Multi-connection communication method for terrestrial and non-terrestrial network MIMO system

Abstract

The application provides a multi-connection communication method of a ground and non-ground network MIMO system. The multi-connection communication method comprises the following steps: a user terminal receives reference signals from a ground base station and an air satellite respectively, and selects a communication link from the base station to the user terminal or a communication link from the satellite to the user terminal with the highest data transmission rate; a gateway switches the user terminal to a corresponding connection mode and performs clock synchronization according to a scheduling result of the base station and the satellite on the user terminal; the user terminal performs MIMO channel estimation from a sending end to itself according to associated information of the user terminal and the sending end, and the sending end performs data transmission according to a channel estimation result. The application is suitable for a multi-connection communication scenario of a base station and a satellite cooperation, can effectively improve a data transmission rate received by each user, improve a coverage probability of a system, and thus improve reliability of a network.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to a multi-connection communication method of a terrestrial and non-terrestrial network MIMO system. BACKGROUND

[0002] With the development of the 5G era, satellites have an increasingly important role in expanding the scale of terrestrial networks and improving communication efficiency due to their deployment characteristics in the universe. Similar to the direct communication of users by terrestrial base stations, in recent years, the academic and industrial circles have also begun to focus on the direct communication of satellites and users and have carried out related research and practice, which is expected to be implemented on a large scale in the near future.

[0003] However, changes in geographical location will limit communication conditions, and relying solely on terrestrial base stations or solely on satellites will result in low communication data rates. Based on existing base stations and satellites, in order to improve communication quality, user terminals need to flexibly select and switch to the most effective connection mode, such as connecting to a base station, connecting to a satellite, or connecting to both a base station and a satellite. SUMMARY

[0004] In view of the above technical status, the present application provides a multi-connection communication method of a terrestrial and non-terrestrial network MIMO system in combination with Multiple-Input Multiple-Output (MIMO) technology, which can flexibly select communication connections with a base station, a satellite, or both a base station and a satellite according to the communication link conditions of a user terminal, thereby effectively improving data transmission rates and network reliability.

[0005] The technical solution provided by the present application is a multi-connection communication method of a terrestrial and non-terrestrial network MIMO system, comprising the following steps:

[0006] Step 201: A user terminal searches for and receives reference signals from a terrestrial base station and from a satellite in the air;

[0007] Step 202: The user terminal determines whether there is an available communication link between itself and a base station or a satellite according to the received reference signals, and if there is, it jumps to step 203, otherwise it jumps to step 201 to search and receive again;

[0008] Step 203: The user terminal determines whether there is an available communication link between itself and a base station, and if there is, it jumps to step 204, otherwise it jumps to step 205;

[0009] Step 204: The user terminal calculates the link data rates of all available base stations to itself, respectively, and then selects a base station that can obtain the highest data rate and sends an association request to the base station;

[0010] Step 205: The user terminal determines whether there is an available communication link between it and the satellite. If so, the process jumps to step 206; otherwise, the process jumps to step 207.

[0011] Step 206: The user terminal calculates the link data rates from all available satellites to itself, selects the satellite that can obtain the highest data rate, and sends an association request to the satellite;

[0012] Step 207: Each base station and satellite schedules the user terminal and pre-allocates communication resources based on the user terminal association request received by each base station and pre-allocates communication resources.

[0013] Step 208: The gateway switches the user terminal to a corresponding connection mode based on the scheduling result of the user terminal and performs clock synchronization on associated devices; the connection mode includes the user terminal being scheduled by both the terrestrial and non-terrestrial networks, the user terminal being scheduled by only the terrestrial network, or the user terminal being scheduled by only the non-terrestrial network.

[0014] Step 209: The system locates the user terminal and obtains the location information of the transmitter, including the location information of the base station (if any) and / or the location information of the satellite (if any);

[0015] Step 210: Based on the information associating the user terminal with the transmitter, the user terminal performs channel estimation based on the MIMO channel between the user terminal and the transmitter.

[0016] Step 211: Based on the channel estimation result and in combination with precoding or codebook, the transmitting end transmits data to the user terminal.

[0017] Preferably, after step 211, the integrity of the data received by the user terminal may be determined, and the user terminal may be asked whether to switch the connection, continue to request the service, etc., and corresponding services may be provided.

[0018] As an implementation method, the following steps are performed after step 211:

[0019] Step 212: The user terminal determines whether all data has been completely received. If so, the process jumps to step 215; otherwise, the process jumps to step 213.

[0020] Step 213: The user terminal requests the transmitting end to retransmit the data;

[0021] Step 214: The transmitting end determines whether the user terminal needs to switch connections. If so, the current connection is disconnected and the process goes to step 201 where the user terminal receives the reference signal again. Otherwise, the process goes to step 207 where scheduling is performed again.

[0022] Step 215: The user terminal determines whether it needs to continue the service to receive other data. If yes, it jumps to step 214. Otherwise, the process ends.

[0023] As a preferred, in step 208, the switching of the connection mode of the user terminal and the clock synchronization process comprises the following steps:

[0024] Step 301: The gateway determines whether the user terminal has selected the base station. If yes, it jumps to step 302. Otherwise, it jumps to step 307.

[0025] Step 302: The gateway determines whether the user terminal has selected the satellite. If yes, it jumps to step 303. Otherwise, it jumps to step 305.

[0026] Step 303: According to the scheduling result of the base station and the satellite to the user terminal, the gateway switches the user terminal to the connection mode 1 corresponding to the current time slot, i.e. the user terminal is scheduled by both the ground network and the non-ground network.

[0027] Step 304: The clock synchronization is performed between the user terminal, the base station and the satellite.

[0028] Step 305: According to the scheduling result of the base station to the user terminal, the gateway switches the user terminal to the connection mode 2 corresponding to the current time slot, i.e. the user terminal is scheduled by the ground network only.

[0029] Step 306: The clock synchronization is performed between the user terminal and the base station.

[0030] Step 307: The gateway determines whether the user terminal has selected the satellite. If yes, it jumps to step 308. Otherwise, it jumps to step 310.

[0031] Step 308: According to the scheduling result of the satellite to the user terminal, the gateway switches the user terminal to the connection mode 3 corresponding to the current time slot, i.e. the user terminal is scheduled by the non-ground network only.

[0032] Step 309: The clock synchronization is performed between the user terminal and the satellite.

[0033] As a preferred, in each step, the satellite includes but is not limited to one or more of low earth orbit (LEO) satellite, medium earth orbit (MEO) satellite, geostationary orbit (GEO) satellite, etc.

[0034] As a preferred, in step 207, the communication resource includes but is not limited to communication bandwidth, etc.

[0035] As a preferred, in step 209, the system locates the user terminal and obtains the position information of the sending terminal by table lookup.

[0036] Preferably, in step 210, the information between the user terminal and the transmitting end includes but is not limited to location information, reference signal and other information.

[0037] Preferably, in step 210, the user terminal sends an uplink pilot signal to the transmitter to perform channel estimation between the user terminal and the transmitter based on the MIMO channel.

[0038] Preferably, in step 211, the precoding method includes but is not limited to using one or two of zero forcing (ZF) precoding, maximum ratio transmission (MRT), etc. to perform precoding at the transmitting end when the transmitting end sends a downlink data signal to the user, and using maximum ratio combining (MRC) to perform precoding at the receiving end when the user terminal receives the downlink data signal.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention combines MIMO technology with existing base station-to-user services in terrestrial networks and satellite-to-user services in non-terrestrial networks to propose a multi-connection communication method that utilizes both terrestrial and non-terrestrial networks. The method includes the following steps: a user terminal receives reference signals from a terrestrial base station and a satellite, respectively, and selects the base station-to-user terminal communication link or / and the satellite-to-user terminal communication link with the highest data transmission rate; a gateway switches the user terminal to the corresponding connection mode and performs clock synchronization based on the scheduling results of the base station and satellite for the user terminal; and the user terminal performs MIMO channel estimation from the transmitter to itself based on the association information between the user terminal and the transmitter, and the transmitter transmits data based on the channel estimation results. Compared to current communication methods that use only base stations or satellites, this method flexibly selects communication connections with base stations, satellites, or both base stations and satellites based on the user terminal's communication link status. This method effectively increases the data transmission rate received by each user, improves the system's coverage probability, and thus enhances network reliability. User terminals communicating using this method can achieve multi-connection communication with both terrestrial and non-terrestrial networks, and has promising application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 3 is a schematic diagram of a model for multi-connection communication of a terrestrial and non-terrestrial network MIMO system in an embodiment of the present invention.

[0042] Figure 2 This is a flow chart of establishing communication and completing data transmission between the terrestrial and non-terrestrial network MIMO system and the user in an embodiment of the present invention.

[0043] Figure 3 This is a flowchart of user connection mode switching and clock synchronization in the terrestrial and non-terrestrial network MIMO system in an embodiment of the present invention.

[0044] Figure 4 3 is a schematic diagram of four scheduling states corresponding to users in a terrestrial and non-terrestrial network MIMO system in an embodiment of the present invention.

[0045] Figures 1 to 4 In this context, the user includes the concept of user terminal. DETAILED DESCRIPTION

[0046] The following is a clear and complete description of the technical solutions in the embodiments of the present invention so that those skilled in the art can better understand the present invention and thus clearly define the scope of protection of the present invention. The embodiments described in the present invention are only some of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative work are within the scope of protection of the present invention.

[0047] Reference Figure 1 and Figure 2 A multi-connection communication method for a terrestrial and non-terrestrial network MIMO system comprises the following steps:

[0048] Step 201: The user terminal searches for and receives reference signals from ground base stations and from satellites in the air, including but not limited to low earth orbit satellites, medium earth orbit satellites, geostationary orbit satellites, etc.

[0049] Step 202: The user terminal determines whether there is an available communication link between it and the base station or satellite based on the received reference signal. If so, the process jumps to step 203; otherwise, the process jumps to step 201 to search and receive again.

[0050] Step 203: The user terminal determines whether there is an available communication link between it and the base station. If yes, the process jumps to step 204; otherwise, the process jumps to step 205.

[0051] Step 204: The user terminal calculates the link data rates of all available base stations to itself, selects the base station that can obtain the highest data rate, and sends an association request to the base station;

[0052] Step 205: The user terminal determines whether there is an available communication link between it and the satellite. If so, the process jumps to step 206; otherwise, the process jumps to step 207.

[0053] Step 206: The user terminal calculates the link data rates from all available satellites to itself, selects the satellite that can obtain the highest data rate, and sends an association request to the satellite;

[0054] Step 207: Each base station and satellite schedules the user terminal according to the user terminal association request received by each base station and pre-allocates communication resources, such as communication bandwidth.

[0055] Step 208: The gateway switches the user terminal to the corresponding connection mode according to the scheduling result of the user terminal and synchronizes the clocks of the associated devices;

[0056] Step 209: The system locates the user terminal and obtains the location information of the transmitter by looking up the table, including the location information of the base station (if any) and / or the location information of the satellite (if any);

[0057] Step 210: Based on the location of the associated user terminal and the transmitter, the reference signal, and other information, the user terminal sends an uplink pilot signal to the transmitter, performs channel estimation between the user terminal and the transmitter based on the MIMO channel, and returns the channel estimation result to the transmitter.

[0058] Step 211: Based on the channel estimation result, the transmitting end transmits data to the associated user terminal through precoding or using a codebook. For example, when using precoding, the user terminal uses zero-forcing precoding, maximum ratio transmission, etc. for precoding when sending signals, and uses maximum ratio combining, etc. for precoding when receiving signals.

[0059] Step 212: The user terminal determines whether all data has been completely received. If so, the process jumps to step 215; otherwise, the process jumps to step 213.

[0060] Step 213: The user terminal requests the transmitting end to retransmit the data;

[0061] Step 214: The transmitting end determines whether the user terminal needs to switch connections. If so, the current connection is disconnected and the process goes to step 201 where the user terminal receives the reference signal again. Otherwise, the process goes to step 207 where scheduling is performed again.

[0062] Step 215: The user terminal determines whether it needs to continue the service to receive other data. If so, it jumps to step 214; otherwise, the process ends.

[0063] In this embodiment, refer to Figure 3 and Figure 4 In step 208, the process of switching the user terminal connection mode and clock synchronization includes the following steps:

[0064] Step 301: The gateway determines whether the user terminal has selected a base station. If so, the gateway jumps to step 302; otherwise, the gateway jumps to step 307.

[0065] Step 302: The gateway determines whether the user terminal has selected a satellite. If so, the gateway jumps to step 303; otherwise, the gateway jumps to step 305.

[0066] Step 303: Based on the scheduling results of the user terminal by the base station and the satellite, the gateway switches the user terminal to connection mode 1 corresponding to the current time slot, that is, the user terminal is scheduled by both the terrestrial and non-terrestrial networks;

[0067] Step 304: The user terminal, base station, and satellite perform clock synchronization.

[0068] Step 305: Based on the scheduling result of the base station for the user terminal, the gateway switches the user terminal to connection mode 2 corresponding to the current time slot, that is, the user terminal is only scheduled by the ground network;

[0069] Step 306: The user terminal and the base station perform clock synchronization;

[0070] Step 307: The gateway determines whether the user terminal has selected a satellite. If so, the gateway jumps to step 308; otherwise, the gateway jumps to step 310.

[0071] Step 308: Based on the satellite's scheduling result for the user terminal, the gateway switches the user terminal to connection mode 3 corresponding to the current time slot, i.e., the user terminal is only scheduled by the non-terrestrial network;

[0072] Step 309: The user terminal and the satellite perform clock synchronization.

[0073] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-connection communication method for a terrestrial and non-terrestrial network MIMO system, characterized by: The following steps are involved: Step 201: The user terminal searches for and receives reference signals from a ground base station and from an aerial satellite; Step 202: The user terminal determines whether there is an available communication link between it and the base station or satellite based on the received reference signal. If yes, the process jumps to step 203; otherwise, the process jumps to step 201. Step 203: The user terminal determines whether there is an available communication link between it and the base station. If yes, the process jumps to step 204; otherwise, the process jumps to step 205. Step 204: The user terminal calculates the link data rates of all available base stations to itself, selects the base station that can obtain the highest data rate, and sends an association request to the base station; Step 205: The user terminal determines whether there is an available communication link between it and the satellite. If so, the process jumps to step 206; otherwise, the process jumps to step 207. Step 206: The user terminal calculates the link data rates from all available satellites to itself, selects the satellite that can obtain the highest data rate, and sends an association request to the satellite; Step 207: Each base station and satellite schedules the user terminal and pre-allocates communication resources based on the user terminal association request received by each base station and pre-allocates communication resources. Step 208: The gateway switches the user terminal to a corresponding connection mode based on the scheduling result of the user terminal and performs clock synchronization on associated devices; the connection mode includes the user terminal being scheduled by both the terrestrial and non-terrestrial networks, the user terminal being scheduled by only the terrestrial network, or the user terminal being scheduled by only the terrestrial network. Step 209: The system locates the user terminal and obtains the location information of the transmitter, including the location information of the base station and / or the location information of the satellite. Step 210: Based on the information associating the user terminal with the transmitter, the user terminal performs channel estimation based on the MIMO channel between the user terminal and the transmitter. Step 211: Based on the channel estimation result and in combination with precoding or codebook, the transmitting end transmits data to the user terminal.

2. The multi-connection communication method according to claim 1, wherein: After step 211, the integrity of the data received by the user terminal is determined, and the user terminal is asked whether to switch the connection and whether to continue to request the service, and the corresponding service is provided.

3. The multi-connection communication method according to claim 1, wherein: The step 211 further includes the following steps: Step 212: The user terminal determines whether all data has been completely received. If so, the process jumps to step 215; otherwise, the process jumps to step 213. Step 213: The user terminal requests the transmitting end to retransmit the data; Step 214: The sending end determines whether the user terminal needs to switch connections. If so, the current connection is disconnected and the process goes to step 201. Otherwise, the process goes to step 207. Step 215: The user terminal determines whether it needs to continue the service to receive other data. If so, it jumps to step 214; otherwise, the process ends.

4. The multi-connection communication method according to claim 1, wherein: In step 208, the process of switching the user terminal connection mode and clock synchronization includes the following steps: Step 301: The gateway determines whether the user terminal has selected a base station. If so, the gateway jumps to step 302; otherwise, the gateway jumps to step 307. Step 302: The gateway determines whether the user terminal has selected a satellite. If so, the gateway jumps to step 303; otherwise, the gateway jumps to step 305. Step 303: Based on the scheduling results of the user terminal by the base station and the satellite, the gateway switches the user terminal to connection mode 1 corresponding to the current time slot, that is, the user terminal is scheduled by both the terrestrial and non-terrestrial networks; Step 304: The user terminal, base station, and satellite perform clock synchronization. Step 305: Based on the scheduling result of the base station for the user terminal, the gateway switches the user terminal to connection mode 2 corresponding to the current time slot, that is, the user terminal is only scheduled by the ground network; Step 306: The user terminal and the base station perform clock synchronization; Step 307: The gateway determines whether the user terminal has selected a satellite. If so, the gateway jumps to step 308; otherwise, the gateway jumps to step 310. Step 308: Based on the satellite's scheduling result for the user terminal, the gateway switches the user terminal to connection mode 3 corresponding to the current time slot, i.e., the user terminal is only scheduled by the non-terrestrial network; Step 309: The user terminal and the satellite perform clock synchronization.

5. The multi-connection communication method according to claim 1, wherein: The satellites include one or more of low earth orbit satellites, medium earth orbit satellites, and geostationary orbit satellites.

6. The multi-connection communication method according to claim 1, wherein: In step 207, the communication resources include communication bandwidth.

7. The multi-connection communication method according to claim 1, wherein: In step 210, the information between the user terminal and the transmitter includes one or both of location information and reference signals.

8. The multi-connection communication method according to claim 1, wherein: In step 210, the user terminal sends an uplink pilot signal to the transmitter to perform channel estimation between the user terminal and the transmitter based on the MIMO channel.

9. The multi-connection communication method according to claim 1, wherein: In step 211, the precoding method includes zero-forcing precoding or / and maximum ratio transmission precoding applied by the transmitting end when transmitting a signal to the user terminal, and maximum ratio combining precoding applied when the user terminal receives the signal.

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