG14 is a flow chart of another communication method in an embodiment of the present application;

[0061] FIG15 is a flow chart of another communication method in an embodiment of the present application;

[0062] FIG16 is a schematic diagram of the coverage areas of the first satellite and the second satellite at different times in an embodiment of the present application;

[0063] FIG17 is a structural diagram of a communication device provided in an embodiment of the present application;

[0064] FIG18 is a structural diagram of another communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0065] The embodiments of the present application provide a communication method and device, wherein the method and device are based on the same technical concept. Since the method and device solve problems based on similar principles, the implementation of the device and the method can refer to each other, and the repeated parts will not be repeated.

[0066] Below, some terms in this application are explained to facilitate understanding by those skilled in the art.

[0067] 1) Communication device generally refers to a device with communication function. For example, the communication device may be, but is not limited to, a terminal device, a network device, a relay device, a ground station device, etc.

[0068] 2) Network equipment: A device in a mobile communication system connects a terminal device to a wireless network. As a node in a radio access network (RAN), a network device can also be called a base station, a radio access network (RAN) node (or device), an access point (AP), or an access network (AN) device.

[0069] Currently, some examples of network devices include: next-generation Node B (gNB), transmission reception point (TRP), evolved Node B (eNB), radio network controller (RNC), Node B (NB), base station controller (BSC), base transceiver station (BTS), wireless relay node, wireless backhaul node, transmission point (TP), mobile switching center, or home base station (e.g., home evolved NodeB, or HNB). A network device can also be one or a group of antenna panels of a base station. Furthermore, a network device can also be a network node that constitutes a gNB or TP, such as a baseband unit (BBU) or a distributed unit (DU). The network device may also be a device that performs network-side functions in a device-to-device (D2D) communication system, a machine-to-machine (M2M) communication system, an Internet of Things (IoT), an Internet of Vehicles communication system, or other communication systems.

[0070] 3) Terminal equipment is a device that provides voice and / or data connectivity to users. Terminal equipment can also be called user equipment (UE), terminal, access terminal, terminal unit, terminal station, subscriber unit, subscriber station, mobile station (MS), remote station, remote terminal, mobile terminal (MT), wireless communication device, customer premise equipment (CPE), wireless communication device, user agent, user device, or terminal agent.

[0071] For example, the terminal device can be a handheld device with wireless connection function, or it can be a vehicle with communication function, on-board equipment (such as an on-board communication device, an on-board communication chip), a wearable device, a computing device, or other processing equipment connected to a wireless modem. Currently, some examples of terminal devices include: mobile phones, satellite phones, cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless data cards, wireless modems, machine type communication devices, wireless local loop (WLL) stations, personal digital assistants (PDAs), tablet computers, computers with wireless transceiver functions, laptop computers, handheld computers, mobile internet devices (MIDs), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, wireless terminals in self-driving cars, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, etc.

[0072] 4) Ground station equipment is a device that is installed on the ground and can communicate with NTN equipment in the NTN system. Ground station equipment is, for example, core network (CN) equipment. CN equipment is a network element included in the CN part of the mobile communication system. CN equipment can connect terminal equipment to different data networks and perform services such as authentication, billing, mobility management, session management, policy control, and user plane forwarding. CN equipment can be used for current mobile communication systems (such as the 5th generation (5G) th The CN devices in the 5G generation (5G) mobile communication system may also be CN devices in future mobile communication systems. In mobile communication systems of different standards, the names of CN devices with the same function may vary. However, the embodiments of the present application do not limit the specific names of CN devices with each function.

[0073] For example, in the 4th generation (4 th In the 4G (4th generation) mobile communication system (i.e., long term evolution, LTE), the network element responsible for access control, security control, and signaling coordination is the mobility management entity (MME); the network element serving as the local mobility management anchor point is the serving gateway (S-GW); the network element serving as the anchor point for switching to the external data network and responsible for allocating Internet protocol (IP) addresses is the packet data network (PDN) gateway (P-GW); the network element storing user-related data and subscription data is the home subscriber server (HSS); and the network element responsible for policy and charging functions is called the policy and charging rule function (PCRF) network element.

[0074] For example, in a 5G mobile communication system, the core network can be divided into a control plane (CP) and a user plane (UP) according to specific logical functional divisions. The network elements in the CN responsible for control plane functions can be collectively referred to as control plane network elements, and the network elements responsible for user plane functions can be collectively referred to as user plane network elements. Specifically, in the user plane, the network element that serves as the interface to the data network and is responsible for user plane data forwarding and other functions is the user plane function (UPF) network element. In the control plane, the network element responsible for access control and mobility management functions is called the access and mobility management function (AMF) network element; the network element responsible for session management and control policy execution is called the session management function (SMF) network element; the network element responsible for managing subscription data, user access authorization, and other functions is called the unified data management (UDM) network element; the network element responsible for billing and policy control functions is called the policy control function (PCF) network element; and the application function (AF) network element is responsible for transmitting the application side's requirements to the network side.

[0075] 5), NTN communication:

[0076] NTN communications can utilize drones, high altitude platform stations (HAPS), satellites, and other equipment to form a network, providing data transmission, voice communication, and other services to terminal devices. High altitude platforms can be 8 to 50 kilometers (km) above the ground. Based on satellite altitude, or the height of the satellite's orbit, the satellite communication system in NTN communications can include geostationary Earth orbit (GEO), medium Earth orbit (MEO), and low Earth orbit (LEO) satellites. Each of these is described below.

[0077] 1. GEO Satellite: Also known as a geosynchronous satellite or geostationary satellite. GEO satellites move at the same speed as the Earth's rotation, thus remaining stationary relative to the Earth. Accordingly, the cells of GEO satellites are also stationary. GEO satellites orbit at a high altitude, for example, up to 35,786 km, providing a wide coverage area. The diameter of a GEO satellite cell is typically 500 km.

[0078] 2. MEO satellites are a type of non-geostationary Earth orbit (NGEO) satellite. Non-geostationary Earth orbit satellites move at a speed different from the Earth's rotation speed, and therefore, they are in motion relative to the ground. MEO satellites have orbital altitudes ranging from 2,000 to 35,786 km, enabling global coverage with a relatively small number of satellites. MEO satellites are primarily used for positioning and navigation.

[0079] 3. LEO satellites: These are another type of NGEO satellites. LEO satellites orbit at altitudes between 300 and 2000 km and offer advantages such as low data transmission latency, minimal transmission loss, and low launch costs. LEO satellites move relatively quickly relative to the ground, at approximately 7 km / s, so the coverage area they provide also moves.

[0080] In NTN communications, the operating modes of NTN equipment (eg, a high-altitude platform or a satellite, etc.) may include: a transparent mode and a non-transparent mode.

[0081] Transparent transmission is also called bent-pipe forwarding transmission. When operating in transparent transmission mode, NTN equipment has a relay forwarding function. The NTN equipment can perform frequency conversion and / or amplification processing on the signal without changing the content of the signal. For example, the application scenario of the transparent transmission mode can be shown in Figure 2A. In the application scenario shown in Figure 2A, the network equipment is set on the ground and can be connected to the data network (DN) through the CN; the satellite and gateway equipment can serve as the remote radio unit (RRU) of the network equipment to transmit information between the network equipment and the terminal equipment.

[0082] Non-transparent transmission mode is also known as regenerative mode. NTN equipment operating in non-transparent transmission mode possesses all or some of the capabilities of network devices. An exemplary application scenario for non-transparent transmission mode is shown in Figure 2B . In this scenario, a satellite can function as a network device, forming an access network with a gateway device, and communicating with the core network through the gateway device. For example, a satellite can function as a network device, establishing an N2 interface or Ng interface connection with the AMF in the core network through the gateway device. Furthermore, the satellite can provide wireless access services to terminal devices.

[0083] 6) SSB, which can include the primary synchronisation signal (PSS), the secondary synchronisation signal (SSS) and the physical broadcast channel (PBCH). Among them, PSS can be used to transmit the cell number, and SSS can be used to transmit the cell group number. The cell number and the cell group number together determine the multiple physical cell identities (PCIs) in the mobile communication system. Once the terminal device successfully searches for the PSS and SSS, it will know the physical cell number of the carrier carrying the PSS and SSS, and thus has the ability to parse the system messages contained in the SSB.

[0084] The system information in the SSB can be carried by the PBCH. Since this information is necessary for terminal devices to access the network, it can be called the main information block (MIB). The MIB can contain the system frame number and the initial access subcarrier spacing, etc.

[0085] The information contained in the MIB is limited and is not sufficient to support terminal devices accessing a cell. Therefore, the terminal device can also obtain other system information, such as system information block (SIB) 1. SIB1 can be transmitted on the physical downlink shared channel (PDSCH) with a period of 160 milliseconds (ms). The terminal device can obtain the parameters used for SIB1 transmission in the MIB carried by the PBCH, so that it can receive SIB1. In this way, the terminal device can obtain the system information required to access the cell and can subsequently access the cell.

[0086] 7) Radio Resource Control (RRC) Connection Status: In a mobile communication system, the RRC connection status of a terminal device includes: RRC connected state (RRC_connected, referred to as connected state) and RRC idle state (RRC_idle, referred to as idle state).

[0087] When the terminal device is in idle state, the RRC connection between the terminal device and the network device is disconnected, the network device and the terminal device no longer save the terminal device context information, and the terminal device can receive broadcast information (such as system information) and paging messages sent by the network device.

[0088] When a terminal device is in a connected state, an RRC connection exists between the terminal device and the network device, and the two can communicate through the RRC connection. In the RRC connected state, if a cell handover failure, radio link failure, or RRC connection reconfiguration process failure occurs, the terminal device will trigger the RRC connection reestablishment process.

[0089] 8) In the present application, the parameters used to reflect signal quality may include but are not limited to at least one of the following: reference signal receiving power (RSRP), reference signal receiving quality (RSRQ), or received signal strength indication (RSSI).

[0090] 9) Beam position, which can be the area covered by the beam. For example, as shown in Figure 1, at time T1, the area covered by beam 0 is a beam position.

[0091] In the embodiments of the present application, the device for implementing the functions of a satellite can be a satellite; it can also be a device capable of supporting the function in a form factor, such as a chip system, which can be installed in a satellite. When describing the technical solutions provided in the embodiments of the present application below, the technical solutions provided in the embodiments of the present application are described using the example of a satellite as the device for implementing the functions of a satellite.

[0092] In the embodiments of the present application, the device for realizing the function of the terminal device can be a terminal device; it can also be a device that can support the terminal device to realize the function, such as a chip system, which can be installed in the terminal device. In the embodiments of the present application, the chip system can be composed of chips, or it can include chips and other discrete devices. In the technical solutions provided in the embodiments of the present application, the technical solutions provided in the embodiments of the present application are described by taking the terminal device as an example in which the device for realizing the function of the terminal device is a terminal device.

[0093] In the embodiments of the present application, the number of nouns, unless otherwise specified, means "singular noun or plural noun", that is, "one or more". "At least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items.

[0094] In addition, it should be understood that, in the description of this application, words such as "first" and "second" are only used for the purpose of distinguishing the description, and should not be understood as indicating or implying relative importance, nor should they be understood as indicating or implying order.

[0095] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0096] Figure 3 shows the structure of a mobile communication system to which the method provided in the embodiment of the present application is applicable. Referring to Figure 3 , the system includes: network equipment and terminal equipment (eg, terminal equipment a and terminal equipment b shown in Figure 3 ).

[0097] The network device is an entity on the network side that can receive and transmit wireless signals. It is responsible for providing wireless access-related services to terminal devices within its coverage area, and realizes physical layer functions, resource scheduling and wireless resource management, Quality of Service (QoS) management, wireless access control and mobility management functions.

[0098] The terminal device is a user-side entity that can receive and transmit wireless signals and needs to access the network through the network device. The terminal device can be any device that provides voice and / or data connectivity to the user. For example, as shown in Figure 3, the terminal device can be an in-vehicle device, a smartphone, etc.

[0099] FIG4 illustrates the structure of another mobile communication system to which the methods provided in the embodiments of the present application are applicable. This communication system may be an NTN communication system. In the embodiments of the present application, the NTN communication system is described as a satellite communication system. As shown in FIG4 , the NTN communication system includes satellites (e.g., satellites 401, 402, and 403 in FIG4 ), CN equipment, and terminal equipment.

[0100] The CN device and the terminal device may refer to the above descriptions of the CN device and the terminal device respectively.

[0101] The satellites can be NGEO satellites, such as LEO satellites. The satellites can wirelessly communicate with terminal devices by broadcasting communication signals and navigation signals. Optionally, each satellite can provide communication services, navigation services, and positioning services to terminal devices using multiple beams. For example, each satellite can use multiple beams to cover its service area, and the relationships between different beams can be one or more of time division, frequency division, and space division. At least one satellite can communicate with ground station equipment. For example, satellite 403 can connect to a CN device and wirelessly communicate with the CN device.

[0102] Satellites can operate in transparent transmission mode, for example, satellite 403 in Figure 4 operates in transparent transmission mode. Satellites can also operate in non-transparent transmission mode, for example, satellites 401 and 402 in Figure 4 operate in non-transparent transmission mode. In addition, satellites can also operate in quasi earth-fixed mode or satellite-fixed mode. Among them, quasi earth-fixed mode, also known as staring mode, means dynamically adjusting the satellite's beam pointing so that it can continuously serve a certain physical area over a period of time. Satellite-fixed mode means that the satellite's beam moves with the satellite, and the physical area it serves also changes continuously.

[0103] The satellite mentioned in the embodiments of the present application may be a satellite base station, may also include an orbital receiver or repeater for relaying information, or may be a network device carried on a satellite.

[0104] It should also be pointed out that the mobile communication system shown in Figure 3 or Figure 4 is used as an example and does not limit the communication system to which the method provided in the embodiment of the present application is applicable. In short, the method provided in the embodiment of the present application is applicable to communication systems and application scenarios in which various terminal devices support multi-transmission capabilities, that is, the embodiment of the present application can also be applied to communication systems of various types and standards, such as: 5G communication system, LTE communication system, wireless fidelity (wireless fidelity, Wi-Fi) system, vehicle to everything (vehicle to everything, V2X), long-term evolution - vehicle network (LTE-vehicle, LTE-V), vehicle to vehicle (vehicle to vehicle, V2V), vehicle network, machine type communications (machine type communications, MTC), Internet of Things (Internet of things, IoT), long-term evolution - machine to machine (LTE-machine to machine, LTE-M), machine to machine (machine to machine, M2M), integrated communication and navigation (IcaN) system, global navigation satellite system (GNSS) or ultra-dense low-orbit satellite communication system, etc., and the embodiment of the present application is not limited.

[0105] In order to facilitate understanding of this application, the relevant technology is described below.

[0106] 1. CD-SSB and NCD-SSB:

[0107] CD-SSB contains: configuration information of the associated control resource set (i.e., configuration information of CORESET 0), and configuration information of the monitoring timing of Type 0 physical downlink control channel common search space (Type 0-PDCCH CSS). Currently, CD-SSB can be used for initial access, cell reselection, or cell switching. A terminal device in an idle state can perform initial access or cell reselection based on CD-SSB. A terminal device in a connected state can perform cell switching based on CD-SSB.

[0108] The NCD-SSB does not include the configuration information of the associated control resource set (i.e., the configuration information of CORESET 0) or the configuration information of the monitoring opportunity of Type 0-PDCCH CSS. The NCD-SSB can be used for radio resource management.

[0109] Currently, CD-SSB and NCD-SSB are frequency-division multiplexed, meaning they are carried on different frequencies. Optionally, CD-SSB and NCD-SSB are carried on different bandwidth parts (BWPs). For example, as shown in Figure 5, CD-SSB includes SSB1 and SSB3, and NCD-SSB includes SSB2 and SSB4. If UE1's operating frequency includes the initial BWP, for example, UE1's operating frequency is dedicated BWP1, which includes the initial BWP, then UE1 can perform initial access, cell handover, or cell reselection based on SSB3 in the initial BWP. NCD-SSB is located outside the initial BWP, and terminal devices operating outside the initial BWP can perform signal measurements based on NCD-SSB. For example, if UE2's operating frequency is dedicated BWP2, which does not include the initial BWP, then UE2 can perform signal measurements based on SSB4.

[0110] In addition, there may be a certain offset (hereinafter referred to as frequency offset) between the transmission frequency of CD-SSB and the transmission frequency of NCD-SSB. After detecting NCD-SSB, the terminal device can determine the position of CD-SSB in the frequency domain based on the frequency offset. Among them, the frequency offset can be indicated by the parameter K_SSB carried in NCD-SSB, and corresponds to the SSB subcarrier offset (ssb-SubcarrierOffset) parameter in the main information block (MIB) message.

[0111] 2. Cell switching:

[0112] When a terminal device is in a connected state, the network device can send measurement configuration information to the terminal device via an RRC connection reconfiguration message. Based on the measurement configuration information sent by the network device, the terminal device measures the signal strength of the serving cell and neighboring cells and reports the measurement results. The network device can then determine whether to perform a handover based on the measurement results. The current handover process is described below with reference to Figure 6.

[0113] S601: The source network device sends a first RRC reconfiguration (RRCReconfiguration) message to the terminal device.

[0114] The first RRC reconfiguration message may include measurement configuration information of at least one cell. The at least one cell may include a serving cell and a neighboring cell of the terminal device.

[0115] S602: The terminal device sends a first RRC reconfiguration completion (RRCReconfigurationComplete) message to the source network device.

[0116] Among them, the first RRC reconfiguration completion message can be used to indicate that the terminal device has received the first RRC reconfiguration message.

[0117] S603: The terminal device performs measurement according to the measurement configuration information and sends a measurement report to the source network device.

[0118] Optionally, the terminal device may use the SSB associated with the currently activated BWP to perform measurements of the serving cell and / or neighboring cell based on the measurement configuration information. In some possible ways, the terminal device may periodically send measurement reports to the source network device. The period for sending the measurement report may be pre-set or may be obtained by the terminal device from the source network device. In other possible ways, the terminal device may send a measurement report to the source network device when the measurement result meets the reporting conditions. The reporting conditions may include at least one of the following: the signal quality of the serving cell is less than or equal to the first signal quality threshold, and the signal quality of the neighboring cell is greater than or equal to the second signal quality threshold.

[0119] S604: The source network device performs a handover decision according to the measurement report from the terminal device.

[0120] For example, if the measurement report of the terminal device includes the signal quality of the cell of the target network device, and the signal quality of the cell of the target network device is greater than or equal to the second signal quality threshold, the source network device may determine to switch the terminal device to the target network device.

[0121] S605: The source network device sends a handover request message to the target network device.

[0122] The switching request is used to request to switch the terminal device from the source network device to the target network device.

[0123] S606: The target network device performs admission control.

[0124] For example, the target network device may configure resources required for handover for the terminal device.

[0125] S607: The target network device sends a handover request acknowledgement message to the source network device.

[0126] The switching request response message may be used to indicate that the target network device agrees to switch the terminal device to the target network device.

[0127] S608: The source network device sends a second RRC reconfiguration message to the terminal device.

[0128] The second RRC reconfiguration message may also be referred to as a switching command, which is used to instruct the terminal device to switch from the source network device to the target network device.

[0129] Optionally, the second RRC reconfiguration message may include configuration parameters of the cell of the target network device, for example, an identifier of the cell of the target network device, or a frequency of the cell of the target network device.

[0130] S609: The source network device sends a sequence number (SN) status transfer (SN status transfer) message to the target network device.

[0131] The SN state transfer message may include a sequence number for indicating a data packet that has been transmitted from the source network device to the terminal device.

[0132] Optionally, the source network device forwards the data to be sent to the terminal device to the target network device.

[0133] S610: The terminal device sends a random access message to the target network device according to the configuration parameters of the cell of the target network device in the second RRC reconfiguration message to request access to the cell of the target network device.

[0134] The random access preamble in the random access message is a dedicated preamble, which is different from the contention-based random access preamble used during initial access. In addition, the period of the resource used to send the random access message can be at least one of the following: 10ms, 20ms, 40ms, 80ms or 160ms.

[0135] S611: The target network device sends a random access response (RAR) message to the terminal device.

[0136] S612: The terminal device sends a second RRC reconfiguration completion message to the target network device.

[0137] After accessing the target network device, the terminal device can exchange data with the target network device. For example, the terminal device can send uplink data to the target network device. For another example, the terminal device can receive downlink data from the target network device.

[0138] S613: The target network device sends a path switch request message to the AMF.

[0139] The path switching request message may be used to request the core network to send the data of the terminal device to the target network device.

[0140] S614: AMF sends a path switch request acknowledgement message to the target network device.

[0141] After receiving the path switch request response message, the target network device may send uplink data from the terminal device to the core network.

[0142] Through the method shown in FIG6 , the terminal device can be switched from the source network device to the target network device.

[0143] 3. Cell reselection:

[0144] When the terminal device is in idle state, after camping on the serving cell, the terminal device can continuously reselect the cell by measuring the signal strength of the serving cell and the neighboring cells, so as to camp on a cell with higher priority or better channel quality. The cell reselection process may include steps H1-H3:

[0145] H1: The cell of the first network device broadcasts measurement configuration information of at least one cell. The at least one cell may include a serving cell and a neighboring cell of the terminal device.

[0146] H2: The terminal device measures the signal quality of at least one cell according to the measurement configuration information.

[0147] Optionally, the terminal device may use the SSB associated with the currently activated BWP to measure the serving cell and / or neighboring cell according to the measurement configuration information, thereby obtaining the signal quality of the serving cell and / or neighboring cell.

[0148] H3: When the reselection condition is met, the terminal device may reselect to the cell of the second network device.

[0149] The reselection condition may include at least one of the following: the signal quality of the cell of the second network device is greater than the signal quality of the cell of the first network device, and the signal quality of the cell of the second network device is greater than or equal to a third signal quality threshold. The third signal quality threshold may be pre-set or obtained by the terminal device from the first network device.

[0150] Currently, SSBs are used for both initial access and cell handover or cell reselection. Therefore, cells need to frequently transmit SSBs so that terminal devices can perform initial access, cell handover, or cell reselection based on these SSBs. This results in high SSB transmission overhead and low communication efficiency. Reducing SSB overhead and improving SSB measurement efficiency are key issues addressed in this application.

[0151] Furthermore, current cell switching or cell reselection methods are typically designed based on the mobility of terminal devices, with cell switching or cell reselection performed based on the signal quality detected by the terminal device. However, the near-far effect in NTN communication systems is not significant, and relying on signal quality to trigger cell switching or cell reselection is inefficient. When satellites use beam hopping for regional coverage, terminal devices within the area covered by one or more beams may need to frequently perform cell switching or cell reselection. Improving the efficiency of cell switching or cell reselection is another issue that this application needs to address.

[0152] The solution provided in this application is described below with reference to the accompanying drawings.

[0153] The embodiment of the present application provides a communication method, which can be applied to the communication system shown in Figure 3 or Figure 4. The flow of the method will be described in detail below with reference to the flowchart shown in Figure 7A.

[0154] S701: The first cell sends the first SSB.

[0155] The first SSB is the SSB used for initial access. For example, the first SSB can be used for the initial random access procedure. Furthermore, the first SSB can also be used for procedures other than cell handover or cell reselection, such as beam failure recovery, uplink data transmission, or RRC connection reestablishment.

[0156] The first cell may be a cell within the coverage area of ​​the first satellite, and the first satellite may cover at least one area.

[0157] Optionally, the first cell may send the first SSB according to configuration information of the first SSB (hereinafter referred to as the first configuration information). The first configuration information may include at least one of the following:

[0158] 1. Time domain length of the first SSB: This may indicate the time length of the time domain resources occupied by the first SSB. For example, the time domain length of the first SSB is four orthogonal frequency division multiplexing (OFDM) symbols.

[0159] 2. First SSB transmission period: This indicates the period for transmitting the first SSB. For example, the first SSB transmission period may be 5ms, 10ms, 20ms, 40ms, 80ms, or 160ms.

[0160] 3. The SSB bitmap (also called bit indication) of the first SSB: can be used to indicate whether one or more SSBs exist. For example, assuming that there are a maximum of 4 SSBs (for example, these 4 SSBs can be identified as SSB0, SSB1, SSB2, and SSB3), the 4 bits in the SSB bitmap correspond one-to-one to the 4 SSBs, and each bit is used to indicate whether the corresponding SSB exists. When the value of one bit in the SSB bitmap is 0, it means that the corresponding SSB does not exist in a certain time period; when the value of one bit in the SSB bitmap is 1, it means that the corresponding SSB exists in a certain time period. For example, when the SSB bitmap is 0011, it means that SSB0 and SSB1 do not exist in the current time period, and SSB2 and SSB3 exist in the current time period; when the SSB bitmap is 1011, it means that SSB0, SSB2, and SSB3 exist in the current time period, and SSB1 does not exist in the current time period.

[0161] 4. Measurement window configuration of the first SSB: can be used to indicate multiple time windows in which the first SSB can be measured. The measurement window configuration may include information for indicating one time window in the multiple time windows, and the time interval between each two adjacent time windows in the multiple time windows. The time interval between each two adjacent time windows may be the same as the transmission period of the first SSB. For example, the measurement window configuration may include: the start time information (e.g., 0ms) and end time information (e.g., 5ms) of time window 1 in which the first SSB can be measured, and the time interval between each two adjacent time windows (e.g., 20ms). For another example, the measurement window configuration may include: the start time information (e.g., 0ms) of time window 1 in which the first SSB can be measured, the time length occupied by time window 1 (e.g., 5ms), and the time interval between each two adjacent time windows (e.g., 20ms).

[0162] 5. Measurement window offset of the first SSB: Indicates the offset of the start time of the measurement window of the first SSB relative to the time reference point, which can be a frame boundary or a system-defined time point. For example, if the measurement window offset of the first SSB is 4ms, it means that the start time of the measurement window of the first SSB is delayed by 4ms from the frame boundary or the system-defined time point.

[0163] 6. Reference location of the first SSB: indicates the projected position of the center point of the beam where the first SSB is located on the spherical surface (for example, the longitude and latitude position or the xyz coordinates in the earth-centered earth-fixed (ECEF) coordinate system).

[0164] The first configuration information may be pre-set, determined for the first cell, or set for the first cell by other equipment (eg, ground network equipment).

[0165] In addition, the first configuration information may be updated in the same manner as the update mechanism of SIB1. When the first configuration information is updated, the update of SIB1 of the first cell may be triggered.

[0166] Optionally, the first cell may indicate, in an explicit or implicit manner, that the first SSB is the SSB for initial access. For example, the first SSB includes a first indication, and the first indication is used to indicate that the current SSB is the SSB for initial access. The first indication may be located in the first field of the first SSB, and when the value of the first field is a first value, the current SSB is the SSB for initial access. In this way, the terminal device may determine that the received SSB is the first SSB based on the first indication. For another example, the first SSB includes a first default parameter. In this way, the terminal device may determine that the received SSB is the first SSB based on the first default parameter. For another example, the first SSB is carried on a first set frequency. In this way, the terminal device may determine that the received SSB is the first SSB based on the first set frequency that carries the first SSB.

[0167] S702: The first cell sends a second SSB. Correspondingly, the terminal device receives the second SSB from the first cell.

[0168] The second SSB is an SSB specifically used for cell switching or cell reselection. In this way, a terminal device that receives the second SSB can switch or reselect to the first cell according to the second SSB.

[0169] Optionally, the first cell may send a second SSB according to the configuration information of the second SSB (hereinafter referred to as the second configuration information). The second configuration information may include at least one of the following: the time domain length of the second SSB, the transmission period of the second SSB, the SSB bit map of the second SSB, the measurement window configuration of the second SSB, the measurement window offset of the second SSB, and the reference point position of the second SSB. The specific content of the second configuration information can refer to the description of the first configuration information, except that the first SSB is replaced by the second SSB, and the repeated parts are not repeated.

[0170] The second configuration information may be pre-set, determined for the first cell, or set for the first cell by other equipment (eg, ground network equipment).

[0171] Optionally, the first cell may indicate the second SSB in an explicit or implicit manner. For example, the second SSB includes a second indication, and the second indication is used to indicate that the current SSB is the SSB used for cell switching or cell reselection. The second indication may be located in the second field of the second SSB, and when the value of the second field is the second value, the current SSB is the SSB used for cell switching or cell reselection. In this way, the terminal device may determine that the received SSB is the second SSB based on the second indication. For another example, the second SSB includes a second default parameter. In this way, the terminal device may determine that the received SSB is the second SSB based on the second default parameter. For another example, the second SSB is carried on a second set frequency. In this way, the terminal device may determine that the received SSB is the second SSB based on the second set frequency carrying the second SSB.

[0172] Optionally, in the method shown in FIG7A , the first SSB is not used for cell switching or cell reselection, so that a terminal device receiving the first SSB does not switch or reselect to the first cell based on the first SSB. The second SSB is not used for initial access, so that a terminal device receiving the second SSB does not initially access the first cell based on the second SSB.

[0173] Optionally, in the method shown in FIG7A , the first SSB and the second SSB may be implemented in one of the following ways:

[0174] Implementation 1: Both the first and second SSBs are NR SSBs. That is, the first and second SSBs can reuse the NR SSB pattern. This approach reuses the NR SSB pattern, improving the solution's usability and facilitating implementation.

[0175] Implementation method 2: The first SSB is CD-SSB, and the second SSB is NCD-SSB. In this case, the first SSB can reuse the pattern of NR SSB, occupy the time window of NR SSB, and use the sequence number of NR SSB. The second SSB may not occupy the time window of NR SSB and does not use the sequence number of NR SBB. For example, the time window length of NR SSB is 5ms, and the maximum sequence number of NR SSB is 64. In this method, the second SSB does not use the time window and sequence number of NR SSB, thereby expanding more available SSBs and improving the efficiency of cell reselection and cell switching.

[0176] Optionally, in implementation 2, the second configuration information may further include a set of NCD-SSBs to be tested. Exemplarily, the set of NCD-SSBs to be tested may include sequence number information of the NCD-SSBs to be tested. For example, the set of NCD-SSBs to be tested may include one or more of {NCD-SSB0, NCD-SSB1, …, NCD-SSBM}. Where M is the maximum number of NCD-SSBs supported by the network, such as 4, 8, 16, 32, or 64.

[0177] In addition, in implementation 2, when a time window contains multiple CD-SSBs and / or NCD-SSBs, CD-SSBs and NCD-SSBs can be distinguished by at least one of the following:

[0178] 1. SSB pattern: The pattern of CD-SSB is different from that of NCD-SSB. Therefore, the terminal device can determine whether the received SSB is CD-SSB or NCD-SSB based on the pattern.

[0179] 2. SSB transmission period: The transmission period of CD-SSB and NCD-SSB can be different. For example, the period of CD-SSB is 20ms, and the period of NCD-SSB is 5s. Therefore, the terminal device can determine whether the received SSB is CD-SSB or NCD-SSB based on the SSB transmission period.

[0180] 3. MIB: In some possible ways, the MIB may include a first type of indication information for indicating the type of SSB, and the first type of indication information may occupy 1 bit. For example, when the value of the first type of indication information is 0, it means that the current SSB is CD-SSB; when the value of the first type of indication information is 1, it means that the current SSB is NCD-SSB. In other possible ways, the MIB may also indicate the type of SSB in an implicit way. For example, when the scrambling method of the MIB is the first scrambling method, it means that the current SSB is CD-SSB; when the scrambling method of the MIB is the second scrambling method, it means that the current SSB is NCD-SSB. The first scrambling method and the second scrambling method are different. For another example, when the demodulation reference signal (DMRS) pattern corresponding to the MIB is the first pattern, it means that the current SSB is CD-SSB; when the DMRS pattern corresponding to the MIB is the second pattern, it means that the current SSB is NCD-SSB. The first pattern and the second pattern are different.

[0181] 4. PBCH payload: In some possible ways, the PBCH payload may include a second type of indication information for indicating the type of SSB, and the second type of indication information may occupy 1 bit. For example, when the value of the second type of indication information is 0, it means that the current SSB is CD-SSB; when the value of the second type of indication information is 1, it means that the current SSB is NCD-SSB. In other possible ways, the PBCH payload may also indicate the type of SSB in an implicit way. For example, when the scrambling method of the PBCH payload is the third scrambling method, it means that the current SSB is CD-SSB; when the scrambling method of the PBCH payload is the fourth scrambling method, it means that the current SSB is NCD-SSB. Among them, the third scrambling method and the fourth scrambling method are different.

[0182] Using the method shown in FIG7A , the first cell can transmit a first SSB for initial access and a second SSB for cell handover or cell reselection. Thus, when a terminal device needs to access the first cell, the first cell can transmit the first SSB; when the terminal device needs to handover or reselect to the first cell, the first cell can transmit the second SSB. This allows SSBs to be transmitted on demand, reducing the overhead of SSB transmission and improving the efficiency of SSB measurement by the terminal device.

[0183] Furthermore, the first cell transmits a first SSB for initial access and a second SSB for cell handover or cell reselection. Thus, the terminal device performs cell handover or cell reselection based on the second SSB after receiving it. This avoids the inefficiency caused by relying solely on signal quality to trigger cell handover or cell reselection in NTN communications, thereby improving the efficiency of cell reselection and cell handover.

[0184] Optionally, in S701, the first cell may send a first SSB within the first area. For example, as shown in FIG7B , S701 includes S701a: the first cell sends a first SSB to a terminal device within the first area. In S702, the first cell may send a second SSB within the second area. For example, as shown in FIG7B , S702 includes S702a: the first cell sends a second SSB to a terminal device within the second area.

[0185] The first area may be the area where the first cell transmits data signals, and the second area may be within the area where the second cell transmits data signals. The second cell may be a cell within the coverage area of ​​the second satellite. The first and second satellites are adjacent satellites, and the second satellite may cover at least one area. For example, as shown in Figure 8, the first cell of the first satellite may transmit data signals in wavelengths 1 through 4, while the second cell of the second satellite may transmit data signals in wavelengths 5 through 8. Both the first and second satellites are moving to the right. In this case, the first cell transmits the first SSB in wavelengths 1 through 4. The first cell transmits the second SSB in wavelength 5.

[0186] Through this method, the first cell can transmit a first SSB for initial access within the first area and a second SSB for cell handover or cell reselection within the second area. Thus, in a beam-hopping system, a terminal device located in the second area can measure the broadcast signal quality and perform downlink synchronization based on the second SSB before the first cell uses a beam for transmitting data signals to cover the second area. This allows the terminal device to seamlessly reselect or handover to the first cell when the first cell uses a beam for transmitting data signals to cover the second area, thereby improving the efficiency of cell reselection and cell handover.

[0187] Optionally, in the method shown in FIG7A , the transmission time of the first SSB and the transmission time of the second SSB do not overlap. In other words, the transmission times of the first SSB and the second SSB are time-divided. For example, as shown in FIG9 , when the first SSB and the second SSB are both NR SSBs, the first SSB and the second SSB are both located in an NR SSB burst, and the transmission time of the first SSB and the transmission time of the second SSB do not overlap. For another example, as shown in FIG10 , when the first SSB is a CD-SSB and the second SSB is an NCD-SSB, the first SSB is located in an NR SSB burst, and the second SSB is located outside the NR SSB burst.

[0188] Through this method, the first SSB and the second SSB do not overlap in the time domain, thereby reducing interference between the first SSB and the second SSB.

[0189] Optionally, in the method shown in FIG7A , the transmission period of the first SSB is less than the transmission period of the second SSB. Exemplarily, the transmission period of the first SSB is one of the following: 5ms, 10ms, 20ms, 40ms, 80ms, 160ms; the transmission period of the second SSB is several to several hundred seconds. For example, as shown in FIG9 , when the first SSB and the second SSB are both NR SSBs, each NR SSB burst contains the first SSB, and some NR SSB bursts contain the second SSB. In this way, the transmission period of the second SSB is greater than the transmission period of the first SSB. For another example, as shown in FIG10 , when the first SSB is CD-SSB and the second SSB is NCD-SSB, the transmission period of the second SSB is period 2, and the transmission period of the first SSB is period 1, and period 2 is greater than period 1.

[0190] Through this method, the sending period of the first SSB is smaller than the sending period of the second SSB, thereby reducing the overhead of sending the second SSB.

[0191] Optionally, in the method shown in Figure 7A, the first random access occasion (random access channel (RACH) occasion, RO) associated with the first SSB is different from the second RO associated with the second SSB. The first RO is the access occasion associated with the first SSB, and the terminal device can perform access related to initial random access, beam recovery or data transmission request at the first RO. The second RO is the access occasion associated with the second SSB, and the terminal device after group switching can access at the second RO. RO may represent the resources occupied by sending the random access guide code (such as time domain position and / or time length).

[0192] The first RO and the second RO have at least one parameter different from each other:

[0193] 1. Time Domain Period: This may represent the period of the RO's resources in the time domain. Optionally, as shown in Figure 11, in the time domain, the first RO may be located after the associated first SSB, and the time domain period of the first RO may be the same as the transmission period of the first SSB; in the time domain, the second RO may be located after the associated second SSB, and the time domain period of the second RO may be the same as the transmission period of the second SSB. For example, if the transmission period of the first SSB is period 1, the time domain period of the first RO is also period 1; and / or, if the transmission period of the second SSB is period 2, the time domain period of the second RO is also period 2.

[0194] 2. Duration: This indicates the duration of the time domain resource of the RO. For example, if the time domain resource of the first RO is 3ms, the duration of the first RO is 3ms; if the time domain resource of the second RO is 10ms, the duration of the second RO is 10ms.

[0195] 3. Frequency domain position: It can represent the position of the RO resource in the frequency domain. The frequency domain position of the first RO and the frequency domain position of the second RO may partially overlap or may not overlap.

[0196] 4. Polarization: This field indicates the polarization mode corresponding to the RO, such as left-hand circular polarization, right-hand circular polarization, elliptical polarization, or linear polarization. For example, the polarization mode corresponding to the first RO is left-hand circular polarization, and the polarization mode corresponding to the second RO is right-hand circular polarization.

[0197] Optionally, when the first cell sends the first SSB and the second SSB using the method shown in FIG7A , the terminal device may switch through process 1 below or reselect through process 2 below. This will be described below.

[0198] Process 1:

[0199] The method in process 1 is described below with reference to FIG12. The method includes:

[0200] S1201: The second cell sends a third SSB to the terminal device. Correspondingly, the terminal device receives the third SSB from the second cell.

[0201] The third SSB is the SSB used for initial access. For example, the third SSB can be used for the initial random access procedure. Furthermore, the third SSB can also be used for procedures other than cell handover or cell reselection, such as beam failure recovery, uplink data transmission, or RRC connection reestablishment.

[0202] The second cell may be a cell of the second satellite. For details, please refer to the description of the second cell in FIG. 7A , which will not be repeated here.

[0203] Optionally, the second cell may send a third SSB according to the configuration information of the third SSB (hereinafter referred to as the third configuration information). The third configuration information may include at least one of the following: the time domain length of the third SSB, the period of the third SSB, the SSB bit map of the third SSB, the measurement window configuration of the third SSB, the measurement window offset of the third SSB, and the reference point position of the third SSB. For the specific content of the third configuration information, please refer to the description of the first configuration information, except that the first SSB is replaced by the third SSB, and the repeated parts are not repeated.

[0204] The third configuration information may be pre-set, determined for the second cell, or set for the second cell by other equipment (eg, ground network equipment).

[0205] Optionally, the second cell may indicate the third SSB as the SSB for initial access in an explicit or implicit manner. The indication method can refer to the description of "indicating the first SSB as the SSB for initial access" in S701, except that the first SSB is replaced by the third SSB, which will not be repeated here.

[0206] In addition, the third SSB is not used for cell switching or cell reselection. In this way, the terminal device that receives the third SSB will not switch or reselect to the second cell based on the third SSB.

[0207] S1202: The terminal device accesses the second cell according to the third SSB.

[0208] Optionally, the terminal device may be a terminal device in the second area. Exemplarily, the second area may be included in the area where the second cell sends data signals. The specific content of the second area can be referred to the description of the second area in the method shown in Figure 7A, and will not be repeated here.

[0209] This application does not limit the specific process of the terminal device accessing the second cell according to the third SSB. After accessing the second cell, the terminal device is in a connected state.

[0210] S1203: The first cell sends a second SSB. Correspondingly, the terminal device receives the second SSB from the first cell.

[0211] For the specific content of S1203, please refer to the description of S702 in the method shown in FIG7A , which will not be repeated here.

[0212] S1204: The terminal device sends a measurement report to the second cell according to the second SSB.

[0213] Optionally, the terminal device may determine the signal quality of the received first cell based on the second SSB. When the signal quality of the received first cell meets the set reporting conditions, the terminal device may send a measurement report to the second cell. The set reporting conditions may include: the signal quality of the first cell is greater than a set signal quality threshold. The measurement report may include: the sequence number of the second SSB and the signal strength of the first cell received by the terminal device.

[0214] After receiving the measurement report, the second cell may determine to switch the terminal device to the first cell, and switch the terminal device from the second cell to the first cell through the method shown in S605-S608.

[0215] By using this method, a terminal device in a connected state can be switched to the first cell according to the second SSB. When all the terminal devices in the second area in the connected state are switched to the first cell by using this method, the efficiency of group switching can be improved.

[0216] Optionally, the method shown in FIG12 further includes step A1:

[0217] A1: The terminal device obtains the second configuration information.

[0218] The second configuration information is used to indicate the configuration of the first cell sending the second SSB. The specific content of the second configuration information can be referred to S702 and will not be repeated here.

[0219] Optionally, when the second SSB is an NCD-SSB, the second configuration information may include: the measurement window configuration of the second SSB, the measurement window offset of the second SSB, the reference point position of the second SSB, and the NCD-SSB set to be measured.

[0220] Optionally, the terminal device may obtain the second configuration information in one of the following ways:

[0221] Method 1: The terminal device receives the second configuration information broadcast by the first cell.

[0222] The first cell may send the second configuration information via a broadcast message, so that the terminal device obtains the second configuration information via the broadcast message from the first cell.

[0223] Optionally, in method 1, the execution order between step A1 and S1201 - S1202 is not limited.

[0224] Method 2: The terminal device may receive the second configuration information from the first cell forwarded by the second cell.

[0225] Method 2 may include steps B1-B2:

[0226] B1: The first cell sends second configuration information to the second cell.

[0227] Optionally, the first cell may send the configuration information to the second cell in at least one of the following situations:

[0228] Case 1: The first cell initially determines the configuration for the first cell to send the second SSB. In this case, the second configuration information sent by the first cell to the second cell is used to indicate the initially determined configuration for the first cell to send the second SSB.

[0229] Case 2: The first cell updates the configuration of sending the second SSB by the first cell. In this case, the second configuration information sent by the first cell to the second cell is used to indicate the updated configuration of sending the second SSB by the first cell.

[0230] Optionally, in case 2, the first cell does not update the SIB1 of the cell.

[0231] B2: The second cell sends second configuration information to the terminal device. Correspondingly, the terminal device receives the second configuration information from the second cell.

[0232] The second configuration information may be carried in an existing message or in a new message, and this application does not impose any limitation on this.

[0233] Optionally, in method 2, step A1 may be performed after S1202.

[0234] After step A1, S1203 may include: the terminal device receives the second SSB from the first cell according to the second configuration information. For example, when the second configuration information includes the measurement window configuration of the second SSB, the terminal device may receive the second SSB from the first cell within the time window indicated by the measurement window configuration. For another example, when the second configuration information includes the period of the second SSB, the terminal device detects the second SSB from the first cell with the period of the second SSB as the period. For another example, the second SSB is an NCD-SSB. For another example, the terminal device may select a suitable initial NCD-SSB based on its own global navigation satellite system (GNSS) position and reference point position, and receive the initial NCD-SSB. Exemplarily, the terminal device may select the initial NCD-SSB based on the criterion of the closest distance between the terminal device position and the reference point position or the criterion of the minimum angle among the terminal device position, the satellite position and the reference point position.

[0235] Through this method, the terminal device can receive the second SSB from the first cell according to the second configuration information, thereby avoiding the terminal device from blindly detecting the second SSB, and further reducing the energy consumption of the terminal device.

[0236] Optionally, after S1204, the method shown in FIG12 further includes steps C1-C2:

[0237] C1: The second cell sends a handover command to the terminal device. Correspondingly, the terminal device receives the handover command from the second cell.

[0238] The handover command may be used to instruct the terminal device to handover to the first cell. The handover command may be the second RRC reconfiguration message in S608. For details, please refer to S608 and will not be described in detail here.

[0239] C2: The terminal device receives the first SSB from the first cell.

[0240] In some possible ways, the terminal device can blindly detect the first SSB from the first cell and access the first cell based on the detected first SSB.

[0241] In some other possible methods, the terminal device may receive the first SSB from the first cell based on the received second SSB. Optionally, the method includes steps D1-D2:

[0242] D1: The terminal device receives a first offset indication.

[0243] The first offset indication is used to indicate the time offset between the transmission time of the second SSB and the transmission time of the first SSB adjacent to the second SSB. For example, the transmission time of the second SSB is T1, and the transmission time of the first SSB adjacent to the second SSB is T2, then the time offset indicated by the first offset indication is ΔT=T2-T1.

[0244] Optionally, the first offset indication may be indicated by adding a ΔT field to messages such as the MIB, SIB1, or RRC. Alternatively, the first offset indication may be indicated by reusing the parameter K_SSB in an existing protocol. For example, the reserved bits in the parameter K_SSB may include the first offset indication. The time offset indicated by the first offset indication may be in units of symbols, time slots, milliseconds, or frames.

[0245] Optionally, the terminal device may receive the first offset indication in one of the following ways:

[0246] Method 1: The terminal device receives the first offset indication broadcast by the first cell.

[0247] The first cell may send the first offset indication via a broadcast message, so that the terminal device obtains the first offset indication via the broadcast message from the first cell.

[0248] Optionally, in method 1, the execution order between step D1 and S1201 - S1204 is not limited.

[0249] Method 2: The terminal device may receive a first offset indication from the first cell forwarded by the second cell.

[0250] Optionally, method 2 may include steps E1-E2:

[0251] E1: The first cell sends a first offset indication to the second cell. Correspondingly, the second cell receives the first offset indication from the first cell.

[0252] The first cell may send the first offset indication to the second cell via an interface between the first cell and the second cell.

[0253] E2: The second cell sends a first offset indication to the terminal device. Correspondingly, the terminal device receives the first offset indication.

[0254] The first offset indication may be carried in an existing message or in a new message.

[0255] D2: The terminal device receives the first SSB from the first cell based on the first offset indication and the time at which the second SSB is received. For example, if the time offset indicated by the first offset indication is ΔT, and if the terminal device receives the second SSB at time T3 in S1203, the terminal device may receive the first SSB from the first cell at time T3+ΔT.

[0256] The following describes steps D1 and D2 using the example of a CD-SSB as the first SSB and an NCD-SSB as the second SSB. The first cell can transmit an NCD-SSB and a CD-SSB sequentially on the same wavelength. On the same wavelength, there is a certain time domain offset between the transmission time of the NCD-SSB and the transmission time of the CD-SSB. For example, as shown in Figure 13, at time T1, the beam containing the NCD-SSB transmitted by the first cell can cover wavelengths 5 and 7, and the beam containing the CD-SSB transmitted by the first satellite can cover wavelengths 1 through 4. At time T2, the beam containing the NCD-SSB transmitted by the first cell covers wavelengths 6 and 8, and the beam containing the CD-SSB transmitted by the first cell covers wavelengths 2, 4, 5, and 7. UE1 is located in wavelength 5. At time T1, UE1 can measure the NCD-SSB from the first cell; at time T2, UE1 can measure the CD-SSB from the first cell. Since there is a certain time domain offset between the sending time of NCD-SSB and the sending time of CD-SSB, UE1 can determine the expected time to receive CD-SSB based on the time when NCD-SSB is received.

[0257] Through this method, the terminal device can receive the first SSB from the first cell based on the first offset indication and the time of receiving the second SSB, thereby eliminating the need for the terminal device to blindly detect the first SSB and the need for the second cell to send configuration information of the first SSB to the terminal device, thereby reducing the energy consumption of the terminal device and reducing the overhead of obtaining the configuration information of the first SSB.

[0258] Optionally, when the first SSB may be a CD-SSB and the second SSB may be an NCD-SSB, the method shown in FIG12 further includes step D1:

[0259] D1: The terminal device communicates with the first cell using the resources for switching and / or the random access preamble for switching corresponding to the NCD-SSB.

[0260] In the present application, the NCD-SSB may correspond to the resources used for handover and / or the random access preamble used for handover. The correspondence between the NCD-SSB and the resources used for handover and / or the random access preamble used for handover may be pre-set or determined by a network device (e.g., a first satellite or a network device located on the ground). When the correspondence is pre-set, the terminal device may store the correspondence. When the correspondence is determined by the network device, the terminal device may obtain the correspondence from the network device.

[0261] When the NCD-SSB corresponds to a resource used for handover, the terminal device may send a random access message to the first cell through the resource. When the NCD-SSB corresponds to a random access preamble used for handover, the terminal device may send a random access preamble corresponding to the NCD-SSB to the first cell.

[0262] Through this method, NCD-SSB can be associated with dedicated handover resources and / or random access preambles for handover, which can be used for uplink random access during group handover, thereby improving the efficiency of group handover. Furthermore, through the handover resources associated with NCD-SSB, the terminal device does not need to obtain resource configuration information for group handover, thereby reducing overhead. Through the random access preamble associated with NCD-SSB, conflicts between the random access preamble used for handover and the random access preamble used for initial access can be avoided, thereby improving the success rate of group handover.

[0263] Process 2:

[0264] The method in process 2 is described below with reference to FIG14. The method includes:

[0265] S1401: The terminal device receives a first offset indication.

[0266] Among them, the first offset indication is used to indicate the time offset between the transmission time of the second SSB and the transmission time of the first SSB adjacent to the second SSB.

[0267] The specific content of S1401 can be found in the description of step D1, and the repeated parts will not be repeated here.

[0268] In addition, the terminal device may be a terminal device in an idle state in the second area. For example, the second area may be included in the area where the second cell sends data signals. For details of the second area, please refer to the description of the second area in the method shown in Figure 7A.

[0269] S1402: The first cell sends a second SSB. Correspondingly, the terminal device receives the second SSB from the first cell.

[0270] For the specific content of S1402, please refer to the description of S702 in the method shown in FIG7A, and the repeated parts will not be repeated.

[0271] S1403: The terminal device reselects the first cell based on the second SSB.

[0272] This application does not limit the process of the terminal device reselecting to the first cell based on the second SSB. For example, when the terminal device determines that the signal quality from the first cell is greater than the set signal quality threshold based on the second SSB, the terminal device may reselect to the first cell.

[0273] In addition, this application does not limit the order of S1401 and S1402-S1403.

[0274] S1404: The terminal device receives the first SSB from the first cell according to the time of receiving the second SSB and the first offset indication.

[0275] The specific content of S1404 can be referred to step D3, and the repeated parts will not be repeated.

[0276] Optionally, when the terminal device is in an idle state, the terminal device may search for an SSB on a synchronization raster to be detected. If the terminal device determines that the received SSB is the first SSB according to the explicit or implicit manner in S701, the terminal device may access and reside according to the first SSB.

[0277] By using this method, a terminal device in an idle state can reselect to the first cell according to the second SSB. When all idle terminal devices in the second area reselect to the first cell using this method, the efficiency of group reselection can be improved.

[0278] Moreover, through this method, the terminal device can receive the first SSB from the first cell based on the first offset indication and the time of receiving the second SSB, thereby eliminating the need for the terminal device to blindly detect the first SSB, and eliminating the need for the second cell to send configuration information of the first SSB to the terminal device, thereby reducing the energy consumption of the terminal device and reducing the overhead of obtaining the configuration information of the first SSB.

[0279] The embodiment of the present application provides a communication method, which can be applied to the communication system shown in Figure 3 or Figure 4. The flow of the method will be described in detail below with reference to the flowchart shown in Figure 15.

[0280] S1501: During a first time period, a first cell transmits a data signal and an SSB in a third area. Accordingly, during the first time period, a terminal device in the third area can receive the data signal and the SSB from the first cell.

[0281] The first cell may be a cell within the coverage area of ​​the first satellite, and the first satellite may cover at least one area.

[0282] For example, as shown in Figure 16, time T4 belongs to the first time period. At time T4, the first cell transmits data signals and SSBs within beam positions 1 through 4. In other words, the beam used for transmitting data signals and the beam used for transmitting SSBs of the first cell cover beam positions 1 through 4. A beam used for transmitting data signals is referred to as a service beam. A beam used for transmitting SSBs is referred to as a broadcast beam. The second cell of the second satellite transmits data signals and SSBs within beam positions 5 through 8. In other words, the service beam and broadcast beam of the second cell cover beam positions 5 through 8. The first and second satellites move to the right.

[0283] Optionally, in the method shown in Figure 15, the SSB may be either NR SSB or CD-SSB. SSB may be used for both initial access and cell reselection or cell handover.

[0284] In addition, in the method shown in FIG15 , the beams of different satellites do not overlap at the beam position level.

[0285] S1502: During a second time period, the first cell transmits a data signal within a third area and transmits an SSB signal within a fourth area. Accordingly, during the second time period, a terminal device within the third area can receive the data signal from the first cell, and a terminal device within the fourth area can receive the SSB signal from the first cell.

[0286] The second time period is a time period after the first time period. For example, the first time period is 0 to 5 seconds (s), and the second time period is 6 to 11 seconds.

[0287] For example, as shown in Figure 16, time T5 belongs to the second time period. At time T5, the first cell transmits data signals in beams 1 through 4 and SSBs in beams 2, 4, 5, and 7. The second cell transmits data signals in beams 5 through 8 and SSBs in beams 6, 8, 9, and 10. Thus, terminal devices in beams 5 and 7 can switch or reselect to the first cell.

[0288] S1503: During the third time period, the first cell transmits data signals and SSB in the fourth area. Accordingly, during the third time period, the terminal device in the fourth area can receive the data signals and SSB from the first cell.

[0289] The third time period is the time period after the second time period. For example, the second time period is 6 to 11 seconds, and the third time period is 12 to 17 seconds. The start time of the third time period may be the time when a set proportion of terminal devices in the fourth area completes cell handover or cell reselection. The set proportion is, for example, 1 / 3.

[0290] For example, as shown in Figure 16, time T6 belongs to the third time period. At time T6, the first cell transmits data signals and SSB in beam positions 2, 4, 5, and 7. The second cell of the second satellite transmits data signals and SSB in beam positions 6, 8, 9, and 10.

[0291] With this method, the first cell can first transmit an SSB within the fourth area before transmitting a data signal within the fourth area. Thus, in a beam-hopping system, a terminal device within the fourth area can measure broadcast signal quality and perform downlink synchronization based on the SSB before the first cell uses a beam for transmitting data signals to cover the fourth area. This allows the terminal device to seamlessly reselect or switch to the first cell when the first cell uses a beam for transmitting data signals to cover the fourth area, thereby improving the efficiency of cell reselection and cell switching.

[0292] Optionally, in the method shown in FIG15 , the terminal device may determine the correspondence between the time when the first cell sends a signal and the area through implementation method one or implementation method two.

[0293] Implementation method 1: The terminal device obtains the third configuration information and the fourth configuration information respectively. The third configuration information is used to indicate the correspondence between the time and area when the first satellite transmits the data signal; the fourth configuration information is used to indicate the correspondence between the time and area when the first satellite transmits the SSB.

[0294] Optionally, the first implementation may include steps F1-F4:

[0295] F1: The first cell sends the third configuration information. Correspondingly, the terminal device receives the third configuration information.

[0296] The first cell directly sends the third configuration information to the terminal device. For example, if the terminal device is located at waveband 2, the first cell may send the third configuration information via a broadcast message, or send the third configuration information to the terminal device in a connected state via a unicast message.

[0297] The first cell may also send the third configuration information to the terminal device through other cells. For example, the terminal device is located at waveband 5, and the first cell forwards the third configuration information to the terminal device through the second cell of the second satellite.

[0298] Optionally, the third configuration information can be used to indicate the correspondence between the time and area in which the first satellite currently sends the data signal. For example, the current time is moment T4, which belongs to the first time period. The third configuration information includes: indication information of the first time period and indication information of the third area. This means that within the first time period, the first cell can send data signals within the third area. The information used to indicate the first time period may be specific time information, such as 0 to 5 seconds; the information used to indicate the first time period may also be the start time and duration of the first time period, for example, the start time is 0 seconds and the duration is 5 seconds. The indication information of the third area may be an identifier of the third area or an identifier of a wave position within the third area.

[0299] The third configuration information can also be used to indicate the correspondence between the time and region in which the first satellite transmits data signals within the current and future time periods. For example, if the current time is T4, which belongs to the first time period, the third configuration information includes: indication information for the first time period and indication information for the third region, indication information for the second time period and indication information for the third region, and indication information for the third time period and indication information for the fourth region. This indicates that during the first and second time periods, the first cell can transmit data signals within the third region, and during the third time period, the first cell can transmit data signals within the fourth region. The specific content of the indication information for the second and third time periods can be found in the description of the information used to indicate the first time period. The indication information for the fourth region can refer to the description of the indication information for the third region.

[0300] F2: The terminal device receives the data signal from the first cell according to the third configuration information.

[0301] The terminal device can receive data signals from the first cell within the corresponding area during the time period indicated by the third configuration information. The following description uses the example of the third configuration information including: indication information for the first time period and indication information for the third area. If the third configuration information received by the terminal device includes: indication information for the first time period and indication information for the third area, the terminal device can receive data signals from the first cell within the third area during the first time period.

[0302] F3: The first cell sends the fourth configuration information. Correspondingly, the terminal device receives the fourth configuration information.

[0303] Among them, the way in which the terminal device receives the fourth configuration information can refer to step F1, except that the third configuration information is replaced by the fourth configuration information, and the data signal is replaced by SSB.

[0304] Optionally, the fourth configuration information may be used to indicate the correspondence between the time and region in which the first satellite currently transmits SSBs. For example, if the current time is T4, which falls within the first time period, the fourth configuration information includes information indicating the first time period and information indicating the third region. This indicates that during the first time period, the first cell may transmit SSBs within the third region. The information indicating the first time period and the third region can be found in step F1 and will not be further described here.

[0305] The fourth configuration information can also be used to indicate the correspondence between the time and area in which the first satellite transmits SSBs within the current and future time periods. For example, if the current time is T4, which belongs to the first time period, the fourth configuration information includes: indication information for the first time period and indication information for the third area, indication information for the second time period and indication information for the fourth area, and indication information for the third time period and indication information for the fourth area. This indicates that during the first time period, the first cell can transmit SSBs within the third area, and during the second and third time periods, the first cell can transmit SSBs within the fourth area. For the specific content of the indication information for the second and third time periods, refer to the description of the information used to indicate the first time period. The indication information for the fourth area can refer to the description of the indication information for the third area.

[0306] F4: The terminal device receives the SSB from the first cell according to the fourth configuration information.

[0307] The terminal device can receive the SSB from the first cell within the corresponding area during the time period indicated by the fourth configuration information. The following description takes the fourth configuration information including: indication information for the first time period and indication information for the third area as an example. If the fourth configuration information received by the terminal device includes: indication information for the first time period and indication information for the third area, the terminal device can receive the SSB from the first cell within the third area during the first time period.

[0308] This application does not limit the order of steps F1-F2 and steps F3-F4.

[0309] Optionally, the terminal device may also determine the time during which the first cell can provide services to the terminal device (hereinafter referred to as the service time) based on the third configuration information and the fourth configuration information. Outside the service time, the terminal device does not detect signals from the first cell. For example, as shown in Figure 16, the terminal device is located at wave position 5. The third configuration information indicates that the first cell sends data signals at wave position 1-wave position 4 from 0 to 5 seconds; the fourth configuration information indicates that the first cell sends SSB at wave position 1-wave position 4 from 0 to 5 seconds, and sends SSB at wave position 2, wave position 4, wave position 5 and wave position 7 from 6 to 11 seconds. The terminal device can then determine that the first cell does not provide services to the terminal device from 0 to 6 seconds, and during this time period, the terminal device does not detect signals from the first cell. Through this method, the power consumption of the terminal device can be reduced.

[0310] Implementation method 2: The terminal device obtains fifth configuration information and a second offset indication. The fifth configuration information indicates the correspondence between the time and region at which the first satellite transmits the first signal; the second offset indication indicates the time interval between the time at which the first satellite transmits the first signal and the time at which the first satellite transmits the second signal within the third region or the fourth region. The first signal is a data signal and the second signal is SSB; alternatively, the first signal is SSB and the second signal is a data signal.

[0311] Optionally, the second implementation may include steps G1-G4:

[0312] G1: The first cell sends the fifth configuration information. Correspondingly, the terminal device receives the fifth configuration information.

[0313] When the first signal is a data signal, the fifth configuration information may be the third configuration information in step F1, and step G1 may refer to step F1. When the first signal is SSB, the fifth configuration information may be the fourth configuration information in step F3, and step G2 may refer to step F3.

[0314] G2: The terminal device receives the first signal from the first cell according to the fifth configuration information.

[0315] When the first signal is a data signal, step G2 may refer to step F2. When the first signal is an SSB signal, step G2 may refer to step F4.

[0316] G3: The first cell sends a second offset indication, and accordingly, the terminal device receives the second offset indication.

[0317] The first cell directly sends the second offset indication to the terminal device. For example, if the terminal device is located at waveband 2, the first cell may send the second offset indication via a broadcast message, or send the second offset indication to the terminal device in a connected state via a unicast message.

[0318] The first cell may also send the second offset indication to the terminal device via other cells. For example, the terminal device is located at waveband 5, and the first cell forwards the second offset indication to the terminal device via the second cell of the second satellite.

[0319] G4: The terminal device receives the second signal from the first cell according to the fifth configuration information and the second offset indication.

[0320] The following description uses the example of the first signal being an SSB and the second signal being a data signal. For example, the fifth configuration information includes: indication information for the second time period and indication information for the fourth area. If the second time period is 6 to 11 seconds and the time offset indicated by the second offset indication is 6 seconds, the terminal device can determine that the data signal from the first cell is received in the fourth area within 12 to 17 seconds.

[0321] Through this implementation, the terminal device can determine the time to receive the second signal based on the configuration information of the first signal and the second offset indication, without receiving the configuration information of the second signal, thereby reducing overhead.

[0322] Optionally, similar to implementation method 1, the terminal device may also determine the time during which the first cell can provide service to the terminal device (hereinafter referred to as the service time) based on the fifth configuration information and the second offset indication. Outside the service time, the terminal device does not detect signals from the first cell. This method can reduce power consumption of the terminal device.

[0323] Optionally, the method shown in FIG15 further includes steps H1-H2:

[0324] H1: The first cell sends indication information for the fourth time period. Correspondingly, the terminal device receives the indication information for the fourth time period.

[0325] In the fourth time period, the first transmit beam of the first cell may be paired with the first receive beam of the terminal device. In other words, the fourth time period is the time period in which the first transmit beam and the first receive beam are paired.

[0326] The first cell may directly send the indication information of the fourth time period to the terminal device. For example, if the terminal device is located at wave position 2, the first cell may send the indication information of the fourth time period via a broadcast message, or send the indication information of the fourth time period to the terminal device in the connected state via a unicast message.

[0327] The first cell may also send the indication information of the fourth time period to the terminal device through other cells. For example, the terminal device is located at waveband 5, and the first cell forwards the indication information of the fourth time period to the terminal device through the second cell of the second satellite.

[0328] In addition, the specific content of the indication information of the fourth time period can refer to the indication information of the first time period in step F1, except that the first time period is replaced by the fourth time period, which will not be repeated here.

[0329] G2: During the fourth time period, the terminal device may receive data signals and / or SSB from the first cell through the first receiving beam.

[0330] Using this method, a terminal device receives data signals and / or SSB signals from the first cell using the first receive beam during the fourth time period indicated by the first cell. During the fourth time period, the first receive beam is paired with the first transmit beam of the first cell, thereby improving communication quality. Furthermore, this method eliminates the need for the terminal device to detect which beam can be paired with the transmit beam of the first cell, thereby improving communication efficiency.

[0331] Based on the same technical concept as the method embodiments of Figures 7A to 16, the embodiment of the present application provides a communication device through Figure 17, which can be used to perform the functions of the relevant steps in the above method embodiments. The functions can be implemented by hardware, or by software or hardware executing corresponding software implementations. The hardware or software includes one or more modules corresponding to the above functions. The structure of the communication device is shown in Figure 17, including a communication unit 1701 and a processing unit 1702. The communication device 1700 can be applied to the network equipment, satellite or terminal equipment in the communication system shown in Figure 3 or Figure 4, and can implement the communication methods provided in the above embodiments of the present application and examples. The functions of each unit in the communication device 1700 are introduced below.

[0332] The communication unit 1701 is configured to receive and transmit data. The communication unit 1701 may be implemented by a transceiver, such as a mobile communication module. The mobile communication module may include at least one antenna, at least one filter, a switch, a power amplifier, a low noise amplifier (LNA), and the like.

[0333] The processing unit 1702 can be used to support the communication device 1700 in performing the processing actions in the above method embodiment. The processing unit 1702 can be implemented by a processor. For example, the processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor can be a microprocessor or any conventional processor.

[0334] In one embodiment, the communication device 1700 is applied to a network device or a satellite in the communication system shown in Figure 3 or Figure 4. The specific functions of the processing unit 1702 in this embodiment are described below.

[0335] The processing unit 1702 is used to: send a first SSB through the communication unit 1701, where the first SSB is an SSB used for initial access; and send a second SSB through the communication unit 1701, where the second SSB is an SSB used for cell switching or cell reselection.

[0336] Optionally, the first SSB is not used for cell switching or cell reselection, and the second SSB is not used for initial access.

[0337] Optionally, the processing unit 1702 is specifically used to: send a first SSB within the first area through the communication unit 1701; and send a second SSB in the second area through the communication unit 1701.

[0338] Optionally, the processing unit 1702 is specifically used to: send configuration information to the second cell through the communication unit 1701, and the configuration information is used to indicate the configuration of the first cell to send the second SSB.

[0339] Optionally, the sending time of the first SSB and the sending time of the second SSB do not overlap.

[0340] Optionally, the sending period of the first SSB is smaller than the sending period of the second SSB.

[0341] Optionally, the first SSB and the second SSB are both NR SSB.

[0342] Optionally, the first SSB is CD-SSB and the second SSB is NCD-SSB.

[0343] Optionally, the NCD-SSB corresponds to resources used for switching and / or a random access preamble used for switching.

[0344] Optionally, the processing unit 1702 is specifically used to: send a first offset indication to the second cell through the communication unit 1701, and the first offset indication is used to indicate the time offset between the sending time of the second SSB and the sending time of the first SSB adjacent to the second SSB.

[0345] Optionally, the processing unit 1702 is specifically used to: update the configuration of the first cell sending the second SSB, and not update the system information block SIB of the first cell.

[0346] In another embodiment, the communication device 1700 is applied to a terminal device in the communication system shown in Figure 3 or Figure 4. The specific functions of the processing unit 1702 in this embodiment are introduced below.

[0347] The processing unit 1702 is used to: receive a third SSB from the second cell through the communication unit 1701, where the third SSB is an SSB used for initial access; access the second cell according to the third SSB; receive a second SSB from the first cell through the communication unit 1701, where the second SSB is an SSB used for cell switching or cell reselection; and send a measurement report to the second cell according to the second SSB through the communication unit 1701.

[0348] Optionally, the processing unit 1702 is specifically used to: receive configuration information from the second cell through the communication unit 1701, where the configuration information is used to indicate the configuration of the first cell to send the second SSB; and receive the second SSB from the first cell through the communication unit 1701 according to the configuration information.

[0349] Optionally, the second SSB is NCD-SSB, and the processing unit 1702 is specifically used to communicate with the first cell through the communication unit 1701 using the resources for switching and / or the random access preamble for switching corresponding to the NCD-SSB.

[0350] Optionally, the processing unit 1702 is specifically used to: receive a switching command from the second cell through the communication unit 1701, the switching command is used to instruct the terminal device to switch to the first cell; receive a first SSB from the first cell through the communication unit 1701, the first SSB is an SSB used for initial access.

[0351] Optionally, the processing unit 1702 is specifically used to: receive a first offset indication through the communication unit 1701, the first offset indication being used to indicate the time interval between the sending time of the second SSB and the sending time of the first SSB adjacent to the second SSB; and receive the first SSB from the first cell through the communication unit 1701 according to the first offset indication and the time when the second SSB is received.

[0352] Optionally, the first SSB is not used for cell switching or cell reselection, and the second SSB is not used for initial access.

[0353] Optionally, the sending time of the first SSB and the sending time of the second SSB do not overlap.

[0354] Optionally, the sending period of the first SSB is smaller than the sending period of the second SSB.

[0355] Optionally, the first SSB and the second SSB are both NR SSB.

[0356] Optionally, the first SSB is CD-SSB and the second SSB is NCD-SSB.

[0357] In yet another embodiment, the communication device 1700 is applied to a terminal device in the communication system shown in Figure 3 or Figure 4. The specific functions of the processing unit 1702 in this embodiment are described below.

[0358] The processing unit 1702 is used to: receive a second SSB from the first cell through the communication unit 1701, where the second SSB is an SSB used for cell switching or cell reselection; receive a first offset indication through the communication unit 1701, where the first offset indication is used to indicate the time offset between the transmission time of the second SSB and the transmission time of the first SSB adjacent to the second SSB, where the first SSB is an SSB used for initial access; reselect to the first cell according to the second SSB; receive the first SSB from the first cell through the communication unit 1701 according to the time when the second SSB is received and the first offset indication.

[0359] Optionally, the first SSB is not used for cell switching or cell reselection, and the second SSB is not used for initial access.

[0360] Optionally, the sending time of the first SSB and the sending time of the second SSB do not overlap.

[0361] Optionally, the sending period of the first SSB is smaller than the sending period of the second SSB.

[0362] Optionally, the first SSB and the second SSB are both NR SSB.

[0363] Optionally, the first SSB is CD-SSB and the second SSB is NCD-SSB.

[0364] It should be noted that the division of modules in the above embodiments of the present application is illustrative and is only a logical functional division. In actual implementation, there may be other division methods. In addition, the functional units in the various embodiments of the present application may be integrated into a processing unit, or may exist separately physically, or two or more units may be integrated into a single unit. The above-mentioned integrated units may be implemented in the form of hardware or in the form of software functional units.

[0365] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0366] Based on the same technical concept, the embodiment of the present application provides a communication device as shown in Figure 18, which can be used to perform the relevant steps in the above method embodiment. The communication device can be applied to the network equipment, satellite or terminal equipment in the communication system shown in Figure 3 or Figure 4, and can implement the communication method provided in the above embodiments and examples of the present application, and has the functions of the communication device shown in Figure 17. Referring to Figure 18, the communication device 1800 includes: a communication module 1801, a processor 1802 and a memory 1803. Among them, the communication module 1801, the processor 1802 and the memory 1803 are interconnected.

[0367] Optionally, the communication module 1801, the processor 1802, and the memory 1803 are interconnected via a bus 1804. The bus 1804 may be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of illustration, FIG18 shows only one thick line, but this does not mean that there is only one bus or one type of bus.

[0368] The communication module 1801 is used to receive and send data to realize communication interaction with other devices. For example, the communication module 1801 can be realized through a physical interface, a communication module, a communication interface, and an input / output interface.

[0369] The processor 1802 can be used to support the communication device 1800 in executing the processing actions in the above-described method embodiment. When the communication device 1800 is used to implement the above-described method embodiment, the processor 1802 can also be used to implement the functions of the processing unit 1702. The processor 1802 can be a CPU, other general-purpose processors, DSPs, ASICs, FPGAs, other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0370] In one embodiment, the communication device 1800 is applied to a network device or a satellite in the communication system shown in FIG3 or FIG4. The processor 1802 is specifically configured to: send a first SSB through the communication module 1801, where the first SSB is an SSB for initial access; and send a second SSB through the communication module 1801, where the second SSB is an SSB for cell handover or cell reselection.

[0371] In another embodiment, the communication device 1800 is applied to a terminal device in the communication system shown in FIG3 or FIG4. The processor 1802 is specifically configured to: receive, through the communication module 1801, a third SSB from the second cell, where the third SSB is an SSB for initial access; access the second cell according to the third SSB; receive, through the communication module 1801, a second SSB from the first cell, where the second SSB is an SSB for cell handover or cell reselection; and send, through the communication module 1801, a measurement report to the second cell according to the second SSB.

[0372] In another embodiment, the communication device 1800 is applied to a terminal device in the communication system shown in FIG3 or FIG4 . The processor 1802 is specifically configured to: receive, through the communication module 1801, a second SSB from a first cell, where the second SSB is an SSB used for cell switching or cell reselection; receive, through the communication module 1801, a first offset indication, where the first offset indication is used to indicate a time offset between a transmission time of the second SSB and a transmission time of a first SSB adjacent to the second SSB, where the first SSB is an SSB used for initial access; reselect to the first cell based on the second SSB; and receive, through the communication module 1801, the first SSB from the first cell based on the time when the second SSB is received and the first offset indication.

[0373] The specific functions of the processor 1802 can refer to the description of the communication method provided in the above embodiments and examples of the present application, as well as the specific functional description of the communication device 1700 in the embodiment of the present application shown in Figure 17, which will not be repeated here.

[0374] The memory 1803 is used to store program instructions and data. Specifically, the program instructions may include program code, which includes computer operating instructions. The memory 1803 may include RAM, and may also include non-volatile memory (non-volatile memory), such as at least one disk storage. The processor 1802 executes the program instructions stored in the memory 1803 and uses the data stored in the memory 1803 to implement the above functions, thereby realizing the communication method provided in the above embodiment of the present application.

[0375] It is understood that the memory 1803 in FIG. 18 of the present application can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be ROM, programmable read-only memory (Programmable ROM, PROM), erasable programmable read-only memory (Erasable PROM, EPROM), electrically erasable programmable read-only memory (Electrically EPROM, EEPROM) or flash memory. The volatile memory can be RAM, which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct RAM bus random access memory (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0376] Based on the above embodiments, an embodiment of the present application further provides a computer program, which, when executed on a computer, enables the computer to execute the method provided in the above embodiments.

[0377] Based on the above embodiments, an embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a computer, the computer executes the method provided in the above embodiments.

[0378] The storage medium may be any available medium that can be accessed by a computer. By way of example and not limitation, computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer.

[0379] Based on the above embodiments, an embodiment of the present application further provides a chip, which is used to read a computer program stored in a memory to implement the method provided in the above embodiments.

[0380] Based on the above embodiments, embodiments of the present application provide a chip system, which includes a processor for supporting a computer device to implement the functions involved in each device in the above embodiments. In one possible design, the chip system also includes a memory for storing the necessary programs and data for the computer device. The chip system can be composed of a chip or can include a chip and other discrete devices.

[0381] In summary, the embodiments of the present application provide a communication method and apparatus, in which the first cell may send a first SSB, which is an SSB for initial access. The first cell may also send a second SSB, which is an SSB for cell switching or cell reselection. Through this method, the first cell may respectively send a first SSB for initial access and a second SSB for cell switching or cell reselection. In this way, when the terminal device needs to access the first cell, the first cell may send the first SSB; when the terminal device needs to switch or reselect to the first cell, the first cell may send the second SSB, so that the SSB can be sent on demand, reducing the overhead of sending the SSB and improving the efficiency of the terminal device in measuring the SSB.

[0382] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0383] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0384] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the present application. It should be understood that each flow and / or box in the flow chart and / or block diagram, as well as the combination of the flow chart and / or box in the flow chart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device for implementing the functions specified in one or more flow charts and / or one or more boxes in the block diagram.

[0385] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0386] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0387] Obviously, those skilled in the art may make various changes and modifications to the present application without departing from the scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include these modifications and variations.

Claims

1. A communication method, applied to a first cell, characterized in that: include: Sending a first synchronization signal block SSB, where the first SSB is an SSB for initial access; A second SSB is sent, where the second SSB is an SSB used for cell switching or cell reselection.

2. The method according to claim 1, wherein The first SSB is not used for cell switching or cell reselection, and the second SSB is not used for initial access.

3. The method according to claim 1 or 2, wherein: Sending a first SSB includes: sending the first SSB within a first area; Sending a second SSB includes: sending the second SSB within a second area.

4. The method according to any one of claims 1 to 3, wherein The method further comprises: Send configuration information to the second cell, where the configuration information is used to instruct the first cell to send the configuration of the second SSB.

5. The method according to any one of claims 1 to 4, characterized in that The transmission time of the first SSB and the transmission time of the second SSB do not overlap.

6. The method according to any one of claims 1 to 5, wherein: The transmission period of the first SSB is smaller than the transmission period of the second SSB.

7. The method according to any one of claims 1 to 6, wherein: The first SSB and the second SSB are both new wireless NR SSB.

8. The method according to any one of claims 1 to 7, wherein: The first SSB is a cell-defined synchronization signal block CD-SSB, and the second SSB is a non-cell-defined synchronization signal block NCD-SSB.

9. The method according to claim 8, wherein The NCD-SSB corresponds to resources used for handover and / or a random access preamble used for handover.

10. The method according to any one of claims 1 to 9, wherein The method further comprises: A first offset indication is sent to the second cell, where the first offset indication is used to indicate the time offset between the transmission time of the second SSB and the transmission time of the first SSB adjacent to the second SSB.

11. The method according to any one of claims 1 to 10, wherein: The method further comprises: Update the configuration of the first cell sending the second SSB, and do not update the system information block SIB of the first cell.

12. A communication method, applied to a terminal device, characterized in that: include: receiving a third synchronization signal block SSB from the second cell, where the third SSB is an SSB for initial access; Accessing the second cell according to the third SSB; receiving a second SSB from the first cell, where the second SSB is an SSB used for cell handover or cell reselection; According to the second SSB, a measurement report is sent to the second cell.

13. A communication method, applied to a terminal device, characterized in that: include: receiving a second synchronization signal block SSB from the first cell, where the second SSB is an SSB used for cell handover or cell reselection; receiving a first offset indication, where the first offset indication is used to indicate a time offset between a transmission time of the second SSB and a transmission time of a first SSB adjacent to the second SSB, where the first SSB is an SSB for initial access; reselecting to the first cell according to the second SSB; Receive the first SSB from the first cell based on the time when the second SSB is received and the first offset indication.

14. The method according to claim 12, wherein: The method further comprises: receiving configuration information from the second cell, where the configuration information is used to instruct the first cell to send a configuration of the second SSB; Receiving the second SSB from the first cell includes: receiving the second SSB from the first cell according to the configuration information.

15. The method according to claim 12 or 14, characterized in that The second SSB is an NCD-SSB, and the method further includes: Communicate with the first cell using resources for handover and / or random access preamble for handover corresponding to the NCD-SSB.

16. The method according to claim 12, 14 or 15, wherein: The method further comprises: receiving a handover command from the second cell, where the handover command is used to instruct the terminal device to handover to the first cell; A first SSB is received from the first cell, where the first SSB is an SSB used for initial access.

17. The method according to claim 16, wherein The method further comprises: receiving a first offset indication, where the first offset indication is used to indicate a time interval between a transmission time of the second SSB and a transmission time of a first SSB adjacent to the second SSB; Receiving the first SSB from the first cell includes: receiving the first SSB from the first cell according to the first offset indication and the time when the second SSB is received.

18. The method according to claim 13, 16 or 17, wherein: The first SSB is not used for cell switching or cell reselection, and the second SSB is not used for initial access.

19. The method according to any one of claims 13, 16-18, characterized in that: The transmission time of the first SSB and the transmission time of the second SSB do not overlap.

20. The method according to any one of claims 13, 16 to 19, characterized in that: The transmission period of the first SSB is smaller than the transmission period of the second SSB.

21. The method according to any one of claims 13, 16 to 20, characterized in that: The first SSB and the second SSB are both new wireless NR SSB.

22. The method according to any one of claims 13, 16 to 21, characterized in that: The first SSB is a cell-defined synchronization signal block CD-SSB, and the second SSB is a non-cell-defined synchronization signal block NCD-SSB.

23. A communication device, characterized in that: The device comprises a processor and a memory, wherein the processor and the memory are coupled, and the processor is configured to execute computer program instructions stored in the memory, so that the method according to any one of claims 1 to 11 is implemented.

24. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is run on a computer, the method according to any one of claims 1 to 11 is implemented.

25. A chip, characterized in that: The chip is coupled to a memory, and the chip reads a computer program stored in the memory to implement the method according to any one of claims 1 to 11.

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