JP7622819B2 - CONTROL SYSTEM, CONTROL METHOD, CONTROLLER, AND PROGRAM - Google Patents

Description

The present disclosure relates to a control system, a control method, a controller, and a program for allocating communication bandwidth within an access network.

In recent years, studies have been underway to accommodate multiple services and applications with various network requirements on the same network infrastructure. To achieve this, it is necessary to guarantee the quality required by each service or application accommodated on the same network in the end-to-end sections from "terminal to terminal" or "terminal to application server."

The end-to-end of a network can be divided into wireless and wired sections. In the wireless section, there is a priority control function called Enhanced Distributed Channel Access (EDCA) of IEEE 802.11 as an existing technology (Non-Patent Documents 1 and 2).

EDCA is a terminal (destination)-based control, and there is a problem that it is difficult to control on a traffic flow basis, which would enable quality control on a service and application basis.One possible solution to this problem is for the controller to allocate communication bandwidth based on notification of packet volume from the terminal.

However, in real-world communications, delays always occur between transmission and reception, which can lead to a time lag between the packet volume notification from each terminal and access point and the scheduling notification from the controller, resulting in a difference between the actual volume of packets stored in the buffer and the volume of packets sent in response to a transmission instruction. For example, even if the maximum packet storage volume within a scheduling cycle is eight packets, if packet transmission occurs within the scheduling cycle, a transmission instruction is received for a volume of packets greater than the volume of packets stored in the buffer, which can reduce packet transmission efficiency.

IEEE 802.11e-2005 - IEEE Standard for Information technology--Local and metropolitan area networks--Specific requirements--Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications - Amendment 8: Medium Access Control (MAC) Quality of Service Enhancements "IEEE802.11e: A wireless LAN standard that realizes QoS," Journal of the Institute of Image Information and Television Engineers, Vol. 57, No. 11 (2003)

The present disclosure aims to prevent a decrease in packet transmission efficiency even when packet transmission occurs within a scheduling period.

The terminal embeds a forced update flag in the packet amount notification sent immediately after transmitting a packet, which causes the controller to update the packet amount in the buffer where the transmission was performed. If the forced update flag is present, the controller forcibly updates the database with the packet amount in the notification.

The control system according to the present disclosure comprises:
A control system for controlling traffic in a wireless network, comprising:
a terminal and an access point for transmitting packets to each other via the wireless network;
A controller that performs transmission control on the terminal and the access point;
Equipped with
the controller refers to a database storing a packet amount for each buffer of the terminal determined based on a packet amount notification received from the terminal, and controls packet transmission from the terminal to the access point based on the database;
the terminal embeds a forced update flag for forcibly updating the database in a packet amount notification immediately after a packet transmission under the control of the controller, and transmits the packet amount notification;
When a forced update flag is embedded in the received packet amount notification, the controller updates the packet amount of the buffer of the terminal notified in the packet amount notification in the database to the packet amount in the packet amount notification.

The control method according to the present disclosure includes:
A method for controlling traffic in a wireless network, comprising:
The control method includes a transmission control performed by a controller on a terminal and an access point that transmit packets to each other via the wireless network,
referring to a database storing the amount of packets per buffer of the terminal determined based on the packet amount notification received from the terminal, and controlling packet transmission from the terminal to the access point based on the database;
If a forced update flag is embedded in the received packet amount notification, the packet amount of the buffer of the terminal notified in the packet amount notification in the database is updated to the packet amount in the packet amount notification.

The controller according to the present disclosure comprises:
A controller for controlling traffic in a wireless network, comprising:
The controller is a device that performs transmission control on a terminal and an access point that transmit packets to each other via the wireless network,
referring to a database storing the amount of packets per buffer of the terminal determined based on the packet amount notification received from the terminal, and controlling packet transmission from the terminal to the access point based on the database;
If a forced update flag is embedded in the received packet amount notification, the packet amount of the buffer of the terminal notified in the packet amount notification in the database is updated to the packet amount in the packet amount notification.

The present disclosure is a program for causing a computer to function as the controller. The controller can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

According to the present disclosure, a decrease in packet transmission efficiency can be prevented even when packet transmission occurs within a scheduling period.

1 illustrates an example of a basic configuration of a control system according to the present disclosure. 1 illustrates an example of a system configuration of a control system according to the present disclosure. 13 is an example of information held in a database provided in the controller. FIG. 4 is a diagram illustrating a control method according to the present invention. An example of packet scheduling in which the scheduling period is 1/5 of the packet amount notification period and transmission times are scheduled for a total of five packets is shown. FIG. 1 is a diagram illustrating a problem to be solved by the present disclosure. An example of a control method according to this embodiment will be described. 1 shows an example of the operation of a control system according to an embodiment of the present disclosure.

Below, the embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings are considered to be identical to each other.

(Basic configuration)
First, the basic configuration of the control system of this embodiment will be described. Fig. 1 is a diagram illustrating a control system 300 of this embodiment.
The control system 300 is a control system that controls traffic of the wireless network 15,
A terminal 11 and an access point 12 which transmit packets to each other via a wireless network 15;
a controller 13 that performs transmission control for the terminal 11 and the access point 12;
Equipped with.

The control system 300 of the present disclosure is configured in a network including an access point 12, a controller 13, and a plurality of terminals 11,
The controller 13 refers to a database DB3 that stores the packet amount for each buffer of the terminal 11 determined based on the packet amount notification received from the terminal 11, and controls packet transmission from the terminal 11 to the access point 12 based on the database DB3.
The terminal 11 transmits a packet amount notification including a forced update flag for forcibly updating the database DB3 immediately after transmitting the packet under the control of the controller 13,
When the forced update flag is included in the received packet amount notification, the controller 13 forcibly updates the packet amount for each buffer of the terminal 11 in the database DB3 based on the packet amount in the packet amount notification.

(First embodiment)
2 is a diagram illustrating the control system of this embodiment. The control system of this embodiment includes N terminals 11, an access point 12 that communicates with these terminals 11, and a controller 13 that allocates communication bandwidth to the terminals 11. The terminals 11, the access point 12, and the controller 13 can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

The terminal 11, the access point 12 and the controller 13 each have a function of controlling the communication quality of the terminal 11 based on a notification of the amount of packets from the terminal 11. Specifically, each of the terminals 11 and the controller 13 has the following configuration.
The terminal 11 includes a main signal transmitting/receiving unit MTR1, a main signal buffer unit MB1, flow unit buffer units FB1#1-#L, applications AP1#1-#L, a scheduler unit SCH1, a packet amount notifying unit NTF1, and a control signal transmitting/receiving unit CTR1.
The access point 12 includes a main signal transmission/reception unit (lower) MTR2, a main signal buffer unit MB2, flow unit buffer units FB2#1-#K, a main signal transmission/reception unit (upper) MTRU, a packet quantity notification unit NTF2, a scheduler unit SCH2, and a control signal transmission/reception unit CTR2.
The controller 13 includes a database unit DB3, a scheduling unit SCH3, and a control signal transmission/reception unit CTR3.

Each of the terminal 11 and the access point 12
Buffers (FB1, FB2) for storing transmission packets for each traffic flow;
an apparatus-side transmitting/receiving unit (CTR1, CTR2) that transmits to a controller 13 the amount of transmission packets accumulated for each traffic flow in a buffer (FB1, FB2) and receives from the controller 13 the transmission time and the transmission amount of the transmission packets for each traffic flow;
a main signal transmitting unit (MTR1, MTR2) for transmitting the transmission packets for each traffic flow in the buffer (FB1, FB2) to a wireless network 15 according to the transmission time and the transmission amount;
Equipped with.

The controller 13 is
a control signal transmitting/receiving unit CTR3 that receives the stored amount from each of the terminal 11 and the access point 12 and transmits the transmission time and the transmission amount to each of the terminal 11 and the access point 12;
a scheduling unit SCH3 that determines the transmission time and the transmission amount of the transmission packet for each traffic flow based on the accumulated amount;
Equipped with.

The control system communicates control signals between the controller 13 and the access point 12/terminal 11 using a communication means separate from the communication means for the main signal (traffic packets). Specifically, the control signals are transmitted and received between the control signal transmitting/receiving unit CTR1 of the terminal 11 and the control signal transmitting/receiving unit CTR3 of the controller 13, and between the control signal transmitting/receiving unit CTR2 of the access point 12 and the control signal transmitting/receiving unit CTR3 of the controller 13.

Each terminal 11 and access point 12 periodically notifies the controller 13 of the amount of packets stored in the per-flow buffer units (FB1, FB2) as a control signal.
The terminal 11 accumulates packets from each application AP1 in a buffer FB1 for each application (for each flow). The packet amount notification unit NTF1 periodically checks the amount of packets accumulated in each buffer FB1, and notifies the controller 13 of the amount of packets accumulated in each buffer FB1 as a control signal via the control signal transmission/reception unit CTR1. In this disclosure, this control signal is referred to as a "packet amount notification."
The flow unit buffer unit FB1 may be owned by the application AP1.

The packet amount notification unit NTF1 of the present disclosure inserts a forced update flag into the packet amount notification immediately after transmitting a packet. The packet amount notification into which the forced update flag is inserted may be a packet amount notification that is performed periodically, but is not limited to this in the present disclosure. For example, the packet amount notification unit NTF1 may transmit a packet amount notification with a forced update flag inserted to the controller 13 before the periodic packet amount notification. In this case, the terminal 11 may perform a packet amount notification without waiting for confirmation of packet reception at the access point 12, but may also perform a packet amount notification when the reception of a packet at the access point 12 is confirmed.

In addition, the access point 12 accumulates 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 amount of packets accumulated in each buffer FB2 and notifies the controller 13 of this as a control signal via the control signal transmission/reception unit CTR2.

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 based on this, determines the transmission time and transmission amount for each buffer and notifies each terminal 11 and access point 12 as a control signal.

The control signal transmission/reception unit CTR3 of the controller 13 receives control signals from each terminal 11 and access point 12, and organizes the packet accumulation amount contained in the control signal, information on the terminal 11, the access point 12, and the flow unit buffers (FB1, FB2) in a database DB3.

FIG. 3 is a diagram illustrating an example of information organized in the database DB3.
This database DB3 organizes the following three pieces of information.
The item number is a serial 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 amount of packets stored in a buffer having a corresponding buffer number. For example, item number K+2 indicates the amount of packets stored in the per-flow buffer unit FB1#2 of the terminal 11#1, and the amount is "B12."

The scheduling unit SCH3 of the controller 13 uses a scheduling method described below to determine the transmission time and transmission amount for each buffer from the contents of the database unit DB3. The scheduling unit SCH3 then uses the determined transmission time and transmission amount as a control signal and transmits it from the control signal transmission/reception unit CTR3 to the terminal 11 and the access point 12.

Each terminal 11 and access point 12 extracts packets stored in the flow unit buffer units (FB1, FB2) at the notified transmission time and transmission amount and inputs them to the main signal buffer units (MB1, MB2). The main signal transmission/reception units (MTR1, MTR2) transmit the packets in the main signal buffer units (MB1, MB2) to the wireless network 15.

4 is a flowchart illustrating the above-described operation. The control method of this embodiment is a method for controlling traffic in the wireless network 15, and includes the steps of:
The control method is a transmission control performed by a controller 13 on a terminal 11 and an access point 12 which transmit packets to each other via a wireless network 15,
Storing transmission packets for each traffic flow in the buffers (FB1, FB2) of the terminal 11 and the access point 12 (steps S111, S112, S121, S122);
Transmitting to the controller the amount of the transmission packets stored in each of the buffers for each traffic flow (steps S113 and S123);
determining, in the controller, a transmission time and a transmission amount of the transmission packet for each traffic flow based on the accumulated amount received from each of the terminal and the access point (steps S131 and S132);
Transmitting the transmission time and the transmission amount from the controller to each of the terminal and the access point (step S133); and transmitting the transmission packets for each traffic flow from the buffers of each of the terminal and the access point to the wireless network according to the transmission time and the transmission amount (steps S114, S124).
It is characterized by:

In real communication, delay time always occurs between transmission and reception, so there may be a time difference between the packet amount notification from each terminal 11 and access point 12 and the scheduling notification from the controller 13, and there may be a difference between the actual packet amount stored in the buffer FB1 and the packet amount transmitted by the terminal 11 due to the transmission instruction. For example, as shown in FIG. 5, if the scheduling period is 1/5 of the packet amount notification period and the controller 13 schedules the transmission time of buffer number #M of terminal 11 #N for a total of 5 packets, as shown in FIG. 6, even if the maximum packet accumulation amount within the scheduling period is 8 packets, if packet transmission occurs within the scheduling period, the packet transmission efficiency may decrease because a packet amount transmission instruction larger than the packet amount accumulated in the buffer is received. Therefore, the terminal 11 of the present disclosure embeds a forced update flag in the packet amount notification transmitted immediately after packet transmission, and forcibly updates the database DB3 of the controller 13.

An example of the control method of this embodiment is shown in Fig. 7. The control method of this embodiment is a control method for controlling traffic in the wireless network 15, and executes the following steps when transmitting a packet stored in buffer number #M of terminal 11#N.
The terminal 11#N is
When a packet is stored in the buffer FB1#M (S311), the packet amount notifying unit NTF1 counts the amount of packets in the buffer FB1#M (S312) and determines whether or not it is immediately after a packet transmission (S313).
If it is immediately after packet transmission (Yes in S313), the packet amount notifying unit NTF1 inserts a forced update flag into the packet amount notification of the buffer FB1 immediately after transmission (S314).
If it is not immediately after packet transmission (No in S313), or after step S114, the packet amount notifying unit NTF1 notifies the controller 13 of the amount of packets stored in the buffer FB1#M (315).

When the controller 13 receives a packet amount notification from the terminal 11#N, it determines whether or not there is a forced update flag (S321).
If there is no forced update flag (No in S321), it is determined whether the packet amount in the notification is greater than the packet amount of buffer number #M of terminal 11#N recorded in database unit DB3 (S322). If the packet amount in the notification is less than the packet amount of buffer number #M of terminal 11#N recorded in database unit DB3 (No in S322), the notification is discarded.
If a forced update flag is present (Yes in S321), or if the notification packet volume is greater than the packet volume of buffer number #M of terminal 11 #N recorded in database unit DB3 (Yes in S322), the packet volume of buffer number #M that needs to be updated is recorded in database unit DB3 (S323).
Then, the controller 13 determines the transmission time and transmission amount of the packet stored in buffer number #M of terminal 11#N from the records in the database unit DB3 in the scheduling unit SCH3 (S324), and notifies each access point 12 and terminal 11#N of the packet transmission time and transmission amount of buffer number #M of terminal 11#N determined by the scheduling unit SCH3 (S325).

When terminal 11#N receives a notification from controller 13, scheduler unit SCH1 transmits the stored packet in buffer #M according to the transmission time and transmission amount determined by scheduling unit SCH3 (S316).

8 shows an example of packet scheduling when the database unit DB3 is updated using the forced update flag. When the controller 13 schedules the transmission time _T1 and end time ( _T1 + _t1 ) of the buffer number #M of the terminal 11#N for a total of five packets, the terminal 11#N embeds a forced update flag in the packet amount notification immediately after transmitting the fifth packet.

For example, if the packet amount of buffer number #M of terminal 11#N is 4 when the packet amount notification is sent immediately after the transmission of the fifth packet, terminal 11#N sends a packet amount notification to controller 13 indicating that the packet amount of buffer number #M is 4 and including a forced update flag. When controller 13 receives this packet amount notification, it updates the packet amount of buffer number #M in database unit DB3 to 4 according to the forced update flag received from terminal 11#N. This allows controller 13 to schedule the transmission time _T2 and end time ( _T2 + _t2 ) for a total of five packets.

[Scheduling method]
Here, the scheduling method performed by the scheduling unit SCH13 of the controller 13 will be described.
[1] Fair Scheduling This scheduling method performs calculations to divide the bandwidth or time by the total number of per-flow buffers (FB1, FB2) in which packets are stored in the terminal 11 and the access point 12.
The parameters are explained below.
The number of per-flow buffers in which packets are stored, including the terminal 11 and the access point 12: n
Time for 1 cycle: T [sec]
Total transmission limit of main signal per cycle time: Z [Bytes/sec]
Time to transmit the first stored packet: t _start [sec]

フロー単位バッファ＃Ｊの送信時刻Ｔ_Ｊ［ｓｅｃ］は、

フロー単位バッファ＃Ｊの送信時刻ｔ_Ｊ［ｓｅｃ］は、

と計算される。 in this case,
The transmission amount S _J [Bytes] of the per-flow buffer #J is

The transmission time T _J [sec] of the per-flow buffer #J is

The transmission time t _J [sec] of per-flow buffer #J is expressed as follows:

It is calculated as follows.

The order in which flow unit buffers start transmitting may be, for example, starting from the lowest item number organized in the database unit DB3 of the controller 13.

[2] Scheduling Considering Bandwidth Weighting This scheduling method is determined based on the number of per-flow buffers (FB1, FB2) in which packets are stored in the terminal 11 and the access point 12, and the amount of packets stored therein.
The parameters are explained below.
Packet accumulation amount in per-flow buffer #J: B _J [Bytes]
Time for 1 cycle: T [sec]
Transmission limit per cycle: Z [Bytes/sec]
Time required to transmit all packets stored in all per-flow buffers: T _all [sec]
Time when the first packet is transmitted from all packets stored in the per-flow buffer: t _start [sec]

とすると、
フロー単位バッファ＃Ｊの送信量Ｓ_Ｊ［Ｂｙｔｅｓ］は、
Ｔ_ａｌｌ≦Ｔの場合、

Ｔ_ａｌｌ＞Ｔの場合、

フロー単位バッファ＃Ｊの送信時刻Ｔ_Ｊ［ｓｅｃ］は、
Ｔ_ａｌｌ≦Ｔの場合、

Ｔ_ａｌｌ＞Ｔの場合、

フロー単位バッファ＃Ｊの送信時刻ｔ_Ｊ［ｓｅｃ］は、
Ｔ_ａｌｌ≦Ｔの場合、

Ｔ_ａｌｌ＞Ｔの場合、

と計算される。 in this case,

Then,
The transmission amount S _J [Bytes] of the per-flow buffer #J is
If T _all ≦T,

If T _all >T,

The transmission time T _J [sec] of the per-flow buffer #J is
If T _all ≦T,

If T _all >T,

The transmission time t _J [sec] of per-flow buffer #J is expressed as follows:
If T _all ≦T,

If T _all >T,

It is calculated as follows.

In addition, when T _all > T, packets that cannot be transmitted are carried over to the next transmission timing. In addition, in the present embodiment, an example of allocating a transmission time and a transmission amount as an example of a communication band that the controller 13 allocates to each terminal 11 is shown, but the present disclosure is not limited thereto.

As described above, the embodiment of the present disclosure includes:
The terminal 11 inserts a forced update flag into a packet amount notification immediately after a packet transmission,
The controller 13 forcibly updates the database DB3 based on the forcible update flag embedded in the packet amount notification.
As a result, the present disclosure can prevent a decrease in packet transmission efficiency even when packet transmission occurs within a scheduling period.
Furthermore, successively updating the packet amount notified at a fixed interval in the database unit DB3 of the controller 13 places a heavy load on the controller 13 when the packet amount notification interval is short and there are a large number of terminals. In this regard, the present disclosure updates the database in buffer units at the timing when an update is required, thereby reducing the load on the controller 13.

This disclosure can be applied to the information and communications industry.

11: Terminal 12: Access point 13: Controller 15: Wireless network 50: Upper network device 300: Control system

Claims (4)

A control system for controlling traffic in a wireless network, comprising:
a terminal and an access point for transmitting packets to each other via the wireless network;
A controller that performs transmission control on the terminal and the access point;
Equipped with
the controller refers to a database storing a packet amount for each buffer of the terminal determined based on a packet amount notification received from the terminal, and controls packet transmission from the terminal to the access point based on the database;
the terminal embeds a forced update flag for forcibly updating the database in a packet amount notification when transmitting packets under the control of the controller, and transmits the packet amount notification;
When a forced update flag is embedded in the received packet amount notification, the controller updates the packet amount of the buffer of the terminal notified in the packet amount notification in the database to the packet amount in the packet amount notification.
Control system. A method for controlling traffic in a wireless network, comprising:
The control method includes a transmission control performed by a controller on a terminal and an access point that transmit packets to each other via the wireless network,
referring to a database storing the amount of packets per buffer of the terminal determined based on the packet amount notification received from the terminal, and controlling packet transmission from the terminal to the access point based on the database;
When a forced update flag for forcibly updating the database is embedded in the packet amount notification at the time of packet transmission from the terminal under the control of the controller among the received packet amount notifications, the packet amount of the buffer of the terminal notified in the packet amount notification in the database is updated to the packet amount of the packet amount notification.
Control methods. A controller for controlling traffic in a wireless network, comprising:
The controller is a device that performs transmission control on a terminal and an access point that transmit packets to each other via the wireless network,
referring to a database storing the amount of packets per buffer of the terminal determined based on the packet amount notification received from the terminal, and controlling packet transmission from the terminal to the access point based on the database;
When a forced update flag for forcibly updating the database is embedded in the packet amount notification at the time of packet transmission from the terminal under the control of the controller among the received packet amount notifications, the packet amount of the buffer of the terminal notified in the packet amount notification in the database is updated to the packet amount of the packet amount notification.
controller. A program for causing a computer to function as the controller according to claim 3.

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