KR101345135B1 - SCHEDULING METHOD AND SYSTEM FOR IEEE802.11e HCCA PROTOCOL - Google Patents

Abstract

The present invention relates to a scheduling method and system of the HCCA protocol, wherein an access point (AP) receives accurate queue status information from a station (STA) through a frame such as an RTS / CTS during uplink scheduling, and thus status information. By reducing the lag, which is the time delay between the reception time and the TXOP allocation time, efficient scheduling is possible as in the scheduler of a wired network in a wireless medium having various channel conditions according to time or location. Therefore, it is possible to allow more traffic streams, thereby improving the performance of the wireless network.

HCCA, Queue, Rack, Scheduling

Description

ICHEE METHOD AND SYSTEM FOR IEEE802.11e HCCA PROTOCOL

The present invention relates to a scheduling method and system based on the HCCA protocol capable of efficient scheduling.

IEEE 802.1 is a working group of IEEE that is involved in the redefinition of wireless network standards. It is setting standards for DSSS, FHSS, and infrared methods. The IEEE ratified the FHSS and DSSS 2 Mbps protocols in 1998, and at the end of 1998, furthered the interoperability of 802.11 FHSS and DSSS.In late 1999, the IEEE ratified the IEEE 802.11 high-speed standard (2.4 GHz 11 Mbps). did.

The IEEE 802.11 standard does not satisfy the various Quality of Service (QoS) requirements of the Distributed Cordination Function (DCF) and Point Cordination Function (PCF), which are defined in the MAC layer. Therefore, IEEE 802.11e was created to improve the 802.11 MAC layer to support various QoS.

The channel access method proposed by IEEE 802.11e for the purpose of QoS improvement is HCF (Hybrid Coordination Function), and HCF uses a polled channel access method and a polled channel access method called EDCF (Enhanced DCF).

In the conventional IEEE 802.11e scheme, a coordinator assigns intervals to stations, and allocates bandwidth to the entire spectrum by applying data transmission only during the interval. This section is called TXOP (Transmission Opportunity). Stations are informed of the dynamic queue state in addition to the bandwidth information promised by the coordinator to be allocated more or less TXOP as needed. Such queue size information is transmitted in a data frame during the TXOP period.

However, this method must wait for an interval during TXOP allocated to other stations until it is notified of the queue size of the station and the TXOP is allocated when there is a plurality of STAs, and thus the queue size increases or decreases. It was impossible to accurately reflect on the disadvantage.

SUMMARY OF THE INVENTION The present invention has been made to improve the prior art as described above, wherein an access point (AP) receives accurate queue state information from a station (STA) through a frame such as RTS / CTS during uplink scheduling. It is aimed at reducing lag.

In addition, according to the present invention, in a wireless medium having a variety of channel conditions according to time or location, as in the scheduler of a wired network such as WFF and DRR, efficient scheduling is possible, thereby allowing more traffic streams. It aims to improve performance.

In order to achieve the above object and solve the problems of the prior art, the scheduling method of the HCCA protocol according to an aspect of the present invention, the AP transmits a non-competition poll (CF-Poll) containing information associated with the TXOP to the station And transmitting, by the station, a data frame (during an assigned TXOP duration) based on the information related to the TXOP, wherein the transmitting of the frame comprises: Transmitting the queue state information of the station to the access point side, and controlling the station to transmit a data frame based on the received queue state information and the access point receiving the queue state information. do.

According to another aspect of the present invention, the queue status information is polled TXOP duration information polled on the station.

According to another aspect of the present invention, the queue status information is included in a frame transmitted from the station to the access point side.

According to another aspect of the invention, the frame is a Request to Send (RTS) frame.

According to another aspect of the invention, the step of controlling the station to transmit the data frame, based on the queue status information of the station received by the access point, a polled TXOP duration on the station (Polled TXOP duration Determining, by the access point, the transmission of the determination result to the station, and receiving, by the station, the determination result and transmitting a data frame based on the received determination result. .

According to another aspect of the present invention, the determination result is included in a frame transmitted from the access point to the station side.

According to another aspect of the invention, the frame is a CTS (Clear to Send) frame.

According to the present invention, an access point (AP) may receive accurate queue state information from a station (STA) through a frame such as RTS / CTS during uplink scheduling to reduce lag.

Accordingly, according to the present invention, in a wireless medium having various channel conditions according to time or location, efficient scheduling is possible, such as a scheduler of a wired network such as WFF and DRR, and thus, it is possible to allow more traffic streams. Can improve the performance.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings and accompanying drawings, but the present invention is not limited to or limited by the embodiments. Like reference symbols in the drawings denote like elements.

IEEE 802.11e is a standardization group for MAC enhancement such as QoS (Quality of Service) guarantee and security combined with 802.1x in IEEE. Thus, enhancing the 802.11.MAC layer to support LAN applications with QoS requirements and security. The aim is to improve the efficiency and capabilities of the protocol.

The HCF Controlled Channel Access (HCCA) protocol, a hybrid coordination function (HCF) non-competitive channel access method, supports parameter QoS based on a contract between an access point and a station.

1 is a diagram illustrating an example of a scheduling system of the HCCA protocol of the present invention.

As shown in FIG. 1, the scheduling system of the HCCA protocol according to the present invention includes an access point (AP) and a station (STA), and the access point 110 includes a control unit 111 and a transmission unit. 112, etc., the station 120 includes a receiver 121, a transmitter 122, and the like.

The access point (AP) provides a non-competition poll (CF-Poll) containing information related to the TXOP, receives the queue status information from the station (STA) and based on the received queue status information, the station is a data frame Control to send.

The station STA transmits the queue status information of the station to the access point side based on the information related to the TXOP, and transmits a data frame during the assigned TXOP duration.

In this case, the queue status information is transmitted TXOP duration information polled on the station, which is included in a frame transmitted from the station to the access point, and the frame is used to request to send (RTS). Can be.

The transmitting unit 112 of the access point 110 transmits a non-competitive poll (CF-Poll) including information related to the TXOP to the station, and the control unit 111 is a queue of the station as a response to the non-competitive poll. Receives status information and controls the station to transmit a data frame based on the received queue status information.

In particular, the controller 111 determines the adjustment of the polled TXOP duration polled on the station based on the received queue state information of the station, and the transmitter 112 determines the determination result. Transmit to the station side.

In the access point of the HCCA protocol, the control unit 111 of the present invention may use a hybrid coordinator (HC) used for central management of wireless medium access.

The HC centrally manages wireless media, increasing network efficiency by reducing competition for wireless media between stations. Under the control of the HC, the frame exchange can be kept at a very short and constant transmission delay time.

Thus, unlike the CW (Contention Window) in the EDCA protocol, HC does not increase the interframe transmission delay even if the traffic on the network increases. In addition, there is little possibility of collision between transmission frames except for a station (STA) which is not controlled by the same HC but uses the same frequency band. For parameter QoS support, individual QoS parameters are applied to specific QoS traffic from application services and strict transmission delays and scheduling controls.

The HCCA preferentially establishes a virtual connection called a traffic stream before initiating transmission of any frame requiring parameterized QoS. The traffic stream may correspond to an uplink of a station STA and an access point, a downlink between an access point and a station, or a direct link between a station and a station.

In order to establish a traffic stream between an access point and a station, QoS requirements such as frame size, average transmission rate, and latency are exchanged through mutual negotiation. In addition, HC implements a call control algorithm to make a final decision whether to accept a specific traffic stream as a corresponding basic service set (BSS).

The receiving unit 121 of the station 120 receives a non-competitive poll (CF-Poll) including information related to the TXOP, and the transmitting unit 122 receives the queue state information of the station as a response to the non-competitive poll. And transmits the data frame to the access point 110 under the control of the access point 110 based on the queue state information.

In particular, the receiver 121 receives a result of determining adjustment of a polled TXOP duration polled on the station from the access point, and the transmitter 122 receives a data frame based on the received determination result. Send it.

In this case, the determination result is included in a frame transmitted from the access point to the station side, and the frame may be a clear to send (CTS) frame.

2 is a diagram illustrating a superframe according to an example of the present invention, which shows a superframe in which an HC provides TXOP in a non-competition period and a contention period.

As shown in FIG. 2, a superframe according to the present invention includes a contention free period (CFP) and a contention period (CP).

In the non-competition period (CFP) 210, the control unit 111 of the access point 110 of the present invention, that is, the hybrid coordinator (HC), gives the station a transmission opportunity with overall control over the medium. In addition, in the contention period (CP: 220), a transmission opportunity is given to the station by the EDCA method.

When the HC transmits the QoS CF-Poll frame 230 to the station side, a TXOP restriction value defining the concept of transmission opportunity (TXOP), which is a service provision time allowed to the station, is included in the QoS control field. That is, the HC performs a function of controlling allocation of medium access time using TXOP.

TXOP limit value, one of HCCA's important QoS parameters, is determined by TSPEC (Traffic Specification), which includes nominal MSDU size, maximum MSDU size, and minimum service interval , Maximum Service Interval, Inactivity Interval, Minimum Data Rate, Mean Data Rate, Maximum Burst Size, Minimum PHY Rate, Peak Data Rate, Delay Bound, and Suplus Badnwidth Allowed.

The TSPEC is requested by the station, and the access point may allow or reject the TSPEC's request depending on the network situation.

When the access point AP transmits a CF-Poll frame 230 including information related to TXOP, the station STA receives the CF-Poll frame 230.

The CF-Poll frame 230 includes information related to TXOP, that is, information about a frame that can be transmitted in the TXOP 240 of a station (STA).

The station STA receives the CF-Poll frame 230 and transmits a frame 241 including queue status information to the access point, wherein the frame is to use clear to send (CTS). Can be. In particular, the queue status information is Polled TXOP duration information polled on a station.

The access point (AP) receives the frame 241 including the queue status information as described above, and adjusts the polled TXOP duration on the station based on the queue status information on the station. After the determination, the determination result is transmitted to the station STA. In this case, the access point AP may include the determination result in the frame 242 and transmit the determination result. In particular, the frame may be a request to send (RTS), and in 802.11e, the use of the RTS / CTS during a non-competition period (CFP) or a controlled access period (CAP) is optional.

The station STA receives the frame 242 including the determination result and transmits the data frame 243 based on the determination result.

Thereafter, when the transmission of the data frame 243 is completed, the access point AP transmits the Ack frame 244.

That is, a polled station (STA), called a TXOP owner, receives a frame 241 containing queue status information, for example, Request to send (CTS), for a time equal to the TXOP limit value of the queue status information. Send data frame 243 with authority to channel access. At this time, other stations set their own Network Allocation Vector (NAV) by adding TXOP time and a certain time, and do not compete for channel access during this time.

Accordingly, according to the present invention, during the uplink scheduling, the access point (AP) may receive accurate queue state information from the station (STA) through a frame such as RTS / CTS to reduce the lag.

Therefore, in a wireless medium having various channel conditions according to time or location, efficient scheduling can be performed like a scheduler of a wired network such as WFF and DRR, thereby allowing more traffic streams to improve the performance of the wireless network. .

3 is a diagram illustrating a configuration of a scheduling system of the HCCA protocol according to an example of the present invention.

As shown in FIG. 3, the 802.11e HCCA Uplink System may be configured in the form of a server having a switch output port.

The station 120 may provide accurate queue state information through a frame such as an RTS, and the access point 110 may receive queue state information to reduce lag. Thus, the efficient distribution of resources 140 to each station 120 is controlled by the access point 110.

That is, in the conventional wireless server, the state of the queue 130 is transmitted after a certain time, which is called a lag, and such a rack exists within a service interval.

However, according to the present invention, as in the case of a wired server, since the state of the queue 130 is immediately transmitted to the scheduler 115 side, it is possible to minimize the rack.

4 is a diagram illustrating an RTS frame according to an example of the present invention, and FIG. 5 is a diagram illustrating a CTS frame according to an example of the present invention.

As shown in FIG. 4, an RTS frame (Request to send) or a CTS (2D) includes duration fields 410 and 420 having a 2-byte size indicating the size of the frame.

In 802.11e, the use of an RTS / CTS frame during a non-competition period (CFP) or a controlled access period (CAP) is optional. In the present invention, a queue state on a station (STA) using the above-described RTS / CTS frame is used. By providing information to the access point (AP) side, the polled TXOP duration on the station STA is adjusted.

6 is a flowchart illustrating a control method of a scheduling system of an HCCA protocol according to an example of the present invention.

When the AP 110 transmits a non-competition poll (CF-Poll) including information related to TXOP to the station (STA) 120 (S610), the station (STA) 120 recalls the queue status information of the station. Transmit to the access point (S620). In this case, the queue status information is polled TXOP duration information polled on the station, and is included in a frame transmitted from the station to the access point, wherein the frame uses a request to send (RTS) frame. Can be.

On the basis of the received queue state information of the access point (AP), it is determined to adjust the polled TXOP duration polled on the station (S630), and the access point transmits the determination result to the station side. Transmit (S640).

In this case, the determination result is included in a frame transmitted from the access point to the station side, and the frame may be a clear to send (CTS) frame.

The station STA receives the determination result and transmits a data frame based on the received determination result (S650).

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

1 is a diagram illustrating an example of a scheduling system of the HCCA protocol of the present invention.

2 is a diagram illustrating a superframe according to an example of the present invention.

3 is a diagram illustrating a configuration of a scheduling system of the HCCA protocol according to an example of the present invention.

4 illustrates an RTS frame according to an example of the present invention.

5 illustrates a CTS frame according to an example of the present invention.

6 is a flowchart illustrating a control method of a scheduling system of an HCCA protocol according to an example of the present invention.

<Explanation of symbols for the main parts of the drawings>

110: access point (AP)

111:

112: transmission unit

120: station (STA)

121: receiver

122: transmitter

Claims (33)

Sending, by the AP, a non-competitive poll (CF-Poll) including information related to the TXOP to the station; And The station transmitting a data frame based on the information related to the TXOP In the scheduling method of the HCCA protocol comprising a, The step of transmitting the frame, The station transmitting queue state information of the station to the access point side; And The access point receiving the queue state information and controlling the station to transmit a data frame based on the received queue state information; Including, Controlling the station to transmit the data frame, Determining an adjustment of a polled TXOP duration polled on the station based on the queue state information of the station received by the access point; The access point transmitting the determination result to the station side; And The station receiving the determination result and transmitting a data frame based on the received determination result Scheduling method of the HCCA protocol, characterized in that it comprises a. The method of claim 1, The queue status information is Scheduling method of the HCCA protocol, characterized in that the polled TXOP duration (polled TXOP duration) information on the station. The method of claim 1, The queue status information is Scheduling method of the HCCA protocol, characterized in that it is included in a frame transmitted from the station to the access point. The method of claim 3, The frame, Scheduling method of the HCCA protocol, characterized in that the Request to Send (RTS) frame. delete The method of claim 1, The determination result is, Scheduling method of the HCCA protocol, characterized in that it is included in a frame transmitted from the access point to the station side. The method according to claim 6, The frame, A scheduling method of the HCCA protocol, characterized in that the CTS (Clear to Send) frame. An access point (AP) providing a non-competitive poll (CF-Poll) comprising information related to the TXOP; And A station for transmitting a data frame based on the information related to the TXOP In the scheduling system of the HCCA protocol comprising: The access point comprising: Receiving queue status information of the station, determining an adjustment of a polled TXOP duration polled on the station based on the received queue status information, and transmitting the determination result to the station side, Controls the station to transmit data frames, The station, And transmitting the queue state information to the access point, receiving the determination result from the access point, and transmitting a data frame based on the received determination result. 9. The method of claim 8, The queue status information is Scheduling system of the HCCA protocol, characterized in that the polled TXOP duration (polled TXOP duration) information on the station. 9. The method of claim 8, The queue status information is And a frame transmitted from the station to the access point. The method of claim 10, The frame, A scheduling system of the HCCA protocol, characterized in that the Request to Send (RTS) frame. delete 9. The method of claim 8, The determination result is, And a frame transmitted from the access point to the station side. 14. The method of claim 13, The frame, A scheduling system of the HCCA protocol, characterized in that the CTS (Clear to Send) frame. Transmitting a non-competitive poll (CF-Poll) including information related to the TXOP to the station; And Receiving queue status information of the station as a response to the non-competition poll, and controlling the station to transmit a data frame based on the received queue status information; Including, Controlling the station to transmit the data frame, Determining an adjustment of a polled TXOP duration polled on the station based on the queue state information of the station received by the access point; And The access point transmitting the determination result to the station side Method of controlling the access point of the HCCA protocol comprising a. 16. The method of claim 15, The queue status information is Method of controlling the access point of the HCCA protocol, characterized in that the polled TXOP duration (polled TXOP duration) information on the station. 16. The method of claim 15, The queue status information is And a frame transmitted from the station to the access point side. delete A transmitter for transmitting a non-competitive poll (CF-Poll) including information related to the TXOP to the station; And A control unit which receives the queue state information of the station as a response to the non-competition poll, and controls the station to transmit a data frame based on the received queue state information Including, Wherein, Based on the received queue status information of the station, determine the adjustment of the polled TXOP duration (polled TXOP duration) on the station, The transmission unit, And the determination result is transmitted to the station side. 20. The method of claim 19, The queue status information is Access point of the HCCA protocol, characterized in that the polled TXOP duration information polled on the station. 20. The method of claim 19, The queue status information is Access point of the HCCA protocol, characterized in that included in the frame transmitted from the station to the access point. delete 20. The method of claim 19, The determination result is, Access point of the HCCA protocol, characterized in that included in the frame transmitted from the access point to the station side. Receiving a non-competition poll (CF-Poll) including information related to the TXOP; In response to the non-competition poll, transmitting queue status information of the station to an access point side; And Transmitting a data frame under control of the access point based on the queue state information Including, The step of transmitting the data frame by the station, Receiving a result of determining adjustment of a polled TXOP duration polled on the station from the access point; And Transmitting a data frame based on the received determination result Method of controlling the station of the HCCA protocol, comprising a. 25. The method of claim 24, The queue status information is Method of controlling a station of the HCCA protocol, characterized in that the polled TXOP duration (polled TXOP duration) information on the station. 25. The method of claim 24, The queue status information is The method of controlling a station of the HCCA protocol, characterized in that included in the frame transmitted from the station to the access point. delete 25. The method of claim 24, The determination result is, The control method of a station of the HCCA protocol, characterized in that included in the frame transmitted from the access point to the station side. Receiving unit for receiving a non-competition poll (CF-Poll) including information related to the TXOP; And Transmitter for transmitting the queue status information of the station to the access point in response to the non-competition poll, and transmits a data frame under the control of the access point based on the queue status information Including The receiver may further comprise: Receiving a result of determining an adjustment of a polled TXOP duration polled on the station from the access point, The transmitter may further comprise: The station of the HCCA protocol, characterized in that for transmitting a data frame based on the received determination result. 30. The method of claim 29, The queue status information is Station of the HCCA protocol, characterized in that the polled TXOP duration (polled TXOP duration) information on the station. 30. The method of claim 29, The queue status information is A station of the HCCA protocol, characterized in that it is included in the frame transmitted from the station to the access point. delete 30. The method of claim 29, The determination result is, A station of the HCCA protocol, characterized in that it is included in the frame transmitted from the access point to the station side.

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