Control device and switching control method

Abstract

A control device for a communication system involving both one-way communication and round-trip communication, the control device comprising: a required delay acquisition unit that uses coordination information to acquire, for each traffic, information on required delay and priority information regarding the traffic, the coordination information being obtained by traffic transmitted from a plurality of wireless terminals and indicating communication states between the plurality of wireless terminals and a base station that performs wireless communication with the plurality of wireless terminals; a traffic-specific congestion calculation unit that calculates a congestion delay in a wired section on the basis of the priority information acquired by the required delay acquisition unit for each traffic; a round-trip delay calculation unit that calculates a round-trip delay on the basis of the congestion delay in the wired section calculated by the traffic-specific congestion calculation unit and a downlink delay; and a path change control unit that transmits, if the round-trip delay calculated by the round-trip delay calculation unit does not satisfy the required delay, a control signal including an instruction to switch a path to a relay device that relays the traffic.　

Description

[Technical Field]

[0001] The present invention relates to a control device and a switching control method. [Background technology]

[0002] Conventional communication control using route switching to achieve low latency communications controls one-way communications according to the latency requirements and traffic volume. In the future, it is expected that use cases for round-trip communications, such as remote control in real time based on video, will increase. When performing real-time remote control based on video, the latency requirement for the round-trip from video transmission to control reflection will become the latency requirement for the application. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Chao Zhou, “Deadline and Priority-aware Congestion Control for Delay-sensitive Multimedia Streaming”, MM '21, October 20-24, 2021. [Non-patent document 2] Bowen Bao, “TDTS: Three-Dimensional Traffic Scheduling in Optical Fronthaul Networks with Conv-LSTM”, Photonics 2021. [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-14112 Summary of the Invention [Problem to be solved by the invention]

[0005] In a system where one-way and round-trip communications coexist, if control is performed based on the latency requirements for one-way communications as in the past, route switching will be performed even in cases where route switching is not necessary when considering round-trip communications. In such cases, unnecessary switching will cause delays. As a result, the delays and overhead caused by switching may make it impossible to achieve high-capacity, low-latency communications.

[0006] In view of the above circumstances, an object of the present invention is to provide a technology that can realize large-capacity, low-latency communication in a system in which one-way communication and round-trip communication coexist. [Means for solving the problem]

[0007] One aspect of the present invention is a control device in a communication system in which one-way communication and round-trip communication coexist, comprising: a required delay acquisition unit that acquires, for each traffic, information on the required delay and priority of the traffic based on coordination information obtained from traffic transmitted from a plurality of wireless terminals and indicating the communication status between the plurality of wireless terminals and a base station that performs wireless communication; a traffic-specific congestion calculation unit that calculates a congestion delay in a wired section based on the priority information acquired for each traffic by the required delay acquisition unit; a round-trip delay calculation unit that calculates a round-trip delay based on the congestion delay in the wired section calculated by the traffic-specific congestion calculation unit and the downlink delay; and a route change control unit that transmits a control signal including an instruction to switch routes to a relay device that relays the traffic if the round-trip delay calculated by the round-trip delay calculation unit does not satisfy the required delay.

[0008] One aspect of the present invention is a switching control method performed by a control device in a communication system in which one-way communication and round-trip communication are mixed, the switching control method comprising: obtaining, for each traffic, information on the required delay and priority information for the traffic based on coordination information obtained from traffic transmitted from a plurality of wireless terminals and indicating the communication status between the plurality of wireless terminals and a base station that performs wireless communication; calculating a congestion delay in a wired section based on the priority information obtained for each traffic; calculating a round-trip delay based on the calculated congestion delay in the wired section and the delay in the downlink direction; and, if the round-trip delay does not satisfy the required delay, transmitting a control signal including an instruction to switch paths to a relay device that relays the traffic. [Effects of the Invention]

[0009] The present invention makes it possible to realize high-capacity, low-latency communication in a system in which one-way communication and round-trip communication coexist. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram for explaining the overall configuration of a mobile NW system according to the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of each device in the mobile NW system according to the first embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of the configuration of a traffic-specific congestion calculation unit in the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining a process of calculating congestion delay by priority performed by a traffic-specific congestion calculation unit in the first embodiment. [Figure 5] 4 is a flowchart showing a processing flow of a control device in the first embodiment. [Figure 6] FIG. 3 is a sequence diagram showing a processing flow of the mobile NW system in the first embodiment. [Figure 7] FIG. 10 is a diagram illustrating an example of the configuration of each device in a mobile NW system according to a second embodiment. [Figure 8]FIG. 10 is a diagram illustrating an example of the configuration of a transmission delay determination unit in the second embodiment. [Figure 9] FIG. 10 is a diagram illustrating an example of the configuration of each device in a mobile NW system according to a third embodiment. [Figure 10] FIG. 11 is a diagram illustrating an example of the configuration of a required delay calculation unit in the third embodiment. [Figure 11] FIG. 13 is a diagram illustrating an example of the configuration of each device in a mobile NW system according to a fourth embodiment. [Figure 12] FIG. 13 is a diagram illustrating an example of the configuration of each device in a mobile NW system according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. (Overall composition) FIG. 1 is a diagram illustrating the overall configuration of a mobile NW system 100 according to the present invention. First, the overall configuration of the mobile NW system 100 will be described. The mobile NW system 100 is, for example, a fifth-generation mobile communication system (hereinafter referred to as "5G"). The mobile NW system 100 is an example of a communication system. The mobile NW system 100 includes one or more base stations 10, multiple Ph-GWs 20, a server 30, and a control device 40. The example shown in FIG. 1 illustrates a case where there is one base station 10 and three Ph-GWs 20. Hereinafter, the direction from the base station 10 to the server 30 is referred to as the uplink direction, and the direction from the server 30 to the base station 10 is referred to as the downlink direction.

[0012] Optical fibers that transmit optical signals are connected between the base station 10 and Ph-GW20-1, between Ph-GW20-1 and Ph-GW20-2, between Ph-GW20-1 and Ph-GW20-3, between Ph-GW20-2 and server 30, and between Ph-GW20-3 and server 30. Electrical wires or optical fibers that transmit electrical signals are connected between the base station 10 and the control device 40, and between Ph-GW20 and control device 40.

[0013] The base station 10 includes one or more antennas and performs wireless communication with the wireless terminal 60. For example, each base station 10 receives a signal indicating a traffic request amount or actual traffic from the wireless terminal 60. The actual traffic is a signal addressed to the server 30. The traffic transmitted from the wireless terminal 60 is one-way traffic or round-trip traffic. Here, one-way traffic is, for example, traffic transmitted from the wireless terminal 60 to the server 30 that does not require a response. Round-trip traffic is, for example, traffic transmitted from the wireless terminal 60 to the server 30 that requires a response to that traffic. The base station 10 is, for example, a Distributed Unit (DU) in the 5G communication standard. The base station 10 acquires cooperation information based on the signal indicating the traffic request amount.

[0014] The cooperation information is information indicating the state of communication between each base station 10 and the wireless terminal 60. The cooperation information includes, for example, wireless quality information. The cooperation information includes, for example, information on traffic volume. The cooperation information includes, for example, traffic allocation information. The cooperation information includes, for example, IP addresses. The wireless quality information is, for example, 5QI (5 QoS Identifier) in the 5G communication standard. The traffic allocation information is, for example, Transport Block Size (TBS) and Buffer Status Report (BSR) for each logical channel.

[0015] The Ph-GW 20 is a relay device equipped with an optical switch. The Ph-GW 20 switches the path in accordance with an instruction from the control device 40.

[0016] The server 30 receives traffic transmitted from the wireless terminal 60. If the received traffic is round-trip traffic, the server 30 provides the wireless terminal 60 with a response according to the traffic transmitted from the wireless terminal 60. The server 30 is a higher-level device.

[0017] The control device 40 acquires cooperation information from the base station 10. Based on the acquired cooperation information, the control device 40 instructs the Ph-GW 20 to switch the path. Specifically, the control device 40 instructs the Ph-GW 20 to switch the path when the required delay is not satisfied.

[0018] The core network 50 is, for example, an optical network.

[0019] The wireless terminal 60 transmits traffic. The traffic transmitted by the wireless terminal 60 is a signal indicating the requested amount of traffic or actual traffic, which is transmission data addressed to the server 30. The wireless terminal 60 performs round-trip communication or one-way communication. One-way communication is communication in only the uplink or downlink direction. Round-trip communication is communication in both the uplink and downlink directions.

[0020] (First embodiment) In the first embodiment, a configuration will be described in which the number of times switching is reduced by determining switching based on round-trip delay using round-trip delay requirements.

[0021] Fig. 2 is a diagram illustrating an example of the configuration of each device in the mobile NW system 100 in the first embodiment. Fig. 2 illustrates a base station 10, a Ph-GW 20, a server 30, a control device 40, and a wireless terminal 60, but here, specific configurations of the base station 10, the Ph-GW 20-1, and the control device 40 will be described.

[0022] The base station 10 includes an information acquisition unit 11. The information acquisition unit 11 acquires a traffic request amount (BSR) and radio quality information (CQI) from traffic transmitted from the wireless terminal 60. The information acquisition unit 11 acquires a traffic volume (TBS) based on the acquired traffic request amount (BSR) and radio quality information (CQI). The information acquisition unit 11 transmits the acquired radio quality information and traffic volume to the control device 40 as link information. When the base station 10 receives actual traffic from the wireless terminal 60, it transmits the received signal to the Ph-GW 20-1.

[0023] The control device 40 includes a required delay calculation unit 41, a traffic-specific congestion calculation unit 42, a round-trip delay calculation unit 43, and a route change instruction unit 44. The required delay calculation unit 41 calculates the required delay and traffic priority for each traffic based on wireless quality information transmitted from the base station 10. The required delay represents, for example, the allowable delay time for a round-trip flow.

[0024] The traffic-specific congestion calculation unit 42 calculates congestion delay based on information on the priority of each traffic type and information on the traffic volume included in the cooperation information transmitted from each base station 10. For example, the traffic-specific congestion calculation unit 42 sorts the traffic transmitted from each wireless terminal 60 according to the traffic priority calculated by the required delay calculation unit 41, and calculates congestion delay based on the bandwidth of the wired section obtained in advance.

[0025] The round-trip delay calculation unit 43 calculates a round-trip delay based on the congestion delay obtained by the traffic-specific congestion calculation unit 42, the delay time in the downlink direction in the wired section, and the propagation delay in the wireless section. Information on the delay time in the downlink direction in the wired section is acquired by the Ph-GW 20-1 and notified to the round-trip delay calculation unit 43. Note that the Ph-GW 20-1 may measure the delay time in the downlink direction using ping, or may measure the delay time in the downlink direction by attaching a timestamp to traffic transmission and transmitting it. Information on the propagation delay in the wireless section is acquired by the base station 10 and notified to the round-trip delay calculation unit 43. Note that the information on the propagation delay in the wireless section may also be acquired by the wireless terminal 60. In this case, the wireless terminal 60 includes the acquired information on the propagation delay in the wireless section in cooperation information and transmits it to the base station 10.

[0026] The route change instruction unit 44 determines whether the delay requirement is satisfied based on the required delay calculated by the required delay calculation unit 41 and the round-trip delay calculated by the round-trip delay calculation unit 43. Specifically, the route change instruction unit 44 determines whether the delay requirement is satisfied by comparing the required delay calculated by the required delay calculation unit 41 with the round-trip delay calculated by the round-trip delay calculation unit 43.

[0027] If the round-trip delay is within the delay requirement, the route change instruction unit 44 determines that the delay requirement is met. On the other hand, if the round-trip delay exceeds the delay requirement, the route change instruction unit 44 determines that the delay requirement is not met. If the delay requirement is not met, the route change instruction unit 44 generates a control signal including an instruction to switch to another optical path and transmits the control signal to Ph-GW20-1.

[0028] Ph-GW20-1 includes an information acquisition unit 21 and a route change unit 22. The information acquisition unit 21 acquires information on downstream delay times. The route change unit 22 switches routes based on a control signal transmitted from the control device 40. For example, when Ph-GW20-1 is connected to a route that outputs upstream traffic to Ph-GW20-2, the route change unit 22 switches the route so that the upstream traffic is output to another route (for example, Ph-GW20-3).

[0029] 3 is a diagram showing an example of the configuration of the traffic-based congestion calculation unit 42 in the first embodiment. The traffic-based congestion calculation unit 42 includes a traffic priority-based rearrangement unit 421 and a priority-based congestion delay calculation unit 422.

[0030] Traffic priority sorting unit 421 receives information on the priority of traffic determined by traffic priority calculation unit 413 and information on the traffic volume determined by traffic volume calculation unit 415. Traffic priority sorting unit 421 sorts the traffic in descending order of priority based on the input traffic priority information and traffic volume information.

[0031] The priority-based congestion delay calculation unit 422 calculates congestion delay using the traffic volume, link rate, and queuing volume, starting with the highest priority. In this way, the priority-based congestion delay calculation unit 422 calculates the congestion delay of traffic by priority. The calculation granularity is performed at intervals shorter than the required delay from the viewpoint of calculation time. It may also be calculated at the transmission interval of traffic in the wireless section. Whether the calculation cycle is independent or common, it is performed so as to satisfy strict required delays.

[0032] If the required delay differs depending on the priority, to reduce the calculation load, higher priority traffic is determined based on the smaller required delay than priorities with smaller required delays. For example, if the required delay for "high" priority is 10 ms, the required delay for "medium" priority is 5 ms, and the required delay for "low" priority is 10 ms, the priority-specific congestion delay calculation unit 422 calculates the congestion delay at intervals shorter than 5 ms for "high" and "medium" priorities, and at intervals shorter than 10 ms for "low" priority. The priority-specific congestion delay calculation unit 422 calculates the congestion delay on a packet-by-packet or burst-by-burst basis. For calculations in 1 us or 5 ms increments, the calculation load can be reduced by increasing the calculation interval. Considering the timing difference in the burst traffic cycle, if the length of the required delay differs between the uplink and downlink by about half the amount of the required delay, a 1 ms increment may be used.

[0033] 4 is a diagram illustrating the process of calculating congestion delay by priority performed by the traffic-specific congestion calculation unit 42 in the first embodiment. As shown in FIG. 4, it is assumed that a traffic volume of 500 kbits (priority=6), a traffic volume of 500 kbits (priority=7), and a traffic volume of 300 kbits (priority=8) are input to the traffic-specific congestion calculation unit 42. The traffic priority sorting unit 421 first sorts the input traffic volumes in descending order of priority. Here, the traffic priority sorting unit 421 sorts the traffic volume of 300 kbits (priority=8), which has the highest priority, as a "high" priority, the traffic volume of 500 kbits (priority=7), which has the next highest priority, as a "medium" priority, and the traffic volume of 500 kbits (priority=6), which has the lowest priority, as a "low" priority.

[0034] The priority-based congestion delay calculation unit 422 allocates traffic in descending order of priority. Assume here that the required delay for each traffic is 5 ms and the link rate is 5 Mbit. High-priority traffic is 1.5 Mbit (300 kbit × 5 ms) for a link rate of 5 Mbit. Therefore, transmission can be performed without congestion. Medium-priority traffic is 2.5 Mbit (500 kbit × 5 ms) for a link rate of 5 Mbit - 1.5 Mbit = 3.5 Mbit. Therefore, transmission can be performed without congestion. On the other hand, low-priority traffic is 2.5 Mbit (500 kbit × 5 ms) for a link rate of 5 Mbit - 1.5 Mbit - 2.5 Mbit = 1 Mbit. In this case, congestion of 1.5 Mbit occurs. If we consider that the congestion traffic is processed at 200 Mbps (1 Mbit / 5 ms), the priority-based congestion delay calculation unit 422 calculates a congestion delay of 1.5 / 200=7.5 ms.

[0035] FIG. 5 is a flowchart showing the flow of processing by the control device 40 in the first embodiment. The required delay calculation unit 41 collects cooperation information transmitted from each base station 10 (step S101). The required delay calculation unit 412 calculates a required delay for each traffic based on wireless quality information included in the cooperation information transmitted from each base station 10 (step S102). The traffic priority calculation unit 413 determines a priority for each traffic based on the wireless quality information included in the cooperation information transmitted from each base station 10 (step S103). The traffic priority calculation unit 413 outputs information on the determined priority for each traffic to the traffic-specific congestion calculation unit 42.

[0036] The traffic-specific congestion calculation unit 42 calculates congestion delay based on the information on priority of each traffic output from the traffic priority calculation unit 413 and the information on the traffic volume included in the cooperation information transmitted from each base station 10 (step S104). The traffic-specific congestion calculation unit 42 outputs the calculated congestion delay information to the round-trip delay calculation unit 43.

[0037] The round-trip delay calculation unit 43 calculates a round-trip delay based on the congestion delay obtained by the traffic-specific congestion calculation unit 42, the delay time in the downlink direction in the wired section obtained by Ph-GW20-1, and the propagation delay in the wireless section (step S105). The round-trip delay calculation unit 43 outputs information on the calculated round-trip delay to the route change instruction unit 44.

[0038] The path change instruction unit 44 determines whether the delay requirement is satisfied based on the required delay calculated by the required delay calculation unit 41 and the round-trip delay calculated by the round-trip delay calculation unit 43 (step S106). If the path change instruction unit 44 determines that the delay requirement is satisfied (step S106-YES), the control device 40 ends the processing. If the path change instruction unit 44 determines that the delay requirement is not satisfied (step S106-NO), the path change instruction unit 44 transmits a path switching instruction to the Ph-GW 20-1 (step S107). Specifically, the path change instruction unit 44 generates a control signal including an instruction to switch the path. The path change instruction unit 44 transmits the generated control signal to the Ph-GW 20-1.

[0039] 6 is a sequence diagram showing the flow of processing in the mobile NW system 100 in the first embodiment. In the explanation of FIG. 6, it is assumed that the wireless terminal 45-1 is connected to the base station 10-1 and the wireless terminal 45-2 is connected to the base station 10-2.

[0040] The wireless terminal 45-1 transmits traffic (for example, a signal indicating a required amount of traffic) to the base station 10-1 (step S201). The base station 10-1 receives the traffic transmitted from the wireless terminal 45-1. The information acquisition unit 11 of the base station 10-1 acquires wireless quality information and traffic volume information from the received traffic. The information acquisition unit 11 of the base station 10-1 transmits the acquired wireless quality information and traffic volume information to the control device 40 as cooperation information (step S202).

[0041] The wireless terminal 45-2 transmits traffic (for example, a signal indicating a required amount of traffic) to the base station 10-2 (step S203). The base station 10-2 receives the traffic transmitted from the wireless terminal 45-2. The information acquisition unit 11 of the base station 10-2 acquires wireless quality information and traffic volume information from the received traffic. The information acquisition unit 11 of the base station 10-2 transmits the acquired wireless quality information and traffic volume information to the control device 40 as link information (step S204).

[0042] The control device 40 collects cooperation information transmitted from each of the base stations 10-1 and 10-2. The control device 40 executes processing based on the collected cooperation information (step S205). Here, the processing based on the cooperation information is, for example, the processing from step S102 to step S105 in FIG. 5. The control device 40 determines whether switching of Ph-GW 20-1 is necessary based on the calculated round-trip delay (step S206). Here, it is assumed that it is determined that switching is necessary. In other words, the fact that switching of Ph-GW 20-1 is necessary means that the round-trip delay does not satisfy the delay requirement.

[0043] The control device 40 instructs the Ph-GW 20-1 to switch the path. Specifically, the control device 40 generates a control signal including an instruction to switch the path. The control device 40 transmits the generated control signal to the Ph-GW 20-1 (step S207).

[0044] The route change unit 22 of Ph-GW20-1 switches the route by switching the optical path in accordance with the control signal transmitted from the control device 40 (step S208). Specifically, the route change unit 22 of Ph-GW20-1 switches the route so that the uplink traffic is forwarded to a Ph-GW 20 different from Ph-GW20-2. As a result, Ph-GW20-1 forwards the uplink traffic to another Ph-GW 20 (e.g., Ph-GW20-3) that is the switching destination.

[0045] Next, a concrete example of processing when using a conventional method will be described. The bandwidth of the wired section (upstream: 1 Gbps, downstream: 1 Gbps) is assumed to be known. The wireless quality information and traffic volume acquired by the base station 10 are transmitted to the control device 40. <Input flow information: Upstream> Round-trip communication (1): slot length 1 ms, traffic volume 300 kbit, 5 QI = 86 Round-trip communication (2): slot length 1 ms, traffic volume 500 kbit, 5 QI = 85 Round-trip communication (3): slot length 1 ms, traffic volume 500 kbit, 5 QI = 85

[0046] <Input flow information: Downstream> Measurement delay: 0.7 ms one way The required delay calculation unit 41 calculates the allowable delay time and the priority based on the wireless quality information (5QI). <Tolerable delay and priority> Round-trip communication (1): 5QI=86, priority 18, allowable delay 5ms Round-trip communication (2): 5QI=85, priority 21, allowable delay 5ms Round-trip communication (3): 5QI=85, priority 21, allowable delay 5ms

[0047] The traffic-specific congestion calculation unit 42 calculates the congestion delay of the traffic based on the traffic volume and bandwidth in order of priority. <Congestion delay> Round-trip communication (1) = 0, round-trip communication (2) = 0.42 ms, round-trip communication (3) = 0.42 ms

[0048] The round-trip delay calculation unit 43 calculates the one-way delay based on the calculated congestion delay, the downstream delay (propagation delay) of the wired section (0.7 ms) measured by Ph-GW20-1, and the propagation delay of the wireless section (4 ms). One-way delay = Propagation delay in wireless section (one-way) + Propagation delay in wired section (one-way) + Congestion delay <One-way delay> Round trip communication (1) = 4 + 0.7 + 0 = 4.7 ms Round trip communication (2) = 4 + 0.7 + 0.42 = 5.12 ms Round trip communication (3) = 4 + 0.7 + 0.42 = 5.12 ms

[0049] The route change instruction unit 44 determines whether the delay is satisfied based on the one-way delay and the required delay, and makes a switchover decision. <Route change decision> Round-trip communication (1): One-way delay 4.7 ms, required delay 5 ms → No switching. Round-trip communication (2): One-way delay 5.12 ms, required delay 5 ms → Switch. Round-trip communication (3): One-way delay 5.12 ms, required delay 5 ms → Switch.

[0050] Next, specific processing in the first embodiment will be described using a specific example. The bandwidth of the wired section (upstream: 1 Gbps, downstream: 1 Gbps) is assumed to be known. The wireless quality information and traffic volume acquired by the base station 10 are transmitted to the control device 40. <Input flow information: Upstream> Round-trip communication (1): slot length 1ms, traffic volume 300kbit, 5QI=86 Round-trip communication (2): slot length 1ms, traffic volume 500kbit, 5QI=85 Round-trip communication (3): slot length 1ms, traffic volume 500kbit, 5QI=85

[0051] <Input flow information: Downstream> Measurement delay: 0.7 ms one way The required delay calculation unit 41 calculates the allowable round-trip delay time and priority of the flow from the wireless quality information (5QI). <Round-trip delay tolerance and priority> Round-trip communication (1): 5QI=86, priority 18, allowable delay 10ms Round-trip communication (2): 5QI=85, priority 21, allowable delay 10ms Round-trip communication (3): 5QI=85, priority 21, allowable delay 10ms

[0052] The traffic-specific congestion calculation unit 42 calculates the congestion delay of the traffic based on the traffic volume and bandwidth in order of priority. <Congestion delay> Round-trip communication (1) = 0, round-trip communication (2) = 0.42 ms, round-trip communication (3) = 0.42 ms

[0053] The round-trip delay calculation unit 43 calculates the round-trip delay based on the calculated congestion delay, the downstream delay (propagation delay) of the wired section (0.7 ms) measured by Ph-GW20-1, and the propagation delay of the wireless section (4 ms). Round trip delay = Propagation delay in wireless section (round trip) + Propagation delay in wired section (round trip) + Congestion delay <Round Trip Delay> Round trip communication (1) = 8 + 1.4 + 0 = 9.4 ms Round trip communication (2) = 8 + 1.4 + 0.42 = 9.82 ms Round trip communication (3) = 8 + 1.4 + 0.42 = 9.82 ms

[0054] The route change instruction unit 44 determines whether the delay is satisfied based on the round trip delay and the required delay, and makes a switchover decision. <Route change decision> Round-trip communication (1): Round-trip delay 9.4 ms, required delay 10 ms → No switching. Round-trip communication (2): Round-trip delay 9.82 ms, required delay 10 ms → No switching. Round-trip communication (3): Round-trip delay 9.82 ms, required delay 10 ms → No switching.

[0055] As described above, by making a switching decision based on the round-trip delay as in the first embodiment, it can be seen that switching does not occur in round-trip communication (2) and round-trip communication (3) as compared to the conventional method, and this makes it possible to reduce the number of switching times.

[0056] In the mobile network system 100 configured as described above, the control device 40 includes a required delay calculation unit 41 that acquires required delay information and priority information for each traffic stream based on the cooperation information obtained from each base station 10; a traffic-specific congestion calculation unit 42 that calculates congestion delay in the wired section based on the priority information acquired for each traffic stream; a round-trip delay calculation unit 43 that calculates round-trip delay based on the calculated congestion delay in the wired section and the downlink delay; and a path change instruction unit 44 that transmits a control signal including an instruction to switch paths to the Ph-GW 20-1 if the calculated round-trip delay does not satisfy the required delay. This prevents path switching from being performed for traffic that satisfies the round-trip communication delay requirements but does not satisfy the one-way communication delay requirements due to congestion delay in the uplink communication. This reduces the number of unnecessary path changes. As a result, high-capacity, low-latency communication can be achieved in the mobile network system 100, which combines one-way and round-trip communication.

[0057] (Second embodiment) In the first embodiment, the round-trip delay time is estimated using information on the delay in the wired section measured by the Ph-GW and the delay in the wireless section measured by the base station. In this case, the bandwidth is used for the delay measurement. Therefore, in the second embodiment, a configuration is described in which the round-trip delay time is estimated without measuring the delay. For example, in the second embodiment, the round-trip delay time is estimated based on the IP address and the traffic volume.

[0058] Fig. 7 is a diagram illustrating an example of the configuration of each device in a mobile NW system 100a in the second embodiment. Fig. 7 illustrates a base station 10a, a Ph-GW 20a-1, a Ph-GW 20-2, a server 30, a control device 40a, and a wireless terminal 60, but the specific configurations of the base station 10a, the Ph-GW 20a-1, and the control device 40a will be described here. Note that the Ph-GW 20-2, the server 30, and the wireless terminal 60 are the same as those in the first embodiment.

[0059] The base station 10a includes an information acquisition unit 11. The information acquisition unit 11 acquires wireless quality information, traffic volume, and IP address from a signal indicating a requested traffic volume transmitted from the wireless terminal 60. The information acquisition unit 11 transmits the acquired wireless quality information, traffic volume, and IP address as cooperation information to the control device 40a. When the base station 10a receives actual traffic from the wireless terminal 60, it transmits the received signal to the Ph-GW 20a-1.

[0060] The Ph-GW 20a-1 includes an information acquisition unit 21 and a route change unit 22. The information acquisition unit 21 acquires information on the traffic volume of the outbound route. The route change unit 22 switches the route based on a control signal transmitted from the control device 40.

[0061] The control device 40a includes a required delay calculation unit 41, a traffic-specific congestion calculation unit 42, a round-trip delay calculation unit 43a, a route change instruction unit 44, and a transmission delay determination unit 45. The control device 40a differs in configuration from the control device 40 in that it includes a round-trip delay calculation unit 43a instead of the round-trip delay calculation unit 43 and in that it newly includes a transmission delay determination unit 45. The other configurations of the control device 40a are the same as those of the control device 40. The round-trip delay calculation unit 43a and the transmission delay determination unit 45 will be described below.

[0062] As shown in FIG. 8, the transmission delay determination unit 45 includes a wired section propagation delay determination unit 451, a wireless section transmission delay determination unit 452, a return path congestion estimation unit 453, and a processing delay determination unit 454.

[0063] The wired section propagation delay determination unit 451 estimates the transmission distance in the wired section (for example, the transmission distance from the base station 10a to the destination server 30) based on the destination of the traffic, such as an IP address, included in the cooperation information transmitted from each base station 10. The wired section propagation delay determination unit 451 estimates the propagation delay in the wired section based on the estimated transmission distance.

[0064] The wireless section transmission delay determining unit 452 estimates the propagation delay in the wireless section (for example, the section from the wireless terminal 60 to the base station 10a) based on the position and quality (CQI: Channel Quality Indicator) of the wireless terminal 60.

[0065] The return path congestion estimation unit 453 estimates the return path traffic volume (e.g., the downlink traffic volume) based on the outbound path traffic volume obtained from Ph-GW 20a-1 and the past return path traffic volume (e.g., the downlink traffic volume). The return path congestion estimation unit 453 estimates the downlink processing delay and the downlink congestion delay based on the estimated return path traffic volume.

[0066] The processing delay determination unit 454 estimates the processing delay required for routing processing and the like based on the traffic volume obtained from the Ph-GW 20a-1.

[0067] The round-trip delay calculation unit 43a estimates the round-trip delay based on the upstream congestion delay calculated by the traffic-specific congestion calculation unit 42, the propagation delay in the wired section estimated by the wired section propagation delay determination unit 451, the propagation delay in the wireless section estimated by the wireless section transmission delay determination unit 452, the downstream processing delay and congestion delay estimated by the return path congestion estimation unit 453, and the processing delay estimated by the processing delay determination unit 454.

[0068] The control device 40a may include a server processing delay determination unit that determines the processing delay of the server 30 according to the flow ID. When configured in this manner, the round-trip delay calculation unit 43a calculates the round-trip delay including the processing delay on the server 30.

[0069] Next, a concrete example of processing when using a conventional method will be described. The IP address, wireless quality information, and traffic volume acquired by the base station 10 are transmitted to the control device 40a. <Input flow information> (Upstream: Link 1Gbps) Round-trip communication (1): IP (133.15.xx.xx), traffic volume 300Mbps, priority 18, delay 5ms Round-trip communication (2): IP (130.69.xx.yy), traffic volume 500Mbps, priority 21, delay 5ms Round-trip communication (3): IP (133.100.xx.zz), traffic volume 500Mbps, priority 21, delay 5ms

[0070] The required delay calculation unit 41 obtains the allowable delay time and priority for one way. <Priority and Tolerable Delay> Round-trip communication (1): Priority 18, 5 ms one way Round-trip communication (2): Priority 21, 5 ms each way Round-trip communication (3): Priority 21, 5 ms each way

[0071] The traffic-specific congestion calculation unit 42 calculates the congestion delay of the traffic from the traffic volume and bandwidth at intervals shorter than the required delay. <Congestion delay> Round-trip communication (1) = 0, round-trip communication (2) = 2.14 ms, round-trip communication (3) = 2.14 ms

[0072] The wired section propagation delay determination unit 451 uses the measured propagation delay in the wired section. <Propagation delay in wired sections> Round-trip communication (1): 0.5 ms one way Round-trip communication (2): 0.8 ms one way Round-trip communication (3): 0.9 ms one way

[0073] The control device 40a estimates the total delay based on the congestion delay, propagation delay, and propagation delay in the wireless section (3 ms one way) calculated by the traffic-specific congestion calculation unit 42. Round-trip communication (1) = 3 + 0.5 + 0 = 3.5 ms Round trip communication (2) = 3 + 0.8 + 2.14 = 5.94 ms Round trip communication (3) = 3 + 0.9 + 2.14 = 6.04 ms →The one-way latency requirement of 5 ms is not met, so switch.

[0074] Next, specific processing in the second embodiment will be described using a specific example. The IP address, wireless quality information, and traffic volume acquired by the base station 10 are transmitted to the control device 40a. <Input flow information> (Upstream: Link 1Gbps) Round-trip communication (1): IP (133.15.xx.xx), traffic volume 300Mbps, 5QI=86 Round-trip communication (2): IP (130.69.xx.yy), traffic volume 500Mbps, 5QI=85 Round-trip communication (3): IP (133.100.xx.zz), traffic volume 500Mbps, 5QI=85

[0075] The required delay calculation unit 41 calculates the allowable round-trip delay time and priority of the flow from the wireless quality information (5QI). <Priority and Tolerable Delay> Round-trip communication (1): 5QI=86, priority 18, round-trip time 10ms Round-trip communication (2): 5QI=85, priority 21, round-trip time 10ms Round-trip communication (3): 5QI=85, priority 21, round-trip time 10ms

[0076] The traffic-specific congestion calculation unit 42 calculates the congestion delay of the traffic based on the traffic volume and bandwidth in order of priority and at intervals shorter than the required delay. <Congestion delay> Round-trip communication (1) = 0, round-trip communication (2) = 2.14 ms, round-trip communication (3) = 2.14 ms

[0077] The wired section propagation delay determination unit 451 estimates the transmission distance based on the destination of the traffic such as an IP address, and estimates the propagation delay. <Propagation delay in wired sections> Round-trip communication (1): IP address (133.15.xx.xx) → 0.3 ms one way Round-trip communication (2): IP address (130.69.xx.yy) → 0.5 ms one way Round-trip communication (3): IP address (133.100.xx.zz) → 0.6 ms one way

[0078] The return path congestion estimation unit 453 estimates the traffic volume flowing on the return path based on the upstream traffic volume and the current traffic volume, and determines the congestion delay. <Return congestion delay> Round-trip communication (1): Downstream 100kbit 0ms Round-trip communication (2): Downstream 300kbit 0ms Round-trip communication (3): Downstream 100kbit 0ms

[0079] The processing delay determination unit 454 estimates the time required for routing processing and the like, as well as the downstream traffic volume and processing time, from the traffic volume. <Processing delay> Round-trip communication (1): Uplink 300kbit → 0.2ms, downlink 100kbit 0.1ms Round-trip communication (2): Uplink 500kbit → 0.3ms, downlink 300kbit 0.2ms Round-trip communication (3): Uplink 500kbit → 0.3ms, downlink 100kbit 0.1ms

[0080] The round-trip delay calculation unit 43a estimates a round-trip delay including the congestion delay calculated by the traffic-specific congestion calculation unit 42, propagation delay, processing delay, propagation delay in the wireless section (3 ms one way), and server processing delay (0.1 ms). Round-trip delay = Propagation delay in wireless section × 2 + Propagation delay in wired section × 2 + Processing delay in wired section (outbound) + Processing delay in wired section (return) + Congestion delay + Congestion delay in return + Server processing delay <Round Trip Delay> Round-trip communication (1) = 6 + 0.6 + 0.2 + 0.1 + 0 + 0 + 0.1 = 7.0 ms Round-trip communication (2) = 6 + 1.0 + 0.3 + 0.2 + 2.14 + 0 + 0.1 = 9.74 ms Round-trip communication (3) = 6 + 1.2 + 0.3 + 0.1 + 2.14 + 0 + 0.1 = 9.84 ms →Do not switch.

[0081] The mobile network system 100a configured as described above can achieve the same effects as the first embodiment. Furthermore, the control device 40a does not measure the round-trip delay time, but estimates it based on the traffic volume and IP addresses. Therefore, it is possible to secure the bandwidth used for measurement in the first embodiment and increase the bandwidth available for the main signal.

[0082] (Third embodiment) In the third embodiment, a configuration will be described that enables advance delay estimation and switching by estimating a round-trip delay time based on the traffic allocation amount of a wireless section.

[0083] Fig. 9 is a diagram showing an example of the configuration of each device in a mobile NW system 100b in the third embodiment. Fig. 9 shows a base station 10b, Ph-GWs 20-1 and 20-2, a server 30, a control device 40b, and a wireless terminal 60, but the specific configurations of the base station 10b and the control device 40b will be described here. Note that the Ph-GWs 20-1 and 20-2, the server 30, and the wireless terminal 60 are the same as those in the first embodiment.

[0084] The base station 10b includes an information acquisition unit 11. The information acquisition unit 11 acquires wireless quality information, traffic allocation information, and an IP address from a signal indicating a traffic request amount transmitted from the wireless terminal 60. The traffic allocation information is a Transport Block Size (TBS) and a Buffer Status Report (BSR) for each logical channel. The information acquisition unit 11 transmits the acquired wireless quality information, traffic allocation information, and IP address as cooperation information to the control device 40b. When the base station 10b receives actual traffic from the wireless terminal 60, it transmits the received signal to the Ph-GW 20-1.

[0085] The control device 40b includes a required delay calculation unit 41b, a traffic-specific congestion calculation unit 42, a round-trip delay calculation unit 43b, and a route change instruction unit 44. The control device 40b differs in configuration from the control device 40 in that it is newly equipped with a required delay calculation unit 41b and a round-trip delay calculation unit 43b instead of the required delay calculation unit 41 and the round-trip delay calculation unit 43. The other configurations of the control device 40b are the same as those of the control device 40. The required delay calculation unit 41b and the round-trip delay calculation unit 43b will be described below.

[0086] The required delay calculation unit 41b calculates the required delay and the priority of the traffic based on the wireless quality information transmitted from the base station 10.

[0087] The round trip delay calculation unit 43b includes a propagation delay estimation unit 431, a processing delay estimation unit 432, and a round trip delay estimation unit 433. The propagation delay estimation unit 431 estimates the propagation delay in the wired section and the propagation delay in the wireless section. Specifically, the propagation delay estimation unit 431 estimates the transmission distance based on the destination of the traffic, such as an IP address, included in the cooperation information transmitted from each base station 10. The propagation delay estimation unit 431 estimates the propagation delay in the wired section based on the estimated transmission distance. Furthermore, the propagation delay estimation unit 431 estimates the propagation delay in the wireless section based on the position and quality (CQI: Channel Quality Indicator) of the wireless terminal 60.

[0088] The processing delay estimation unit 432 estimates the uplink processing delay required for routing processing and the like based on the traffic allocation amount included in the cooperation information transmitted from each base station 10.

[0089] The round-trip delay estimation unit 433 estimates the return path traffic volume (downstream traffic volume) based on the outbound path traffic volume obtained from Ph-GW20-1 and the past return path traffic volume (downstream traffic volume). The round-trip delay estimation unit 433 estimates the downstream processing delay and the downstream congestion delay based on the estimated return path traffic volume. The round-trip delay estimation unit 433 estimates the round-trip delay based on the estimated downstream processing delay, the downstream congestion delay, the upstream congestion delay calculated by the traffic-specific congestion calculation unit 42, the propagation delay in the wired section and the propagation delay in the wireless section estimated by the propagation delay estimation unit 431, and the upstream processing delay estimated by the processing delay estimation unit 432.

[0090] 10 is a diagram illustrating an example of the configuration of the required delay calculation unit 41b in the third embodiment. The required delay calculation unit 41b includes a wireless quality information collection unit 411, a required delay calculation unit 412, a traffic priority calculation unit 413, a traffic allocation information collection unit 414, and a traffic volume calculation unit 415.

[0091] The wireless quality information collecting unit 411 collects wireless quality information included in the cooperation information transmitted from each base station 10b. The wireless quality information collecting unit 411 outputs the collected wireless quality information to the required delay calculating unit 412.

[0092] The required delay calculation unit 412 checks the mapping and calculates the required delay based on the wireless quality information included in the cooperation information transmitted from each base station 10b.

[0093] The traffic priority calculation unit 413 checks the mapping based on the wireless quality information included in the cooperation information transmitted from each base station 10b, and determines the priority of the traffic.

[0094] The traffic allocation information collection unit 414 collects traffic allocation information (TBS or BSP) included in the cooperation information transmitted from each base station 10 b. The traffic allocation information collection unit 414 outputs the collected traffic allocation information to the traffic volume calculation unit 415.

[0095] The traffic volume calculation unit 415 determines the traffic volume based on the traffic allocation information output from the traffic allocation information collection unit 414. The traffic volume calculation unit 415 may determine the value indicated in the traffic allocation information (the value of TBS or BSP) as the traffic volume. The traffic volume calculation unit 415 may also determine the value obtained by adding overhead to the value indicated in the traffic allocation information as the traffic volume.

[0096] In the mobile network system 100b configured as described above, the control device 40b estimates the round-trip delay time based on the traffic allocation amount of the wireless section. Therefore, it is possible to secure the bandwidth used for measurement in the first embodiment and increase the bandwidth available for the main signal.

[0097] Furthermore, the mobile network system 100b estimates round-trip delay times based on the traffic allocation amount for wireless sections, making it possible to estimate delays in advance, thereby enabling route switching to be performed in advance.

[0098] (Fourth embodiment) In the fourth embodiment, a configuration will be described in which switching is performed so as to satisfy the delay requirement by re-controlling the return path (for example, communication in the down direction).

[0099] Fig. 11 is a diagram illustrating an example of the configuration of each device in a mobile NW system 100c in the fourth embodiment. Fig. 11 illustrates a base station 10b, Ph-GWs 20-1 and 20c-2, a server 30c, a control device 40c, and a wireless terminal 60, but the specific configurations of the control device 40c, Ph-GW 20c-1, and server 30c will be described here. Note that the base station 10b, Ph-GW 20-1, and wireless terminal 60 are the same as those in the third embodiment.

[0100] The server 30c includes a required delay calculation unit 31 and a required delay transmission unit 32. The required delay calculation unit 31 calculates the delay of the outbound path based on the IP address, the traffic volume, the congestion delay, and the propagation delay in the wireless section. The IP address and the traffic volume are acquired from the main signal transmitted from the base station 10b. When transmitting a control signal from the control device 40c to the Ph-GW 20-1, the Ph-GW 20-1 mixes the information on the propagation delay in the wireless section into the main signal and transmits it to the server 30c, or the base station 10b transmits the propagation delay in the wireless section to the server 30c when transmitting the main signal. The method by which the required delay calculation unit 31 calculates the delay of the outbound path is the same as the processing performed by the round-trip delay calculation unit 43b of the control device 40c. The required delay calculation unit 31 performs calculations similar to the processing performed by the round-trip delay calculation unit 43b of the control device 40c, calculates the delay in the uplink direction, and then calculates the required delay in the downlink direction. Based on the calculated delay on the outbound path and the requested round-trip delay, the requested delay calculation unit 31 calculates the time available for the return path (requested return path delay) based on the processing delay at the server 30c and the delay on the outbound path. The delay on the outbound path may be sent with a timestamp attached when traffic is transmitted from the wireless terminal 60, and measured and calculated on the server 30. Regarding the delay on the outbound path, information on the delay on the outbound path calculated by the round-trip delay calculation unit 43b may be transmitted to the Ph-GW 20-1 together with the transmission of the main signal.

[0101] The requested delay transmission unit 32 transmits the requested delay calculated by the requested delay calculation unit 31 in accordance with the traffic transmission.

[0102] The Ph-GW 20c-2 includes an information acquisition unit 23 and a route change unit 24. The information acquisition unit 23 acquires the return path traffic volume, requested delay, priority, and IP address from the downstream traffic. The information acquisition unit 23 transmits the acquired information on the return path traffic volume, requested delay, priority, and IP address to the control device 40c.

[0103] The path change unit 24 switches the path based on a control signal transmitted from the control device 40c.

[0104] The control device 40c includes a required delay calculation unit 41b, a traffic-specific congestion calculation unit 42, a round-trip delay calculation unit 43b, a route change instruction unit 44, a traffic-specific congestion calculation unit 46, a delay feedback unit 47, and a route change instruction unit 48. The control device 40c differs in configuration from the control device 40b in that it newly includes the traffic-specific congestion calculation unit 46, the delay feedback unit 47, and the route change instruction unit 48. The other configurations of the control device 40c are the same as those of the control device 40b. The traffic-specific congestion calculation unit 46, the delay feedback unit 47, and the route change instruction unit 48 will be described below.

[0105] The traffic-specific congestion calculation unit 46, delay feedback unit 47, and route change instruction unit 48 are functional units that perform processing based on downstream traffic. The traffic-specific congestion calculation unit 46 acquires information on the return path traffic volume (e.g., downstream traffic volume), requested delay, priority, and IP address transmitted from Ph-GW 20c-2. The traffic-specific congestion calculation unit 46 calculates the congestion delay of downstream traffic based on the traffic volume and bandwidth in order of priority.

[0106] The delay feedback unit 47 calculates an estimated downlink delay based on the congestion delay of the downlink traffic calculated by the traffic-specific congestion calculation unit 46, the propagation delay in the wireless section, and the propagation delay in the wired section. The values calculated by the round-trip delay calculation unit 43b are used for the propagation delay in the wireless section and the propagation delay in the wired section. The delay feedback unit 47 outputs information on the calculated estimated downlink delay to the route change instruction unit 48 and also feeds it back to the round-trip delay calculation unit 43b. The delay feedback unit 47 also feeds back the amount of downlink traffic to the round-trip delay calculation unit 43b.

[0107] The route change instruction unit 48 determines whether the delay requirement is satisfied based on the information on the estimated downstream delay output from the delay feedback unit 47. Specifically, the route change instruction unit 48 determines whether the delay requirement is satisfied by comparing the estimated downstream delay output from the delay feedback unit 47 with the required delay acquired by the traffic-specific congestion calculation unit 46.

[0108] If the estimated downstream delay is within the required delay, the route change instruction unit 48 determines that the downstream delay requirement is met. On the other hand, if the estimated downstream delay exceeds the required delay, the route change instruction unit 48 determines that the downstream delay requirement is not met. If the downstream delay requirement is not met, the route change instruction unit 48 generates a control signal including an instruction to switch to another optical path and transmits the control signal to Ph-GW20c-2.

[0109] The round trip delay calculation unit 43b acquires values (information on the estimated downstream delay and downstream traffic volume) fed back from the delay feedback unit 47. The round trip delay calculation unit 43b corrects the downstream traffic volume based on the downstream traffic volume fed back from the delay feedback unit 47. Furthermore, the round trip delay calculation unit 43b corrects the calculated upstream traffic volume and the downstream delay for the IP address by applying feedback from the actual downstream delay.

[0110] Next, specific processing in the fourth embodiment will be described using a specific example. Here, we show a case where the estimated result of the downlink traffic volume is incorrect. Server 30c calculates the requested delay on the return path based on the requested delay, the propagation delay in the wireless section, the propagation delay in the wired section, the congestion delay, the processing delay on the outbound path, and the processing delay at server 30c. <Request Delay> Round-trip communication (1) = 10-3 - 0.3 - 0.2 - 0.1 - 0 = 6.4 ms Round-trip communication (2) = 10-3 - 0.5 - 0.3 - 0.1 - 2.14 = 3.99 ms Round-trip communication (3) = 10-3 - 0.6 - 0.3 - 0.1 - 2.14 = 3.89 ms

[0111] At this time, the downlink (return) traffic volume is (Downstream: 1Gbps link) Round-trip communication (1): Traffic volume 300 kbit, priority 18, IP address (133.15.xx.xx) Round-trip communication (2): Traffic volume 600 kbit, priority 21, IP address (130.69.xx.yy) Round-trip communication (3): Traffic volume 300 kbit, priority 21, IP address (133.100.xx.zz) Let's say that was the case.

[0112] The request delay transmitter 32 transmits the traffic volume and the request delay for the return path. The information acquirer 23 of the Ph-GW 20c-2 acquires the request delay, the IP address, and the traffic volume, and transmits the acquired information on the request delay, the IP address, and the traffic volume to the control device 40c.

[0113] The traffic-specific congestion calculation unit 46 of the control device 40c calculates the congestion delay of downstream traffic based on the traffic volume and bandwidth in order of priority. Congestion delay (round trip communication (1) = 0, round trip communication (2) = 1.4 ms, round trip communication (1) = 1.4 ms)

[0114] The delay feedback unit 47 calculates an estimated downlink delay based on the processing delay (0.2, 0.4, 0.2) calculated based on the congestion delay and traffic volume calculated by the traffic-specific congestion calculation unit 46, the propagation delay in the wireless section, and the propagation delay in the wired section. The delay feedback unit 47 transmits information on the calculated estimated downlink delay to the route change instruction unit 48 and also feeds it back to the round-trip delay calculation unit 43b.

[0115] Excess delay = Request delay - Congestion delay - Processing delay - Propagation delay in wireless section - Propagation delay in wired section <Excess Delay> Round-trip communication (1) = 6.4 - 0 - 0.2 - 3 - 0.3 = 2.9 ms Round-trip communication (2) = 3.99 - 1.4 - 0.4 - 3 - 0.5 = -1.31 ms Transmitted to the route change instruction unit 48 Round-trip communication (3) = 3.89 - 1.4 - 0.2 - 3 - 0.6 = -1.31 ms

[0116] The delay feedback unit 47 outputs to the round trip delay calculation unit 43b: <Delayed Feedback> Round-trip communication (1): Traffic volume 300 kbit, 3.5 ms Round-trip communication (2): Traffic volume 600 kbit, 3.9 ms Round-trip communication (3): Traffic volume 300 kbit, 3.8 ms Provide feedback.

[0117] The route change instruction unit 48 Round trip communication (1) = 2.9 ms, no route change Round trip communication (2) = -1.31 ms Route switching. Round trip communication (3) = -1.31 ms Route switching.

[0118] The mobile network system 100c configured as described above can improve prediction accuracy by comparing the return path traffic volume estimated on the outbound path with the actual return path traffic volume and providing feedback. The mobile network system 100c performs re-switching if it determines that the required delay is not met. This does not affect the estimation accuracy of the return path.

[0119] (Fifth embodiment) In the fifth embodiment, a configuration will be described in which switching is performed to satisfy the delay requirement by re-controlling the return path (for example, downstream communication) as in the fourth embodiment. The following mainly describes the differences from the fourth embodiment.

[0120] Fig. 12 is a diagram illustrating an example of the configuration of each device in a mobile NW system 100d according to the fifth embodiment. Fig. 12 illustrates a base station 10b, Ph-GWs 20-1 and 20c-2, a server 30c, a control device 40d, and a wireless terminal 60, but the specific configuration of the control device 40d will be described here. Note that the base station 10b, Ph-GWs 20-1 and 20c-2, the server 30c, and the wireless terminal 60 are the same as those in the fourth embodiment.

[0121] The control device 40d differs from the control device 40c in that the round trip delay, required delay, estimated downstream traffic volume, and estimated downstream congestion delay calculated on the outbound path are transmitted to a delay feedback unit 47d.

[0122] The control device 40d includes a required delay calculation unit 41b, a traffic-specific congestion calculation unit 42, a round-trip delay calculation unit 43d, a route change instruction unit 44, a traffic-specific congestion calculation unit 46, a delay feedback unit 47d, and a route change instruction unit 48. The control device 40d differs in configuration from the control device 40c in that it includes a round-trip delay calculation unit 43d and a delay feedback unit 47d instead of the round-trip delay calculation unit 43b and the delay feedback unit 47. The other configurations of the control device 40d are the same as those of the control device 40c. The round-trip delay calculation unit 43d and the delay feedback unit 47d will be described below.

[0123] The round trip delay calculation unit 43d performs the same processing as the round trip delay calculation unit 43b in the third embodiment. Furthermore, the round trip delay calculation unit 43d transmits the round trip delay calculated on the outbound path, the required delay, the estimated downstream traffic volume, and the estimated downstream congestion delay to the delay feedback unit 47d.

[0124] The delay feedback unit 47d feeds back the estimated downstream traffic volume and estimated congestion delay transmitted from the round-trip delay calculation unit 43d. The delay feedback unit 47d calculates the round-trip delay when the round-trip delay transmitted from the round-trip delay calculation unit 43d is changed to the feedback congestion delay. The delay feedback unit 47d outputs information on the estimated downstream traffic volume and congestion delay after feedback to the round-trip delay calculation unit 43d.

[0125] The round-trip delay calculation unit 43d acquires values (information on downstream congestion delay and downstream traffic volume) fed back from the delay feedback unit 47d. The round-trip delay calculation unit 43d corrects the downstream traffic volume based on the downstream traffic volume fed back from the delay feedback unit 47d. Furthermore, the round-trip delay calculation unit 43d corrects the calculated upstream traffic volume and the downstream delay for the IP address by applying feedback from the actual downstream congestion delay.

[0126] Next, specific processing in the fifth embodiment will be described using a specific example. Here, a case is shown in which the estimated result of the downlink traffic volume is incorrect. In the control device 40d, the round trip delay calculation unit 43d transmits information on the round trip delay, the required delay, the estimated downlink traffic volume, and the estimated downlink delay to the delay feedback unit 47. <Input flow information> Round-trip communication (1): Round-trip delay 6.7 ms, required delay 10 ms, estimated traffic volume 100 kbit, estimated delay 0.1 ms Round-trip communication (2): Round-trip delay 9.24 ms, required delay 10 ms, estimated traffic volume 300 kbit, estimated delay 0.2 ms Round-trip communication (3): Round-trip delay 9.24 ms, required delay 10 ms, estimated traffic volume 100 kbit, estimated delay 0.1 ms

[0127] The server 30 transmits the downstream (return route) traffic volume and priority. <Input flow information> Round-trip communication (1): Traffic volume 300 kbit, priority 18, IP address (133.15.xx.xx) Round-trip communication (2): Traffic volume 600 kbit, priority 21, IP address (130.69.xx.yy) Round-trip communication (3): Traffic volume 300 kbit, priority 21, IP address (133.100.xx.zz) It was.

[0128] The information acquisition unit 23 of the Ph-GW 20c-2 acquires the traffic volume and priority and transmits them to the control device 40d.

[0129] The traffic-specific congestion calculation unit 46 of the control device 40d calculates the congestion delay of downstream traffic based on the traffic volume and bandwidth in order of priority. <Actual congestion delay> Round-trip communication (1) = 0, round-trip communication (2) = 1.4 ms, round-trip communication (3) = 1.4 ms

[0130] The delay feedback unit 47 calculates the processing delay based on the downstream traffic volume, and feeds back the downstream delay combined with the congestion delay and the downstream traffic volume. <Actual delay including actual processing delay and actual congestion delay> Round-trip communication (1): Traffic volume 300 kbit Processing delay 0.2 ms Delay 0.2 ms Round-trip communication (2): Traffic volume 600 kbit, processing delay 0.4 ms, delay 1.8 ms Round-trip communication (3): Traffic volume 300 kbit, processing delay 0.2 ms, delay 1.6 ms Furthermore, the delay feedback unit 47 calculates the round-trip delay when the delay is changed to the feedback delay based on the round-trip delay output from the round-trip delay calculation unit 43b. Round Trip Delay = Round Trip Delay - Estimated Delay + Actual Delay <Round Trip Delay> Round trip communication (1) = 6.7 - 0.1 + 0.2 = 6.8 ms Round-trip communication (2) = 9.24 - 0.2 + 1.8 = 10.84 ms Round-trip communication (3) = 9.24 - 0.1 + 1.6 = 10.74 ms

[0131] The route change instruction unit 48 determines whether the round trip delay calculated by the delay feedback unit 47 satisfies the required delay. Round trip communication (1) = 6.8 ms without switching. Round trip communication (2) = 10.84 ms switching Round trip communication (3) = 10.74 ms switching

[0132] According to the mobile NW system 100d configured as above, it is possible to obtain the same effects as those of the fourth embodiment.

[0133] Some or all of the functional units of the control devices 40, 40a, 40c, and 40d described above are realized as software by a processor such as a CPU (Central Processing Unit) executing a program stored in a storage device having a non-volatile storage medium (non-transitory storage medium) and a storage unit. The program may be recorded on a computer-readable non-transitory storage medium. Examples of computer-readable non-transitory storage media include portable media such as flexible disks, magneto-optical disks, ROMs (Read Only Memory), and CD-ROMs (Compact Disc Read Only Memory), and storage devices such as hard disks built into computer systems.

[0134] Some or all of the functional units of the above-mentioned control devices 40, 40a, 40c, and 40d may be realized using hardware including electronic circuits (electronic circuits or circuitry) using, for example, an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0135] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention. [Industrial Applicability]

[0136] The present invention can be applied to optical communication system technology such as optical access systems. [Explanation of symbols]

[0137] 10, 10a, 10b... base station, 11... information acquisition unit, 20, 20-1 to 20-2, 20a-1, 20c-2... Ph-GW, 21, 23... information acquisition unit, 22, 24... route change unit, 30, 30c... server, 31... required delay calculation unit, 32... required delay transmission unit, 40, 40a, 40c, 40d... control device, 41, 41b... required delay calculation unit, 42... traffic-specific congestion calculation unit, 43, 43a, 43b, 43d... round-trip delay calculation unit, 44... route change instruction unit, 45... transmission delay determination unit, 46... traffic-specific congestion calculation unit, 47, 47d... delay feedback unit, 48... route change instruction unit, 50... core network, 60... wireless terminal, 100, 100a, 100b, 100c, 100d...mobile NW system, 411...wireless quality information collection unit, 412...request delay calculation unit, 413...traffic priority calculation unit, 414...traffic allocation information collection unit, 415...traffic volume calculation unit, 421...traffic priority-based sorting unit, 422...priority-based congestion delay calculation unit, 431...propagation delay estimator, 432...processing delay estimator, 433...round trip delay estimator, 451...wired section propagation delay determination unit, 452...wireless section transmission delay determination unit, 453...backward path congestion estimator, 454...processing delay determination unit

Claims

1. A control device in a communication system in which one-way communication and round-trip communication are mixed, a request delay acquisition unit that acquires, for each traffic, information on a request delay and information on priority of the traffic based on cooperation information that indicates a communication state between a base station that performs wireless communication with a plurality of wireless terminals and the plurality of wireless terminals, the cooperation information being obtained from the traffic transmitted from the plurality of wireless terminals; a traffic-specific congestion calculation unit that calculates congestion delay in a wired section based on the priority information acquired for each traffic by the requested delay acquisition unit; a round-trip delay calculation unit that calculates a round-trip delay based on the congestion delay in the wired section calculated by the traffic-specific congestion calculation unit and a downstream delay; a route change control unit that transmits a control signal including an instruction to switch a route to a relay device that relays the traffic when the round trip delay calculated by the round trip delay calculation unit does not satisfy a required delay; A control device comprising:

2. the collaboration information includes at least information on traffic volume; the traffic-specific congestion calculation unit calculates a congestion delay in the wired section based on the priority information, the traffic volume information, and bandwidth information; The control device according to claim 1 .

3. The downstream delay includes a downstream delay in a wired section and a propagation delay in a wireless section, and the round-trip delay calculation unit calculates the round-trip delay based on the congestion delay in the wired section calculated by the traffic-specific congestion calculation unit, the downstream delay in the wired section measured by the relay device, and the propagation delay in the wireless section obtained via the base station. The control device according to claim 1 or 2.

4. the association information includes at least destination information indicating a destination of traffic; a wired section propagation delay determination unit that estimates a transmission distance based on the destination information included in the cooperation information and estimates a propagation delay in the wired section based on the estimated transmission distance; a wireless section transmission delay determination unit that estimates a propagation delay in a wireless section based on the positions and qualities of the plurality of wireless terminals; a return path congestion estimation unit that estimates downstream processing delay and downstream congestion delay based on the amount of traffic on the return path; a processing delay determination unit that estimates a processing delay required to process the traffic; the round-trip delay calculation unit calculates the round-trip delay based on the uplink congestion delay calculated by the traffic-specific congestion calculation unit, the wired section propagation delay estimated by the wired section propagation delay determination unit, the wireless section propagation delay estimated by the wireless section transmission delay determination unit, the downlink processing delay and congestion delay estimated by the return path congestion estimation unit, and the processing delay estimated by the processing delay determination unit. The control device according to claim 1 .

5. the cooperation information includes at least information regarding traffic allocation amount; the traffic-specific congestion calculation unit calculates a congestion delay in the wired section based on the priority information, information on the traffic allocation amount, and information on bandwidth. The control device according to claim 1 .

6. a downstream traffic-specific congestion calculation unit that calculates a congestion delay of downstream traffic based on the traffic volume and priority of the return path obtained based on the downstream traffic and the bandwidth; a delay feedback unit that calculates an estimated downstream delay based on the congestion delay of the downstream traffic calculated by the downstream traffic-specific congestion calculation unit, a propagation delay in a wireless section, and a propagation delay in a wired section; a downstream path change instruction unit that determines whether a delay requirement is satisfied based on the information on the estimated downstream delay, The control device according to claim 1 .

7. A switching control method performed by a control device in a communication system in which one-way communication and round-trip communication are mixed, comprising: acquiring, for each traffic, information on a required delay and information on priority of the traffic based on cooperation information indicating a communication state between the plurality of wireless terminals and a base station performing wireless communication, the cooperation information being obtained from the traffic transmitted from the plurality of wireless terminals; calculating a congestion delay in a wired section based on the priority information acquired for each traffic; calculating a round trip delay based on the calculated congestion delay in the wired section and the delay in the downstream direction; A switching control method for transmitting a control signal including an instruction to switch paths to a relay device that relays the traffic when the round trip delay does not satisfy a required delay.

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