Communication system, control method, controller, and program

Abstract

The purpose of the present invention is to provide a communication system, a control method, a controller, and a program capable of preventing a reduction in communication quality caused by making a control signal for quality control wireless.　A communication system according to the present invention is such that: when each of a terminal and an access point transmits an accumulated-packet-amount notification, which is the packet amount accumulated in a buffer, to the controller as the control signal, the accumulated-packet-amount notification having the same content is transmitted a plurality of times; and, the controller determines a schedule for transmitting the packet on the basis of the content of the accumulated-packet-amount notification received from at least one of the terminal and the access point, and, when transmitting the schedule as the control signal to each of the terminal and the access point, transmits the schedule having the same content a plurality of times.

Description

Technical Field

[0001] The present disclosure relates to a communication system, a control method, a controller, and a program for wirelessly transmitting and receiving control signals.

Background Art

[0002] In recent years, consideration has been given to accommodating a plurality of services and applications having various network requirements on the same network infrastructure. For this purpose, in the End-End section from "terminal to terminal" or "terminal to application server", the quality required by each service and application accommodated in the same NW must be guaranteed.

[0003] The End-End of a network can be divided into wireless and wired sections. Among them, in the wireless section, there is a priority control function called Enhanced Distributed Channel Access (EDCA) of IEEE802.11 as an existing technology (see, for example, Non-Patent Documents 1 and 2).

[0004] EDCA is control at the terminal (destination) unit, and it is difficult to perform control in traffic flow units that enable quality control at the service and application units. However, by applying a quality control technology based on centralized control that does not depend on a wireless network (see, for example, Non-Patent Document 3), quality control at the service and application units can be realized.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] Figures 1 to 4 are diagrams for explaining the problems of the present invention. As shown in Figure 1, by wirelessifying the control signal for quality control, there are no restrictions on the wired cable as in the case of main signal communication, and the situations where EDCA can be applied increase. Figure 2 is a sequence diagram for explaining the transmission and reception of the control signal. Let the period Tc at which the controller performs scheduling and the period t at which the terminal or access point notifies the amount of packets accumulated in its own buffer. In Figure 2, the case of Tc = 5t is explained.

[0007] Terminal #N transmits the amount of packets b newly accumulated in buffer #M it holds to the controller every time t as the accumulated packet amount notification I. Specifically, for terminal #N, the amount of packets accumulated in buffer #M is zero at the accumulated packet amount notification I0 (there are no packets in the buffer until I1 is transmitted), That the accumulated packet quantity notification I1 is 1 (that one packet b has been accumulated in buffer #M at cycle t1), That the accumulated packet quantity notification I2 is 3 (that two packets b have been accumulated in buffer #M at cycle t2), That the accumulated packet quantity notification I3 is 4 (that one packet b has been accumulated in buffer #M at cycle t3), That the accumulated packet quantity notification I4 is 5 (that one packet b has been accumulated in buffer #M at cycle t4), is transmitted. After that, terminal #N repeats the above as cycle t1.

[0008] The controller integrates the accumulated packet quantity notifications I that have arrived during period Tc, and recognizes that five packets are accumulated in buffer #M of terminal #N. Then, the controller schedules the transmission time and transmission duration for five packets for buffer #M of terminal #N. The controller transmits the schedule Sc to terminal #N. Note that the transmission time means "the timing to start packet transmission", and the transmission duration means "the length of time during which packet transmission is permitted".

[0009] Terminal #N accesses five packets from buffer #M at the time indicated by schedule Sc and transmits them at the indicated speed toward access point #K (step Bt). Note that FIG. 2 is a sequence diagram when packets are transmitted from the terminal toward the access point, but the same applies when packets are transmitted from the access point toward the terminal.

[0010] On the other hand, when the control signal is wirelessly transmitted, the occurrence of packet loss due to external factors increases compared to wired transmission, events such as those in FIGS. 3 and 4 occur, and appropriate scheduling may not be performed.

[0011] Figure 3 is a sequence diagram for explaining a problem that occurs when a part of the accumulated packet quantity notification I is not reached. Since the accumulated packet quantity notification I4 is not reached, the controller erroneously recognizes that 4 packets are accumulated in buffer #M of terminal #N. Then, the controller schedules the transmission time and transmission duration for 4 packets for buffer #M of terminal #N. For this reason, terminal #N can only transmit 4 packets from buffer #M, resulting in a deterioration of communication quality.

[0012] Figure 4 is a sequence diagram for explaining a problem that occurs when schedule Sc is not reached. Assume that the controller transmits schedule Sc for transmitting 5 packets from buffer #M to terminal #N, but terminal #N fails to receive it. Then, terminal #N cannot transmit packets, resulting in a deterioration of communication quality.

[0013] That is, by wirelessly transmitting the control signal for quality control, the situations where EDCA can be applied increase, but there is a problem that the communication quality may deteriorate due to packet loss of the control signal. Therefore, an object of the present invention is to provide a communication system, a control method, a controller, and a program that can prevent a deterioration of communication quality due to wireless transmission of a control signal for quality control in order to solve the above problems.

Means for Solving the Problems

[0014] In order to achieve the above object, the communication system according to the present invention transmits the same control signal a plurality of times.

[0015] Specifically, the communication system according to the present invention is a communication system that controls the traffic of a wireless network, terminals and access points that mutually transmit packets via the wireless network, a controller that transmits and receives a control signal between the terminals and the access points via the wireless network, and includes When each of the terminal and the access point transmits an accumulated packet amount notification, which is the amount of packets accumulated in a buffer, to the controller as the control signal, it transmits the accumulated packet amount notification with the same content a plurality of times. The controller determines a schedule for transmitting the packets based on the content of the accumulated packet amount notification received from at least one of the terminal and the access point, and transmits the schedule with the same content a plurality of times when transmitting the schedule to each of the terminal and the access point as the control signal. It is characterized by the above.

[0016] Also, a control method according to the present invention is a control method for controlling traffic of a wireless network including a terminal and an access point that mutually transmit packets via the wireless network, and a controller that transmits and receives a control signal between the terminal and the access point via the wireless network, and each of the terminal and the access point transmits the accumulated packet amount notification with the same content a plurality of times when transmitting an accumulated packet amount notification, which is the amount of packets accumulated in a buffer, to the controller as the control signal, and the controller determines a schedule for transmitting the packets based on the content of the accumulated packet amount notification received from at least one of the terminal and the access point, and transmits the schedule with the same content a plurality of times when transmitting the schedule to the terminal and the access point as the control signal. It is characterized by the above.

[0017] Furthermore, a controller according to the present invention is a controller that transmits and receives a control signal via the wireless network between a terminal and an access point that mutually transmit packets via the wireless network, and A receiving unit that receives, as the control signal, a stored packet amount notification that is the amount of packets stored in each buffer, from at least one of the terminal and the access point; A scheduling unit that determines a schedule for transmitting the packets based on the content of the stored packet amount notification; A transmitting unit that transmits the same schedule multiple times when transmitting the schedule to each of the terminal and the access point as the control signal; It is provided with.

[0018] Since the transmitting side transmits the same control information (stored packet amount notification and schedule) multiple times, even if a packet loss occurs during transmission, the receiving side can receive any of the control information transmitted multiple times. Therefore, the present invention can provide a communication system, a control method, a controller, and a program that can prevent a deterioration in communication quality due to wirelessization of a control signal for quality control.

[0019] It is a heavy load for the receiving side to read all of the control information transmitted multiple times. Therefore, a sequence number is assigned to the stored packet amount notification and the schedule, The controller discards the stored packet amount notification whose sequence number is the same as that of the immediately preceding stored packet amount notification, The terminal and the access point preferably discard the schedule whose sequence number is the same as that of the immediately preceding schedule.

[0020] The present invention is a program for causing a computer to function as the controller. The data collection device of the present invention can also be realized by a computer and a program, and it is also possible to record the program on a recording medium or provide it through a network.

[0021] In addition, the above inventions can be combined as much as possible.

Effects of the Invention

[0022] The present invention can provide a communication system, a control method, a controller, and a program that can prevent a deterioration in communication quality due to wireless transmission of a control signal for quality control.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0024] Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In this specification and the drawings, components having the same reference numerals indicate the same components.

[0025] (Embodiment 1) FIG. 5 is a diagram for explaining the communication system 301 of the present embodiment. The communication system 301 is a communication system that controls the traffic of the wireless network 15#2, and terminals 11 and access points 12 that mutually transmit packets via the wireless network 15#2, and a controller 13 that performs transmission control on the terminals 11 and the access points 12, and is provided with The controller 13 determines a schedule (transmission time and transmission amount for each traffic flow) based on at least the amount of packets accumulated in the buffer notified from the terminal 11 (in the case of FIG. 5, there is a buffer for each traffic flow, and the amount of packets accumulated in each buffer), and notifies the terminals 11 and the access points 12 of the schedule.

[0026] Since the controller 13 calculates a schedule for each traffic flow using control information for each traffic flow (see, for example, Non-Patent Document 3), the communication system 301 can guarantee the bandwidth for each traffic flow.

[0027] Note that the communication system 301 in FIG. 5 includes a wireless network 15#2 that transmits a main signal and a wireless network 15#1 that transmits control information (accumulated packet amount notification and schedule), but the main signal and the control information may be transmitted using one wireless network.

[0028] The communication system 301 connects each terminal 11 and access point 12 to the controller 13, accumulates packets in a buffer (FB1, FB2) for each traffic flow in each terminal 11 and access point 12, or in a buffer in the application, notifies the controller 13 of the accumulated amount of packets in advance a plurality of times, determines the transmission time and transmission amount for each traffic in the scheduling unit SCH3 of the controller 13, The controller 13 notifies each terminal 11 and access point 12 of a schedule (transmission time and transmission amount) a plurality of times, and each terminal 11 and access point 12 transmits packets according to the notified transmission time and transmission amount. It is assumed that the times of each terminal 11, access point 12, and controller 13 are synchronized using NTP, PTP, or the like.

[0029] Specifically, the communication system 301 is a communication system that controls the traffic of the wireless network 15, including terminals 11 and access points 12 that mutually transmit packets via the wireless network 15#2, and a controller 13 that transmits and receives control signals to and from the terminals 11 and access points 12 via the wireless network 15#1, and is provided with each of the terminals 11 and access points 12 transmits the same content of the accumulated packet amount notification a plurality of times when transmitting the accumulated packet amount notification, which is the amount of packets accumulated in the buffer (FB1, FB2), to the controller 13 as the control signal, the controller 13 determines a schedule for transmitting the packets based on the content of the accumulated packet amount notification received from at least one of the terminals 11 and access points 12, and transmits the same content of the schedule a plurality of times when transmitting the schedule to each of the terminals 11 and access points 12 as the control signal characterized in that.

[0030] The communication system 301 communicates the control signal between the controller 13 and the access point 12 / terminal 11 through a communication means (wireless network 15#1) different from the communication means (wireless network 15#2) of the main signal (traffic packet). Specifically, the control signal is transmitted and received between the control signal transceiver CTR1 of the terminal 11 and the control signal transceiver CTR3 of the controller 13, and between the control signal transceiver CTR2 of the access point 12 and the control signal transceiver CTR3 of the controller 13.

[0031] Each terminal 11 and access point 12 notifies the controller 13 of the packet amount accumulated in the flow unit buffer parts (FB1, FB2) as a control signal (accumulated packet amount notification) through the wireless network 15#1 at regular intervals. The terminal 11 accumulates the packets from each application AP1 in the buffer FB1 for each application (for each flow). The packet amount notification unit NTF1 periodically checks the packet accumulation amount in each buffer FB1 and notifies the controller 13 of this as a control signal through the control signal transceiver CTR1. Also, the access point 12 accumulates the packets from the upper network device 50 in the buffer FB2 for each application (for each flow). The packet amount notification unit NTF2 periodically checks the packet accumulation amount in each buffer FB2 and notifies the controller 13 of this as a control signal through the control signal transceiver CTR2. Note that the application AP1 may own the flow unit buffer part FB1.

[0032] Here, it is assumed that each terminal 11 and access point 12 notify the controller 13 of the accumulated packet amount at regular intervals of period t. Each terminal 11 and access point 12 transmit the same accumulated packet amount notification n times (n is an integer of 2 or more) in one period. Therefore, the time required to transmit the accumulated packet amount notification n times is equal to or less than the period t.

[0033] The controller 13 records the notified packet accumulation amount, information on the terminal 11, the access point 12, and the flow unit buffers (FB1, FB2), and determines the transmission time and transmission amount (schedule) for each buffer based on this information. Then, the controller 13 notifies the schedule to each terminal 11 and the access point 12 as a control signal via the wireless network 15#1.

[0034] The control signal transceiver CTR3 of the controller 13 receives control signals from each terminal 11 and the access point 12, and arranges the packet amounts stored in the respective flow unit buffers (FB1, FB2) in the database DB.

[0035] FIG. 6 is a diagram for explaining an example of the information arranged in the database DB. This database DB arranges the following three pieces of information. The item number is a sequential number for all the buffers (FB1, FB2) of the terminal 11 and the access point 12. The node number is the number of the access point 12 or the terminal 11. The buffer number is the number of the buffer FB1 held by each terminal 11, or the number of the buffer FB2 held by the access point 12. The packet amount is the packet accumulation amount held by the buffer having each buffer number. For example, item number K + 2 is the packet accumulation amount of the flow unit buffer unit FB1#2 held by the terminal 11#1, and the amount is "B12".

[0036] The scheduling unit SCH3 of the controller 13 uses a scheduling method such as Non-Patent Document 3 to determine the transmission time and transmission amount for each buffer from the content of the database unit DB. Then, the scheduling unit SCH3 transmits the determined schedule as a control signal from the control signal transceiver CTR3 to the terminal 11 and the access point 12.

[0037] Here, it is assumed that the controller 13 notifies the schedule to each terminal 11 and access point 12 at a fixed period Tc. The controller 13 transmits the same schedule m times (m is an integer of 2 or more). Therefore, the time required to transmit the same schedule m times is equal to or less than the period Tc.

[0038] Each terminal 11 and access point 12 extracts the packets accumulated in the flow unit buffer sections (FB1, FB2) based on the transmission time and transmission amount of the notified schedule and inputs them to the main signal buffer sections (MB1, MB2). The main signal transmission / reception sections (MTR1, MTR2) transmit the packets in the main signal buffer sections (MB1, MB2) to the wireless network 15#2.

[0039] FIG. 7 is a diagram illustrating the operations described above in a flowchart. The control method of the present embodiment is The control method is a control method for controlling the traffic of the wireless network 15 including a terminal 11 and an access point 12 that mutually transmit packets via the wireless network 15#2, and a controller 13 that transmits and receives a control signal between the terminal 11 and the access point 12 via the wireless network 15#1, accumulating transmission packets for each traffic flow in the respective buffers (FB1, FB2) of the terminal 11 and the access point 12 (steps S111, S112, S121, S122) each of the terminal 11 and the access point 12 transmitting a plurality of the same accumulation packet amount notifications as the control signal when transmitting an accumulation packet amount notification, which is the amount of packets accumulated in each buffer, to the controller (steps S113, S123), the controller 13 recording the amount of packets stored in each buffer (FB#1, FB#2) in the database section DB from the accumulation packet amount notification (step S131), The controller 13 determines, for each traffic flow, a schedule for transmitting the packets based on the content of the accumulated packet amount notification received from at least one of the terminal 11 and the access point 12 (step S132). When the controller 13 transmits the schedule as the control signal to the terminal 11 and the access point 12, the controller 13 transmits the schedule with the same content a plurality of times (step S133), and the terminal 11 and the access point 12 transmit packets for each traffic flow from their respective buffers (FB#1, FB#2) to the wireless network 15#2 according to the schedule (steps S114, S124). are characterized by.

[0040] [Effect] FIGS. 8 and 9 are diagrams for explaining the effects of the control system 301. The period Tc during which the controller 13 performs scheduling and the period t during which the terminal 11 and the access point 12 notify the amount of packets accumulated in their own buffers i are defined (i is an integer of 0 or more). FIGS. 8 and 9 illustrate the case where Tc = 5t.

[0041] FIG. 8 shows an example in which the terminal 11#N transmits, as the accumulated packet amount notification I, the amount of packets b newly accumulated in the buffer FB1#M held by itself to the controller every time i time t. i is described. Specifically, the terminal 11#N has the amount of packets accumulated in the buffer FB1#M is zero in the accumulated packet amount notification I0 (no packets exist in the buffer until I1 is transmitted), is 1 in the accumulated packet amount notification I1 (one packet b has been accumulated in buffer #M at the period t1), is 3 in the accumulated packet amount notification I2 (two packets b have been accumulated in buffer #M at the period t2), is 4 in the accumulated packet amount notification I3 (one packet b has been accumulated in buffer #M at the period t3), The accumulated packet quantity notification I4 is 5 (one packet b has been accumulated in buffer #M at period t4). Send it. And the terminal #N sends the accumulated packet quantity notification I i at each period t i n times (n = 5 in this example).

[0042] Here, assume that packet loss occurs during the transmission of the accumulated packet quantity notification I4. The accumulated packet quantity notification I4 in which the packet loss occurred will not reach the controller 13, but since the same notification is sent n times, the controller 13 can receive one of the notifications. Therefore, the controller 13 can perform scheduling with accurate information.

[0043] The controller 13 integrates the accumulated packet quantity notifications I i that have arrived during the period Tc, and recognizes that 5 packets are accumulated in the buffer FB1#M of the terminal 11#N. Then, the controller 13 schedules the transmission time and transmission duration for 5 packets for the buffer FB1#M of the terminal 11#N. The controller 13 sends the schedule Sc to the terminal 11#N.

[0044] The terminal 11#N accesses 5 packets from the buffer FB1#M at the time indicated by the schedule Sc and sends them to the access point 12#K at the indicated speed (step Bt). Note that Fig. 8 is a sequence diagram when sending packets from the terminal 11 to the access point 12, and the same applies when sending packets from the access point 12 to the terminal 11.

[0045] Fig. 9 illustrates an example in which the controller 13 sends a schedule to the terminal 11#N. In this example, the operations up to the accumulated packet quantity notification I4 are the same as the description in Fig. 2. The controller 13 integrates the accumulated packet quantity notifications I iIntegrate them and recognize that 5 packets are stored in buffer FB1#M of terminal 11#N. Then, controller 13 schedules the transmission time and transmission duration for 5 packets for buffer #M of terminal #N. Controller 13 transmits the schedule Sc to terminal 11#N m times (in this example, m = 4). Note that terminal 11 receives multiple copies of the same schedule. In such a case, the schedule may be updated each time it is received. Also, in this figure, to avoid complicating the drawing, the description of the transmission of schedule Sc scheduled in a cycle prior to cycle Tc is omitted.

[0046] Here, assume that packet loss occurs during the transmission of schedule Sc. The schedule Sc in which the packet loss occurred does not reach terminal 11#N. However, since the same schedule Sc is transmitted m times, terminal 11#N can receive one of the schedules Sc. Therefore, terminal 11#N can transmit packets with accurate information (step Bt).

[0047] Also, in the control method described in FIG. 4, when packet loss of the schedule occurs, a packet is transmitted after one cycle Tc (a delay of one cycle Tc occurs). However, by performing the control method as shown in FIG. 9, a packet can be transmitted without waiting for one cycle Tc (the delay can be shortened). Specifically, assume that terminal 11#N can receive the schedule for the m s -th time. Then, the delay time is m s ×Tc / m, which can be made shorter than the delay time Tc of the control method in FIG. 4.

[0048] Note that FIG. 9 is a sequence diagram when transmitting a packet from a terminal to an access point. The same applies when transmitting a packet from an access point to a terminal.

[0049] (Embodiment 2) The configuration of the communication system of this embodiment is the same as that of FIG. 5. FIG. 10 is a diagram for explaining the operation of the communication system of this embodiment. The operation of the communication system of this embodiment adds the following steps to the operation of the communication system 301 of Embodiment 1 (FIG. 7). In this communication system, a sequence number is assigned to the accumulated packet amount notification and the schedule, the controller 13 discards the accumulated packet amount notification in which the sequence number is the same as that of the immediately preceding accumulated packet amount notification (steps S130a, S130b), and the terminal 11 and the access point 12 are characterized by discarding the schedule in which the sequence number is the same as that of the immediately preceding schedule (steps S113a, S123a, S150).

[0050] The controller 13 reading the accumulated packet amount notifications from each terminal 11 and access point 12 in a short time, and each terminal 11 and access point 12 reading the schedule from the controller 13 in a short time increase the load on the respective devices, and there is a risk that the quality such as throughput may deteriorate.

[0051] Therefore, a sequence number is assigned to the accumulated packet amount notification and the schedule. For example, the sequence number can be embedded in the header information of the notification and schedule packets.

[0052] Each terminal 11, access point 12, and controller 13 determine whether the notification (accumulated packet amount notification or schedule) has an updated sequence number (steps S130a, S123a, S113a). Then, each terminal 11, access point 12, and controller 13 reads only the content of the updated notification (steps S131, S124, S114) and discards the others (steps S130b, S150).

[0053] According to the control method of this embodiment, even if the accumulated packet amount notification and the schedule are transmitted multiple times, it is possible to avoid a quality degradation such as throughput degradation.

[0054] (Embodiment 3) The controller 13 can also be realized by a computer and a program, and it is also possible to record the program on a recording medium or provide it through a network. FIG. 11 shows a block diagram of the system 100. The system 100 includes a computer 105 connected to a network 135.

[0055] The network 135 is a data communication network. The network 135 may be a private network or a public network, and may include any or all of (a) a personal area network covering, for example, a certain room, (b) a local area network covering, for example, a certain building, (c) a campus area network covering, for example, a certain campus, (d) a metropolitan area network covering, for example, a certain city, (e) a wide area network covering, for example, an area spanning city, regional, or national boundaries, or (f) the Internet. Communication is performed by electronic signals and optical signals via the network 135.

[0056] The computer 105 includes a processor 110 and a memory 115 connected to the processor 110. Although the computer 105 is represented as a stand-alone device in this specification, it is not limited as such, but rather may be connected to other devices not shown in a distributed processing system.

[0057] The processor 110 is an electronic device composed of a logic circuit that responds to and executes instructions.

[0058] Memory 115 is a tangible computer-readable storage medium encoded with a computer program. In this regard, memory 115 stores data and instructions, i.e., program code, that are readable and executable by processor 110 to control the operation of processor 110. Memory 115 can be implemented with random access memory (RAM), a hard drive, read-only memory (ROM), or a combination thereof. One of the components of memory 115 is program module 120.

[0059] Program module 120 includes instructions for controlling processor 110 to execute the processes described herein. Although operations are described herein as being performed by computer 105 or a method or process or a sub-process thereof, those operations are actually performed by processor 110.

[0060] The term "module" is used herein to refer to a functional operation that can be embodied as either a stand-alone component or an integrated configuration consisting of a plurality of sub-components. Thus, program module 120 can be implemented as a single module or as a plurality of modules operating in cooperation with each other. Further, although program module 120 is described herein as being installed in memory 115 and thus implemented in software, it can be implemented in either hardware (e.g., an electronic circuit), firmware, software, or any combination thereof.

[0061] Program module 120 is shown as already loaded into memory 115, but may be configured to be located on storage device 140 for later loading into memory 115. Storage device 140 is a tangible computer-readable storage medium that stores program module 120. Examples of storage device 140 include a compact disk, magnetic tape, read-only memory, optical storage medium, hard drive or a memory unit composed of multiple parallel hard drives, as well as a universal serial bus (USB) flash drive. Alternatively, storage device 140 may be a random access memory or other type of electronic storage device located in a remote storage system (not shown) and connected to computer 105 via network 135.

[0062] System 100 further includes data sources 150A and 150B, collectively referred to herein as data source 150 and communicatively connected to network 135. In practice, data source 150 can include any number of data sources, i.e., one or more data sources. Data source 150 includes unsystematized data and can include social media.

[0063] System 100 further includes user device 130, which is operated by user 101 and connected to computer 105 via network 135. Examples of user device 130 include an input device such as a keyboard or voice recognition subsystem that enables user 101 to convey selections of information and commands to processor 110. User device 130 further includes an output device such as a display device or a printer or a voice synthesizer. A cursor control unit such as a mouse, trackball, or touch-sensitive screen enables user 101 to operate a cursor on the display device to convey further selections of information and commands to processor 110.

[0064] Processor 110 outputs the result 122 of the execution of program module 120 to user device 130. Alternatively, processor 110 can provide the output to a storage device 125 such as a database or memory, for example, or can provide it to a remote device (not shown) via network 135.

[0065] For example, a program that performs steps S131 to S133 in the flowchart of FIG. 7, or steps S130 to S133 in the flowchart of FIG. 10, may be used as program module 120. System 100 can be operated as controller 13.

[0066] The terms “comprising” or “including” are to be construed as specifying the presence of the features, integers, steps, or components recited therein, but not precluding the presence of one or more other features, integers, steps, or components, or groups thereof. The terms “a” and “an” are indefinite articles and thus do not preclude embodiments having a plurality of them.

[0067] (Other embodiments) Note that the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. In short, the present invention is not limited to the upper embodiments as they are, and at the implementation stage, the components can be modified and embodied without departing from the gist.

[0068] Also, various inventions can be formed by appropriately combining the plurality of components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined.

Description of reference numerals

[0069] 11: Terminal 12: Access point 13: Controller 15: Wireless network 50: Upper network device 100: System 101: User 105: Computer 110: Processor 115: Memory 120: Program module 122: Result 125: Storage device 130: User device 135: Network 140: Storage device 150: Data source 301: Communication system

Claims

1. A communication system for controlling the traffic of a wireless network, a terminal and an access point that mutually transmit packets via the wireless network, a controller that transmits and receives control signals between the terminal and the access point via the wireless network, comprising: When each of the terminal and the access point transmits an accumulated packet amount notification, which is the amount of packets accumulated in a buffer, to the controller as the control signal, in order to avoid a deterioration in communication quality caused by packet loss, the same accumulated packet amount notification is transmitted multiple times, The controller determines a schedule for transmitting the packets based on the content of the accumulated packet amount notification received from at least one of the terminal and the access point, and when transmitting the schedule to each of the terminal and the access point as the control signal, the same schedule is transmitted multiple times in order to avoid a deterioration in communication quality caused by packet loss characterized in that A sequence number is assigned to the accumulated packet amount notification and the schedule, The controller discards the accumulated packet amount notification whose sequence number is the same as the immediately preceding accumulated packet amount notification, The terminal and the access point discard the schedule whose sequence number is the same as the immediately preceding schedule A communication system characterized by this.

2. A terminal and an access point that mutually transmit packets via a wireless network, a controller that transmits and receives control signals between the terminal and the access point via the wireless network, A control method for controlling the traffic of the wireless network comprising the above, When each of the terminal and the access point transmits an accumulated packet amount notification, which is the amount of packets accumulated in a buffer, to the controller as the control signal, in order to avoid a deterioration in communication quality caused by packet loss, the same accumulated packet amount notification is transmitted multiple times, and when the controller determines a schedule for transmitting the packets based on the content of the accumulated packet amount notification received from at least one of the terminal and the access point, and transmits the schedule to the terminal and the access point as the control signal, in order to avoid a deterioration in communication quality caused by packet loss, the same schedule is transmitted multiple times characterized in that a sequence number is assigned to the accumulated packet amount notification and the schedule, the controller discards the accumulated packet amount notification whose sequence number is the same as that of the immediately preceding accumulated packet amount notification, and the terminal and the access point discard the schedule whose sequence number is the same as that of the immediately preceding schedule A control method characterized by the above.

3. A controller that transmits and receives a control signal via a wireless network between a terminal and an access point that mutually transmit packets via the wireless network, a receiving unit that receives, as the control signal, an accumulated packet amount notification, which is the amount of packets accumulated in each buffer, from at least one of the terminal and the access point, a scheduling unit that determines a schedule for transmitting the packets based on the content of the accumulated packet amount notification, a transmitting unit that transmits the same schedule multiple times in order to avoid a deterioration in communication quality caused by packet loss when transmitting the schedule to each of the terminal and the access point as the control signal, comprising The accumulated packet quantity notification is assigned a sequence number, The receiving unit discards the accumulated packet quantity notification in which the sequence number is the same as that of the immediately preceding accumulated packet quantity notification. A controller characterized by this.

4. A program for causing a computer to function as the controller according to Claim 3.

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