Cell reselection method, terminal device, storage medium and communication system

Abstract

The invention provides a cell reselection method, terminal equipment, a storage medium and a communication system. The method comprises the following steps: determining whether to trigger cell reselection according to state information of a resident cell; in response to triggering cell reselection, determining a historical frequency offset value of a first cell in the adjacent cells; in response to the condition that the historical frequency offset value is smaller than or equal to a first threshold value, determining other cells except the first cell in the adjacent cells as second cells; determining a first measurement frequency offset value of the second cell; and in response to the situation that the first measurement frequency offset value is located in a preset numerical range, determining a third cell to be reselected from the second cells, and determining a target cell in the third cell. Through the frequency offset values of the resident cell and the adjacent cells, the timeliness of reselection is improved, the improper adjacent cells are screened out in advance, the accuracy of reselection is improved, and the problems of difficult triggering and difficult reselection caused by unobvious signal intensity change of the near-far effect are solved in an auxiliary manner.

Description

Technical Field

[0001] The present application relates to the field of communication technology, and in particular to a cell reselection method, terminal equipment, storage medium and communication system. Background Art

[0002] In the traditional cell reselection method, the signal strength of the resident cell is lower than the threshold to trigger the reselection, and the signal strength of the adjacent cell is compared to see whether it is significantly higher than the signal strength of the resident cell to decide whether to select the adjacent cell. Since the signal strength change of the near-far effect in non-terrestrial networks is not obvious, judging by signal strength may not trigger the reselection, and may lead to difficulties in reselection, such as the reselection results jumping back and forth between different cells. Summary of the invention

[0003] In view of this, the purpose of the present application is to propose a cell reselection method, terminal equipment, storage medium and communication system to solve or partially solve the above problems.

[0004] Based on the above purpose, in a first aspect, the present application provides a cell reselection method, comprising: Determine whether to trigger cell reselection according to the status information of the resident cell; In response to triggering cell reselection, determining a historical frequency offset value of a first cell among neighboring cells; In response to the historical frequency offset value being less than or equal to a first threshold, determining other cells among the neighboring cells except the first cell as second cells; determining a first measurement frequency offset value of the second cell; In response to the first measured frequency offset value being within a preset value range, a third cell to be reselected is determined from the second cells, and a target cell is determined from the third cells.

[0005] In a second aspect of the present application, a terminal device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method described in the first aspect when executing the program.

[0006] According to a third aspect of the present application, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium stores computer instructions, wherein the computer instructions are used to cause a computer to execute the method described in the first aspect.

[0007] In a fourth aspect of the present application, a communication system is provided, comprising the terminal device as described in the second aspect.

[0008] As can be seen from the above, the present application provides a cell reselection method, terminal equipment, storage medium and communication system. The method includes: determining whether to trigger cell reselection according to the status information of the resident cell; in response to triggering cell reselection, determining the historical frequency deviation value of the first cell in the adjacent cell; in response to the historical frequency deviation value being less than or equal to the first threshold, determining the other cells in the adjacent cell except the first cell as the second cell; determining the first measured frequency deviation value of the second cell; in response to the first measured frequency deviation value being within a preset numerical range, determining the third cell to be reselected from the second cell, and determining the target cell in the third cell. By using the frequency deviation values ​​of the resident cell and the adjacent cell, the timeliness of the reselection is improved, inappropriate adjacent cells are screened out in advance, the accuracy of the reselection is improved, and the problem of triggering difficulty and reselection difficulty caused by the unclear change in signal strength due to the near-far effect is assisted. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the technical solutions in the present application or related technologies, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0010] Figure 1 A schematic diagram showing an exemplary terminal received signal strength according to an embodiment of the present application is shown.

[0011] Figure 2 A schematic flow chart of an exemplary cell reselection method is shown.

[0012] Figure 3 A schematic contour diagram of an exemplary Doppler frequency shift according to an embodiment of the present application is shown. Figure 4 A schematic diagram of an exemplary downlink signal pre-compensation according to an embodiment of the present application is shown.

[0013] Figure 5 A schematic diagram shows a frequency offset value when an exemplary terminal receives downlink signals from different cells according to an embodiment of the present application.

[0014] Figure 6 A schematic diagram of an exemplary communication system according to an embodiment of the present application is shown.

[0015] Figure 7 A schematic diagram of another exemplary communication system according to an embodiment of the present application is shown.

[0016] Figure 8 A schematic diagram of another exemplary communication system according to an embodiment of the present application is shown.

[0017] Fig. 9 A schematic diagram of yet another exemplary communication system according to an embodiment of the present application is shown.

[0018] Fig.10 A schematic diagram of yet another exemplary communication system according to an embodiment of the present application is shown.

[0019] Fig.11 A schematic diagram of another exemplary communication system according to an embodiment of the present application is shown.

[0020] Fig.12 A schematic diagram of another exemplary communication system according to an embodiment of the present application is shown.

[0021] Fig.13 A schematic diagram of another exemplary communication system according to an embodiment of the present application is shown.

[0022] Fig.14 A schematic flow chart of an exemplary cell reselection method according to an embodiment of the present application is shown.

[0023] Fig.15 A schematic diagram of an exemplary terminal device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0025] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present application should be the usual meanings understood by people with ordinary skills in the field to which the present application belongs. The "first", "second" and similar words used in the embodiments of the present application do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing in front of the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0026] Unlike traditional cellular networks, the integrated air-ground network includes two parts: terrestrial network (TN) and non-terrestrial network (NTN). Terrestrial networks include cellular networks, and non-terrestrial networks include satellite networks. In non-terrestrial networks, base station antennas can be set up on high-altitude platforms or satellites, located in the sky or space tens to tens of thousands of kilometers above the ground. Each non-terrestrial network cell provided by a satellite is a wireless coverage area that can cover a large range. Depending on the height of the transmitting antenna, the coverage diameter can reach tens to hundreds of kilometers. Non-terrestrial networks are mainly used to cover areas without terrestrial networks, such as oceans and deserts. With the gradual integration and evolution of satellite communications and ground cellular technologies, users are provided with satellite-ground integrated communications in which mobile phones are directly connected to satellites. As a trend of future network evolution, the integration of air-ground and space will have a profound impact on the original network architecture and communication process.

[0027] The NTN network for mobile terminals based on 4G / 5G is divided into two categories in terms of technical routes.

[0028] The first category is a technical model that provides satellite communications for existing commercial LTE (Long Term Evolution) / 5G terminals. It customizes satellites and base stations and enhances the capabilities of satellite and base station equipment to adapt to cellular terminals and air interface protocols to support ordinary existing mobile phones to access satellite networks. Mobile terminals do not need to be replaced to achieve satellite communications, and user terminals are still based on 4G LTE or 5G NR (5G New Radio, 5G new wireless access technology) Rel-15 / 16 (two important versions of 5G NR). This solution is suitable for the early stage of network construction when the penetration rate of NTN services is low, and satellite services can be quickly promoted. At present, many satellite companies around the world have completed technical trials. However, this solution requires customized constellation design and satellite base station design, which is difficult and costly to implement, and requires the use of ground cellular frequencies to solve frequency licensing and license issues.

[0029] The second category is the NTN standard of 3GPP (3rd Generation Partnership Project) NR Release-17 (the third major version of 5G technical standards). This route is committed to enhancing 5G technology to make it compatible with satellite communication capabilities, and enhancing the capabilities of satellites / base stations and mobile terminals on the basis of NR standards, solving problems such as Doppler frequency deviation and time offset of downlink and uplink signals, as well as random access, and improving the low efficiency of data retransmission caused by large delays. This technical route can more fully solve the difficulties of satellite and mobile phone communications, and the difficulty of implementation is less than the first technical route. However, it requires the joint support of the satellite and communication industries, and commercial deployment will take some time, and it is necessary to upgrade Release-17 and later versions of mobile phones, which will affect market penetration. Therefore, it can be used as a medium- and long-term technical route.

[0030] In the air interface technologies of the fourth generation (4G) mobile communication technology Long Term Evolution (LTE) and the fifth generation (5G) mobile communication technology New Radio (NR), the mobility management of the terminal in the idle state or inactive state of the radio resource control (RRC) is mainly completed through cell selection / reselection, which selects the target cell by measuring the signal strength over the air.

[0031] For terrestrial networks (TN), the terminal can select and reselect cells according to the S criterion and the R criterion. For example, the terminal can determine whether the terminal is at the cell edge by comparing the significant difference between the measured reference signal receiving power (RSRP) and the RSRP of the cell center, thereby triggering the reselection process; for example, the terminal can decide whether to select the target cell by comparing whether the RSRP of the measured target cell is significantly improved with the RSRP of the resident cell.

[0032] Figure 1 A schematic diagram showing exemplary terminal received signal strength according to an embodiment of the present application is shown.

[0033] In non-terrestrial networks or integrated air-ground networks, the difference between the signal strength at the center of the satellite beam and the signal strength at the edge of the beam is small, such as Figure 1 As shown in the figure, in the ground network of scenario (a), the received signal strength of terminal 1 located near the cell center is significantly stronger than the received signal strength of terminal 2 located at the cell edge. In the non-ground network of scenario (b), the difference in received signal strength between terminal 1 and terminal 2 located at the cell center and cell edge respectively is not obvious.

[0034] Since RSRP has no obvious near-far effect, it may cause the cell reselection to be triggered too late and the terminal may select back and forth between different cells. Therefore, the traditional method of cell reselection based on RSRP strength cannot meet the cell reselection requirements of the air-ground integrated network.

[0035] Cell selection refers to the process in which, when a terminal is turned on or enters a coverage area from a blind area, the terminal searches for all frequencies allowed by the PLMN (Public Land Mobile Network) and selects a suitable cell to reside in.

[0036] Cell reselection refers to the process in which a UE (User Equipment) in idle mode (RRC_IDLE) monitors the signal quality of neighboring cells and the resident cell to select the best cell to provide resident signals. Cell reselection can ensure that the UE in idle mode resides in the appropriate cell to the greatest extent possible.

[0037] Figure 2 A schematic flow chart of an exemplary cell reselection method is shown.

[0038] like Figure 2 As shown in the figure, the overall process of cell reselection includes triggering cell reselection and co-frequency or inter-frequency measurement and selection. First, the cell reselection process is triggered (the triggering criterion of the ground network is that the signal strength of the resident cell is lower than the threshold). Select a neighboring cell from the (co-frequency or inter-frequency) neighboring cell list in the system information of the resident cell. Perform reselection measurement of this neighboring cell, that is, measure the RSRP value, and obtain the measurement result of this neighboring cell. Finally, sort the measurement results of multiple neighboring cells, and the cell with the highest score is the target neighboring cell selected for reselection.

[0039] Among them, the reselection measurement of this adjacent cell, that is, the measurement of RSRP value, the main factors affecting reselection include the reception of system messages such as MIB (Master Information Block, Management Information Block), SIB (System Information Block, System Information Block), the status of the adjacent cell, and whether the S criterion and R criterion are met. Among them, the "S criterion" is used to determine whether the cell is suitable for residence, and the "R criterion" is used to evaluate the signal strength difference between the reselected adjacent cell and the source cell.

[0040] (I) “S criteria” for community residence

[0041] Through initial cell selection or stored information cell selection, the UE will select a suitable cell to camp on. The "S criterion" is used to determine whether a cell is suitable for camping.

[0042] The initial cell selection is that the UE searches all radio frequency channels in the frequency band, selects the strongest cell on each carrier frequency and reads the system information of the cell. The UE judges the cell according to the "S criterion". If the cell passes the "S criterion", the cell selection ends; if the cell does not pass the "S criterion", the UE judges other carrier frequency cells in turn according to the "S criterion" until a cell passes the "S criterion".

[0043] For the cell selection based on stored information, the UE needs to obtain the carrier frequency information and even the cell parameter information through the measurement control information received previously or the detected cell, and judge whether the cell is a suitable cell according to the "S criterion". If the cell is a suitable cell, the cell is selected and the cell selection process is completed; if the cell is not a suitable cell, the next cell is searched until a suitable cell is selected; if none of the stored cells meet the requirements, the initial cell selection process is started.

[0044] The above-mentioned "S criteria" requires that the cell-related parameters meet the conditions before staying in the cell. The specific conditions of the "S criteria" are S rxlev >0 and S qual >0, where S rxlev is the received RSRP value, S qual It is the received RSRQ (Reference Signal Receiving Quality) value.

[0045] 2. Triggering criteria for cell reselection.

[0046] After the UE successfully camps, the UE will continue to measure the camped cell. The UE obtains the cell reselection related parameters through the system message sent by the network side. Considering the energy saving requirements of cellular phones, the neighboring cell start measurement threshold must be reached to trigger reselection. After the UE measures the camped cell, the UE compares the RSRP and RSRQ measurement results of the camped cell with threshold 1 (same-frequency measurement start threshold) and threshold 2 (different-frequency / different-system measurement start threshold) as the decision condition for whether to start the neighboring cell measurement. If the RSRP or RSRQ of the camped cell is less than threshold 1, the same-frequency measurement is performed. If there is a neighboring cell with a low priority or the same priority frequency, and the RSRP or RSRQ of the camped cell is less than threshold 2, the different-frequency measurement is performed. That is, the cell reselection trigger condition determines whether to trigger the neighboring cell measurement based on the signal quality of the camped cell.

[0047] For the same-frequency measurement of the terminal, if the camping cell meets the following conditions: S rxlev >S intraSearch And S qual >S intraSearchQ , the terminal may choose not to measure the adjacent cells with the same frequency, where SintraSearch is the RSRP signal level threshold for starting the same-frequency measurement, S intraSearchQ It is the RSRQ signal level threshold for starting the same-frequency measurement; otherwise, if any of the above conditions is not met, the terminal starts to measure the adjacent cells.

[0048] For frequencies of equal priority or lower priority in different frequencies / systems, if: S rxlev >S nonIntraSearch And S qual >S nonIntraSearchQ , the terminal may choose not to measure the adjacent cells of different frequencies / systems; otherwise, the terminal starts to measure the adjacent cells, where S nonIntraSearch is the RSRP signal level threshold for starting inter-frequency measurement, S nonIntraSearchQ It is the RSRQ signal level threshold for starting inter-frequency measurement.

[0049] In summary, the reselection of the traditional method is triggered by the signal strength or signal quality of the resident cell being lower than the threshold. Since the signal strength change of the near-far effect in non-terrestrial networks is not obvious, the reselection may not be triggered by judging that the signal strength is too low.

[0050] (III) “R Criteria” for cell reselection

[0051] Cell reselection is divided into intra-frequency cell reselection and inter-frequency cell reselection. Intra-frequency cell reselection has no priority concept, while inter-frequency and inter-system reselection has high-priority cell reselection and low-priority cell reselection.

[0052] First, if there is a high-priority inter-frequency neighboring cell, the UE measures the high-priority inter-frequency neighboring cell and then determines whether to reselect to this neighboring cell. Secondly, when there is no suitable high-priority inter-frequency neighboring cell, if there is a co-frequency neighboring cell and the "R criterion" is met, the UE reselects to this neighboring cell. Finally, when there are no other suitable cells on the high-priority and co-priority frequency layers, if there is a low-priority inter-frequency neighboring cell and the signal strength of the resident cell meets the neighboring cell trigger condition, the UE measures this neighboring cell and then determines whether to reselect to this neighboring cell.

[0053] The cell reselection criterion is based on the comparison of the signal strengths of the neighboring cells and the resident cells. Taking the comparison of the signal strengths of the same-frequency neighboring cells and the resident cells as an example, the specific condition of the "R criterion" is that R n >R s , where R s =Q meas,s +Q hyst -Qoffset temp , R n = Q meas,n -Qoffset -Qoffsettemp , where R n is the ranking score of the signal strength of the neighboring cells, R s is the ranking score of the signal strength of the camping cell, Q meas,s is the reference signal received power (RSRP) measurement value of the resident cell, Q hyst It is the hysteresis value of the resident cell, which is used to control the hysteresis degree of staying in the resident cell. meas,n is the RSRP measurement value of the adjacent cell. Qoffset is the offset of the adjacent cell, which is used to control the difficulty of reselecting to the adjacent cell. For same-frequency reselection, if there is a valid Qoffset between cells in the system broadcast s,n , then it is equal to Qoffset s,n , otherwise it is equal to 0, where Qoffset s,n It is the offset of the adjacent cell provided by the network to the terminal through the system information broadcast. For inter-frequency reselection, if there is a valid cell-to-cell Qoffset in the system broadcast, s,n , then it is equal to Qoffset s,n Add Qoffset frequency , otherwise it is equal to Qoffset frequency , where Qoffset frequency Qoffset is the offset for adjacent cells with different frequencies. temp It is a temporary offset, which is used as a penalty factor after the connection establishment of the neighboring cell fails.

[0054] For the same frequency adjacent cell, when the measured value meets the "R criterion" that is, R n >R s , and the duration reaches T reselection When the neighboring cell selection process is triggered, T reselection is the timer value for cell reselection. According to the "R criterion", the target cell with the highest ranking score is selected, and finally the terminal reselects to the cell with the highest ranking score.

[0055] In summary, the traditional reselection method determines the target cell to be reselected by comparing the signal strength of the adjacent cell with the signal strength of the resident cell. Since the signal strength variation of the near-far effect in non-terrestrial networks is not obvious, comparing the signal strength between two cells may cause reselection difficulties, such as switching back and forth between two cells.

[0056] In order to at least solve the above problems, the present application provides a cell reselection method, terminal equipment, storage medium and communication system. The method includes: determining whether to trigger cell reselection according to the status information of the resident cell; in response to triggering cell reselection, determining the historical frequency deviation value of the first cell in the adjacent cell; in response to the historical frequency deviation value being less than or equal to the first threshold, determining the other cells in the adjacent cell except the first cell as the second cell; determining the first measured frequency deviation value of the second cell; in response to the first measured frequency deviation value being within a preset numerical range, determining the third cell to be reselected from the second cell, and determining the target cell in the third cell. Through the frequency deviation values ​​of the resident cell and the adjacent cell, the triggering conditions of the resident cell are increased, the timeliness of reselection is improved, inappropriate adjacent cells are screened out in advance, the accuracy of reselection is improved, and the problem of triggering difficulty and reselection difficulty caused by the unclear change in signal strength due to the near-far effect is assisted, and the reselection process is accelerated and the power consumption of the terminal is reduced.

[0057] The inventor of the present application discovered that the frequency offset value of a cell can be used to implement cell reselection, and thus proposed the present solution. The following first explains the professional terms in the embodiments of the present application.

[0058] The frequency deviation value of a cell refers to the difference between the cell frequency seen by the terminal when receiving and the cell frequency seen when sending. The cell frequency of the sending end is the frequency point used by the base station when sending. Before the terminal searches for adjacent cells, the system information of the resident cell where the terminal is located can provide the cell frequency point of the adjacent cell to the terminal, helping the terminal to easily find the synchronization signal of the adjacent cell in frequency. The cell frequency point transmitted to the terminal through the system information here refers to the cell frequency point when sending. When the terminal performs cell search or cell synchronization, it needs to search for matching cell synchronization signals in the time domain and frequency domain. The cell frequency point measured after the search is successful is the cell frequency point seen by the terminal when receiving. The difference between the different cell frequencies seen by the sending end and the receiving end is the frequency deviation value of the cell. In the terrestrial network, the cell frequency deviation comes from a small amount of Doppler frequency deviation caused by the low or medium speed movement of the terminal, or a small amount of frequency deviation caused by the error of the terminal's frequency generator; in the non-terrestrial network, due to the large Doppler frequency deviation caused by the high-speed movement of the satellite, there is still a significant cell frequency deviation even after the satellite pre-compensates the downlink signal.

[0059] Figure 3 A schematic contour diagram of an exemplary Doppler frequency shift according to an embodiment of the present application is shown.

[0060] The satellites that make up the NTN network nodes can be of various types and their characteristics are as follows. Different types of satellites include: Geosynchronous Earth Orbit (GEO) satellites, with an altitude of 35,768 km, a cell size between 200 km and 3,500 km, and a round-trip time of about 541.46 ms; Medium Earth Orbit (MEO) satellites, with altitudes between 7000km-25000km, cell sizes between 100km-1000km, and round-trip times of about 120ms; Low Earth Orbit (LEO) satellites, with altitudes between 300km-1500km, cell sizes between 100km-1000km, and round-trip times of about 41.77ms; High Altitude Platform Station (HAPS), with an altitude between 8km-50km, a cell size between 5km-200km, and a round-trip time of about 14ms.

[0061] Among them, LEO satellites have slightly smaller delays and larger coverage areas, and are mostly used to provide voice and data services.

[0062] The speed of a LEO satellite at an altitude of 600 km is 7.56 km / s, which is much faster than that of a ground terminal. Therefore, the Doppler frequency deviation of the communication link between the satellite and the ground terminal is mainly caused by the satellite motion. The Doppler frequency deviation of a LEO satellite at an altitude of 600 km can reach up to ±24ppm.

[0063] For terminals at different locations (that is, the signal propagation direction between the satellite and the terminal is different), the component of the satellite velocity vector in the signal propagation direction will be different, and the resulting Doppler frequency deviation in the non-terrestrial network can be expressed as Figure 3 In the form of contour lines.

[0064] like Figure 3 As shown in the figure, due to the Doppler effect, the downlink signal from the satellite will be offset in frequency. When received at different locations on the ground (that is, different transmission directions of the satellite signal), the value of the Doppler frequency deviation will be different, which is represented by contour lines in the figure. Figure 3 The subsatellite point and the direction of satellite movement in are the projections of the satellite position and the satellite velocity vector on the ground toward the center of the earth. The Doppler frequency deviation is 0 when the terminal at the subsatellite point receives; the satellite and the terminal on the right side of the subsatellite point are close to each other, so the Doppler frequency deviation is positive (for example, 2ppm, 4ppm, 6ppm); the satellite and the terminal on the left side of the subsatellite point are far away from each other, so the Doppler frequency deviation is negative (for example, -2ppm, -4ppm, -6ppm).

[0065] Figure 4 A schematic diagram of downlink signal pre-compensation according to an embodiment of the present application is shown.

[0066] In order to facilitate the terminal to receive the downlink signal, the satellite will perform pre-compensation on the frequency before sending the downlink signal. The purpose is to make the frequency deviation value of the downlink signal received by the terminal zero or a smaller value. The specific value of the pre-compensation is the opposite value of the Doppler frequency deviation of the satellite beam center.

[0067] like Figure 4 As shown in the figure, the satellite performs frequency pre-compensation before sending the downlink signal. The pre-compensation value is the opposite value of the Doppler frequency deviation value in the direction of the beam center. Its effect is that the Doppler frequency deviation and the pre-compensation value of the terminal at the center of the satellite spot beam are completely offset, that is, the frequency deviation value of the downlink signal received by the terminal is 0ppm; while other terminals at non-center positions will have a small amount of residual frequency deviation when receiving, for example, within ±1ppm.

[0068] Figure 5 A schematic diagram shows a frequency offset value when an exemplary terminal receives downlink signals from different cells according to an embodiment of the present application. Figure 5 The symbol “-+” indicates the size of the cell frequency deviation value measured by the terminal.

[0069] For multiple spot beam satellites, each spot beam corresponds to a cell of NR or a beam within a cell. In order to offset the Doppler frequency deviation at the center of each spot beam, each spot beam uses a different pre-compensation value. When the same terminal receives downlink signals from different cells, the Doppler frequency deviation from the satellite to the terminal is the same value, but the pre-compensation of different cells is different. This causes the terminal to measure different frequency deviation values ​​when receiving downlink signals from different cells.

[0070] like Figure 5 As shown in Figure 1, the frequency deviation value when the terminal receives downlink signals from different cells (or beams). Figure 5 For the cell where the lower point of the satellite is located), since the pre-compensation value and the Doppler frequency deviation roughly cancel each other out, the frequency deviation value of the downlink signal of this cell received by the terminal is approximately 0; for the cell on the far left in the figure, since the pre-compensation value is a large positive value, which is larger than the Doppler frequency deviation in the direction of the terminal, the frequency deviation value of the downlink signal of the leftmost cell received by the terminal is a large positive value; similarly, the frequency deviation value of the downlink signal of the rightmost cell received by the terminal is a negative value.

[0071] The frequency offset value of a certain neighboring cell measured by the terminal reflects the difference between the pre-compensation value of the neighboring cell and the ideal pre-compensation value for the terminal, and indirectly reflects the difference between the neighboring cell and the location of the terminal in the direction of satellite motion.

[0072] Figure 6 A schematic diagram of an exemplary communication system 600 according to an embodiment of the present application is shown. Figure 6 The symbol “-+” indicates the size of the cell frequency deviation value measured by the terminal.

[0073] like Figure 6 As shown, the communication system 600 is an earth mobile cell formed by the ground mobile beam mode of the satellite system. The ground mobile beam is a commonly used beamforming technology in the satellite system. The satellite beam is fixed relative to the satellite, and it is easier for the on-board antenna to implement this beam. Its beam follows the satellite to slide on the ground, especially for low-orbit constellation satellites. As the satellite moves, the coverage of the satellite beam on the ground moves (for example, the communication system 600 includes a ground coordinate axis X and a ground coordinate axis Y. The direction of satellite movement is along the direction of the ground coordinate axis X, and the coverage of the satellite beam on the ground also moves along the direction of the ground coordinate axis X), and the cell formed by the satellite beam coverage also moves accordingly. Scenes (a) and (b) show the satellite beam and the ground cell at different times, as well as the frequency deviation of the terminal receiving different cell signals. In some embodiments, for a certain cell, the angle from the satellite to the center of the cell is fixed, so the Doppler pre-compensation is also a fixed value. However, for a terminal on the ground, since the angle from the satellite to the terminal is changing, the Doppler frequency deviation from the satellite to the terminal is also changing. To be more precise, the Doppler frequency deviation is gradually decreasing. Combining the above cell pre-compensation and the Doppler frequency deviation from the satellite to the terminal, it can be seen that the frequency deviation of the downlink signal of a certain cell received by the terminal is gradually decreasing. In scenes (a) and (b), the frequency deviation values ​​of the downlink signals of different cells are represented by gray values. As shown in the figure, the frequency deviation value of each cell is gradually decreasing.

[0074] like Figure 6 As shown, the network cells may include cell PCIs 0 to 8. In some embodiments, in the communication system 600, the frequency offset value of the network cell may be used to trigger cell reselection and filter out unsuitable neighboring cells.

[0075] As mentioned above, the cell reselection in traditional terrestrial networks is divided into three steps: triggering reselection, measuring the RSRP of neighboring cells, and selecting a neighboring cell according to the ranking.

[0076] As for triggering reselection, the traditional cell reselection method is triggered by the signal strength of the resident cell being lower than a threshold. Since the signal strength changes due to the near-far effect in non-terrestrial networks are not obvious, reselection may not be triggered by judging that the signal strength is too low. The inventors of the present application have discovered that the frequency deviation value of the resident cell can be used to assist in triggering reselection. For example, when the frequency deviation value is too large or too small, reselection should be triggered in a timely manner regardless of whether the signal strength is sufficient. The frequency deviation threshold determines the sensitivity and frequency of the trigger, which can be configured to the terminal by the network, or determined by the terminal itself. Similarly, in order to solve the problem of unclear signal strength changes, reselection can also be triggered by cell coverage information or the expected service duration of the cell. The above criteria can be used in combination to improve the accuracy and timeliness of triggering reselection.

[0077] Regarding the selection of suitable neighboring cells, the inventors of the present application have also found that if the historical frequency deviation value of the neighboring cell frequency deviation value is too small, for example, less than -2ppm, then the neighboring cell can be directly eliminated without any measurement, that is, no frequency deviation measurement or RSRP measurement is required. This is because once the neighboring cell frequency deviation value is too small, it means that the neighboring cell has passed the terminal in the direction of satellite movement and is already far away from the terminal, and in the future, as the satellite moves, it is only possible to get farther and farther away from the terminal.

[0078] For neighboring cells without historical frequency deviation values, or neighboring cells with historical frequency deviation values ​​greater than the negative threshold, these neighboring cells may not have crossed the terminal in the direction of satellite movement, that is, these neighboring cells may be suitable. It is necessary to measure the current value of the frequency deviation for further judgment. If the measured current value of the frequency deviation is too large or too small, for example, greater than +2ppm or less than -2ppm, it means that the neighboring cell is still far away from the terminal; on the contrary, if the measured current value of the frequency deviation does not exceed the threshold, for example, within ±2ppm, the neighboring cell has passed the frequency deviation judgment and survived.

[0079] All neighboring cells that have passed the frequency deviation judgment and survived will then use the cell reselection criteria of the traditional terrestrial network, that is, measuring the RSRP of the neighboring cells, and finally selecting the neighboring cell with the highest score based on RSRP as the final result of the cell reselection.

[0080] For example, for Figure 6The resident cell PCI0 (Physical Cell Id) in scenario (a) will have a frequency deviation value of PCI0 in scenario (b) that exceeds the negative threshold after a period of time, which means that PCI0 is far away from the terminal and will trigger cell reselection. Secondly, in some embodiments, if the historical frequency deviation value of the cell frequency deviation is too small, the cell can be directly eliminated. For example, the frequency deviation values ​​of cells PCI5, 7, and 8 are lower than the negative threshold at the moment of scenario (a), which means that these cells are far away from the terminal and cannot become suitable neighboring cells. In the subsequent scenario (b), these cells will be further away from the terminal, and the frequency deviation values ​​of cells PCI5, 7, and 8 in scenario (b) will be further reduced. Thirdly, in some embodiments, for cells PCI0, 1, 2, 3, 4, and 6 at the moment of scenario (b), the historical frequency deviation values ​​of these cells (that is, the frequency deviation values ​​measured at the moment of scenario (a)) are greater than the negative threshold and cannot be directly eliminated. The frequency deviation values ​​need to be measured again at the moment of scenario (b). Finally, in some embodiments, at the moment of scenario (b), the current frequency deviation values ​​of cells PCI0, 1, 2, 3, 4, 6, etc. are measured again, and it is measured that the current frequency deviation values ​​of cells PCI0, 3, 4, 6, etc. are outside the preset numerical range, and they are then judged as unsuitable cells and screened out. Only the current frequency deviation values ​​of PCI1 and 2 are within the preset numerical range, and then the cell reselection criteria of the traditional terrestrial network are used to select the final cell among PCI1 and 2 according to the signal strength.

[0081] In addition, in the cell reselection method provided in the present application, the reselection behavior is a unilateral measurement and synchronization of the mobile phone, and there is no signaling interaction between the mobile phone terminal and the network. Therefore, the method provided in the present application solves the problem that it is difficult for the base station or the network to guide the mobile phone terminal to reselect. The method provided in the present application improves the cell reselection process of the mobile phone terminal, and assists in solving the problem that the traditional method cannot be applied to the cell reselection of the air-ground integration or non-ground network due to the unclear change of RSRP due to the far-near effect. At the same time, there is no need for interaction between the mobile phone terminal and the base station, and the measurement and synchronization can be completed unilaterally by the mobile phone, without modifying the process on the network side or providing additional signaling (providing additional signaling will affect the standardization process), and the power consumption of the terminal is also reduced without the need for interaction.

[0082] The method provided in the embodiment of the present application can use the frequency deviation value of a neighboring cell measured by the terminal to determine whether the neighboring cell is far away from the terminal or is still far away from the terminal, thereby eliminating inappropriate neighboring cells that are far away. Specifically: according to the frequency deviation value of the resident cell, the operation of performing cell reselection is triggered; and before performing the reselection measurement and reselection judgment operations, the part of the target cell that is far away from the terminal in the direction of satellite movement can be eliminated based on the historical measurement value and current measurement value of the frequency deviation of the target cell. The method of this embodiment can improve the timeliness and accuracy of reselection, speed up the reselection process and reduce the power consumption of the terminal.

[0083] Figure 7 A schematic diagram of another exemplary communication system 700 according to an embodiment of the present application is shown. Figure 7 The symbol “-+” indicates the size of the cell frequency deviation value measured by the terminal.

[0084] In some embodiments, another scenario in which the method provided by the present application is applicable is a fixed cell mode on the earth, such as Figure 7 As shown in the figure. The beamforming technology of this satellite system is a fixed beam relative to the ground in the staring mode. The beam radiates to the ground and remains relatively stationary. The satellite needs to continuously adjust the beamforming vector to keep the ground coverage fixed. Figure 7 As shown in scenes (a) and (b) in the figure, the beam always covers a fixed area on the ground during the entire time that the satellite is overhead. In the earth-fixed cell mode, the terminal stays in the cell for a longer time and does not need to reselect the cell too frequently. The method provided in this application is applicable to this scenario without the need for additional information, such as indicating the satellite beam mode. Compared with the traditional reselection process, the method provided in this application can eliminate unsuitable cells in advance, saving the terminal measurement time and power consumption. For example, for Figure 7 PCI5, 7, and 8 in Figure 7 In scenario (a), the frequency deviation value at the moment is smaller than the negative threshold, which means that these cells are too far away from the terminal and cannot become suitable neighboring cells, so they can be directly eliminated without any measurement.

[0085] Figure 8 A schematic diagram of another exemplary communication system 800 according to an embodiment of the present application is shown.

[0086] like Figure 8As shown, the communication system 800 may include cell PCIs 0 to 8. In some embodiments, the method provided in the present application is applicable to a communication system 800 in which one beam of multiple spot beam satellites corresponds to one cell. The above-mentioned communication systems 600 and 700 are such cell deployment methods. For such a communication system, the measured value of the signal strength of the cell refers to the measured value of the signal strength of the cell synchronization signal of the LTE system or the cell SSB (Synchronization Signal / PBCH Block) of the NR system, and the frequency deviation value of the cell refers to the difference between the frequency point value measured by the terminal receiving end of the cell synchronization signal of the LTE system or the cell SSB of the NR system and the nominal value of the transmitting end.

[0087] Fig. 9 A schematic diagram of yet another exemplary communication system 900 according to an embodiment of the present application is shown.

[0088] like Fig. 9 As shown, the communication system 900 may include cell PCI0, 1, 2 and SSB0, 1, 2 in each cell. In some embodiments, the method provided in the present application is applicable to a group of beams of multiple spot beam satellites corresponding to an NR cell, wherein the NR cell contains multiple cell beams, and one satellite spot beam corresponds to an NR cell beam. For the communication system, each NR cell beam is represented by its own SSB. For example, the signal strength of a certain NR cell beam is represented by the signal strength of its corresponding SSB. For another example, the frequency deviation value of a certain NR cell beam is the difference between the measured frequency point of its corresponding SSB and the nominal frequency point of the transmitting end. Furthermore, the signal strength of the cell is represented by the signal strength of the strongest cell beam, and the frequency deviation value of the cell is represented by the frequency deviation value of the cell beam with the smallest absolute value (closest to zero).

[0089] Fig.10 A schematic diagram of yet another exemplary communication system 1000 according to an embodiment of the present application is shown.

[0090] In some embodiments, the method provided by the present application is applicable to cell reselection under multiple satellites. Fig.10 As shown, two cells (e.g., cell PCI0 and cell PCI1) are formed by two satellites (e.g., satellite 0 and satellite 1) in the communication system 1000. Since the method provided by the present application only adds frequency offset measurement, the terminal can apply the method provided by the present application to perform cell reselection without knowing the composition relationship between the satellites and the cells.

[0091] Fig.11 A schematic diagram of yet another exemplary communication system 1100 according to an embodiment of the present application is shown.

[0092] In some embodiments, the method provided by the present application is applicable to cell reselection of multiple cells formed by multiple satellites. Fig.11 As shown, there are two satellites in the communication system 1100, each satellite includes multiple spot beams, which respectively form multiple cells (for example, the cells PCI0, 1, 2, 3, 4, 5 formed by satellite 0, and the cells PCI6, 7, 8, 9, 10 formed by satellite 1). Similar to the above communication system 1000, the terminal does not need to know the composition relationship between the satellites and the cells, and the method provided in the present application can be applied to this scenario.

[0093] Fig.12 A schematic diagram of yet another exemplary communication system 1200 according to an embodiment of the present application is shown.

[0094] In some embodiments, the method provided by the present application is applicable to cell reselection of multiple cells formed by satellites and ground base stations. Fig.12 As shown, similar to the above-mentioned communication system, the terminal in the communication system 1200 does not need to know whether the cell is composed of satellite or ground base stations, and the method provided by the present application can be applied. The frequency deviation value of the ground cell will be smaller, and it can pass the screening based on the frequency deviation value, and then the traditional cell reselection based on signal strength will be performed. The frequency deviation value of the ground cell measured by the terminal is caused by the movement of the terminal, which is smaller than the frequency deviation value of the satellite cell caused by the movement of the satellite, and will fall within the positive and negative thresholds. In terms of actual data, the Doppler frequency deviation caused by the terminal speed of 120km / h is at most 0.111ppm, which is far less than the ±2ppm threshold. In addition, because the prior task of measuring the RSRP of the neighboring cell is the synchronization in time and frequency, obtaining the frequency deviation value of the neighboring cell is a prior task of the neighboring cell measurement, which will not increase the extra time and power consumption.

[0095] Fig.13 A schematic diagram of yet another exemplary communication system 1300 according to an embodiment of the present application is shown.

[0096] In some embodiments, the method provided in the present application is applicable to cell reselection consisting entirely of ground base stations, such as Fig.13 As shown in the above scenario, the reason is the same as that of the above scenario. When the method provided by the present application is applied, all ground cells can pass the screening based on the frequency offset value, which is equivalent to the traditional cell reselection based on signal strength.

[0097] Fig.14 FIG. 1 is a flow chart of an exemplary cell reselection method 1400 according to an embodiment of the present application. The method 1400 can be applied to the above-mentioned communication systems 600 to 1300. Fig.14 As shown, method 1400 may include the following steps.

[0098] In step 1402, it is determined whether to trigger cell reselection according to the state information of the camped cell.

[0099] The state information includes a second measured frequency offset value of the resident cell. In some embodiments, whether to trigger cell reselection is determined based on the second measured frequency offset value and a second threshold.

[0100] The status information also includes signal strength, coverage information and expected service duration. In some embodiments, whether to trigger cell reselection is determined based on at least one of the signal strength, the coverage information and the expected service duration.

[0101] In step 1404, in response to triggering cell reselection, a historical frequency offset value of a first cell among neighboring cells is determined.

[0102] In step 1406, in response to the historical frequency offset value being less than or equal to a first threshold, other cells among the neighboring cells except the first cell are determined as second cells.

[0103] In step 1408, a first measurement frequency offset value of the second cell is determined.

[0104] In step 1410, in response to the first measured frequency offset value being within a preset value range, a third cell to be reselected is determined from the second cells, and a target cell is determined from the third cells.

[0105] In some embodiments, the cell is a wireless coverage area provided by a satellite or a ground base station, and the historical frequency deviation value, the first measured frequency deviation value, and the second measured frequency deviation value are measurement values ​​of the terminal for the cell frequency deviation, wherein the cell frequency deviation is caused by the combined effect of the Doppler frequency deviation caused by the satellite movement and the pre-compensation of the downlink signal by the satellite, or is caused by the Doppler frequency deviation caused by the terminal movement.

[0106] In some embodiments, in response to the first measured frequency offset value being within a preset numerical range, the third cell to be reselected is determined from the second cell; and a target cell is determined from the third cell according to the signal strength of the third cell.

[0107] In some embodiments, each of the cells corresponds to one or more satellite beams.

[0108] In some embodiments, the satellite is a single-beam satellite or a multi-beam satellite, and the single-beam satellite or the multi-beam satellite is used to deploy the cell.

[0109] In some embodiments, the cell is a ground network cell, a non-ground network cell, or an integrated air-space network cell.

[0110] The present application provides a cell reselection method, terminal equipment, storage medium and communication system. The method includes: determining whether to trigger cell reselection according to the status information of the resident cell; in response to triggering cell reselection, determining the historical frequency deviation value of the first cell in the adjacent cells; in response to the historical frequency deviation value being less than or equal to the first threshold, determining the other cells in the adjacent cells except the first cell as the second cell; determining the first measured frequency deviation value of the second cell; in response to the first measured frequency deviation value being within a preset numerical range, determining the third cell to be reselected from the second cell, and determining the target cell in the third cell. Through the frequency deviation values ​​of the resident cell and the adjacent cell, the triggering conditions of the resident cell are increased, the timeliness of the reselection is improved, the inappropriate adjacent cells are screened out in advance, the accuracy of the reselection is improved, and the triggering difficulty and reselection difficulty caused by the unclear change in signal strength due to the near-far effect are assisted, and the reselection process is accelerated and the power consumption of the terminal is reduced.

[0111] It should be noted that the method of the embodiment of the present application can be performed by a single device, such as a computer or a resident device. The method of the present embodiment can also be applied to a distributed scenario and completed by multiple devices cooperating with each other. In the case of such a distributed scenario, one of the multiple devices can only perform one or more steps in the method of the embodiment of the present application, and the multiple devices will interact with each other to complete the described method.

[0112] It should be noted that the above describes some embodiments of the present application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0113] Based on the same technical concept, corresponding to any of the above-mentioned embodiments, the present application also provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, method 1400 as described in any of the above embodiments is implemented.

[0114] Fig.15A schematic diagram of an exemplary terminal device according to an embodiment of the present application is shown, and the device may include: a processor 1510, a memory 1520, an input / output interface 1530, a communication interface 1540, and a bus 1550. The processor 1510, the memory 1520, the input / output interface 1530, and the communication interface 1540 are connected to each other in communication within the device through the bus 1550.

[0115] The processor 1510 can be implemented by a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this specification.

[0116] The memory 1520 may be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage device, dynamic storage device, etc. The memory 1520 may store an operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented by software or firmware, the relevant program codes are stored in the memory 1520 and are called and executed by the processor 1510.

[0117] The input / output interface 1530 is used to connect the input / output module to realize information input and output. The input / output module can be configured in the device as a component (not shown in the figure), or it can be externally connected to the device to provide corresponding functions. The input device may include a keyboard, a mouse, a touch screen, a microphone, various sensors, etc., and the output device may include a display, a speaker, a vibrator, an indicator light, etc.

[0118] The communication interface 1540 is used to connect a communication module (not shown) to realize communication interaction between the device and other devices. The communication module can realize communication through wired means (such as USB, network cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0119] The bus 1550 includes a path that transmits information between the various components of the device (eg, the processor 1510 , the memory 1520 , the input / output interface 1530 , and the communication interface 1540 ).

[0120] It should be noted that, although the above device only shows the processor 1510, the memory 1520, the input / output interface 1530, the communication interface 1540 and the bus 1550, in the specific implementation process, the device may also include other components necessary for normal operation. In addition, it can be understood by those skilled in the art that the above device may also only include the components necessary for implementing the embodiments of the present specification, and does not necessarily include all the components shown in the figure.

[0121] The terminal device of the above embodiment is used to implement the corresponding method 1400 in any of the above embodiments, and has the beneficial effects of the corresponding method embodiment, which will not be repeated here.

[0122] Based on the same technical concept, corresponding to any of the above-mentioned embodiments, the present application also provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions are used to enable the computer to execute method 1400 described in any of the above embodiments.

[0123] The computer-readable medium of this embodiment includes permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, read-only compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device.

[0124] The computer instructions stored in the storage medium of the above embodiment are used to enable the computer to execute method 1400 as described in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0125] A person skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application (including the claims) is limited to these examples. In line with the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

[0126] In addition, to simplify the description and discussion, and in order not to make the embodiments of the present application difficult to understand, the known power / ground connections to the integrated circuit (IC) chip and other components may or may not be shown in the provided drawings. In addition, the device may be shown in the form of a block diagram to avoid making the embodiments of the present application difficult to understand, and this also takes into account the fact that the details of the implementation of these block diagram devices are highly dependent on the platform on which the embodiments of the present application are to be implemented (that is, these details should be fully within the scope of understanding of those skilled in the art). Where specific details (e.g., circuits) are set forth to describe exemplary embodiments of the present application, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details or with changes in these specific details. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0127] Although the present application has been described in conjunction with specific embodiments of the present application, many alternatives, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may use the discussed embodiments.

[0128] The embodiments of the present application are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present application should be included in the scope of protection of the present application.

Claims

1. A cell reselection method, include: Determine whether to trigger cell reselection according to the status information of the resident cell; In response to triggering cell reselection, determining a historical frequency offset value of a first cell among neighboring cells; In response to the historical frequency offset value being less than or equal to a first threshold, determining other cells among the neighboring cells except the first cell as second cells; determining a first measurement frequency offset value of the second cell; In response to the first measured frequency offset value being within a preset value range, a third cell to be reselected is determined from the second cells, and a target cell is determined from the third cells.

2. The method according to claim 1, in, The state information includes a second measured frequency offset value of the resident cell, and determining whether to trigger cell reselection according to the state information of the resident cell further includes: Whether to trigger cell reselection is determined according to the second measured frequency offset value and the second threshold.

3. The method according to claim 2, in, The cell is a wireless coverage area provided by a satellite or a ground base station, and the historical frequency deviation value, the first measured frequency deviation value and the second measured frequency deviation value are measurement values ​​of the cell frequency deviation by the terminal, wherein the cell frequency deviation is caused by the combined effect of the Doppler frequency deviation caused by the satellite movement and the pre-compensation of the downlink signal by the satellite, or is caused by the Doppler frequency deviation caused by the terminal movement.

4. The method according to claim 1, in, The state information further includes signal strength, coverage information and expected service duration, and determining whether to trigger cell reselection according to the state information of the resident cell further includes: Determine whether to trigger cell reselection according to at least one of the signal strength, the coverage information, and the expected service duration.

5. The method according to claim 1, in, In response to the first measured frequency offset value being within a preset value range, determining a third cell to be reselected from the second cell, and determining a target cell from the third cell further comprises: In response to the first measured frequency offset value being within a preset value range, determining the third cell to be reselected from the second cell; A target cell is determined in the third cell according to the signal strength of the third cell.

6. The method according to claim 1, in, Each of the cells corresponds to one or more satellite beams.

7. The method according to claim 3, in, The satellite is a single-beam satellite or a multi-beam satellite, and the single-beam satellite or the multi-beam satellite is used to deploy the cell.

8. The method according to claim 1, in, The cell is a ground network cell, a non-ground network cell or an air-space integrated network cell.

9. A terminal device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, in, When the processor executes the program, the method according to any one of claims 1 to 8 is implemented.

10. A non-transitory computer-readable storage medium storing computer instructions, in, The computer instructions are used to enable a computer to execute the method according to any one of claims 1 to 8.

11. A communication system, comprising the terminal device according to claim 9.

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