RU2799887C2 - Method and device for uplink time synchronization - Google Patents

Abstract

FIELD: communications.

SUBSTANCE: invention is proposed with the purpose of providing the possibility of time synchronization of the uplink. It is achieved by determining, based on the beam information of the first beam and the ephemeris information of the satellite base station, the uplink synchronization frame number of the first cell corresponding to the first beam, determining the timing information of the first terminal apparatus in the first cell based on the uplink synchronization frame number communication lines of the first cell, where the timing information is used to indicate a time advance or a time lag, and output the timing information.

EFFECT: providing the possibility of time synchronization of the uplink.

28 cl, 15 dwg

Description

[0001] The present application claims priority based on Chinese Patent Application No. 201910252495.X, filed with the National Intellectual Property Administration of China on March 29, 2019 and entitled "METHOD AND APPARATUS FOR UPLINK TIMING SYNCHRONIZATION", which is incorporated herein by reference in its entirety.

Technical field

[0002] The present application relates to the field of satellite communication technologies and, more specifically, to a method and apparatus for uplink time synchronization.

State of the art

[0003] In uplink transmission in a wireless communication system, in order to avoid interference between terminal devices, the time at which uplink signals from terminal devices in the same cell arrive at the base station must be substantially aligned, i.e., uplink time synchronization is required. In order to guarantee the uplink time synchronization at the receiving side (base station side), a timing advance (TA) mechanism has been introduced.

[0004] From the point of view of the UE side, TA is essentially an offset between the start time of reception of the downlink subframe from the base station and the time of sending the uplink subframe from the base station. The base station side can control, by configuring different offsets for different terminal devices, the time at which uplink signals of different terminal devices arrive at the base station to be substantially aligned. For example, compared to a terminal device that is closer to a base station, a terminal device that is farther from the base station has a larger transmission delay. Therefore, the uplink signal needs to be sent earlier.

[0005] The base station side configures, for each terminal device in the cell, a TA that belongs to the terminal device, and delivers the TA to the terminal device. Thus, each terminal device sends an uplink signal based on the TA of the terminal device. In a satellite communication system, the transmission delays of terminal devices in a cell are not only different from each other, but are very different from each other. The uplink sync frame numbers which are on the base station side and which are determined by the terminal devices whose transmission delay difference is larger than the subframe length based on the time advances (TA) of the terminal devices are different. However, many physical layer operations are associated with an uplink sync frame number. If the uplink synchronization frame numbers from the terminal devices in the cell to the satellite base station side are different, there is a large storage overhead for managing the uplink synchronization frame numbers by the satellite base station.

The essence of the invention

[0006] The present application provides an uplink time synchronization method applied in a satellite communication system. It can reduce storage overhead in a satellite base station.

[0007] According to a first aspect, the present application provides a method for uplink time synchronization. The method includes: determining, based on the beam information of the first beam and the ephemeris information of the satellite base station, an uplink synchronization frame number of the first cell corresponding to the first beam; determining timing information of the first terminal device in the first cell based on the uplink synchronization frame number of the first cell, where the timing information is used to indicate timing advance or timing delay; and outputting the timing information of the first terminal device.

[0008] It should be noted that in the present application, the timing advance not only includes the timing advance value, but also includes the timing value. Similarly, the time lag includes not only the time lag value, but also includes the timing value. Alternatively, the timing value may also be referred to as the timing value. Early or late indicates that the UE should send the uplink signal in advance or send the uplink signal late.

[0009] In the technical solutions of the present application, the satellite base station determines, based on the beam information of the generated beam and the ephemeris information of the satellite base station, the uplink synchronization frame number of the cell corresponding to this beam. The satellite base station configures, for each UE in the cell, timing information that allows the uplink timing of the UE to be matched to the uplink synchronization frame number of the cell, and delivers the timing information for each UE. Each UE sends on the uplink based on its own timing information. For a satellite base station, the uplink sync frame number does not need to be stored for each UE in a cell, and only the uplink sync frame number per cell needs to be stored, thereby reducing storage overhead.

[0010] Unlike TA information in LTE or NR, timing information in this embodiment of the present application is used to indicate timing advance or timing delay. In other words, in the present application, the timing can be a positive or negative number. When it's a positive number, the timing is called time lead, and when it's a negative number, the timing is called time lag. In other words, in the technical solutions of the present application, the existing TA is expanded to a negative number. In a cell, the uplink timing of some terminal devices may be time advance, and the uplink timing of some terminal devices may be time lag, so that the uplink synchronization frame numbers of various terminal devices that are in the cell and are on the satellite base station side are unified.

[0011] Optionally, after outputting the timing information of the first terminal device, the method further includes sending the timing information to the first terminal device.

[0012] With respect to the first aspect, in some implementations of the first aspect, determining, based on the beam information of the first beam and the satellite base station ephemeris information, the uplink synchronization frame number of the first cell corresponding to the first beam includes: determining, based on the beam information of the first beam and the satellite base station ephemeris information, a second terminal device and a third terminal device in the first cell, where the second terminal device is a terminal device that resides in the first cell. the one is closest to the satellite base station, and the third terminal device is the terminal device which is located in the first cell and is the furthest from the satellite base station; determining a set of potentially suitable frame numbers based on a first round trip delay for signal transmission between the second terminal device and the satellite base station and a second round trip delay for signal transmission between the third terminal device and the satellite base station; and selecting the first frame number from the set of potentially suitable frame numbers as the uplink sync frame number for the first cell.

[0013] With respect to the first aspect, in some implementations of the first aspect, determining, based on the first round trip delay and the second round trip delay, the set of potentially candidate frame numbers includes: determining, based on the first round trip delay, the second round trip delay, and a plurality of first limit conditions, a set of potentially candidate frame numbers for the first cell, where the set of first constraint conditions includes: potential candidate numbers frames are integer multiples of a unit of time for communication between a satellite base station and terminal devices; the minimum value of potentially eligible frame numbers is an integer not greater than and closest to the first round trip delay; and the maximum value of potentially eligible frame numbers is an integer that is not less than and nearest to the second round trip delay.

[0014] With regard to the first aspect, in some implementations of the first aspect, one selects, from a set of potentially suitable frame numbers, $$x$$ with the least $$\left|x-\mathrm{<figure-callout\; id="1"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}T{D}_{}{}_1\right|+\left|x-\mathrm{<figure-callout\; id="2"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}T{D}_{}{}_2\right|$$ or $$\left|x-\frac{\mathrm{<figure-callout\; id="1"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}T{D}_{}{}_1+\mathrm{<figure-callout\; id="2"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}T{D}_{}{}_2}{2}\right|$$ as the uplink sync frame number for the first cell, where $$x$$ is the first frame number, RTD ₁ is the first round trip delay, and RTD ₂ is the second round trip delay.

[0015] With respect to the first aspect, in some implementations of the first aspect, after the first terminal device accesses the first cell, the method further includes: determining that the first terminal device initiates a handoff for the cell; determining whether the uplink synchronization frame number of the target cell matches the uplink synchronization frame number of the first cell; and, upon determining that the uplink sync frame number of the target cell does not match with the uplink sync frame number of the first cell, outputting timing information of the target cell.

[0016] In addition, after outputting the target cell timing information, the method further includes: sending the target cell timing information to the first terminal device.

[0017] In this embodiment, when the satellite base station determines that the uplink timing of the target cell does not match the uplink timing of the source cell, the satellite base station notifies the terminal device of the uplink synchronization frame number of the target cell.

[0018] Regarding the first aspect, in some implementations of the first aspect, the method further includes: upon determining that the uplink synchronization frame number of the target cell matches the uplink synchronization frame number of the first cell, handover the first terminal device from the first cell to the target cell.

[0019] Regarding the first aspect, in some implementations of the first aspect, the timing information includes a timing value and whether the timing value is positive or negative. When the timing value is positive, the timing information is specifically used to indicate the timing advance, and when the timing value is negative, the timing information is specifically used to indicate the timing delay.

[0020] Optionally, sending the timing information to the first terminal device includes: sending the timing information to the first terminal device using a random access response message. Whether the timing value is positive or negative can be indicated by a reserved bit of the TA control field (timing advance command) in the random access response message.

[0021] According to a second aspect, the present application provides a method for uplink time synchronization. The method includes: receiving timing information used to perform uplink timing synchronization with a first cell; determining a timing advance or timing delay based on the timing information; and performing uplink time synchronization based on the time advance or time lag.

[0022] Regarding the second aspect, in some implementations of the second aspect, before determining the timing advance or the timing information based on the timing information, the method further includes determining that the timing information is coming from a satellite base station.

[0023] Regarding the second aspect, in some implementations of the second aspect, the timing information includes a timing value and whether the timing value is positive or negative, and determining a timing advance or a timing delay based on the timing information includes: when determining that the timing value is positive, determining a timing advance based on the timing value; or when determining that the timing value is negative, determining the time delay based on the timing value.

[0024] Regarding the second aspect, in some implementations of the second aspect, after the first terminal device accesses the first cell, the method further includes: starting a handover for the cell; receiving target cell timing information from the satellite base station; and updating the timing information of the first cell to the timing information of the target cell.

[0025] With regard to the second aspect, in some implementations of the second aspect, the method further includes the step of: performing uplink time synchronization with the target cell based on the timing information of the target cell.

[0026] According to a third aspect, the present application provides a handover method for a cell. The method includes: determining that the first terminal device initiates a handover for the cell; determining whether the uplink sync frame number of the target cell matches the uplink sync frame number of the source cell; and upon determining that the uplink sync frame number of the target cell does not match the uplink sync frame number of the source cell, sending the target cell timing information to the first terminal device, where the timing information is used to indicate timing advance or timing delay.

[0027] Regarding the third aspect, in some implementations of the third aspect, the method further includes: upon determining that the uplink synchronization frame number of the target cell matches the uplink synchronization frame number of the source cell, handover the first terminal device from the source cell to the target cell.

[0028] According to a fourth aspect, the present application provides a handover method for a cell, where the method includes: starting a handover for the cell; receiving target cell timing information from the satellite base station, where the timing information is used to indicate timing advance or timing delay, and the timing information is sent by the satellite base station when determining that the uplink synchronization frame number of the target cell is inconsistent with the source cell's uplink synchronization frame number; and determining a time advance or a time lag based on the timing information, and performing uplink time synchronization with the target cell based on the time advance or time lag.

[0029] Optionally, the timing information includes a timing value and whether the timing value is positive or negative, and determining a timing advance or a timing delay based on the timing information includes: when determining that the timing value is positive, determining a timing advance based on the timing value; or when determining that the timing value is negative, determining the time delay based on the timing value.

[0030] According to the fifth aspect, the present application provides a communication device. The communication device has the function of implementing a method according to any one of the first aspect or possible implementations of the first aspect, or any one of the third aspect or possible implementations of the third aspect. This function may be implemented using hardware, or may be implemented by executing appropriate software using hardware. The hardware or software includes one or more modules corresponding to the above functions.

[0031] According to the sixth aspect, the present application provides a communication device. The communication device has the function of implementing a method according to any of the second aspect or possible implementations of the second aspect, or any one of the fourth aspect or possible implementations of the fourth aspect. This function may be implemented using hardware, or may be implemented by executing appropriate software using hardware. The hardware or software includes one or more modules corresponding to the above functions.

[0032] According to a seventh aspect, the present application provides a network device including a processor and a memory. The memory is adapted to store a computer program, and the processor is configured to call and execute the computer program stored in the memory, such that the network device executes a method according to any of the first aspect or possible implementations of the first aspect, or any one of the third aspect or possible implementations of the third aspect.

[0033] According to the eighth aspect, the present application provides a terminal device including a processor and a memory. The memory is adapted to store a computer program, and the processor is configured to call and execute the computer program stored in the memory, such that the terminal device executes the method according to any of the second aspect or possible implementations of the second aspect, or any one of the fourth aspect or possible implementations of the fourth aspect.

[0034] According to a ninth aspect, the present application provides a computer-readable storage medium. The computer-readable storage medium stores computer instructions, and when the computer instructions are executed on the computer, the computer executes the method according to any one of the first aspect or possible implementations of the first aspect, or the method according to any one of the third aspect or possible implementations of the third aspect.

[0035] According to a tenth aspect, the present application provides a computer-readable storage medium. The computer-readable storage medium stores computer instructions, and when the computer instructions are executed on the computer, the computer executes the method according to any of the second aspect or possible implementations of the second aspect, or the execution of the method according to any one of the fourth aspect or possible implementations of the fourth aspect.

[0036] According to an eleventh aspect, the present application provides a chip including a processor. The processor is configured to read and execute a computer program stored in the memory to execute a method according to any of the first aspect or possible implementations of the first aspect, or to perform a method according to any one of the third aspect or possible implementations of the third aspect.

[0037] Optionally, the chip further includes a memory, and the memory and the processor are connected to the memory via a circuit or a wire.

[0038] In addition, optionally, the chip includes a communication interface.

[0039] According to a twelfth aspect, the present application provides a chip including a processor. The processor is configured to read and execute a computer program stored in the memory to perform a method according to any of the second aspect or possible implementations of the second aspect, or to perform a method according to any of the fourth aspect or possible implementations of the fourth aspect.

[0040] Optionally, the chip further includes a memory, and the memory and the processor are connected to the memory via a circuit or a wire.

[0041] In addition, optionally, the chip includes a communication interface.

[0042] According to the thirteenth aspect, the present application provides a computer program product. The computer program product includes computer program code, and when the computer program code is run on the computer, the computer is caused to execute a method according to any one of the first aspect or possible implementations of the first aspect, or to execute the method according to any one of the third aspect or possible implementations of the third aspect.

[0043] According to the fourteenth aspect, the present application provides a computer program product. The computer program product includes a computer program code, and when the computer program code is executed on the computer, the computer executes the method according to any of the second aspect or possible implementations of the second aspect, or the method according to any one of the fourth aspect or possible implementations of the fourth aspect.

[0044] In the technical solutions of this application, the satellite base station determines, based on the beam information of the generated beam and the ephemeris information of the satellite base station, the uplink synchronization frame number for the cell corresponding to this beam. The satellite base station configures, for each UE in the cell, timing information that allows the uplink timing of the UE to be matched to the uplink synchronization frame number of the cell, and delivers the timing information for each UE. Each UE sends on the uplink based on its own timing information. For a satellite base station, it is only necessary to store one uplink synchronization frame number per cell, thereby reducing storage overhead.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG. 1 is an architectural diagram of a satellite communication system;

[0046] FIG. 2 is a simplified schematic diagram of a satellite communications system;

[0047] FIG. 3 is a schematic diagram of configuring a TA to provide uplink time synchronization in a satellite communication system;

[0048] FIG. 4 is a schematic diagram of determining uplink synchronization frame numbers of two different UEs by a satellite communication system;

[0049] FIG. 5 is a flow diagram of an uplink timing synchronization method 200 applicable to a satellite communication system according to the present application;

[0050] FIG. 6 is an example of an application of the uplink time synchronization method in a satellite communication system according to the present application;

[0051] FIG. 7 is an example of a procedure in which a satellite base station configures timing information for a UE according to the present application;

[0052] FIG. 8 is a schematic diagram of the display of timing information in RAR;

[0053] FIG. 9 is a flowchart of RAR processing at the UE side according to the present application;

[0054] FIG. 10 is a schematic diagram of a UE serving beam changing during satellite operation;

[0055] FIG. 11 is a block diagram of a handover for a cell in a satellite communication system according to the present application;

[0056] FIG. 12 is a schematic block diagram of a communication device 600 according to the present application;

[0057] FIG. 13 is a schematic block diagram of a communication device 700 according to the present application;

[0058] FIG. 14 is a schematic structural representation of a network device according to the present application; And

[0059] FIG. 15 is a schematic structural representation of a terminal device according to this present application.

Description of Embodiments

[0060] The following describes the technical solutions of the present application with reference to the accompanying drawings.

[0061] The technical solutions of the present application can be applied to a satellite communication system. Fig. 1 is an architectural diagram of a satellite communication system. The satellite communication system 100 typically includes three parts: a space segment, a ground segment, and a user segment. The space segment may include a geostationary earth orbit (GEO) satellite, a non-geostationary earth orbit (NGEO) satellite, or a satellite network 101 including a plurality of GEO satellites and NGEO satellites. The ground segment generally includes a satellite control center 102, a network control center (NCC) 103, various gateway stations (gateway) 104, and the like, and the gateway station is also called a gateway. The Network Control Center is also called the System Control Center (SCC). The user segment includes various terminal devices. The terminal device may be various mobile terminals 106, such as a satellite mobile phone, or may be various fixed terminals 107, such as a ground communication station. In FIG. 1, the dotted line refers to the communication signal between the satellite and the terminal. The solid line indicates the communication signal between the satellite and the device on the ground segment. The double arrow line indicates the communication signal between network elements in the ground segment. In a satellite communication system, a satellite may also be referred to as a satellite base station. In FIG. 1, a satellite base station may transmit data on a downlink to a terminal device. The downlink data may be transmitted to the terminal device after channel coding, modulation, and mapping. The terminal apparatus may also transmit uplink data to a satellite base station. The uplink data may also be transmitted to the satellite base station after channel coding, modulation and mapping.

[0062] The satellite control center 102 in the ground segment performs functions such as maintaining, monitoring and controlling the orbital position and attitude of the satellite, as well as managing the satellite ephemeris. The network control center 103 has functions for processing user registration, identity verification, charging, and other network management. In some satellite mobile communication systems, the network control center and the satellite control center are combined. Gateway 104 has functions such as call handling and handover, as well as interaction with the terrestrial communications network. The terrestrial communication network 105 is part of the terrestrial segment of the satellite network used to switch the satellite data packet to the core network and send the data packet to the terminal terminal device. The terrestrial communications network may be a public switched telephone network (PSTN), a public land mobile network (PLMN), or other private networks. Different terrestrial networks require different gateway functions of the gateway station.

[0063] In some satellite communication systems, the space segment of the satellite communication system may be a layered structure including a control satellite and one or more serving satellites. In a multilayer satellite communication system network, a space segment may include one or more control satellites and service satellites controlled by the control satellites. The satellite or satellite base station referred to in this application is not limited to a control satellite or a serving satellite.

[0064] A satellite base station and a terminal device communicate using a communication system that includes, but is not limited to, the following: a global system of mobile communications (GSM), a code division multiple access (CDMA) system, a wideband code division multiple access (WCDMA) system, a general packet radio service (GPRS), a Long Term Evolution ( long term evolution (LTE), frequency division duplex (FDD) LTE, LTE time division duplex (TDD), universal mobile telecommunications system (UMTS), worldwide interoperability for microwave access (WiMAX), future 5th generation (5G) or new radio (new radio, NR) system.

[0065] The terminal device in this embodiment of the present application needs to access a mobile satellite communication network using the terrestrial segment of the satellite communication system to perform mobile communication. A terminal device may be referred to as a user equipment (user equipment, UE), access terminal, user equipment, subscriber station, mobile station, mobile console, remote station, remote terminal, mobile device, user terminal, terminal, wireless communications device, user agent, or user device. The terminal device can be a cellular phone, a wireless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a portable device with a wireless communication function, a computing device, other data processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal device in a future network. 5G or a terminal device in a future public land mobile network (PLMN) enhanced network. The terminal device, represented by a satellite phone and a vehicle-mounted satellite system, can communicate directly with the satellite. The fixed terminal represented by the ground communication station can communicate with the satellite only after relaying by the ground station. The terminal device establishes and obtains the communication status by setting the antenna of the wireless transceiver in order to communicate.

[0066] FIG. 2 is a simplified schematic diagram of a satellite communication system. As shown in FIG. 2, an inter-satellite link may exist between satellites to provide a backhaul (not shown in FIG. 2). A satellite typically generates multiple beams, and each beam corresponds to one cell (or sector). Delays for different terminal devices located in the same cell in terms of arrival at the satellite are different. It is necessary to use uplink synchronization technology to ensure that the uplink signals of different terminal devices arrive at the satellite base station at substantially the same time to ensure that the terminal devices do not interfere with each other.

[0067] For example, in FIG. 2, UE #1 and UE #2 are located in the same cell. However, communication delays between UE #1 and satellite and communication between UE #2 and satellite are different, and an uplink synchronization mechanism is required to ensure that UE #1 and UE #2 do not interfere with each other. In a time division duplexing (TDD, TDD) communication system, a communication signal is divided into several slots of a certain length in terms of time. The slot can only be one of the uplink and downlink slot, and the satellite cannot receive and send signals at the same time at the same time. In a TDD system, uplink synchronization not only prevents interference between users, but also ensures matching between uplink and downlink frames to avoid uplink and downlink mutual interference.

[0068] To ensure uplink synchronization at the receiving end, LTE offers a timing advance (TA) mechanism. From the point of view of the UE side, the essence of the time advance is a negative offset between the start time at which the downlink subframe is received and the time at which the uplink subframe is transmitted. The base station can control, by properly managing the offset of each UE, the time at which uplink signals from different UEs arrive at the base station. Briefly, due to the longer transmission delay, the UE which is further away from the base station has to send the uplink signal in advance compared to the UE which is closer to the base station.

[0069] It should be understood that the uplink subframe timing and the downlink subframe timing on the base station side are the same, and there is an offset between the uplink subframe timing and the downlink subframe timing on the UE side. Different UEs have different TAs. Therefore, the TAs are configured at the UE level.

[0070] The following describes an uplink time synchronization process in a satellite communication system with reference to FIG. 3.

[0071] FIG. 3 is a schematic diagram of configuring a TA to provide uplink time synchronization in a satellite system. As shown in FIG. 3, it is assumed that the communication signal is slotted at 1 ms interval, and the delay for UE #1 in terms of arrival at the satellite is 3.62 ms. To ensure that the uplink signal sent by UE #1 arrives at the satellite base station after an integer multiple of the slot duration (which in this example is 7 ms in particular), the satellite base station adjusts TA=240 µs for UE #1. Thus, the time period obtained by subtracting the time advance from the round trip delay (RTD) for signal transmission between the satellite base station and the UE is equal to an integer multiple of the slot. Therefore, it can be ensured that the uplink signal sent by the user equipment UE #1 arrives at the satellite base station after an integer multiple slot. Sending the uplink signal by the user equipment UE #2 is similar.

[0072] TA is a key technology used in LTE and NR to eliminate time differences between user equipments (UEs) in a cell. The base station measures the transmission delay between the base station and the UE based on the physical random access channel (PRACH) sent by the user equipment (UE) in the random access process and configures a TA for the UE. The base station then notifies the UE of the configured TA by using a random access response. The UE adjusts the sending time of the uplink signal based on the TA to perform uplink time synchronization.

[0073] In a satellite communication system, since the transmission delay between a UE and a satellite base station is relatively large and typically exceeds a slot duration (or subframe length) of 1 ms, different UEs in a cell have different uplink synchronization frame numbers on the satellite base station side. However, many physical layer operations are associated with a frame number, such as scrambling and pilot. If the uplink synchronization frame numbers from different UEs in the cell to the base station do not match, the satellite base station must store the uplink synchronization frame number of each UE in the cell.

[0074] The following uses FIG. 4 as an example to describe the problem that uplink synchronization frame numbers of different UEs in a satellite system do not match. Fig. 4 is a schematic diagram of determining uplink synchronization frame numbers of two different UEs by a satellite communication system.

[0075] It is assumed that the transmission delay of UE #1 is 3.62 ms, and the transmission delay of UE #2 is 4.4 ms. According to the TA configuration method described above, in order to ensure that the uplink signals of UE #1 and UE #2 arrive at the base station after an integer multiple slot, the base station configures the TA for UE #1 as 240 µs, and the base station configures the TA for UE #2 as 80 µs. Therefore, the uplink synchronization frame number of the UE #1 uplink signal to arrive at the base station is 7, and the uplink synchronization frame number of the UE #2 uplink signal to arrive at the base station is 8. The base station needs to store the UE #1 uplink synchronization frame number 7 and the UE #2 uplink synchronization frame number 8. However, a very large number of UEs are usually attached to a cell. Therefore, the satellite base station stores the uplink synchronization frame number for each UE, and the storage overhead in the satellite base station is very large.

[0076] Thus, the present application provides an uplink time synchronization method applied in a satellite communication system. This can reduce storage overhead at the satellite base station.

[0077] The following describes in detail the uplink time synchronization method provided in the present application.

[0078] In the present application, timing information is input to a satellite communication system, and the timing information is used to indicate timing advance or timing delay, so that the uplink synchronization frame numbers of different UEs in the same cell are unified in the satellite base station. Therefore, the satellite base station only needs to store one uplink sync frame number per cell. Compared to storing one uplink synchronization frame number per UE, the storage overhead for a satellite base station can be reduced.

[0079] Optionally, the timing information includes a timing value and whether the timing value is positive or negative. When the timing value is positive, the timing information is specifically used to indicate the timing advance. When the timing value is negative, the timing information is specifically used to indicate a time lag.

[0080] It should be noted that, as described above, the existing TA timing advance can only be a positive number, and TA indicates the offset of the uplink timing start time relative to the downlink timing. Therefore, TA being a positive number means that the uplink timing start time is a positive offset from the downlink timing. In other words, the uplink timing precedes the downlink timing, which is commonly referred to as timing advance.

[0081] In this application, the timing value in a satellite communication system can be a positive or negative number. That the timing value is a positive number expresses the same meaning as the existing TA, namely timing advance. That the timing value is a negative number indicates that the start time of the uplink timing is a negative offset from the downlink timing, i.e. the uplink timing is after the downlink timing. In the present application, the case in which the timing value is a negative number is called the time delay.

[0082] FIG. 5 is a flow diagram of an uplink timing synchronization method 200 applicable to a satellite communication system according to the present application. Method 200 may be performed by a satellite base station.

[0083] 210: Based on the beam information of the first beam and the ephemeris information of the satellite base station, the uplink synchronization frame number for the first cell corresponding to the first beam is determined.

[0084] At step 210, the satellite base station knows beam information such as beam direction and beam width, and ephemeris information. Based on this information, the satellite base station can determine the uplink synchronization frame number for the first cell. It should be understood that the ephemeris information herein may include information such as the orbit in which the satellite base station is located and the altitude of the orbit.

[0085] The first beam is any of the beams generated by the satellite base station. Alternatively, the first beam can also be considered as the current beam of the satellite base station.

[0086] The satellite base station can determine, based on the beam information of the first beam and the ephemeris information, the UE (hereinafter referred to as the second terminal device) which is located in the first cell corresponding to the first beam and which is closest to the satellite base station, and the UE (hereinafter referred to as the third terminal device) which is located in the first cell corresponding to the first beam and which is farthest from the satellite base station. Then, the satellite base station determines the transmission delay between the second terminal device and the satellite base station and the transmission delay between the third terminal device and the satellite base station, and then determines the uplink synchronization frame number of the first cell based on the transmission delay between the second terminal device and the satellite base station and the transmission delay between the third terminal device and the satellite base station.

[0087] Here, the satellite base station can determine the UE at the near end and the UE at the far end, and determine the transmission delays of the UE at the near end and the UE at the far end using the existing method. Details are not described here.

[0088] The following describes in detail a process in which the satellite base station determines the uplink synchronization frame number for the first cell based on the transmission delays of the second terminal apparatus and the third terminal apparatus.

[0089] Alternatively, the UE closest to the satellite base station (namely, the second terminal device) is also referred to as the near end UE, and the UE furthest from the satellite base station (namely, the third terminal device) is also referred to as the far end UE.

[0090] Next, UE #1 and UE #2 shown in FIG. 3 as an example for describing the uplink synchronization of the cell determination process, which is applicable to a satellite communication system and which is provided in the present application.

[0091] It should be noted that if FIG. 3 is used as an example to describe, in this case, UE #1 and UE #2 shown in FIG. 3 are not any two UEs in a cell, but are, respectively, a near-end UE and a far-end UE with respect to the satellite base station.

[0092] The round trip delays of UE #1 and UE #2, which are determined by the satellite base station, are assumed to be 7.24 ms and 8.8 ms, respectively (referred to below as RTD ₁ and RTD ₂ , respectively) _.

[0093] The satellite base station determines a set of potentially suitable frame numbers based on the UE's near-end round-trip propagation delay (referred to below as the first round-trip delay), the far-end UE's round-trip delay (referred to below as the second round-trip delay), and a plurality of first limiting conditions regarding the uplink synchronization frame number. The satellite base station selects, from a set of potentially suitable frame numbers, the first frame number that satisfies the second constraint as the uplink synchronization frame number for the cell.

[0094] It can be understood that in the present application, the uplink synchronization frame number corresponds to the cell level and not the UE level.

[0095] The plurality of first limiting conditions include:

[0096] (1) The uplink sync frame number should be an integer multiple of the time unit used for communication between the satellite base station and the terminal device.

[0097] The time unit here may be a slot, a subframe, or the like. This application is not limited. The following slot is used as an example for description.

[0098] (2) The minimum value of a potentially eligible frame number is an integer that is at most and is closest to the first round trip delay and that satisfies condition (1).

[0099] (3) The maximum value of a potentially eligible frame number is an integer that is not less than and is closest to the second round trip delay and that satisfies condition (2).

[00100] A set of potentially suitable frame numbers can be determined based on the aforementioned first limiting conditions.

[00101] For example, in the example shown in FIG. 3, the slot length is 1ms. Therefore, the minimum value of a potentially eligible frame number that satisfies the above conditions (1) to (3) should be 7 ms, and the maximum value of a potentially eligible frame number that satisfies the above conditions (1) to (3) should be 9 ms. After determining the minimum value and maximum value of a potentially suitable frame number, a set of potentially suitable frame numbers can be determined. In the example of FIG. 3, the set of potentially eligible frame numbers should be {7, 8, 9}.

[00102] In addition, the first frame number (denoted below as $$x$$ ) is selected from a set of potentially suitable frame numbers, so that $$\left|x-\mathrm{<figure-callout\; id="1"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}TD1\right|+\left|x-\mathrm{<figure-callout\; id="2"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}TD2\right|$$ is the smallest. The uplink sync frame number for the cell is $$x$$ corresponding to the mentioned conditions.

[00103] It should be understood that the second limiting condition is that $$x$$ is chosen so that $$\left|x-\mathrm{<figure-callout\; id="1"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}TD1\right|+\left|x-\mathrm{<figure-callout\; id="2"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}TD2\right|$$ was the smallest.

[00104] Optionally, $$\left|x-\mathrm{<figure-callout\; id="1"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}TD1\right|+\left|x-\mathrm{<figure-callout\; id="2"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}TD2\right|$$ can be expressed in another way, for example, $$\left|x-\frac{\mathrm{<figure-callout\; id="1"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}TD1+\mathrm{<figure-callout\; id="2"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}TD2}{2}\right|$$ . This application is not limited.

[00105] In the example of FIG. 3, $$x$$ , which satisfies the second constraint and which is selected from a set of potentially eligible frame numbers, must be 8 ms. 8 ms is the uplink synchronization frame number of the serving cell of UE #1 and UE #2, which is calculated by the satellite base station.

[00106] FIG. 6 is an example of an application of the uplink time synchronization method in a satellite communication system according to the present application.

[00107] As shown in FIG. 6, according to the above step 210, the uplink timing of UE #1 and the uplink timing of UE #2 at the base station side are 8 ms. For UE #1, the timing value is negative, i.e., for UE #1, it is the time delay. UE #1 performs uplink transmission with a delay of 0.76 ms based on the uplink timing. For UE #2, the timing value is positive, i.e., for UE #2, it is a timing advance. UE #2 performs uplink transmission 0.8 ms earlier based on the uplink timing.

[00108] Optionally, in this embodiment of the present application, when the timing value is a positive number, the timing information in this case has the same value as the existing TA.

[00109] Comparing the uplink timing of UE #1 and the uplink timing of UE #2 shown in FIG. 6 with the uplink timing of UE #1 and the uplink timing of UE #2 in FIG. 4, the uplink synchronization frame numbers for UE #1 and UE #2 are the same. Therefore, for a cell, the base station side only needs to store the uplink synchronization frame number configured for that cell, and it is not necessary to store the uplink synchronization frame number for each UE in the cell, so that the storage overhead can be reduced.

[00110] 220: Timing information of the first terminal device in the first cell is determined based on the uplink synchronization frame number of the first cell.

[00111] As described above, the timing information is used to indicate a time advance or a time lag.

[00112] Here, the first terminal device refers to any terminal device in the first cell. In other words, the first cell is the serving cell of the first terminal device.

[00113] In step 220, the satellite base station calculates, based on the RTD of the first terminal device, timing information that allows the uplink timing of the first terminal device to match the uplink synchronization frame number of the first cell.

[00114] FIG. 3 is used as an example. It is assumed that the first terminal device in FIG. 6 corresponds to UE #1 shown in FIG. 3. As described above, the RTD of UE #1 = 7.24 ms, and in order to match the uplink synchronization frame number (namely, frame number 8) of the first cell, the uplink signal must be sent with a delay. Therefore, it is first determined that the timing value is negative. Also, the latency (namely the timing value) should be (8ms - 7.24ms) = 0.76ms. Therefore, TA UE #1 = -0.76 ms.

[00115] As another example, it is assumed that the first terminal device in FIG. 6 corresponds to UE #2 shown in FIG. 3. As described above, the RTD of UE #2 = 8.8 ms, and in order to match the uplink synchronization frame number of the first cell, an uplink signal must be sent in advance. Therefore, it is first determined that the timing value is positive. Also, the lead (namely the timing value) should be (8.8ms - 8ms) = 0.8ms. Therefore, TA UE #2 = 0.8 ms.

[00116] 230: Send timing information to the first terminal device.

[00117] In the technical solutions of the present application, the satellite base station introduces a positive or negative timing value, so that the timing may be time advance or may be time delay, and the uplink synchronization frame numbers of terminal devices in the same cell can be unified. The satellite base station only needs to store one uplink sync frame number per cell, and does not need to store one uplink sync frame number for each UE in a cell. Therefore, storage overhead can be reduced.

[00118] Next, the procedure shown in FIG. 7 as an example to describe a process in which a satellite base station configures timing information for a UE.

[00119] FIG. 7 is an example of a procedure in which a satellite base station configures timing information for a UE according to the present application.

[00120] 310: The satellite base station determines, based on the beam information of the first beam and the orbit information of the satellite base station, the uplink synchronization frame number for the first cell.

[00121] For information on the specifics of the process should refer to the description 210. Details are not described here again.

[00122] 320: The satellite base station receives the PRACH UE.

[00123] It should be understood that the UE at step 320 is any UE in the first cell.

[00124] 330: The satellite base station determines the UE timing information based on the PRACH so that the UE's uplink timing matches the uplink synchronization frame number of the first cell.

[00125] It should be understood that the satellite base station can determine, based on the PRACH sent by the UE, the transmission delay between the UE and the satellite base station, and further determine the timing information used by the UE to perform uplink timing synchronization.

[00126] The timing information is used to indicate a time advance or a time lag.

[00127] FIG. 7, that the satellite base station determines the transmission delay of the UE using the PRACH sent by the UE to determine the timing information of the UE is just an example. Alternatively, the satellite base station may determine the transmission delay and further determine the timing information based on another uplink signal sent by the UE. This application is not limited.

[00128] 340: Satellite base station displays UE timing information in RAR.

[00129] After determining the timing information of the UE by calculation, the satellite base station maps the timing information to the PRACH response message in step 320, that is, the random access response (RAR).

[00130] The display of timing information in RAR is described below with reference to FIG. 8.

[00131] FIG. 8 is a schematic diagram for displaying timing information in RAR. As shown in FIG. 8, RAR includes a plurality of fields. The first three bits are reserved bits (marked R in FIG. 8). The timing advance command field contains a total of 12 bits.

[00132] In addition, the "object" shown in FIG. 8 is an object, "UL grant" represents an uplink grant, and "temporary C-RNTI" represents a cell-radio network temporary identity.

[00133] As described above, the timing information includes information used to indicate whether the timing value is positive or negative. Optionally, information used to indicate whether the timing value is positive or negative is mapped to the first reserved bit, the second reserved bit, or the third reserved bit.

[00134] Optionally, information used to indicate whether the timing value is positive or negative may be further mapped to the first or last bit of the TA field. This application is not limited.

[00135] In addition, the timing value may be mapped to another bit of the TA field.

[00136] 350: The satellite base station returns the RAR to the UE.

[00137] In step 350, the satellite base station returns the RAR to the UE, so that the UE is notified of the timing information mapped to the RAR.

[00138] RAR processing at the UE side will be described below with reference to FIG. 9.

[00139] FIG. 9 is a flowchart of RAR processing at the UE side according to the present application.

[00140] 401: The UE receives the RAR from the network side.

[00141] 402: The UE determines whether the RAR originates from a satellite base station.

[00142] In step 402, the UE determines if the received RAR is from a satellite base station. More specifically, the UE makes the determination based on the indication of the satellite base station. In fact, before performing random access, the UE may know whether it will next access a terrestrial base station or a satellite base station.

[00143] If the received RAR is from a terrestrial base station, the UE performs step 403. If the received RAR is from a satellite base station, the UE performs step 404.

[00144] 403: The UE performs timing information analysis with the TA processing method specified in the LTE or NR standard and proceeds to step 405.

[00145] 404: The UE determines whether the timing value is positive or negative and proceeds to step 405.

[00146] After receiving the RAR from the satellite base station, the UE determines whether the timing value is positive or negative based on the timing information carried in the RAR.

[00147] For example, at step 340, if information used to indicate whether the timing value is positive or negative is mapped to the first RAR reserved bit, the UE may determine based on the first RAR reserved bit that the timing value is positive or negative.

[00148] 405: The UE calculates the timing.

[00149] In step 405, the UE calculates the timing according to formula (1):

$$\text{Timing}=\pm N_{TA}\times T_C$$ (1)

[00150] In formula (1), T_Cis the minimum granularity used for TA tuning in LTE/NR, which is also applicable in this application. Specific T value_C depends on system configuration. For details, refer to the 3GPP reference document TS38.211. N_TA applies to the timing value in the timing information carried in RAR.

[00151] It should be understood that the positive or negative sign in formula (1) is determined by whether the timing value determined in step 404 is positive or negative.

[00152] It should be understood that whether the timing value is positive or negative in this embodiment of the present application can alternatively be expressed as that the timing value is positive or negative.

[00153] 406: The UE uses the calculated timing for uplink timing.

[00154] From the block diagram shown in FIG. 9, it can be seen that after receiving the RAR, the UE first determines whether the base station that sends the RAR is a satellite base station. If the base station is not a satellite base station, the timing information in RAR is processed by the TA processing method specified in the standard in LTE or NR. In other words, it is not necessary to determine whether the timing value is positive or negative (because TAs are positive), and the timing value can be calculated directly. If the base station that sends the RAR is a satellite base station, the UE needs to analyze the timing information to determine whether the timing value is positive or negative and calculate the timing value.

[00155] Subsequently, the UE uses the calculated timing for transmission on the uplink.

[00156] It should be understood that what is shown in FIG. 7 - fig. 9, the satellite base station determines the transmission delay corresponding to the UE using the PRACH and notifies the UE of the timing information using the RAR is just an example. In fact, the satellite base station can determine the transmission delay of the UE by using any UE uplink signal and determine the timing information of the UE. In these cases, the processing of the downlink signal, which is received from the satellite base station and which carries the timing information, by the UE, is similar to the RAR processing process shown in FIG. 9. Details are not described here again.

[00157] It is considered that the satellite base station is continuously moving in orbit, in the working process, the serving beam for one UE may change accordingly.

[00158] FIG. 10 is a schematic diagram of a UE serving beam changing during satellite operation. For example, during the process of moving the satellite in orbit, for example, in the process of moving from position 1 to position 2, the serving beam of the UE switches from beam 1 to beam 2. It will be understood that when the satellite is in position 1, the serving beam of the UE is beam 1, and when the satellite moves from position 1 to position 2, the serving beam of the UE switches to beam 2.

[00159] In a terrestrial communication system, the UE needs to initiate the random access procedure for handover for the cell again. However, since the signal transmission delay between the satellite and the earth is relatively long, the beam switching (namely, the handover for the cell) caused by the operation of the satellite occurs more frequently. If random access is re-initiated in every handover for a cell, the UE service must be interrupted, resulting in low handover efficiency.

[00160] In view of the above cases, the present application further proposes a handover method for a cell applied to a satellite communication system. The following describes the method with reference to FIG. eleven.

[00161] FIG. 11 is a block diagram of a handover for a cell in a satellite communication system according to the present application.

[00162] 501: The source base station determines that the UE initiates a handover for the cell.

[00163] Here, the factor for triggering a handover for a serving cell by a UE is not limited. For example, in FIG. 10 above, the fact that the satellite is orbiting may trigger a handover for a serving cell (namely, a serving beam) of the UE.

[00164] 502: The source base station determines whether the uplink timing of the target cell matches the uplink timing of the source cell.

[00165] It should be understood that the uplink timing of the target cell and the uplink timing of the source cell in this document refer to the uplink timing at the cell level proposed in this application.

[00166] If the target cell's uplink timing matches the source cell's uplink timing, the source base station performs step 504, i.e., the source base station directly triggers a handover for the cell.

[00167] If the target cell's uplink timing does not match the source cell's uplink timing, the source base station performs step 503.

[00168] 503: The source base station sends a RAR to the UE, where the RAR carries the UE timing information determined based on the target cell's uplink synchronization frame number.

[00169] It should be understood that RAR carries timing information corresponding to the target cell, which is used by the UE to update the source cell timing information to the target cell timing information. In other words, when the uplink timing of the source cell does not match the uplink timing of the target cell, the source base station notifies the UE of the target cell timing information by using RAR.

[00170] After step 503, the source base station performs step 504.

[00171] After receiving the RAR, the UE updates the stored source cell timing information to the target cell timing information and sends an uplink signal to the target cell based on the target cell timing information.

[00172] It can be understood that the uplink timing synchronization method and the cell handover method provided in the present application may be used together or may be used separately. This application is not limited.

[00173] When these two methods are used together, the first terminal device can be considered to perform uplink time synchronization with the first cell according to the uplink time synchronization method provided in the present application. After accessing the first cell, if the first terminal apparatus triggers a handover for the cell, the satellite base station performs handover for the cell in accordance with the handover procedure for the cell provided in the present application.

[00174] Embodiments of the present application are described in detail above. The communication device provided in the present application is described below.

[00175] FIG. 12 is a schematic block diagram of a communication device 600 according to the present application. The communication device 600 includes a processing unit 610 and a communication unit 620 .

[00176] In an embodiment, communication device 600 performs the function of a satellite base station according to an embodiment of an uplink time synchronization method. For example, communication device 600 may be a microchip or an integrated circuit. In this case, the blocks of the communication device 600 are separately configured to perform the following operations and/or processing.

[00177] The processing unit 610 is configured to determine, based on the beam information of the first beam and the ephemeris information of the satellite base station, the uplink synchronization frame number of the first cell corresponding to the first beam, and determine the timing information of the first terminal device in the first cell based on the uplink synchronization frame number of the first cell, where the timing information is used to indicate timing advance or timing delay.

[00178] The communication unit 620 is configured to output timing information.

[00179] In this case, the processing unit 610 may be a processor. The communication unit 620 may be a communication interface, such as an input/output interface or a transceiver circuit.

[00180] Optionally, the processing unit 610 is further configured to determine, based on the beam information of the first beam and the ephemeris information of the satellite base station, the second terminal device and the third terminal device in the first cell, to determine the set of potentially suitable frame numbers of the first cell based on the first round trip delay for signal transmission between the second terminal device and the satellite base station and the second round trip delay for signal transmission between the third terminal device and the satellite base station. base station, and select the first frame number from the set of potentially suitable frame numbers as the uplink synchronization frame number for the first cell. The second terminal device is the terminal device which is located in the first cell and which is closest to the satellite base station, and the third terminal device is the terminal device which is located in the first cell and which is the furthest from the satellite base station.

[00181] Optionally, processing unit 610 is further configured to determine a set of potentially suitable frame numbers based on a first round trip delay, a second round trip delay, and a plurality of first constraint conditions. For information about a plurality of first limiting conditions, refer to the description of the embodiments of the method.

[00182] Optionally, processing unit 610 is specifically configured to select from a set of potentially suitable frame numbers, $$x$$ with the least or $$\left|x-\frac{\mathrm{<figure-callout\; id="1"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}T{D}_{}{}_1+\mathrm{<figure-callout\; id="2"\; label="R\; T\; D"\; filenames="00000012.png,00000013.png"\; state="\{\{state\}\}">R</figure-callout>}T{D}_{}{}_2}{2}\right|$$ as the uplink sync frame number for the first cell, where - $$x$$ the first frame number, RTD ₁ is the first round trip delay, and RTD ₂ is the second round trip delay.

[00183] In another embodiment, the communication device 600 performs the function of a satellite base station according to an embodiment of a handover method for a cell. In this case, the blocks of the communication device 600 are separately configured to perform the following operations and/or processing.

[00184] The processing unit 610 is configured to: when determining that the first terminal device initiates a handover for the cell, determine whether the uplink synchronization frame number of the target cell matches the uplink synchronization frame number of the source cell.

[00185] The communication unit 620 is configured: when the processing unit 610 determines that the uplink synchronization frame number of the target cell is inconsistent with the uplink synchronization frame number of the source cell, output target cell timing information, where the timing information is used to indicate timing advance or timing delay to perform uplink timing synchronization between the first terminal device and the target cell.

[00186] In this case, the processing unit 610 may be a processor. The communication unit 620 may be a communication interface, such as an input/output interface or a transceiver circuit.

[00187] Optionally, the processing unit 610 is further configured to: upon determining that the uplink synchronization frame number of the target cell matches the uplink synchronization frame number of the first cell, to perform handover of the first terminal device from the first cell to the target cell using the communication unit 620.

[00188] Optionally, communication device 600 may also have a function of configuring an uplink synchronization frame number for a cell by a satellite base station and a function of performing handover for a cell according to method embodiments. For a similar description, reference should be made to the aforementioned method embodiments. To avoid repetition, details are again omitted here.

[00189] Alternatively, the processor 610 may be a processor, and some or all of the functions of the processor may be implemented using software.

[00190] In an implementation, some or all of the functions of the processing device may be implemented using software. In this case, the processing device may include a memory and a processor. The memory is adapted to store a computer program, and the processor reads and executes the computer program stored in the memory to perform the steps implemented internally by the satellite base station according to the method embodiments.

[00191] Optionally, in another implementation, the processing device includes a processor. A memory adapted to store a computer program is located outside the processing device. The processor is connected to the memory via a circuit/wire and is configured to read and execute a computer program stored in the memory.

[00192] In another implementation, all functions of the processing device may be implemented using hardware. In this case, the processing device may include an input interface circuit, a logic circuit, and an output interface circuit. The front end circuit is configured to obtain first beam beam information and satellite base station ephemeris information. The logic circuitry is configured to determine, based on the beam information of the first beam and the satellite base station ephemeris information, which are obtained by the input interface circuitry, the uplink synchronization frame number of the first cell corresponding to the first beam. The output interface circuit is configured to output the uplink synchronization frame number of the first cell.

[00193] Optionally, the output interface circuit outputs the uplink synchronization frame number of the first cell to the memory, and the memory stores the uplink synchronization frame number of the first cell.

[00194] Optionally, processing unit 610 may be a baseband device.

[00195] In another embodiment, communication device 600 may correspond to a satellite base station according to the embodiments of FIG. 5 - fig. 8. In this case, the processing unit 610 included in the communication device 600 may be a processor, and the communication unit 620 included in the communication device 600 may be a transceiver. The transceiver includes a transmitter and a receiver.

[00196] The processor determines, based on the beam information of the first beam and the ephemeris information of the satellite base station, the uplink synchronization frame number of the first cell corresponding to the first beam, and determines the timing information of the first terminal device in the first cell based on the uplink synchronization frame number of the first cell. The transceiver is configured to send timing information to the first terminal device so that the terminal device performs uplink time synchronization with the first cell.

[00197] Alternatively, when determining that the first terminal device initiates a handoff for a cell, the processor determines whether the target cell's uplink synchronization frame number matches the source cell's uplink synchronization frame number. When the uplink synchronization frame number of the target cell does not match with the uplink synchronization frame number of the source cell, the processor determines the timing information of the first terminal device in the target cell, where the timing information is used to indicate a timing advance or a timing delay to perform uplink timing synchronization between the first terminal device and the target cell, and the transceiver sends the target cell timing information to the terminal device so that the terminal device performs uplink timing synchronization with the target cell. toy. When the uplink sync frame number of the target cell matches the uplink sync frame number of the source cell, the processor and the transceiver directly perform handover of the first terminal device from the source cell to the target cell.

[00198] In this case, the blocks included in the communication device 600 are separately configured to perform respective operations and/or processing performed by the satellite base station according to the method embodiments. For a similar description, reference should be made to the aforementioned method embodiments. To avoid repetition, details are again omitted here.

[00199] FIG. 13 is a schematic block diagram of a communication device 700 according to the present application. The communication device 700 includes a communication unit 710 and a processing unit 720.

[00200] In an embodiment, the blocks of the communication device 700 are separately configured to perform the following operations and/or processing.

[00201] The communication unit 710 is configured to obtain timing information used for uplink timing.

[00202] The processing unit 720 is configured to determine a timing advance or a timing delay based on the timing information received via the communication interface.

[00203] The communication unit 710 is further configured to output a time advance or a time lag determined by the processing unit 720.

[00204] In this case, the communication unit 710 may be a communication interface, such as an input/output interface or a transceiver circuit. Processing unit 720 may be a processor.

[00205] In an embodiment, the units of the communication device 700 are separately configured to perform the following operations and/or processing.

[00206] The communication unit 710 is configured to receive target cell timing information, where the timing information is used to indicate timing advance or timing delay.

[00207] The processing unit 720 is configured to determine a timing advance or a timing delay based on the timing information.

[00208] In this case, the communication unit 710 may be a communication interface, such as an I/O interface or a transceiver circuit. Processing unit 720 may be a processor.

[00209] Optionally, the processing unit 720 is further configured to determine that the timing information is from a satellite base station.

[00210] Optionally, the processing unit 720 is further configured to determine a timing advance or a timing delay based on the timing information.

[00211] Optionally, the communication unit 710 is further configured to receive target cell timing information from the satellite base station, and the processing unit 720 is further configured to update the first cell timing information to the target cell timing information.

[00212] Alternatively, the processor 720 may be a processor, and some or all of the functions of the processor may be implemented using software.

[00213] In an implementation, some or all of the functions of the processing device may be implemented using software. In this case, the processing device may include a memory and a processor. The memory is adapted to store the computer program, and the processor reads and executes the computer program stored in the memory to perform the steps implemented internally by the terminal device in the method embodiments.

[00214] Optionally, in another implementation, the processing device includes a processor. A memory adapted to store a computer program is located outside the processing device. The processor is connected to the memory via a circuit/wire and is configured to read and execute a computer program stored in the memory.

[00215] In another implementation, all functions of the processing device may be implemented using hardware. In this case, the processing device may include an input interface circuit, a logic circuit, and an output interface circuit. The input interface circuit is configured to receive timing information. The logic circuitry is configured to analyze the timing information to determine timing advance or timing delay. The output interface circuit is configured to output timing advance or timing delay.

[00216] Optionally, in some embodiments, the logic is further configured to: determine if the timing information is from the satellite base station, and analyze the timing information when determining that the timing information is from the satellite base station. If the logic circuit determines that the time information is from the ground station, the logic circuit analyzes the timing information in the TA processing method specified in the standard in LTE or NR (that is, it is not necessary to determine whether the timing value is positive or negative), and determines the timing value directly. If the logic determines that the timing information is from the satellite base station, it is necessary to determine whether the timing value is positive or negative based on the timing information, and it is necessary to calculate the timing value.

[00217] Optionally, the output interface circuit outputs the analysis result of the timing information to a storage memory.

[00218] In another embodiment, the communication device 700 may fully correspond to a terminal device (eg, the first terminal device of the first cell) in the method embodiments. The respective blocks of the communication device 700 are separately configured to perform the corresponding operation and/or processing performed by the terminal device according to the method embodiments.

[00219] The communication unit 710 included in the communication device 700 may be a transceiver. The transceiver includes a transmitter and a receiver. Processing unit 720 may be a processor.

[00220] The transceiver is configured to receive timing information used to perform uplink time synchronization with the first cell. The processor determines the timing advance or timing delay based on the timing information received by the transceiver. The processor and the transceiver are further configured to perform uplink timing between the terminal device and the first cell based on a timing advance or a timing delay.

[00221] Alternatively, after the terminal device initiates a handover for a cell, the transceiver receives timing information of the target cell. The processor determines, based on the timing information of the target cell received by the transceiver, a time advance or a time lag to perform uplink synchronization with the target cell. After determining the time advance or time lag, the transceiver and the processor perform a handover of the terminal device from the source cell to the target cell.

[00222] In this case, the blocks included in the communication device 700 are separately configured to perform respective operations and/or processing performed by the terminal device according to the method embodiments. For a similar description, reference should be made to the aforementioned method embodiments. To avoid repetition, details are again omitted here.

[00223] FIG. 14 is a schematic structural representation of a network device according to this application. The network device 1000 may correspond to a satellite base station in the method embodiments. As shown in FIG. 14, the network device 1000 includes an antenna 1101, a radio frequency device 1102, and a baseband device 1103. The antenna 1101 is connected to the RF device 1102. In the uplink direction, the RF device 1102 receives a signal from the terminal device using the antenna 1101 and sends the received signal to the baseband device 1103 for processing. In the downlink direction, the baseband device 1103 generates a signal to be sent to the terminal device and sends the generated signal to the RF device 1102. The RF device 1102 transmits the signal using the antenna 1101.

[00224] Baseband device 1103 may include one or more processing units 11031. Block 11031 processing may be, in particular, the processor.

[00225] In addition, the baseband device 1103 may further include one or more storage devices 11032 and one or more communication interfaces 11033. The storage unit 11032 is adapted to store a computer program and/or data. The communication interface 11033 is configured to communicate with the RF device 1102. The storage unit 11032 may be a memory, in particular, and the communication interface 11033 may be an input/output interface or a transceiver circuit.

[00226] Optionally, the storage unit 11032 may be a storage unit located on the same chip as the processing unit 11031, namely an on-chip storage unit, or may be a storage unit located on a chip other than the processing unit, namely an off-chip storage unit. This application is not limited.

[00227] Optionally, when communication device 600 is a satellite base station, processing unit 610 shown in FIG. 12 may be baseband device 1103 shown in FIG. 14. The communication unit 620 may be an RF device 1102.

[00228] Optionally, when communication device 600 is a microchip or integrated circuit, processing unit 610 shown in FIG. 12 may be the processing block 11031 shown in FIG. 14, and communication unit 620 may be communication interface 11033 shown in FIG. 14.

[00229] FIG. 15 is a schematic structural representation of a terminal device according to this application. As shown in FIG. 15, terminal device 7000 includes a processor 7001 and a transceiver 7002.

[00230] Optionally, terminal device 7000 further includes memory 7003. Processor 7001, transceiver 7002, and memory 7003 may communicate with each other via an internal connection path to transmit a control signal and/or a data signal.

[00231] The memory 7003 is adapted to store a computer program. The processor 7001 is configured to execute a computer program stored in the memory 7003 to implement the functions of the communication device 700 according to the above device embodiments.

[00232] In particular, the processor 7001 may be configured to perform an operation and/or processing performed by the processing unit 720 described in the device embodiments (e.g., FIG. 13), and the transceiver 7002 may be configured to perform the operation and/or processing performed by the transceiver unit 710.

[00233] For example, the transceiver 7002 receives TA information from the network side. As another example, the processor 7001 determines whether the TA is positive or negative and the TA value based on the TA information received by the transceiver 7002.

[00234] Optionally, memory 7003 may be integrated with processor 7001 or may be independent of processor 7001.

[00235] Optionally, terminal device 7000 may further include an antenna 7004 adapted to transmit a signal output by transceiver 7002. Alternatively, transceiver 7002 receives the signal via the antenna.

[00236] Optionally, terminal device 7000 may further include a power source 7005 configured to supply power to various devices or circuits in the terminal device.

[00237] In addition, to improve the functions of the terminal device, the terminal device 7000 may further include one or more of an input block 7006, an output block 7007, an audio circuit 7008, a camera lens 7009, a sensor 610, and the like. The audio circuitry may further include a speaker 70082, a microphone 70084, and the like. Details are not described here.

[00238] Optionally, when communication device 700 is a terminal device, communication unit 710 shown in FIG. 13 may be the transceiver 7002 shown in FIG. 15, and processing unit 720 may be a processor 7001.

[00239] Optionally, when the communication device 700 is a microchip or integrated circuit, the communication unit 710 shown in FIG. 13 may be the input block 7006 or the output block 7007 shown in FIG. 15, and processing unit 720 may be a processor 7001.

[00240] In addition, the present application further provides a communication system including a satellite base station and a terminal device described in the method embodiments.

[00241] The present application also provides a computer-readable storage medium. A computer-readable storage medium stores a computer program. When the computer program is executed by the computer, the steps and/or processing according to any of the above method embodiments are performed by the satellite base station on the computer.

[00242] The present application also provides a computer program product. The computer program product includes computer program code. When the computer program code is run on the computer, the steps and/or processing according to any embodiment of the aforementioned method performed by the satellite base station are caused to be performed by the computer.

[00243] The present application further provides a chip, and the chip includes a processor. A memory adapted to store a computer program is located independently of the chip. The processor is configured to execute a computer program stored in the memory to perform steps and/or processing according to any embodiment of the method performed by the satellite base station.

[00244] In addition, the chip may include a memory and a communication interface. The communication interface may be an input/output interface, an output, an input/output circuit, or the like.

[00245] The present application also provides a computer-readable storage medium. A computer-readable storage medium stores a computer program. When the computer program is executed by the computer, the operations and/or processing according to any of the foregoing method embodiments are performed by the terminal device by the computer.

[00246] The present application also provides a computer program product. The computer program product includes computer program code. When the computer program code is run on the computer, the computer is enabled to perform operations and/or processing according to any embodiment of the aforementioned method performed by the terminal device.

[00247] The present application further provides a chip, and the chip includes a processor. A memory adapted to store a computer program is located independently of the chip. The processor is configured to execute a computer program stored in the memory to perform operations and/or processing according to any embodiment of the method performed by the terminal device.

[00248] In addition, the chip may include a memory and a communication interface. The communication interface may be an input/output interface, an output, an input/output circuit, or the like.

[00249] The processor referred to in the above embodiments may be an integrated circuit chip and is configured to process signals. During implementation, the steps in the above method embodiments may be implemented using a hardware integrated logic circuit in a processor or with instructions in the form of software. The processor may be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete logic device based on gates or transistors, or a discrete hardware component. A general purpose processor may be a microprocessor, or the processor may be any conventional processor or the like. The steps in the methods disclosed with reference to embodiments of the present application may be performed directly using a processor with hardware encoding, or may be performed using a combination of hardware and software modules in an encoding processor. The software module may be located on a storage medium commonly known in the art, such as random access memory, flash memory, read only memory, programmable read only memory, electrically erasable programmable memory, or a register. The storage medium is located in the memory and the processor reads the information in the memory and performs the steps of the above methods in conjunction with the processor hardware.

[00250] The memory in the above embodiments may be volatile memory or non-volatile memory, or may include both volatile memory and non-volatile memory. Non-volatile memory can be read-only memory (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. Volatile memory can be random access memory (RAM) used as an external cache. By way of example and not limitation, many forms of RAM can be used, for example, static random access memory (static RAM, SRAM), dynamic random access memory (dynamic RAM, DRAM), synchronous dynamic random access memory (synchronous DRAM, SDRAM), synchronous dynamic random access memory with double data rate (double data rate SDRAM, DDR SDRAM), improved synchronous dynamic random access memory (enhanced SDRAM, ESDRAM), synchronously linked dynamic random access memory (synchlink DRAM, SLDRAM), and rambus direct dynamic random access memory (direct rambus RAM, DR RAM). It should be noted that the memory of the systems and methods disclosed in this specification also includes, but is not limited to, any other appropriate type of memory.

[00251] One skilled in the art may be aware that, in combination with the examples described in the embodiments disclosed herein, the blocks and steps of an algorithm may be implemented using electronic hardware or a combination of computer software and electronic hardware. The performance of functions by hardware or software depends on the particular application and the state of the design constraints of the technical solutions. A person skilled in the art can use various methods to implement the described functions for each particular application, but such an implementation should not be considered to be outside the scope of this application.

[00252] One skilled in the art can clearly understand that for the purposes of a convenient and concise description of the detailed working process of the aforementioned system, apparatus, and unit, reference should be made to the corresponding process in the aforementioned method embodiments, and details are omitted here again.

[00253] In several embodiments provided herein, it should be understood that the disclosed system, apparatus, and method may be implemented in other ways. For example, the described device embodiment is merely an example. For example, the division into blocks is only a logical division into functions, and in the actual implementation, another division may take place. For example, many blocks or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the interconnections or direct links or communication connections shown or described may be implemented using certain interfaces. Indirect connections or communication connections between devices or units can be implemented electrically, mechanically, or take other forms.

[00254] Blocks described as separate parts may or may not be physically separate, and parts shown as blocks may or may not be physical blocks, may be located in the same location, or may be distributed over multiple network blocks. Some or all of the blocks may be selected based on actual requirements in order to achieve the objectives of the decisions in the mentioned embodiments.

[00255] In addition, the functional blocks in the embodiments of the present application may be integrated into one processing unit, or each of the units may exist separately physically, or two or more units are integrated into one unit.

[00256] When the functions are implemented in the form of a software functional block and sold or used as a standalone product, the functions may be stored on a computer-readable storage medium. Based on such an understanding, the technical solutions of the present application per se, or part contributing to the prior art, or some of the technical solutions may be implemented in the form of a software product. The computer program product is stored on a storage medium and includes several instructions for instructing a computing device (which is a personal computer, a server, or a network device) to perform all or some of the steps of the methods described in the embodiments of the present application. The above storage medium includes: any medium that can store program code, such as a USB flash drive, removable hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk.

[00257] The foregoing description is merely specific implementations of the present application, but is not intended to limit the scope of protection of the present application. Any variation or replacement readily detectable by a person skilled in the art within the technical scope disclosed in this application should fall within the protection scope of this application. Therefore, the scope of protection of the present application should be consistent with the scope of protection defined by the claims.

Claims (70)

1. An uplink time synchronization method applied to a satellite communication system, the method comprising: determining, based on the beam information of the first beam and the ephemeris information of the satellite base station, the uplink synchronization frame number of the first cell corresponding to the first beam; determining, based on the uplink synchronization frame number of the first cell, timing information of the first terminal apparatus in the first cell, the timing information being used to indicate timing advance or timing delay; And output timing information of the first terminal device. 2. The method of claim 1, wherein said determining the uplink synchronization frame number of the first cell corresponding to the first beam comprises: determining, based on the beam information of the first beam and the ephemeris information of the satellite base station, a second terminal device and a third terminal device in the first cell, wherein the second terminal device is a terminal device which is located in the first cell and which is closest to the satellite base station, and the third terminal device is a terminal device which is located in the first cell and which is the most distant from the satellite base station; determining a set of potentially suitable frame numbers of the first cell based on a first round trip delay for signal transmission between the second terminal device and the satellite base station and a second round trip delay for signal transmission between the third terminal device and the satellite base station; And selecting the first frame number from the set of potentially suitable frame numbers as the uplink synchronization frame number of the first cell. 3. The method of claim 2, wherein in said determination of a set of candidate frame numbers based on a first round trip delay and a second round trip delay, a set of candidate frame numbers is determined based on the first round trip delay, the second round trip delay, and a plurality of first constraint conditions, wherein the plurality of first constraint conditions comprises: potentially suitable frame numbers are integer multiples of a unit of time for communication between a satellite base station and terminal devices; the minimum value of potentially eligible frame numbers is an integer not greater than and closest to the first round trip delay; And the maximum value of potentially eligible frame numbers is an integer that is not less than and nearest to the second round trip delay. 4. The method according to claim 2 or 3, wherein when said selection of the first frame number from the set of potentially suitable frame numbers as the uplink synchronization frame number for the first cell is selected, from the set of potentially suitable frame numbers, $$x$$ with the least $$\left|x-RT{D}_1\right|+\left|x-RT{D}_2\right|$$ or $$\left|x-\frac{RT{D}_1+RT{D}_2}{2}\right|$$ as the uplink synchronization frame number of the first cell, where $$x$$ is the first frame number, RTD ₁ is the first round trip delay, and RTD ₂ is the second round trip delay. 5. The method according to any one of claims 1 to 4, wherein after the first terminal device accesses the first cell, the method further comprises: determining that the first terminal device initiates a handover for the cell; determining whether the uplink synchronization frame number of the target cell matches the uplink synchronization frame number of the first cell; And when determining that the uplink synchronization frame number of the target cell does not match with the uplink synchronization frame number of the first cell, sending the target cell timing information to the first terminal device. 6. The method according to any one of claims 1 to 4, wherein after the first terminal device accesses the first cell, the method further comprises: determining that the first terminal device initiates a handover for the cell; determining whether the uplink synchronization frame number of the target cell matches the uplink synchronization frame number of the first cell; And when determining that the uplink sync frame number of the target cell matches the uplink sync frame number of the first cell, handover of the first terminal device from the first cell to the target cell is performed. 7. The method according to any one of claims 1 to 6, wherein the timing information contains a timing value and whether the timing value is positive or negative; when the timing value is positive, the timing information is used to indicate the timing advance, or when the timing value is negative, the timing information is used to indicate the timing delay. 8. An uplink time synchronization method applied to a satellite communication system, the method comprising: receiving timing information used to perform uplink timing synchronization with the first cell, the timing information being determined based on the uplink synchronization frame number that belongs to the first cell and which is determined based on the first beam beam information and the satellite base station ephemeris information; determining a timing advance or timing delay based on the timing information; And performing uplink time synchronization with the first cell based on the time advance or time lag. 9. The method of claim 8, wherein before said timing advance or lag determination based on the timing information, the method further comprises determining that the timing information is coming from a satellite base station. 10. The method according to claim 8 or 9, wherein the timing information comprises a timing value and whether the timing value is positive or negative, and said determining the timing advance or timing delay based on the timing information comprises: when determining that the timing value is positive, determining a timing advance based on the timing value; or when determining that the timing value is negative, a time lag is determined based on the timing value. 11. The method of claim 9 or 10, wherein after the first terminal device accesses the first cell, the method further comprises: starting a handoff for the cell; receiving target cell timing information from the satellite base station; And updating the timing information of the first cell to the timing information of the target cell. 12. The method of claim 11, the method further comprising performing uplink timing synchronization with the target cell based on the target cell's timing information. 13. Equipment in a satellite base station designed for time synchronization of the uplink and containing: a processing unit configured to determine, based on the beam information of the first beam and the ephemeris information of the satellite base station, the uplink synchronization frame number of the first cell corresponding to the first beam, the processing unit is further configured to determine, based on the uplink synchronization frame number of the first cell, the timing information of the first terminal device in the first cell, the timing information being used to indicate a time advance or a time lag; And a communication unit configured to output timing information. 14. Apparatus according to claim 13, in which the processing unit is configured to: determine, based on the beam information of the first beam and the ephemeris information of the satellite base station, a second terminal device and a third terminal device in the first cell, wherein the second terminal device is a terminal device which is located in the first cell and which is closest to the satellite base station, and the third terminal device is a terminal device which is located in the first cell and is farthest from the satellite base station; determine a set of potentially suitable frame numbers of the first cell based on the first round trip delay for signal transmission between the second terminal device and the satellite base station and the second round trip delay for signal transmission between the third terminal device and the satellite base station; And select the first frame number from the set of potentially eligible frame numbers as the uplink sync frame number for the first cell. 15. The apparatus of claim 14, wherein the processing unit is configured to determine a set of potentially suitable frame numbers based on a first round trip delay, a second round trip delay, and a plurality of first constraint conditions, the plurality of first constraint conditions comprising: potentially suitable frame numbers are integer multiples of a unit of time for communication between a satellite base station and terminal devices; the minimum value of potentially eligible frame numbers is an integer not greater than and closest to the first round trip delay; And the maximum value of potentially eligible frame numbers is an integer that is not less than and nearest to the second round trip delay. 16. Apparatus according to claim 14 or 15, in which the processing unit is configured to select, from a set of potentially suitable frame numbers, $$x$$ with the least $$\left|x-RT{D}_1\right|+\left|x-RT{D}_2\right|$$ or $$\left|x-\frac{RT{D}_1+RT{D}_2}{2}\right|$$ as the uplink sync frame number for the first cell, where $$x$$ is the first frame number, RTD ₁ is the first round trip delay, and RTD ₂ is the second round trip delay. 17. Apparatus according to any one of claims 13-16, wherein the processing unit is further configured to: determine that the first terminal device initiates a handover for the cell; And determine whether the uplink synchronization frame number of the target cell matches the uplink synchronization frame number of the first cell, wherein when the processing unit determines that the uplink synchronization frame number of the target cell does not match with the uplink synchronization frame number of the first cell, the communication unit is further configured to output timing information of the target cell. 18. Apparatus according to any one of claims 13-16, wherein the processing unit is further configured to: determine that the first terminal device initiates a handover for the cell; And determine whether the uplink synchronization frame number of the target cell matches the uplink synchronization frame number of the first cell, wherein when determining that the uplink synchronization frame number of the target cell matches the uplink synchronization frame number of the first cell, perform handover of the first terminal device from the first cell to the target cell with the communication unit. 19. Equipment in a terminal device (UE) for uplink time synchronization and comprising: a communication unit configured to receive timing information used to perform uplink timing synchronization with the first cell, wherein the timing information is determined based on the uplink synchronization frame number that belongs to the first cell and which is determined based on the first beam beam information and the satellite base station ephemeris information, the first cell being the attachment cell of the first device; And a processing unit configured to determine the timing advance or timing delay based on the timing information, wherein the communication unit is further configured to perform uplink timing synchronization based on the time advance or time lag determined by the processing unit. 20. The apparatus of claim 19, wherein the processing unit is further configured to determine that the timing information is coming from a satellite base station. 21. The apparatus of claim 19 or 20, wherein the timing information comprises a timing value and whether the timing value is positive or negative, and the processing unit is configured to: when determining that the timing value is positive, determine a timing advance based on the timing value; or when determining that the timing value is negative, determine the time delay based on the timing value. 22. The apparatus according to claim 20 or 21, wherein the communication unit is further configured to receive target cell timing information from the satellite base station; and the processing unit is further configured to update the timing information of the first cell to the timing information of the target cell. 23. A computer-readable storage medium containing a computer program, wherein when the computer program is executed on the computer, the method according to any one of claims 1-7 is performed. 24. A computer-readable storage medium containing a computer program, wherein when the computer program is executed on the computer, the method according to any one of claims 8-12 is performed. 25. Equipment in a satellite base station designed for uplink time synchronization and containing a processor and memory, wherein the memory is adapted to store a computer program, and the processor is configured to call and execute a computer program stored in the memory, to perform the method according to any one of claims 1-7. 26. Equipment in a terminal device (UE) for uplink time synchronization and comprising a processor and a memory, wherein the memory is adapted to store a computer program, and the processor is configured to call and execute the computer program stored in the memory, to perform the method according to any one of claims 8-12. 27. A microcircuit containing a processor configured to execute a program stored in memory, wherein, when the program is executed in a device containing a microcircuit, the device executes the method according to any one of claims 1-7. 28. A microcircuit containing a processor configured to execute a program stored in memory, wherein, when the program is executed in a device containing a microcircuit, the device executes the method according to any one of claims 8-12.

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