COMMUNICATION CONTROL DEVICE, WIRELESS COMMUNICATION SYSTEM, AND COMMUNICATION CONTROL METHOD

Abstract

This makes it possible to satisfy QoS even when the communication capacity of the link fluctuates. [Solution] A communication control device in one embodiment controls multiple links connecting multiple base stations that communicate wirelessly with terminals to a core network via a non-terrestrial relay device, and includes a traffic monitoring unit that acquires and monitors the traffic volume between the terminals and the core network, a communication capacity monitoring unit that acquires and monitors the communication capacity between the relay device and the core network, and a control unit that controls the allocation of sessions to each of the multiple links based on the traffic volume acquired by the traffic monitoring unit and the communication capacity acquired by the communication capacity monitoring unit.

Description

[Technical Field]

[0001] The present invention relates to a communication control device, a wireless communication system, and a communication control method. [Background technology]

[0002] In recent years, mobile communication systems have evolved, making it possible to enjoy mobile services over most of the earth. Ultra-coverage is one of the requirements for the 5th generation (5G) or 6th generation (6G) mobile communication systems that are expected to be commercialized in the future. Ultra-coverage refers to expanding the service area to locations where the construction cost of existing base stations is high or difficult, such as mountains, oceans, and the air.

[0003] There is also a need to strengthen the nation's resilience against natural disasters, and there is a desire for a communications system that is resistant to terrestrial disasters.

[0004] To meet these requirements for wireless communication systems, non-terrestrial networks (NTNs) using satellites and unmanned aerial vehicles (high-altitude platform stations: HAPS) that fly in the stratosphere are attracting attention.

[0005] 1 is a diagram showing an example of the configuration of a wireless communication system 1 using a HAPS. The wireless communication system 1 is, for example, a satellite communication system in which multiple terminals 2 communicate wirelessly with a base station 4 via a non-terrestrial relay device (air vehicle) 3. The base station 4 is connected to a data network 6 via a mobile core network (core network) 5.

[0006] A relay device (aircraft) 3 flying in the stratosphere irradiates a beam onto the ground to form a mobile service area. A terminal 2 on the ground within the mobile service area communicates with an application server (not shown) provided in a mobile core network 5 or a data network 6 via the relay device 3.

[0007] Packets transmitted from terminal 2 are then sent to data network 6 via relay device 3, base station 4, and mobile core network 5. Packets addressed to terminal 2 from data network 6 are also relayed in the same way. The link between terminal 2 and relay device 3 is called a service link, and the link between relay device 3 and base station 4 is called a feeder link.

[0008] For example, when a terminal 2 receives a mobile communication service and communicates with an application server or the like present in the data network 6, traffic travels between the terminal 2 and the application server via a service link or a feeder link. A large communication capacity (broadband) is required in the feeder link to transfer a large amount of traffic from the many terminals 2 receiving the mobile communication service to the data network 6, or from the data network 6 to the terminal 2.

[0009] For this reason, in the feeder link, communication capacity is increased by applying multi-level modulation such as 16QAM or 64QAM. Also, in the wireless communication system 1, in the feeder link, a high frequency band such as the Ka band, which enables a wide band, is often used.

[0010] However, high-frequency radio waves are subject to significant power attenuation due to rainfall. Therefore, if it is raining near base station 4, the received power of base station 4 may decrease due to the effects of rainfall. If the received power decreases, the SNR (signal-to-noise ratio) required for communication may not be achieved, making communication impossible and resulting in a link disconnection.

[0011] In such cases, typical satellite communication systems often use transmission power control to compensate for the temporary drop in received power by adjusting the transmission power. However, the amount of increase in transmission power depends on the performance of devices such as power amplifiers, so there is a limit to the amount of transmission power that can be compensated.

[0012] Fig. 2 is a diagram showing an example of the configuration of a wireless communication system 1a that reduces the effects of rainfall using another method. In the figure, the same reference numerals are used to denote substantially the same components. As shown in Fig. 2, the wireless communication system 1a is configured so that, in addition to the wireless communication system 1 shown in Fig. 1, there are multiple base stations 4.

[0013] In the wireless communication system 1a, the relay device 3 is always connected to a plurality of base stations 4, there are a plurality of feeder links, and a method (dual feeder link) is adopted to reduce the influence of rainfall.

[0014] That is, the wireless communication system 1a can increase the communication capacity of the feeder link by performing simultaneous communication over two links. Also, in the wireless communication system 1a, the two base stations 4 are installed at a large distance from each other, which makes it difficult for each base station 4 to be simultaneously affected by rain, making it easier to avoid simultaneous decreases in the communication capacities of the two feeder links, and reducing the impact of rain.

[0015] Furthermore, general wireless communication systems often use adaptive coding and modulation (ACM), which adaptively changes the modulation method according to the received power, error rate, etc. In adaptive modulation control, when the received power decreases or the error rate increases, control is performed to maintain communication by applying a modulation method with a small number of multi-levels that reduces the SNR required to achieve a predetermined error rate.

[0016] In the DVB-S.2 standard, which is a standard for satellite communications, multiple sets of modulation methods and coding rates (MODCOD) are provided, and the reception status is fed back to the transmitting side, and the set of modulation method and coding rate is adaptively changed depending on the reception status (see, for example, non-patent document 1).

[0017] In addition, by combining adaptive modulation control and dual feeder links, it is possible to further reduce the degradation of received power due to rain. In this case, the communication capacity decreases due to rain on links using modulation schemes with a small number of modulation levels.

[0018] When communications go through a feeder link with reduced communication capacity, the amount of traffic that can be sent and received between the NTN and the ground decreases. Therefore, when communications go through this feeder link, terminals 2 that communicate with data networks 6 connected to mobile core networks 5 may not be able to receive satisfactory service.

[0019] Furthermore, if the services that terminal 2 receives include bandwidth-guaranteed and best-effort services, depending on the traffic generated by communication of the best-effort service, it may not be possible to meet the bandwidth required for bandwidth guarantee in traffic transmission of the bandwidth-guaranteed service.

[0020] This will have a significant impact on service quality in applications classified as Ultra-Reliable and Low-Latency Communication (URLLC), such as disaster monitoring and autonomous driving / driving assistance, which require high reliability as part of guaranteed bandwidth services. Furthermore, there is a possibility that necessary communications will not be possible for terminals requiring priority communications, such as terminals for emergency communications and terminals for communications equipment maintenance. [Prior art documents] [Non-patent literature]

[0021] [Non-Patent Document 1] "Outline of the DVB-S.2 Standard for Transmission Line Coding," Association of Radio Industries and Businesses, Digital Broadcasting System Development Committee, CS Digital Broadcasting Enhancement Working Group, February 24, 2006 Summary of the Invention [Problem to be solved by the invention]

[0022] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a communication control device, a wireless communication system, and a communication control method that make it possible to satisfy QoS even when the communication capacity of a link fluctuates. [Means for solving the problem]

[0023] A communication control device according to one embodiment of the present invention is a communication control device that controls multiple links connecting multiple base stations that communicate wirelessly with terminals via non-terrestrial relay devices to a core network, and is characterized by having: a traffic monitoring unit that acquires and monitors the traffic volume between the terminals and the core network; a communication capacity monitoring unit that acquires and monitors the communication capacity between the relay devices and the core network; and a control unit that controls the allocation of sessions to each of the multiple links based on the traffic volume acquired by the traffic monitoring unit and the communication capacity acquired by the communication capacity monitoring unit.

[0024] In addition, a wireless communication system according to one embodiment of the present invention is a wireless communication system including a plurality of base stations that communicate wirelessly with terminals via non-terrestrial relay devices, and a communication control device that controls a plurality of links connecting the relay devices to each of the base stations and a core network, wherein the communication control device has a traffic monitoring unit that acquires and monitors the traffic volume between the terminals and the core network, a communication capacity monitoring unit that acquires and monitors the communication capacity between the relay devices and the core network, and a control unit that controls the allocation of sessions to each of the plurality of links based on the traffic volume acquired by the traffic monitoring unit and the communication capacity acquired by the communication capacity monitoring unit.

[0025] Furthermore, a communication control method according to one embodiment of the present invention is a communication control method for controlling a plurality of links connecting a plurality of base stations that communicate wirelessly with a terminal to a core network via a non-terrestrial relay device, the method comprising the steps of: a traffic monitoring step of acquiring and monitoring traffic volume between the terminal and the core network; a communication capacity monitoring step of acquiring and monitoring communication capacity between the relay device and the core network; and a control step of controlling the allocation of sessions to each of the plurality of links based on the traffic volume acquired by the traffic monitoring step and the communication capacity acquired by the communication capacity monitoring step. [Effects of the Invention]

[0026] According to the present invention, it is possible to satisfy QoS even when the communication capacity of a link fluctuates. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system using HAPS. [Figure 2] FIG. 10 is a diagram illustrating an example of the configuration of a wireless communication system that reduces the effects of rainfall using another method. [Figure 3] 1 is a diagram illustrating an example of the configuration of a wireless communication system according to an embodiment. [Figure 4] FIG. 2 is a diagram illustrating a configuration example of a relay device (aircraft). [Figure 5] FIG. 1 illustrates an example of a configuration of a communication control device according to an embodiment. [Figure 6] This is a diagram showing the 5G protocol stack (U-plane). [Figure 7] 10 is a flowchart illustrating an example of an operation of the communication control device according to an embodiment. [Figure 8] FIG. 1 illustrates a set of modulation schemes. [Figure 9] FIG. 10 is a diagram illustrating information relating to the communication capacity of a feeder link relative to the amount of precipitation. [Figure 10]FIG. 2 is a diagram illustrating an example of a hardware configuration of a communication control device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0028] [Example 1] 3 is a diagram illustrating a configuration example of a wireless communication system 1b according to an embodiment. The wireless communication system 1b according to an embodiment is, for example, a satellite communication system in which one or more terminals (User Equipment: UE) 2 perform wireless communication with multiple base stations 4 via a non-terrestrial relay device (air vehicle) 3. The base stations 4 are connected to a data network 6 via a mobile core network (core network) 5.

[0029] A relay device (aircraft) 3 flying in the stratosphere irradiates a beam onto the ground to form a mobile service area. A ground terminal 2 located within the mobile service area communicates with, for example, an application server (not shown) provided in a 5G mobile core network 5 or a data network 6 via the relay device 3.

[0030] The terminal 2 and the relay device 3 are connected by a service link (wireless), and the relay device 3 and each of the multiple base stations 4 are connected by multiple feeder links (e.g., a first feeder link and a second feeder link).

[0031] The communication control device 7 controls a plurality of links connecting a plurality of base stations 4 that perform wireless communication with the terminal 2 via the relay device 3 to the mobile core network 5 .

[0032] 4 is a diagram showing an example of the configuration of the relay device (air vehicle) 3. The relay device 3 has a base station function unit 30 that has a function as a 5G base station, for example, in addition to functions such as flight function and power generation / storage function (not shown), and a feeder link transmission function unit 32.

[0033] The base station function unit 30 forms a 5G service area on the ground and communicates with terminals 2 within the service area according to the 5G standard via a service link. The base station function unit 30 also transmits traffic destined for the 5G mobile core network 5, for example, to the feeder link transmission function unit 32. Furthermore, when a new session is generated, the base station function unit 30 cooperates with the feeder link transmission function unit 32 to generate a tunnel according to the GPRS Tunneling Protocol (GTP) in the feeder link specified by the communication control device 7, and forms the session.

[0034] The feeder link transmission function unit 32 establishes link connections with two base stations 4, converts traffic destined for the mobile core network 5 into feeder link radio signals, and transmits the converted signals to the base stations 4. The feeder link transmission function unit 32 also transmits traffic destined for the terminal 2, which is transmitted from the base stations 4 using feeder link radio signals, to the base station function unit 30. Furthermore, the feeder link transmission function unit 32 controls the modulation method for radio transmission in the feeder link by adaptive modulation control. The feeder link transmission function unit 32 then cooperates with the base station function unit 30 to form a session in the feeder link specified by the communication control device 7.

[0035] The base station 4 receives the feeder link radio signal from the relay device 3, restores the original traffic, and transmits it to the mobile core network 5. The base station 4 also converts the traffic transmitted from the mobile core network 5 into a feeder link radio signal and transmits it to the relay device 3. Furthermore, the base station 4, in cooperation with the feeder link transmission function unit 32 in the relay device 3, controls the modulation method for radio transmission in the feeder link by adaptive modulation control.

[0036] The mobile core network 5 performs authentication of the terminal 2, management of the location of the terminal 2, and billing, gateway processing between data networks, and the like.

[0037] 5 is a diagram illustrating an example of the configuration of the communication control device 7 according to an embodiment. As shown in FIG. 5, the communication control device 7 includes a traffic monitoring unit 70, a communication capacity monitoring unit 72, and a control unit 74.

[0038] The traffic monitoring unit 70 has a generated traffic monitoring function that acquires and monitors the amount of traffic between the terminal 2 and the mobile core network 5. For example, the traffic monitoring unit 70 acquires, from the mobile core network 5, information about a session formed between the terminal 2 and the mobile core network 5 (for example, the throughput required for the session). The traffic monitoring unit 70 may also have a function that identifies, based on the service information of the session, whether or not the session is a session for a bandwidth-guaranteed service.

[0039] The communication capacity monitoring unit 72 has a feeder link communication capacity monitoring function that acquires and monitors the communication capacity between the relay device 3 and the mobile core network 5. For example, the communication capacity monitoring unit 72 acquires information on the modulation method being applied to the feeder link from the base station 4 and derives the communication capacity of the feeder link. The communication capacity monitoring unit 72 may further acquire information indicating the amount of fluctuation and stability of the communication capacity between the relay device 3 and the mobile core network 5.

[0040] The control unit 74 controls each unit constituting the communication control device 7. For example, the control unit 74 performs control to allocate sessions (for each session) to each of a plurality of links based on the traffic volume and throughput acquired by the traffic monitoring unit 70 and the communication capacity acquired by the communication capacity monitoring unit 72.

[0041] The control unit 74 may also control allocation of sessions to each of the multiple links based on information indicating the fluctuation and stability of communication capacity acquired by the communication capacity monitoring unit 72. The control unit 74 may also control allocation of sessions to each of the multiple links based on the results identified by the traffic monitoring unit 70.

[0042] Next, an example of operation when the wireless communication system 1b performs 5G communication will be described. Fig. 6 is a diagram showing a 5G protocol stack (U-plane). When the terminal 2 connects to the mobile core network 5 and performs communication, a PDU (Protocol Data Unit) session is formed between the terminal 2 and the mobile core network 5 in an upper layer.

[0043] Furthermore, a GPRS (General Packet Radio Service) tunnel based on the GTP protocol is generated between the base station function unit 30 and the mobile core network 5. The traffic monitoring unit 70 acquires service information for a new session when the terminal 2 is newly connected to the base station function unit 30 of the relay device 3 and a new session is formed between the terminal 2 and the mobile core network 5, as well as service information for sessions that have already been formed.

[0044] Specifically, the service information is information indicating whether the session is of the guaranteed bandwidth type or the best-effort type. Furthermore, the traffic monitoring unit 70 acquires guaranteed bit rate information if the session is of the guaranteed bandwidth type, and acquires maximum bit rate information if the session is of the best-effort type.

[0045] When the terminal 2 newly connects to the base station function unit 30 of the relay device 3 and a new session is formed between the terminal 2 and the mobile core network 5, the control unit 74 derives a feeder link through which the session will be formed, based on the information acquired by the traffic monitoring unit 70. That is, the control unit 74 derives an appropriate feeder link through which a GPRS tunnel will be generated, and notifies the mobile core network 5 and the base station function unit 30 in the relay device 3. The control unit 74 also stores information on the session formed in each feeder link.

[0046] A terminal 2 within the service area connects to an application server (not shown) present in a data network 6 via a relay device 3 and a mobile core network 5, and performs various application communications.

[0047] 7 is a flowchart showing an example of the operation of the communication control device 7 according to an embodiment. First, the communication control device 7 acquires service information of a newly created session and an existing session, and information on the guaranteed bit rate or maximum bit rate (S100).

[0048] Next, the communication control device 7 calculates the total traffic volume of the bandwidth guaranteed service and the best effort service for each feeder link (S102).

[0049] Next, the communication control device 7 acquires modulation method information currently applied to each feeder link (S104), and calculates communication capacities C1 and C2 of each feeder link (S106).

[0050] Next, the communication control device 7 determines a feeder link for creating a new session (S108), and notifies the base station function unit 30 and the mobile core network 5 (S110).

[0051] More specifically, when a new session is established between the terminal 2 and the mobile core network 5, the communication control device 7 first acquires service information of the session to be established. In addition, the communication control device 7 acquires service information of existing sessions in each feeder link.

[0052] Next, communication control device 7 calculates the total traffic volume of the bandwidth guaranteed service and best-effort service in each feeder link from the information of existing sessions. If the total traffic volumes of the bandwidth guaranteed service and best-effort service in the first feeder link are TG1 and TB1, respectively, TG1 and TB1 are calculated using the following equations (1) and (2), respectively.

[0053]

number

number

[0054] where L1 and K1 are the number of sessions for the guaranteed bandwidth service and the best-effort service in the first feeder link, sg1(i) is the guaranteed bit rate of the i-th guaranteed bandwidth service in the first feeder link, and sb1(j) is the maximum bit rate of the j-th best-effort service in the first feeder link.

[0055] Similarly, communication control device 7 calculates total traffic volumes TG and TB2 of the bandwidth guaranteed service and best effort service in the second feeder link.

[0056] Next, the communication control device 7 acquires information on the modulation method being applied from each base station 4, derives the communication capacities C1 and C2 of the first and second feeder links, and calculates the ratio RC of C1 and C2 (RC=C1 / C2).

[0057] Next, the communication control device 7 determines the feeder link for forming the newly formed session, i.e., the feeder link for creating the GPRS tunnel. If the new session is a bandwidth-guaranteed session, and the guaranteed bit rate of the new session is nsg, the estimated total traffic volume when allocated to the first feeder link is TG1+nsg.

[0058] In this case, the ratio RTG_1 of the total traffic volume of the bandwidth guaranteed service in the first feeder link to the total traffic volume in the second feeder link is calculated by the following formula (3).

[0059]

number

[0060] Similarly, the estimated total traffic volume when allocated to the second feeder link is TG2+nsg, and the ratio RTG_2 of the total traffic volume of the bandwidth-guaranteed service on the first feeder link to the total traffic volume on the second feeder link is calculated by the following equation (4):

[0061]

number

[0062] Here, the communication control device 7 determines that if RTG_1 is closer to the RC, the new session will be formed on the first feeder link, and if RTG_2 is closer to the RC, the new session will be formed on the second feeder link.

[0063] Similarly, if the new session is of the best effort type, and the maximum bit rate of the new session is nsb, the estimated total traffic volume when allocated to the first feeder link is TB1+nsb.

[0064] At this time, the ratio RTB_1 of the total traffic volume of the best-effort service on the first feeder link to the second feeder link is calculated by the following formula (5).

[0065]

number

[0066] Similarly, the estimated total traffic volume when allocated to the second feeder link is TB2+nsb, and the ratio RTB_2 of the total traffic volume of the bandwidth-guaranteed service on the first feeder link to the second feeder link is calculated using the following equation (6):

[0067]

number

[0068] Here, the communication control device 7 decides to form the new session on the first feeder link if RTB_1 is closer to the RC, and decides to form the new session on the second feeder link if RTB_2 is closer to the RC.

[0069] Then, after determining the feeder link for establishing the new session, the communication control device 7 notifies the determined information to the base station function unit 30 in the relay device 3 and the mobile core network 5. Based on the notified information, the base station function unit 30 generates a GPRS tunnel in the determined feeder link and establishes a new session with the mobile core network 5.

[0070] The following describes a specific example of the operation of the communication control device 7. Here, it is assumed that the service provided to the terminal 2 is only a best-effort service.

[0071] The adaptive modulation control in the first feeder link and the second feeder link is performed using the set shown in Fig. 8. When the packet error rate observed in a certain period exceeds a certain value (for example, 0.1), the communication control device 7 selects the modulation method with the next lower item number (a smaller item number). When the packet error rate observed in a certain period falls below the certain value, the communication control device 7 selects the modulation method with the next higher item number (a larger item number).

[0072] The first feeder link and the second feeder link have different bandwidths due to differences in the performance of the radio equipment each equipped in base station 4. The communication capacity C1 of the first feeder link is 1000 Mbit / s (when modulation method No. 4 is applied), and the communication capacity C2 of the second feeder link is 500 Mbit / s (when modulation method No. 4 is applied).

[0073] Here, it is assumed that initially, there are ten terminals 2 in the mobile service area, and they are connected to the data network 6 and performing communications.

[0074] Terminal 2 receives a web browsing service (best effort type), and the maximum bit rate for web browsing is 50 Mbit / s.

[0075] The first feeder link and the second feeder link normally use the modulation method of item number 4, and have communication capacities C1=1000 Mbit / s and C2=500 Mbit / s, respectively. The number of sessions formed in the first feeder link is 8, and the number of sessions formed in the second feeder link is 2. Session information generated in each of these feeder links is stored in the communication control device 7.

[0076] Now, suppose that a new terminal 2 connects to the communication system and starts communication. First, the communication control device 7 acquires session information for the best-effort service and the maximum bit rate for the web browsing service based on the flow shown in Figure 7. Furthermore, the communication control device 7 determines the number of sessions formed in each feeder link based on the stored information.

[0077] Next, the communication control device 7 calculates the total traffic volume of the best-effort service in each feeder link. For the first feeder link, the number of sessions for terminal 2 of the web browsing service is 8, so TB1 is calculated as 8×50=400. Similarly, for the second feeder link, TB2 is calculated as 2×50=100.

[0078] Next, the communication control device 7 acquires information on the modulation methods applied to the first and second feeder links, derives communication capacities C1 and C2, and calculates the ratio RC of C1 and C2. For example, since the modulation method of item number 4 is used in each feeder link, and C1=1000 Mbit / s and C2=500 Mbit / s, the calculation is RC=1000 / 500=2.

[0079] Next, the control unit 74 determines a feeder link that will form a session for connecting the new terminal 2. RTB_1 and RTB_2 are calculated as in the following equations (7) and (8).

[0080]

number

number

[0081] Since the value of RTG_2 is closer to the value of RC, the communication control device 7 decides to create a new session in the second feeder link. Then, the communication control device 7 notifies the base station function unit 30 in the relay device 3 and the mobile core network 5 that a new session will be created in the second feeder link. Based on the notified information, the base station function unit 30 creates a new session with the mobile core network 5 via the second feeder link.

[0082] At this time, the traffic volumes in the first and second feeder links are 400 Mbit / s and 150 Mbit / s, respectively. After this, it rains around one base station 4, causing the packet error rate to deteriorate, so that the modulation method of item number 1 is applied to the first feeder link by adaptive modulation control.

[0083] In this case, the communication capacity of the first feeder link is 1000×2 / 5=400 [Mbit / s] because the transmission bits per symbol are reduced from 5 bits to 2 bits.

[0084] However, since the traffic volume is below the communication capacity and all traffic can be transmitted over the first feeder link, no degradation in throughput occurs in terminal 2.

[0085] By performing the above control, the communication control device 7 can appropriately determine the feeder link for the session to be generated in the dual feeder link, and can reduce the decrease in throughput at the terminal 2 even if the communication capacity of the feeder link decreases due to rainfall.

[0086] If the communication control device 7 were to form a new session on the first feeder link, the traffic volume on the first feeder link would be 450 Mbit / s, and the first feeder link to which the modulation method of item 1 is applied would be unable to transmit all of the traffic due to rainfall, resulting in a decrease in the throughput of terminal 2.

[0087] [Example 2] In the first embodiment, the communication control device 7 acquires information about the communication capacity of the feeder link and performs control, but in the second embodiment, the communication control device 7 predicts the communication capacity of the feeder link and performs control in advance.

[0088] The communication capacity monitoring unit 72 shown in Fig. 5 has a device that stores past fluctuations in communication capacity in response to weather. For example, as shown in Fig. 9, the communication capacity monitoring unit 72 stores information on the communication capacity of the feeder link in response to precipitation based on past statistics. The communication capacity monitoring unit 72 also has an interface for accessing a weather forecast site to obtain information on weather forecasts.

[0089] For example, if the communication control device 7 obtains information from a weather forecasting site and predicts that 10 mm of precipitation will occur in the next hour, it predicts that the communication capacity of the first feeder link will be 600 Mbit / s based on FIG. 9, and performs control to determine an appropriate feeder link for the new session to be created.

[0090] By performing the above control, the communication control device 7 can perform control according to pre-settings based on weather forecasts, and can quickly respond to fluctuations in the communication capacity of the feeder link due to weather.

[0091] [Example 3] In the first embodiment, control is performed assuming a single service in terminal 2, but in the third embodiment, it is assumed that a bandwidth-guaranteed service and a non-bandwidth-guaranteed service (best-effort service) exist in terminal 2. Here, it is assumed that the configuration of wireless communication system 1b, and the configurations of relay device 3 and communication control device 7 are the same as those shown in Fig. 3, Fig. 4, and Fig. 5. It is also assumed that the operation performed by communication control device 7 is the same as that shown in Fig. 7.

[0092] A specific example of the operation of the communication control device 7 in the third embodiment will be described below. Here, the communication control device 7 performs adaptive modulation control in the first feeder link and the second feeder link as a set shown in Fig. 8. The communication capacity C1 of the first feeder link is a maximum of 1000 Mbit / s (when the modulation method of item No. 4 is applied), and the communication capacity C2 of the second feeder link is a maximum of 500 Mbit / s (when the modulation method of item No. 4 is applied).

[0093] Here, initially, there are 65 terminals 2 in the mobile service area, which are connected to the data network 6 and communicating. For example, 55 of them are cameras for a disaster monitoring service (guaranteed bandwidth type), and the remaining 10 are terminals 2 for a web browsing service (best effort type).

[0094] The guaranteed bit rate for the disaster monitoring service is 10 Mbit / s, and the maximum bit rate for web browsing is 50 Mbit / s. The first and second feeder links normally use the modulation method specified in item 4, with communication capacities C1 = 1000 Mbit / s and C2 = 500 Mbit / s, respectively.

[0095] Here, in the first feeder link, the number of sessions of terminal 2 for the disaster monitoring service is 35 and the number of sessions of terminal 2 for the web browsing service is 8, and in the second feeder link, the number of sessions of terminal 2 for the disaster monitoring service is 20 and the number of sessions of terminal 2 for the web browsing service is 2. The session information formed in each of these feeder links is stored in the communication control device 7.

[0096] Now, suppose that a new terminal 2 providing the disaster monitoring service connects to the wireless communication system 1b and starts communication. First, the communication control device 7 acquires the number of sessions receiving the disaster monitoring service and the web browsing service, the guaranteed bit rate for the disaster monitoring service, and the maximum bit rate for the web browsing service, based on the flowchart shown in Figure 7. Furthermore, the communication control device 7 identifies the sessions formed in each feeder link based on the stored information.

[0097] Next, communication control device 7 calculates the total traffic volume of the bandwidth-guaranteed and best-effort services for each feeder link. For the first feeder link, the number of sessions for terminal 2 for the disaster monitoring service is 35, and the number of sessions for terminal 2 for the web browsing service is 8, so the calculations are TG1 = 35 x 10 = 350 and TB1 = 8 x 50 = 400. Similarly, for the second feeder link, the calculations are TG2 = 20 x 10 = 200 and TB2 = 2 x 50 = 100.

[0098] Next, the communication control device 7 derives the communication capacities C1 and C2 of the first and second feeder links, and calculates the ratio RC of C1 and C2. Here, since C1=1000 Mbit / s and C2=500 Mbit / s, the calculation is RC=1000 / 500=2.

[0099] Next, the communication control device 7 determines a feeder link for forming a new session. Since the new session is a bandwidth guaranteed session, the communication control device 7 calculates RTG_1 and RTG_2 using the following equations (9) and (10).

[0100]

number

number

[0101] The communication control device 7 determines to establish a session in the first feeder link because RTG_1 is closer to RC. The communication control device 7 also notifies the base station function unit 30 in the relay device 3 and the mobile core network 5 that a session will be established in the first feeder link. Based on the notified information, the base station function unit 30 establishes a new session with the mobile core network 5 via the first feeder link.

[0102] In this case, the traffic volumes in the first and second feeder links are 36×10+8×50=760 Mbit / s and 20×10+2×50=300 Mbit / s, respectively.

[0103] After that, it rains around one base station 4, causing the packet error rate to deteriorate, so adaptive modulation control applies modulation scheme 1 to the first feeder link. At this time, the communication capacity of the first feeder link becomes 1000 × 2 / 5 = 400 [Mbit / s] because the transmission bits per symbol drops from 5 bits to 2 bits.

[0104] Since the traffic volume of the first feeder link exceeds the communication capacity, if this continues, a decrease in throughput will occur at terminal 2. Here, the communication control device 7 performs control to set a lower maximum bit rate for the best-effort service. Specifically, the communication control device 7 sets the maximum bit rate to 5 Mbit / s.

[0105] As a result, the traffic volume in the first feeder link becomes 36×10+5×8=400 [Mbit / s], and since all traffic can be transmitted over the first feeder link, there is no decrease in throughput in terminal 2 of the bandwidth-guaranteed service.

[0106] By performing the above control, the communication control device 7 can appropriately determine the feeder link for the session to be formed in the dual feeder link, and even if the communication capacity of the feeder link decreases due to rainfall, it can limit the bit rate of non-bandwidth guaranteed (best effort) services, secure communication capacity for traffic for bandwidth guaranteed services, and guarantee the bit rate of bandwidth guaranteed services.

[0107] If a new session is formed on the second feeder link, the number of sessions for the bandwidth guaranteed service on the second feeder link will be 21, and the total traffic volume of the bandwidth guaranteed service on the second feeder link will be 210 Mbit / s.

[0108] If the communication capacity of the first feeder link drops, similar control will not cause any problems, but if it rains around another base station 4 and the modulation method of item 1 is applied to the second feeder link, the capacity will be 500 × 2 / 5 = 200 Mbit / s, and the second feeder link will not be able to transmit or receive all the traffic for the bandwidth guaranteed service. This will affect the bandwidth guaranteed service of the 21 terminals 2 that have formed sessions on the second feeder link.

[0109] In the third embodiment, it is assumed that there is only one bandwidth guaranteed service and one best-effort service, but even if there are multiple bandwidth guaranteed services and multiple best-effort services, similar processing can be performed by using the guaranteed bit rate and maximum bit rate information of each service.

[0110] [Example 4] In Examples 1 and 2, it was assumed that rainfall would reduce the communication capacity of the feeder link. In a dual feeder link, two base stations 4 are installed as far apart as possible to prevent both base stations 4 from being affected by rain at the same time. Therefore, depending on the time of year and location, one of the base stations 4 may be less affected by rain.

[0111] Furthermore, if one of the base stations 4 is equipped with a high-performance antenna or device, and a high gain can be obtained, the system may be less susceptible to the effects of rain.

[0112] If there is a feeder link that is less susceptible to the effects of rainfall and has stable communication capacity, service quality can be stabilized by controlling the generation of sessions on this feeder link on a priority basis for bandwidth-guaranteed services or services for which momentary interruptions have a significant impact on service quality.

[0113] The communication capacity monitoring unit 72 of the communication control device 7 shown in FIG. 5 acquires information on the modulation method applied to the feeder link and derives the communication capacity, while observing the amount of fluctuation in the communication capacity of the feeder link within a certain period of time.

[0114] For example, when the modulation method shown in FIG. 8 is applied to a certain feeder link, if there are many periods of time during which the modulation method of item 3 or 4 is applied within a certain period of time, the communication capacity monitoring unit 72 determines that the feeder link is less susceptible to the effects of rain and less likely to experience a decrease in communication capacity during this period, and allocates sessions of the bandwidth-guaranteed service preferentially.

[0115] Conversely, if there are many time periods during which item 1 or item 2 is applied within a certain period of time, the communication capacity monitoring unit 72 determines that the feeder link is susceptible to the effects of rain and a decrease in communication capacity during this period, and allocates best-effort service sessions preferentially.

[0116] In this way, the communication control device 7 controls the allocation of sessions to each of multiple links based on the traffic volume acquired by the traffic monitoring unit 70 and the communication capacity acquired by the communication capacity monitoring unit 72, making it possible to satisfy QoS even when the communication capacity of the links fluctuates.

[0117] Furthermore, the wireless communication system 1b has multiple links between multiple base stations 4 and the mobile core network 5, and selects the optimal link for each session, thereby reducing the decrease in transmission speed of each session even when the communication capacity of the link drops due to rainfall, etc. Furthermore, the wireless communication system 1b selects the optimal link for each session based on the service quality required for the session, thereby reducing the deterioration of service quality.

[0118] In addition, each function of the communication control device 7 may be partially or entirely configured by hardware such as a PLD (Programmable Logic Device) or an FPGA (Field Programmable Gate Array), or may be configured as a program executed by a processor such as a CPU.

[0119] For example, the communication control device 7 can be realized using a computer and a program, and the program can be recorded on a storage medium or provided via a network.

[0120] 10 is a diagram illustrating an example of a hardware configuration of a communication control device 7 according to an embodiment. As illustrated in FIG. 10, the communication control device 7 has, for example, an input unit 700, an output unit 710, a communication unit 720, a CPU 730, a memory 740, and an HDD 750 connected via a bus 760, and has the functionality of a computer. The communication control device 7 is also configured to be able to input and output data to and from a computer-readable storage medium 770.

[0121] The input unit 700 is, for example, a keyboard and a mouse. The output unit 710 is, for example, a display device such as a display that outputs images. The communication unit 720 is, for example, a network interface, and may have a function as an output unit that outputs data to the outside.

[0122] As described above, the CPU 730 controls each unit constituting the communication control device 7 and performs predetermined processing, etc. The memory 740 and the HDD 750 are storage units that store data, etc.

[0123] The storage medium 770 is capable of storing programs and the like that cause the communication control device 7 to execute the functions of the communication control device 7. Note that the architecture that configures the communication control device 7 is not limited to the example shown in FIG. [Explanation of symbols]

[0124] 1, 1a, 1b... wireless communication system, 2... terminal, 3... relay device, 4... base station, 5... mobile core network, 6... data network, 7... communication control device, 30... base station function unit, 32... feeder link transmission function unit, 70... traffic monitoring unit, 72... communication capacity monitoring unit, 74... control unit, 700... input unit, 710... output unit, 720... communication unit, 730... CPU, 740... memory, 750... HDD, 760... bus, 770... storage medium

Claims

1. A communication control device controls a plurality of links connecting a plurality of base stations that perform wireless communication with terminals via non-terrestrial relay devices to a core network, a traffic monitoring unit that acquires and monitors a traffic volume between the terminal and the core network; a communication capacity monitoring unit that acquires and monitors a communication capacity between the relay device and the core network; a control unit that controls allocation of sessions to each of the plurality of links based on the traffic volume acquired by the traffic monitoring unit and the communication capacity acquired by the communication capacity monitoring unit; A communication control device comprising:

2. The traffic monitoring unit Get more throughput required for the session, The control unit Controlling allocation for each session to each of the plurality of links based on the throughput acquired by the traffic monitoring unit.

2. The communication control device according to claim 1, wherein:

3. The communication capacity monitoring unit further acquiring information indicating fluctuations and stability of communication capacity between the relay device and the core network; The control unit Controlling allocation for each session to each of the plurality of links based on information indicating fluctuations and stability of communication capacity acquired by the communication capacity monitoring unit.

3. The communication control device according to claim 2, wherein:

4. The traffic monitoring unit Identifying whether the session is a session for a bandwidth-guaranteed service based on the service information of the session; The control unit Based on the results identified by the traffic monitoring unit, control is performed to allocate sessions to each of the plurality of links.

4. The communication control device according to claim 1, wherein:

5. The communication capacity monitoring unit A predicted value of communication capacity based on information obtained from an external source is regarded as the communication capacity between the relay device and the core network.

4. The communication control device according to claim 1, wherein:

6. A wireless communication system including a plurality of base stations that perform wireless communication with terminals via non-terrestrial relay devices, and a communication control device that controls a plurality of links connecting the relay devices to each of the base stations and a core network, The communication control device a traffic monitoring unit that acquires and monitors a traffic volume between the terminal and the core network; a communication capacity monitoring unit that acquires and monitors a communication capacity between the relay device and the core network; a control unit that controls allocation of sessions to each of the plurality of links based on the traffic volume acquired by the traffic monitoring unit and the communication capacity acquired by the communication capacity monitoring unit; A wireless communication system comprising:

7. The traffic monitoring unit Get more throughput required for the session, The control unit Controlling allocation for each session to each of the plurality of links based on the throughput acquired by the traffic monitoring unit.

7. The wireless communication system according to claim 6, wherein:

8. A communication control method for controlling a plurality of links connecting a plurality of base stations that communicate with a terminal via a non-terrestrial relay device to a core network, comprising: a traffic monitoring step of acquiring and monitoring a traffic volume between the terminal and the core network; a communication capacity monitoring step of acquiring and monitoring a communication capacity between the relay device and the core network; a control step of controlling allocation of sessions to each of the plurality of links based on the traffic volume acquired in the traffic monitoring step and the communication capacity acquired in the communication capacity monitoring step; A communication control method comprising:

Images