Wireless communication system, wireless communication method, aggregation device, and program

Abstract

In a wireless communication system according to the present disclosure, a first communication route is established by connecting, through links, at least one aerial node station among a plurality of aerial node stations and at least one terrestrial base station among a plurality of terrestrial base stations. Regarding one or more communication links constituting the first communication route, the respective states are determined to be good or bad. In response to changes of the states of the one or more communication links from good to bad, one or more other communication routes are established in addition to the first communication route. Additionally, in a wireless communication system according to the present disclosure, data items that are transmitted from terminal stations are collected from all the communication routes including the first communication route and the one or more other communication routes. Among the collected data items, a data item from the first communication route is transferred to a core network. However, when the data item from the first communication route is lost, the lost data item is complemented by a data item from the one or more other communication routes.

Description

Wireless communication system, wireless communication method, aggregation device, and program

[0001] The present disclosure relates to a wireless communication system and a wireless communication method that utilize a non-terrestrial network, as well as an aggregation device and a program thereof that are suitable for a wireless communication system.

[0002] In recent years, mobile communication systems have evolved, enabling mobile services to be enjoyed over most of the earth. Ultra-coverage is one of the requirements for the 5th generation (Beyond 5G) or 6th generation mobile communication systems, which are expected to be commercialized in the future. Ultra-coverage refers to expanding the service area to locations where the cost of installing existing base stations is high or difficult, such as mountains, oceans, and the air. Furthermore, there is a need to strengthen the nation's resilience against natural disasters, and the emergence of communication systems that are resistant to terrestrial disasters is desirable.

[0003] As a means for realizing the above-mentioned requirements, non-terrestrial networks (NTNs) have attracted attention. Non-terrestrial networks are wireless networks that use node stations deployed in the air or space, such as satellites, unmanned aerial vehicles (UAVs), high altitude pseudo satellites (HAPSs), and drones. In non-terrestrial networks, the node stations form a network by connecting with each other through communication links, and are further connected to terrestrial mobile networks via terrestrial base stations.

[0004] In non-terrestrial networks, node stations are equipped with mobile base station functions. Traffic packets generated by terminal stations are forwarded within the non-terrestrial network to node stations that can communicate with terrestrial base stations using routing functions, and then sent to the core network via the terrestrial base station. Packets sent from the core network to terminal stations are also processed in the same way using the routing functions of the non-terrestrial network.

[0005] Non-Patent Document 1 discloses a conventional technique for selecting a communication route when routing in a non-terrestrial network. In the conventional technique, a communication route is selected that minimizes the cost value C calculated by the following formula (1). However, in formula (1), C ｉis the cost value of communication link i, n is the total number of links included in the communication path, and R ｉ is the link capacity of communication link i, and B ｒ is the reference value of the link capacity, and d ｉ is the delay time of communication link i, and B ｄ is the reference value of the delay time.

[0006] Tada, Nishiyama, Yoshimura, and Kato, "A Study on Efficient Routing Control in Hierarchical Satellite Networks," IEICE Technical Report SAT2010-9

[0007] However, the above-mentioned conventional technology does not take into consideration the impact of degradation of the communication environment when selecting a communication path. The selected communication path includes multiple communication links, but degradation of the communication environment can occur at the communication link level due to factors such as attenuation due to rainfall or movement of node stations. When the communication environment deteriorates, some data may need to be retransmitted. Furthermore, data retransmission results in a decrease in throughput.

[0008] The present disclosure has been made in view of the above-mentioned problems, and aims to provide a technique that can reduce data retransmission when a communication environment is degraded and improve throughput.

[0009] The present disclosure provides a wireless communication system to achieve the above-mentioned object. The wireless communication system according to one embodiment of the present disclosure is a system for performing communication between a terminal station and a core network via a wireless network including a plurality of aerial node stations and a plurality of terrestrial base stations. The wireless communication system includes a network controller and an aggregation device. The network controller is configured to establish a communication path by linking at least one of the plurality of aerial node stations with one of the plurality of terrestrial base stations. The aggregation device is configured to aggregate data transmitted from the wireless network to the core network. More specifically, the network controller is configured to establish a first communication path, determine whether the status of each of one or more communication links constituting the first communication path is good or bad, and, when the status determination result of any of the one or more communication links changes from good to bad, establish one or more other communication paths in addition to the first communication path. The aggregation device is configured to collect data transmitted from terminal stations from all communication paths including a first communication path and one or more other communication paths, transmit data from the first communication path among the collected data to a core network, and, upon occurrence of a loss in data from the first communication path, complement the lost data from data from one or more other communication paths.

[0010] The present disclosure also provides a wireless communication method for achieving the above object. According to one embodiment of the present disclosure, the wireless communication method is a method for performing communication between a terminal station and a core network via a wireless network including a plurality of aerial node stations and a plurality of terrestrial base stations. The wireless communication method includes establishing a first communication path by linking at least one of the plurality of aerial node stations with one of the plurality of terrestrial base stations, determining whether the status of each of one or more communication links constituting the first communication path is good or bad, and, upon a change in the status determination result of any of the one or more communication links from good to bad, establishing one or more other communication paths in addition to the first communication path. The wireless communication method further includes collecting data transmitted from the terminal station from all communication paths including the first communication path and the one or more other communication paths, transmitting the collected data of the first communication path to the core network, and, upon a loss of data in the first communication path, compensating for the loss of data from data in the one or more other communication paths.

[0011] The present disclosure also provides an aggregation device for achieving the above-mentioned object. According to one embodiment of the present disclosure, the aggregation device is provided in a wireless communication system in which communication between a terminal station and a core network is performed via a wireless network including a plurality of aerial node stations and a plurality of terrestrial base stations, and aggregates data transmitted from the wireless network to the core network. The aggregation device includes a buffer memory and a processing circuit. The buffer memory is configured to collect data transmitted from the terminal station via a plurality of communication paths established by linking at least one aerial node station among the plurality of aerial node stations with one of the plurality of terrestrial base stations. The processing circuit is configured to transmit data of a first communication path included in the plurality of communication paths among the collected data to the core network, and, in response to a loss of data in the first communication path, to complement the lost data from data of one or more other communication paths other than the first communication path.

[0012] Furthermore, the present disclosure provides a program for achieving the above object. The program according to one embodiment of the present disclosure is a program including instructions for causing a processor to execute the processing performed by the aggregation device. The program may be recorded on a computer-readable recording medium or provided via a network.

[0013] According to the technology disclosed herein, when the condition of one or more communication links constituting a first communication path deteriorates, one or more other communication paths are established in addition to the first communication path. Furthermore, when a loss of data occurs in the first communication path, the lost data is compensated for using data from one or more other communication paths. This reduces the need for data retransmission when the communication environment deteriorates, thereby improving throughput.

[0014] FIG. 1 is a diagram illustrating an example of a configuration of a wireless communication system according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating conventional communication control using a non-terrestrial network. FIG. 3 is a diagram illustrating communication control by a wireless communication system according to an embodiment of the present disclosure. FIG. 4 is a diagram illustrating a configuration of a node station-equipped communication device according to an embodiment of the present disclosure. FIG. 5 is a diagram illustrating a configuration of a network controller according to an embodiment of the present disclosure. FIG. 6 is a diagram illustrating a configuration of an aggregation device according to an embodiment of the present disclosure. FIG. 7 is a flowchart illustrating the operation of a network controller according to an embodiment of the present disclosure. FIG. 8 is a flowchart illustrating the operation of an aggregation device according to an embodiment of the present disclosure.

[0015] Hereinafter, a wireless communication system according to an embodiment of the present disclosure will be described with reference to the drawings.

[0016] 1. Configuration of Wireless Communication System First, an example of the configuration of a wireless communication system according to an embodiment of the present disclosure will be described with reference to Fig. 1. As shown in Fig. 1, the wireless communication system 2 includes a non-terrestrial network (NTN) 15 formed from a plurality of airborne node stations (hereinafter simply referred to as node stations) deployed in the sky. The non-terrestrial network 15 includes three types of networks 15A, 15B, 15C, and 15D at different altitudes. These three types of networks 15A, 15B, and 15C are connected by communication links.

[0017] The first network is a low altitude network 15A formed by connecting a first group of node stations 5A deployed at relatively low altitudes via communication links. Hereinafter, the node stations 5A of the first group that make up the low altitude network 15A will be referred to as low altitude node stations. The second network is a medium altitude network 15B formed by connecting a second group of node stations 5B deployed at relatively medium altitudes via communication links. Hereinafter, the node stations 5B of the second group that make up the medium altitude network 15B will be referred to as medium altitude node stations. The third network is a high altitude network 15C formed by connecting a third group of node stations 5C deployed at relatively high altitudes via communication links. Hereinafter, the node stations 5C of the third group that make up the high altitude network 15C will be referred to as high altitude node stations.

[0018] Node stations can be geostationary orbit (GEO) satellites, medium orbit (MEO) satellites, low orbit (LEO) satellites, high altitude pseudo satellites (HAPS), as well as drones, unmanned aerial vehicles (UAVs), and aircraft. Typically, GEO satellites are used as high-altitude node stations 5C, and MEO satellites and LEO satellites are used as medium-altitude node stations 5B. HAPS, drones, UAVs, and aircraft are used as low-altitude node stations 5A. However, whether a node station is a high-altitude node station 5C, a medium-altitude node station 5B, or a low-altitude node station 5A depends on the relative altitude differences between the node stations that make up the non-terrestrial network 15. Therefore, if the node stations that make up the non-terrestrial network 15 are GEO satellites, MEO satellites, and LEO satellites, the LEO will be the low-altitude node station 5A. Also, if the node stations that make up the non-terrestrial network 15 are MEO satellites, LEO satellites, and HAPS, the MEO satellites become the high altitude node stations 5C.

[0019] The types of networks included in the non-terrestrial network 15 are not necessarily limited to the three types of low altitude, medium altitude, and high altitude. The non-terrestrial network 15 may be composed of two types of networks: low altitude and high altitude. For example, the non-terrestrial network 15 may be composed of a GEO network using GEO satellites as high altitude node stations and a HAPS network using HAPS as low altitude node stations. Furthermore, the non-terrestrial network 15 may include only one type of network.

[0020] In the non-terrestrial network 15 shown in FIG. 1 , the low altitude network 15A is linked to the terrestrial base station 3 and connected to the core network 14, which is a terrestrial network, via the terrestrial base station 3. Similarly, the medium altitude network 15B and the high altitude network 15C are linked to the terrestrial base station 3 and connected to the core network 14 via the terrestrial base station 3. A communication link is also established between a node station 5A belonging to the low altitude network 15A and a node station 5B belonging to the medium altitude network 15B. A communication link is also established between a node station 5B belonging to the medium altitude network 15B and a node station 5C belonging to the high altitude network 15C. Furthermore, a communication link can also be established between a node station 5A belonging to the low altitude network 15A and a node station 5C belonging to the high altitude network 15C. The communication link between the node stations may be realized by radio wave wireless communication or other wireless communication such as optical communication. Each communication link includes a communication line and a control line.

[0021] Each node station constituting the non-terrestrial network 15 has a routing function. Each node station transmits packets to a destination by transferring packets between other node stations. Each node station also has a mobile base station function. A terminal station 4 connects to one of the node stations and connects to the core network 14 via the non-terrestrial network 15. The terminal station 4 can connect to the Internet via the core network 14.

[0022] The wireless communication system 2 includes a network controller 10 and an aggregation device 12. The network controller 10 is disposed in the air and connected to a non-terrestrial network 15. The network controller 10 is a device that establishes a communication path by linking at least one of the multiple node stations 5A, 5B, and 5C that form the non-terrestrial network 15 with one of the multiple terrestrial base stations 3. However, the network controller 10 may also be disposed on the ground and connected to a core network 14. The aggregation device 12 is disposed on the ground and connected to the core network 14. The aggregation device 12 is a device that aggregates data transmitted from the non-terrestrial network 15 to the core network 14 via the terrestrial base station 3. In this specification, a network including the non-terrestrial network 15 and the terrestrial base station 3 is collectively referred to as a wireless network. The functions of the network controller 10 and the aggregation device 12 will be described in detail later.

[0023] 2. Communication Control Using a Wireless Communication System First, conventional communication control using a non-terrestrial network will be described with reference to Figure 2. In the example shown in Figure 2, the non-terrestrial network consists of a low altitude network 16 and a high altitude network 17. The low altitude network 16 includes node stations 6-1 and 6-2 connected by a communication link. An example of the node stations 6-1 and 6-2 is a HAPS. The high altitude network 17 includes node stations 7-1 and 7-2 connected by a communication link. An example of the node stations 7-1 and 7-2 is a GEO satellite. The low altitude network 16 and the high altitude network 17 are connected by a communication link. In this example, the node station 6-1 and the node station 7-1 are connected by a communication link.

[0024] The non-terrestrial network is connected to the core network 14 via terrestrial base stations 3-1, 3-2, and 3-3. A node station 6-1 forming a low altitude network 16 is connected to the terrestrial base station 3-1 via a communication link, and a node station 6-2 is connected to the terrestrial base station 3-2 via a communication link. A node station 7-2 forming a high altitude network 17 is connected to the terrestrial base station 3-3 via a communication link.

[0025] As the communication path for communication between the terminal station 4 and the core network 14, for example, the communication path that minimizes the cost value calculated by the above-mentioned formula (1) is selected. In the example shown in Figure 2, the communication path R1 from the terminal station 4 to the terrestrial base station 3-1 via the node station 6-1 is selected as the minimum cost path. The communication path R1 includes a communication link L0 connecting the terminal station 4 and the node station 6-1, and a communication link L1 connecting the node station 6-1 and the terrestrial base station 3-1.

[0026] Now, let us assume that the communication environment deteriorates in the communication link L1 connecting the node station 6-1 and the terrestrial base station 3-1, for example, due to signal attenuation caused by rain. When the communication environment deteriorates, data transmitted to the core network 14 via the communication path R1 may be lost. In this case, the lost data must be retransmitted to the terminal station 4, and the retransmission of data reduces throughput.

[0027] In contrast to conventional communication control that has such problems, the wireless communication system 2 performs communication control as will be explained using Fig. 3. In order to clarify the difference between the communication control by the wireless communication system 2 and conventional communication control, the configuration of the wireless network used in the explanation is assumed to be the same as the configuration shown in Fig. 2.

[0028] 3, the wireless communication system 2 includes a network controller 10 disposed in a high altitude network 17. For example, if the high altitude network 17 is a GEO network, the network controller 10 is also mounted on a GEO satellite. However, the network controller 10 may also be disposed in a low altitude network 16 or on the ground. The wireless communication system 2 also includes an aggregation device 12 disposed at the entrance of the core network 14, that is, between the terrestrial base stations 3-1, 3-2, and 3-3 and the core network 14.

[0029] The network controller 10 monitors the status of each communication link that constitutes a communication path. Examples of monitoring methods include measuring the carrier-to-noise ratio (CNR) received at each node station and measuring the number of data retransmissions. The communication links whose status is monitored by the network controller 10 include the communication link L1 that connects the node station 6-1 and the terrestrial base station 3-1. This communication link L1 forms a communication path R1 (first communication path) that connects the terminal station 4 and the core network 14.

[0030] The network controller 10 determines whether the state of the communication link L1 is good or bad. When the state of the communication link is monitored by measuring the reception CNR, if the reception CNR of the communication link L1 is greater than a predetermined threshold (lower limit of the reception CNR), the state of the communication link L1 is determined to be good. When the reception CNR of the communication link L1 is equal to or less than the threshold, the state of the communication link L1 is determined to be bad. When the state of the communication link is monitored by measuring the number of data retransmissions, if the number of retransmissions of the communication link L1 is smaller than a predetermined threshold (upper limit of the number of retransmissions), the state of the communication link L1 is determined to be good. If the number of retransmissions of the communication link L1 is equal to or greater than the threshold, the state of the communication link L1 is determined to be bad.

[0031] When the determination result of the status of the communication link L1 changes from good to bad, that is, when the status of the communication link L1 deteriorates, the network controller 10 establishes one or more other communication paths in addition to the communication path R1. The network controller 10 communicates the same data as that communicated over the communication path R1 over the established other communication paths. In the example shown in Figure 3, a communication path R2 is established as another communication path from the terminal station 4 to the core network 14, which runs from the node station 6-1 to the terrestrial base station 3-3 via the node stations 7-1 and 7-2 of the high altitude network 17.

[0032] 3, the communication link whose status is to be monitored is only communication link L1, but if communication path R1 is made up of more communication links, the network controller 10 monitors the status of all of those communication links. If the status determination result of any one of the communication links being monitored changes from good to bad, the network controller 10 establishes one or more other communication paths in addition to communication path R1.

[0033] When establishing a communication path other than the communication path R1, it may or may not be necessary to consider whether the communication path includes a communication link in which the communication environment is degraded. The communication path may be determined based on the cost value calculated by the above-mentioned formula (1), or the communication path may be determined regardless of the cost value. Furthermore, there is no limit to the number of communication paths to be established. Only one communication path may be established in addition to the communication path R1, or, for example, as many communication paths as possible may be established within a range in which the amount of power used does not exceed a predetermined limit value.

[0034] The communication route R2 shown in Figure 3 is a preferred example for establishing a communication route other than the communication route R1. The communication route R2 using the high altitude network 17 has a larger data propagation delay than the communication route R1 using only the low altitude network 16. On the other hand, the node stations 7-1 and 7-2 that make up the high altitude network 17 each cover a wide communication area, so there is a high possibility that there is a terrestrial base station within the area that can communicate without being affected by attenuation due to rain. Therefore, by establishing a communication route using the high altitude network 17, stable communication can be achieved.

[0035] The aggregation device 12 collects data transmitted from the terminal station 4. Normally, data from the terminal station 4 is communicated via communication path R1, but if the condition of the communication link L1 deteriorates, the network controller 10 establishes at least one other communication path in addition to communication path R1. The aggregation device 12 collects data transmitted from the terminal station 4 from all of these communication paths. In the example shown in FIG. 3 , data from communication path R1 and data from communication path R2 are collected.

[0036] The aggregation device 12 determines whether there is a data loss on communication path R1. Communication path R1 is the communication path with the smallest cost value, i.e., the communication path with the smallest propagation delay. Therefore, although the same data is transmitted from the terminal station 4 to each communication path at the same time, the data on communication path R1 reaches the aggregation device 12 the earliest of all the communication paths. If there is no loss in the data on communication path R1, the aggregation device 12 transmits the data on communication path R1 to the core network 14 as is. In this case, all data that arrives at the aggregation device 12 after the data on communication path R1 is discarded.

[0037] Depending on the degree of deterioration of the condition of communication link L1, some data on communication path R1 may be missing. In the example shown in FIG. 3 , of data 1, 2, and 3 transmitted from terminal station 4, data 2 is missing on communication path R1. In this case, aggregation device 12 does not transmit the data on communication path R1 directly to core network 14, but waits for data on other communication paths to arrive. In the example shown in FIG. 3 , data on communication path R2, which arrived later than the data on communication path R1, contains all of data 1, 2, and 3 without any missing data. As soon as the data on communication path R2 arrives, aggregation device 12 complements data 2 missing in the data on communication path R1 from the data on communication path R2. Then, once all of data 1, 2, and 3 are complete through the complementation, aggregation device 12 transmits the complete data to core network 14.

[0038] 3, the only communication path other than communication path R1 is communication path R2, but if there are other communication paths, data from the other communication paths may be used to complement missing data from communication path R1. For example, if some of the data from communication path R2 is also missing and the data from communication path R2 cannot complement the missing data from communication path R1, the data from the other communication paths is used to complement the missing data from communication path R1. Also, if data from another communication path arrives at the aggregation device 12 before the data from communication path R2, the data from the other communication path may be used to complement the missing data from communication path R1.

[0039] As described above, in the wireless communication system 2, when the condition of any of the communication links constituting the communication path R1 deteriorates, at least one other communication path is established in addition to the communication path R1. If a loss of data occurs in the communication path R1, the lost data is compensated for using data from the other communication paths. This reduces the need for data retransmission when the communication environment deteriorates, thereby improving throughput.

[0040] 3. Configuration of Node Station Next, we will explain the configuration of the node station for realizing the above-mentioned communication control by the wireless communication system 2. Each node station, including the low altitude node stations 6-1 and 6-2 and the high altitude node stations 7-1 and 7-2, is equipped with a node station-mounted communication device 50 having the configuration shown in Figure 4.

[0041] The node station-mounted communication device 50 comprises an inter-node station communication device 51, an inter-terminal station communication device 52, and an inter-terrestrial base station communication device 53. The inter-node station communication device 51 connects a communication link to communicate with nearby node stations. The inter-terminal station communication device 52 connects a communication link to communicate with terminal stations. The inter-terrestrial base station communication device 53 connects a communication link to communicate with terrestrial base stations.

[0042] The node station-mounted communication device 50 further includes a management device 54 and a route control device 55. The management device 54 aggregates information from the inter-node station communication device 51, the inter-terminal station communication device 52, and the inter-terrestrial base station communication device 53, and notifies the network controller 10 of the aggregated information. The management device 54 also notifies the route control device 55 of information notified from the network controller 10. The route control device 55 controls the inter-node station communication device 51, the inter-terminal station communication device 52, and the inter-terrestrial base station communication device 53 in accordance with the information notified from the network controller 10, and controls link connections for establishing communication paths.

[0043] Each of the above-mentioned devices 51, 52, 53, 54, and 55 included in the node station-equipped communication device 50 can be configured by a processing circuit including a general-purpose processor, an application-specific processor, an integrated circuit, an ASIC, an FPGA, a CPU, a conventional circuit, and / or a combination thereof. When the processing circuit includes a memory in which instructions and data are stored and a processor, the functions of each of the above-mentioned devices 51, 52, 53, 54, and 55 can be realized by having the processor execute the instructions. The program can also be recorded on a recording medium or provided via a network.

[0044] 4. Configuration of the Network Controller Next, the configuration of the network controller 10 for realizing the above-described communication control by the wireless communication system 2 will be described with reference to FIG.

[0045] The network controller 10 comprises a management device 101 and a route control device 102. The management device 101 aggregates information notified from each node station and notifies the aggregated information to the route control device 102. The information notified from each node station includes information on the state of the communication link, such as the reception CNR measured by each node station and the number of data retransmissions.

[0046] Based on the information notified from each node station, the route control device 102 determines whether the status of each communication link constituting the communication path is good or bad. As described above, whether the status of a communication link has deteriorated is determined based on whether the received CNR is below a predetermined threshold or whether the number of data retransmissions is above a predetermined threshold. If it is determined that the status of any communication link constituting the communication path has deteriorated, the route control device 102 determines another communication path to be used in parallel with the current communication path and notifies the management device 101 of the determined communication path. Note that the route control device 102 may use either static routing or dynamic routing to determine the communication path.

[0047] When a new communication path to be established is notified by the path control device 102, the management device 101 notifies each node station to establish the new communication path. The management device 101 also notifies each node station to communicate the same data over the newly established communication path as over the existing communication path.

[0048] Each of the devices 101 and 102 included in the network controller 10 can be configured with a processing circuit including a general-purpose processor, an application-specific processor, an integrated circuit, an ASIC, an FPGA, a CPU, a conventional circuit, and / or a combination thereof. When the processing circuit includes a processor and a memory in which instructions and data are stored, the functions of each of the devices 101 and 102 can be realized by having the processor execute the instructions. The program can be recorded on a recording medium or provided via a network.

[0049] 5. Configuration of Aggregation Device Next, the configuration of the aggregation device 12 for realizing the above-described communication control by the wireless communication system 2 will be described with reference to FIG.

[0050] The aggregation device 12 includes a control device 121 and a buffer memory 122. In the buffer memory 122, buffers BFn, BFn+1, BFn+2, ... are allocated for the number of established communication paths. However, these buffers BFn, BFn+1, BFn+2, ... are a set of buffers allocated for one terminal station, and a different set of buffers is allocated for another terminal station. The buffers hold data for the corresponding communication paths. In the example shown in FIG. 3, data for communication path R1 is held in buffer BF1, and data for communication path R2 is held in buffer BF2.

[0051] Each buffer holds the same data transmitted from the same terminal station 4. The control device 121 checks each buffer to determine whether or not there is missing data. Buffer BFn holds data for the first communication path with the smallest cost value, i.e., data for communication path R1 in the example shown in FIG. 3 . If there is no missing data in buffer BFn, the control device 121 transmits the data as is to the core network 14. If there is missing data in buffer BFn, the control device 121 determines whether the missing data can be complemented from another buffer, and complements the missing data from a buffer that can be complemented. The control device 121 then transmits the complemented data in buffer BFn to the core network 14.

[0052] The control device 121 may be configured with a processing circuit including a general-purpose processor, an application-specific processor, an integrated circuit, an ASIC, an FPGA, a CPU, a conventional circuit, and / or a combination thereof. When the processing circuit includes a memory in which instructions and data are stored and a processor, the functions of the control device 121 may be realized by having the processor execute the instructions. The program may be recorded on a recording medium or provided via a network.

[0053] 6. Operation of Network Controller and Aggregation Device The flowcharts shown in Figures 7 and 8 briefly summarize the operations of the network controller 10 and aggregation device 12 configured as described above. The operations shown in these flowcharts correspond to the wireless communication method according to the embodiment of the present disclosure, which is executed by the wireless communication system 2. In the following description, it is assumed that the wireless communication system 2 is configured as in the example shown in Figure 3.

[0054] In step S11 of the flowchart in FIG. 7, the network controller 10 determines whether the reception CNR of the communication link L1 included in the communication path R1 is equal to or less than a threshold. As described above, the state of the communication link L1 may be determined to be good or bad depending on whether the number of times the data is reproduced is equal to or greater than a threshold. If the reception CNR of the communication link L1 is greater than the threshold, the network controller 10 continues to communicate data using only the communication path R1. However, if the reception CNR of the communication link L1 becomes equal to or less than the threshold, the operation of the network controller 10 proceeds to step S12. In step S12, the network controller 10 derives a communication path R2, which is a communication path other than the communication path R1, and communicates the same data as that communicated from the terminal station 4 to the communication path R1 also to the communication path R2.

[0055] 8, in step S21, the aggregation device 12 determines whether there is a loss in the data collected from communication path R1. If there is no loss in the data collected from communication path R1, the aggregation device 12 transmits the data collected from communication path R1 as is to the core network 14. However, if there is a loss in the data collected from communication path R1, the operation of the aggregation device 12 proceeds to step S22.

[0056] In step S22, the aggregation device 12 determines whether a communication path R2 has been established separately from communication path R1. If communication path R2 has been established, the operation of the aggregation device 12 proceeds to step S23. In step S23, the aggregation device 12 determines whether missing data on communication path R1 can be complemented by data collected from communication path R2. If communication path R2 has not been established, or if the missing data cannot be complemented by data collected from communication path R2, the operation of the aggregation device 12 proceeds to step S25. In step S25, the aggregation device 12 requests the terminal station 4 to resend the missing data. After resending the missing data, the operation of the aggregation device 12 proceeds again to step S21. It is determined whether missing data on communication path R1 can be complemented by data collected from communication path R2.

[0057] If communication route R2 is established and the missing data can be complemented with data collected from communication route R2, the operation of the aggregation device 12 proceeds to step S24. In step S24, the aggregation device 12 complements the missing data with the data collected from communication route R2. The aggregation device 12 then transmits the complemented data of communication route R1 to the core network 14.

[0058] As described above, when the condition of a communication link constituting a communication path deteriorates, the network controller 10 and the aggregation device 12 operate to perform parallel communication using another communication path that allows stable communication. Furthermore, when data loss requires retransmission, the lost data is supplemented with data collected from the other communication path. This reduces the number of data retransmissions and increases throughput.

[0059] 2 Wireless communication system 3, 3-1, 3-2, 3-3 Terrestrial base station 4 Terminal station 5A Low altitude node station 5B Medium altitude node station 5C High altitude node station 6-1, 6-2 Low altitude node station 7-1, 7-2 High altitude node station 10 Network controller 12 Aggregation device 14 Core network 15 Non-terrestrial network 15A Low altitude network 15B Medium altitude network 15C High altitude network 16 Low altitude network 17 High altitude network 50 Node station mounted communication device R1, R2 Communication path L0, L1 Communication link

Claims

1. A wireless communication system in which communication between a terminal station and a core network is performed via a wireless network including a plurality of aerial node stations and a plurality of terrestrial base stations, comprising: a network controller that establishes a communication path by linking at least one of the plurality of aerial node stations with one of the plurality of terrestrial base stations; and an aggregation device that aggregates data transmitted from the wireless network to the core network, wherein the network controller is configured to: establish a first communication path; determine whether the status of each of one or more communication links constituting the first communication path is good or bad; and, when the status determination result of any of the one or more communication links changes from good to bad, establish one or more other communication paths in addition to the first communication path; and the aggregation device collects data transmitted from the terminal station from all communication paths including the first communication path and the one or more other communication paths; and transmits the collected data, the data of the first communication path, to the core network. When a loss occurs in data of the first communication path, the lost data is complemented from data of the one or more other communication paths.

2. A wireless communication method for communicating between a terminal station and a core network via a wireless network including a plurality of aerial node stations and a plurality of terrestrial base stations, comprising: establishing a first communication path by linking at least one of the plurality of aerial node stations with one of the plurality of terrestrial base stations; determining whether the status of each of one or more communication links constituting the first communication path is good or bad; establishing one or more other communication paths in addition to the first communication path when the status determination result of any of the one or more communication links changes from good to bad; collecting data transmitted from the terminal station from all communication paths including the first communication path and the one or more other communication paths; transmitting data of the first communication path from the collected data to the core network; and supplementing the missing data from data of the one or more other communication paths when a loss occurs in the data of the first communication path.

3. An aggregating device provided in a wireless communication system that performs communication between a terminal station and a core network via a wireless network including a plurality of aerial node stations and a plurality of terrestrial base stations, and that aggregates data transmitted from the wireless network to the core network, comprising: a buffer memory configured to collect data transmitted from the terminal station from a plurality of communication paths established by linking at least one of the plurality of aerial node stations with one of the plurality of terrestrial base stations; and a processing circuit configured to transmit data of a first communication path included in the plurality of communication paths among the collected data to the core network, and to supplement the missing data from data of one or more other communication paths other than the first communication path when a loss occurs in the data of the first communication path.

4. A program comprising instructions for causing a processor to execute the processing performed by the aggregation device according to claim 3.

Images