KR101006115B1 - Direct link setup method for IEEE 802.11 WLAN - Google Patents

Abstract

Disclosed is a direct link establishment method in an IEEE 802.11 WLAN environment. In the IEEE 802.11 wireless LAN environment according to the present invention, a method for establishing a direct link in a station may include a basic service set (BSS) used to communicate with an access point (AP) when traffic is destined for another station. Negotiating with the other station to establish a direct link to a secondary channel which is a wireless channel other than a channel; Switching the operating channel of the station from the BSS channel to the secondary channel if the negotiation succeeds in establishing a direct link to the secondary channel as a result of the negotiation; And transmitting data of the generated traffic to the other station through the secondary channel. According to the present invention, it is possible to communicate between a station and an AP and establish a direct link between stations using multiple channels in an IEEE 802.11 WLAN environment.

IEEE 802.11, WLAN, DLS, Direct Link Configuration

Description

Direct link setup method for IEEE 802.11 WLAN environment {Direct link setup method for IEEE 802.11 WLAN}

The present invention relates to an IEEE 802.11 WLAN, and more particularly, to a method and a WLAN station for establishing a direct link between stations in an IEEE 802.11 WLAN environment.

In order to overcome the inconvenience of wired communication, in which communication technology is developed and wire is always required for communication, various wireless communication methods are used. The Institute of Electrical and Electronic Engineers (IEEE) 802.11 series of wireless LANs is one of them.

Basic IEEE 802.11 standard [IEEE 802.11 WG, Part 11: Wireless LAN MAC and PHY specification, IEEE Standard, Aug. 1999.] assumes that all stations belonging to a BSS are set to a single channel (BSS channel) for communication with an access point (AP), and all traffic originating from a station (STA) is passed through the AP to its destination. do. Here, BSS (Basic Service Set) means a set of stations communicating through any one channel, and the wireless LAN communicates by one BSS unit. A station means a device capable of wireless communication as a member of one BSS. In the IEEE 802.11 standard, in case of station-to-station traffic generated within the BSS, two transmissions from a transmitting station to an AP and an AP to a receiving station are made twice even though the distance between the two is close enough. It causes waste.

In order to overcome this inefficiency and allow direct transmission of traffic between stations within the BSS, IEEE 802.11e WG, Part 11: IEEE Standard for Information technology Telecommunications and information exchange between systems 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.] defines a direct link setup (DLS). The DLS defined here allows the QAP (QoS-enabled AP) to be the principal to establish a direct link call between two stations, and subsequently to directly transmit and receive traffic between stations for a certain period of time, thereby improving the efficiency of radio channel resources. Double it up.

However, the DLS defined in the IEEE 802.11e standard requires the addition of a new function to the AP, and thus requires the replacement of the existing APs. This was not welcome in the market, and as a result, many years have passed since the standard was established, but WLAN equipment manufacturers have not applied DLS. Accordingly, a method of establishing a direct link in which the final stations are the main body has been proposed in the past, in which QAP becomes a main body and establishes a direct link between stations. One of them is iDLS [H. Yoon, JW Kim and R. Hsieh, "iDLS: Inter-BSS direct link setup in IEEE 802.11 WLANs," Communications and Information Technologies, 2007. ISCIT '07. International Symposium on, vol., No., Pp. 1015-1020, 17-19 Oct. 2007.].

An object of the present invention is to provide a direct link setting method and a wireless LAN station to enable communication between a station and an AP and establish a direct link between stations using multiple channels in an IEEE 802.11 WLAN environment.

In order to solve the above technical problem, a direct link setting method in a station of an IEEE 802.11 wireless LAN environment according to the present invention includes: (a) an access point (AP) when traffic destined for another station from the station occurs; Negotiating with the other station to establish a direct link to a secondary channel, which is a wireless channel other than a basic service set (BSS) channel used for communication; (b) switching the operating channel of the station from the BSS channel to the secondary channel if the negotiation succeeds in establishing a direct link to the secondary channel as a result of the negotiation; And (c) transmitting data of the generated traffic to the other station through the secondary channel.

The step (a) may include: transmitting a direct link establishment request containing information of the secondary channel to the other station via the AP; And when receiving a direct link establishment response from the other station via the AP, transmitting an ACK to the other station via the AP.

The direct link setting method may further include transmitting data of the generated traffic to the other station through the BSS channel when the negotiation succeeds in establishing a direct link to the BSS channel as a result of the negotiation. have.

The direct link establishment method may include: (d) releasing direct link establishment with another station when traffic destined for the AP is generated at the station after step (c); (e) switching an operating channel of the station from the secondary channel to the BSS channel; And (f) transmitting data of the generated traffic to the AP via the BSS channel.

Wherein step (d) comprises: transmitting a direct link release request to the other station; And receiving an ACK from the other station.

The direct link setting method sets a direct link only to the BSS channel when traffic destined for the other station occurs when a predetermined time has not elapsed since the last transmission and reception of data with the AP after step (e). The method may further include performing negotiation with the other station.

In addition, the direct link setting method further comprises performing a direct link to the secondary channel when traffic destined for the other station occurs after a predetermined time has elapsed since the last transmission and reception of data with the AP after step (e). The method may further include performing negotiation with the other station to establish.

In order to solve the above technical problem, the method for establishing a direct link in an IEEE 802.11 wireless LAN environment according to the present invention may include: (a) the first station or the second station, when traffic destined for the other party is generated; And a second station negotiating for establishing a direct link to a secondary channel, which is a wireless channel other than a basic service set (BSS) channel used for communicating with an access point (AP); (b) the first station and the second station switching an operation channel from the BSS channel to the secondary channel when the negotiation succeeds in establishing a direct link to the secondary channel as a result of the negotiation; And (c) the first station or the second station transmitting data of the generated traffic to the other party through the secondary channel.

The direct link setting method may include: (d) when the traffic destined for the AP is generated at the first station or the second station after the step (c), the first station and the second station communicate with each other. Disabling the direct link setting; (e) switching, from the secondary channel to the BSS channel, an operating channel of the first station and the second station having traffic destined for the AP; And (f) the station generating traffic destined for the AP transmitting data of the generated traffic to the AP through the BSS channel.

In the direct link setting method, traffic destined for the other station does not occur when a predetermined time has not elapsed since the last transmission / reception of data with the AP at the station where the traffic destined for the AP has elapsed after the step (e). If it occurs, the method may further include negotiating with the counterpart station to establish a direct link only to the BSS channel.

In the direct link setting method, the traffic to the other station after a predetermined time has elapsed since the last time data was transmitted / received from the station where the traffic destined for the AP destined after the step (e). If this occurs, the method may further include performing negotiation with a counterpart station for establishing a direct link to the secondary channel.

According to the present invention described above, it is possible to communicate between a station and an AP and establish a direct link between stations by using multiple channels in an IEEE 802.11 WLAN environment.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the accompanying drawings, substantially the same components are denoted by the same reference numerals, and redundant description will be omitted. In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

First, prior to describing the embodiments of the present invention, in order to help the understanding of the present invention will be briefly described with respect to the present inventors iDLS.

1 is a reference diagram for explaining an operation of establishing a direct link between two stations in the iDLS.

In FIG. 1, STA-1 and STA-2 are associated with AP-1, SSID-1, AP-2, and SSID-2, respectively. A service set identifier (SSID) is a unique identifier appended to each header of packets transmitted through a WLAN, and is used as a cipher when wireless devices access a basic service set (BSS). AP-1 and AP-2 are connected by a distribution system. Although FIG. 1 illustrates that STA-1 and STA-2 belong to different BSSs and two APs, STA-1 and STA-2 may belong to the same BSS and one AP may be one.

The start station STA-1 sends a direct link establishment request encapsulated like a normal data frame to AP-2 via AP-1 (1a). The direct link establishment request contains a rate set, capability of STA-1, and MAC addresses of STA-1 and STA-2. In STA-1, a trigger for initiating direct link establishment occurs at an upper layer. The encapsulation method used to send a direct link establishment request as a data frame is described in Wentink et. al., New DLS (nDLS), IEEE 802.11 DLS SG, document 802.11-07 / 0478r0, 2007. can be used.

If the STA-2 approves the direct link establishment request, the STA-2 transmits a direct link establishment response to the STA-1 via the AP-2 and the AP-1 (1b). The direct link establishment response contains the capability of the rate set, STA-2. If the STA-1 approves the direct link establishment response from the STA-2, it transmits an acknowledgment (ACK) to the STA-2 (1c).

When the processes 1a to 1c are completed, the direct link is activated and data frames may be directly transmitted from STA-1 to STA-2 or vice versa. Each station with such a direct link maintains a table containing information about the direct link pair. This table contains information about the direct link, for example, the MAC address of the other station, the communication status, and the like, and each station is indexed by a unique identifier. By referring to this table, a station can distinguish frames designated from or associated with an AP that is designated as a direct link or from a direct link.

2 is a reference diagram for explaining the efficiency of radio channel resources by the direct link establishment method according to the conventional DLS or the iDLS. In FIG. 2, the BSS is composed of an AP and four stations (STA1-4), STA-1 and STA-2 communicate with the AP, respectively, and STA-3 and STA-4 have a sufficiently good channel environment to directly The link is established to send and receive data frames without going through the AP. The radio channel resources are shared by five devices, and the number of transmissions is reduced compared to the case where no DLS or iDLS is used, thereby increasing the use efficiency of the radio channel resources. For example, as shown, the actual number of data frames to be transmitted is six and the number of transmission of the data frames is STA-1-> AP, AP-> STA-1, STA-2-> AP, AP-> STA-2, 6 times with STA-3-> STA-4 and STA-4-> STA-3. Therefore, the normalized throughput represented by "number of data frames to be transmitted / number of transmissions " becomes 6/6 = 1. If STA-3 and STA-4 exchange data frames via the AP without using DLS or iDLS, the number of transmissions is 8 times and normalized throughput is 6/8 = 0.75.

However, if a direct link is established using a channel other than the BSS channel (wireless channel 1) used for communicating with the AP between stations, the use efficiency of radio channel resources can be further increased. 3 is a reference diagram for explaining this concept. If STA-3 and STA-4 wish to transmit and receive each other, the STA-3 and STA-4 establish a direct link to another available channel (wireless channel 2) other than the BSS channel and transmit and receive through this channel. Then, in radio channel 1, the number of data frames to be transmitted and the number of transmissions are 4 and 4, respectively, so that the throughput is 4/4. In radio channel 2, the number and transmission times of the actual data frames to be transmitted are 2 and 2, respectively. This is 2/2. Therefore, it can be seen that the total throughput inside the BSS is 4/4 + 2/2 = 1 so that the use efficiency of radio channel resources can be further increased.

Therefore, in the present invention, when traffic generated by a station is destined for another station, a direct link is temporarily established with a destination station through a channel other than the BSS channel, and a data frame is transmitted and received through the channel. Hereinafter, for convenience, a channel other than the BSS channel will be referred to as a secondary channel. In order to reduce interference with the BSS channel, the secondary channel is preferably a channel orthogonal to the BSS channel, but the present invention is not limited thereto.

4 is a diagram illustrating a structure of a station for an IEEE 802.11 wireless LAN environment according to an embodiment of the present invention. Referring to FIG. 4, a plurality of applications APP (1) to APP (N) are internally installed in a station, and each of the applications generates traffic. This traffic may be destined for the AP associated with the station, or may be destined for a station other than the AP. At the link layer, the traffic classification unit 10 receives the traffic generated from the applications APP (1) to APP (N), and the traffic classifying unit 10 receives the traffic from the STAs (to-AP) and the other stations as the destinations. Classify as traffic (STA-to-STA). The traffic classifier 10 stores the classified traffic in different buffers according to its destination. For example, as shown in the drawing, traffic destined for the AP is stored in the STA-to-AP traffic buffer 20, and traffic destined for another station is stored in the STA-to-STA traffic buffer 30.

Each of the buffers 20 and 30 is connected to the MAC / PHY layer unit 40 that supports multiple channels, and switches the operation channel from the BSS channel to the secondary channel according to a command of the channel switching unit 50 to be described later. Switch from secondary channel to BSS channel. The traffic transmitted from each of the buffers 20 and 30 is transmitted through the BSS channel or the secondary channel.

The channel switching unit 50 determines which of the buffers 20 and 30 to transmit traffic stored in the MAC / PHY layer unit 40 and the operating channel of the MAC / PHY layer unit 40, that is, the operating channel of the station. Determine. For this determination, the channel switching unit 50 has a channel switching policy and measures channel environment and observes internal traffic. That is, the channel switching unit 50 periodically measures the states of available channels other than the BSS channel and the BSS channel, and maintains the measured result information. The STA-to-AP traffic buffer 20 and the STA-to-STA Observe the traffic buffer 30. The channel switching unit 50 determines the operation channel of the MAC / PHY layer unit 40 according to a predetermined channel switching policy based on the result of measuring the channel environment and observing the internal traffic.

The channel switching policy may be set as follows, for example.

For example, it may be set according to the QoS requirement of the operating application. For example, if a video stream requires 20 Mbps over a direct link, the channel switching policy may determine the operating channel of the MAC / PHY layer 40 so that the traffic is sent on a secondary channel having the bandwidth as required. Can be.

As another example, when STA-to-AP traffic is generated in the STA-to-AP traffic buffer 10 while establishing a direct link with another station in the current secondary channel, the direct link is released from the secondary channel and the BSS channel is disconnected. You can negotiate with other stations to establish a direct link. Then, STA-to-AP traffic is transmitted to the AP through the BSS channel.

As another example, the data frame is finally transmitted to the AP, or the BSS channel is operated without channel switching for a predetermined time (T_staying) from the time point received from the AP. That is, it negotiates to set the BSS channel when establishing a direct link within the T_staying time, and negotiates with another station so that it can be set on the secondary channel instead of the BSS channel when there is no transmission / reception with the AP even after the T_staying time elapses. . The T_staying value is the minimum threshold time not to switch from the BSS channel to the secondary channel, and may be set to any suitable value.

Most of the traffic between stations and APs is interactive traffic, such as web browsing or instant messaging. For example, if an HTTP-Request originates from an application on a station, traffic destined for the AP is generated. When the AP receives it, the AP sends an HTTP-Request to the station. Therefore, it is preferable that channel switching is not performed for smooth communication with the AP. However, if no data has been transmitted from or to the AP for some time after the AP has been transmitted or received, it means that the request was not expected in the first place or the response was lost in the network. Therefore, the TSS stays in the BSS channel for an appropriately set T_staying time and switches to the secondary channel if there is no transmission / reception with the AP even after the T_staying time elapses.

FIG. 5 is a diagram illustrating the flow of signals between stations and APs or between stations in accordance with DLS or iDLS in a WLAN environment as shown in FIG. 2. FIG. 6 is a diagram illustrating a WLAN flow as shown in FIG. 3. In accordance with an embodiment of the present invention, a diagram illustrating a signal flow between stations and an AP or between stations.

Referring to FIG. 5, since the stations STA-1 to 4 belonging to the BSS and the AP use a single radio channel, the respective data frames are transmitted at different timings in a multiplexing scheme such as CSMA / CA, for example. . That is, STA-1 and STA-2 communicate with the AP through channel 1, respectively, and STA-3 and STA-4 also establish a direct link through channel 1 to directly transmit and receive to each other, and each of the stations at different timings. Send a data frame to the destination.

Referring to FIG. 6, STA-1, STA-2, and AP communicate using channel 1, and STA-3 and STA-4 establish a direct link through channel 2 to directly transmit and receive data with each other. Accordingly, as illustrated, transmission and reception through a direct link between STA-3 and STA-4 and transmission and reception between STA-1 or STA-2 and the AP may occur simultaneously.

7 is a flowchart illustrating a direct link establishment method in an IEEE 802.11 WLAN environment according to an embodiment of the present invention. The direct link setting method according to the present embodiment consists of the steps processed in the WLAN station described in FIG. 4. Therefore, even if omitted below, the above description about the WLAN station is according to the present embodiment. The same applies to the direct link establishment method.

In the present embodiment, it is assumed that the station operates in channel 1 (BSS channel) as an initial state, and is in a state of communicating with the AP or a state in which data transmission and reception with the AP and other stations do not occur.

In step 720, it is determined whether traffic destined for another station occurs. This can be seen by observing the STA-to-STA traffic buffer 30. If traffic destined for the other station occurs, the process proceeds to step 715 to perform negotiation for establishing a direct link with the station. Hereinafter, the station will be referred to as a counterpart station for convenience. Negotiation for direct link establishment sends a direct link establishment request via the AP to the counterpart station, receives a direct link establishment response from the counterpart station via the AP, and sends an ACK for it to the counterpart station via the AP as well. It means a series of processes. In this embodiment, the channel for the direct link setup includes not only the BSS channel but also a secondary channel other than the BSS channel. Therefore, as a result of the negotiation in step 715, negotiation may be made to establish a direct link to the BSS channel, negotiation may be made to establish a direct link to the secondary channel, or the negotiation may fail. If the negotiation for establishing the direct link fails, for example, it may not receive a direct link establishment response from the other station, or it may be rejecting the direct link establishment because the other station is communicating with the AP. have.

If the negotiation for the direct link fails, the process returns to step 710, and if there is still traffic destined for another station, the process returns to step 715 and attempts to negotiate the direct link again.

If negotiation is made to establish a direct link to the counterpart station and the secondary channel in step 715, the process proceeds to step 720 and the station switches the operation channel to the secondary channel. That is, the MAC / PHY layer unit 40 to operate in the secondary channel. Now, since the direct link is established with the counterpart station through the secondary channel, in step 725, data of the traffic is directly transmitted and received through the counterpart channel with the counterpart station.

Thereafter, when transmission / reception with the counterpart station is completed or traffic destined for the AP occurs (step 730), the process proceeds to step 735 to cancel the direct link setup on the secondary channel. In this case, since the station operates on the secondary channel, the release of the direct link setting is performed by transmitting a direct link release request to another station without passing through the AP and receiving an ACK from the counterpart station.

If the direct link is released, the process proceeds to step 740 and switches back to the BSS channel. The data of the traffic destined for the AP is transmitted to the AP through the BSS channel.

Refer back to step 715. If a negotiation is made to establish a direct link with the counterpart station and the BSS channel in step 715, a direct link is established with the BSS channel, and in step 745, data is directly transmitted and received with the counterpart station through the BSS channel. In this case, the station may also transmit and receive data with the AP through the BSS channel.

If data transmission and reception with the counterpart station is completed in step 750, the process proceeds to step 755 to cancel the direct link setup. In this case, since the station operates on the BSS channel, the release of the direct link setting is performed by sending a direct link release request to another station via the AP and receiving an ACK from the counterpart station via the AP.

See step 740 again. After switching to the BSS channel in step 740, the station observes whether the transmission and reception with the AP occurs for at least T_staying time from the time of the last transmission and reception of data with the AP.

In step 760, if the T_staying time has not elapsed, but traffic destined for another station occurs, the process proceeds to step 765 to negotiate with the corresponding station so that direct link establishment is performed using only the BSS channel. This may include only the BSS channel as a channel available for the direct link establishment request to be described later with reference to FIG. 8. If the negotiation is successful, a direct link is established through the BSS channel, and the flow proceeds to step 745 to directly transmit and receive data with the counterpart station through the BSS channel.

In step 770, if the T_staying time elapses from the time of the last data transmission and reception with the AP, and if there is traffic destined for another station, the process proceeds to step 715 again and performs negotiation for establishing a direct link with the corresponding station.

If you switch to the secondary channel immediately without waiting for a certain time after transmitting and receiving data with the AP, there may be a problem that can not receive data transmitted from the AP through the BSS channel. Therefore, as shown in the present embodiment, the AP establishes a direct link only through the BSS channel for a predetermined time after the data transmission and reception with the AP, stays in the BSS channel, and finally includes the secondary channel after confirming that data transmission and reception with the AP no longer occurs. By performing negotiation for link establishment, it is possible to solve the above problems that may occur due to switching to the secondary channel immediately.

FIG. 8 is a diagram illustrating an example of signal flow that may occur in two stations and an AP through the processes of steps 710 to 740 of FIG. 7. In FIG. 8, CH1 corresponds to a BSS channel, and CH2 and 3 belong to a selectable secondary channel. In the illustrated buffer, the left side represents an STA-to-AP traffic buffer and the right side represents an STA-to-STA traffic buffer.

Referring to Figure 8, STA-3 is transmitting and receiving data through the AP and CH1 (①, ②). Then, traffic destined for STA-4 occurs, and the traffic is stored in the STA-to-STA traffic buffer (ⓐ). Then, the STA-3 attempts to negotiate direct link establishment with the STA-4.

For negotiation, STA-3 transmits a link establishment request directly to STA-4 via the AP (③-1, ③-2). At this time, the direct link establishment request includes information on channels available for direct link establishment. The available channels can be determined according to the state of each channel and the channel switching policy measured at the station. In the example shown in FIG. 8, the STA-3 selects CH 1, 2, and 3 as available channels.

Upon receiving the direct link establishment request, the STA-4 transmits a direct link establishment response to the STA-3 via the AP (④-1, ④-2). At this time, the STA-4 selects a channel available to itself among the available channels included in the direct link establishment request and includes the information in the direct link establishment response. In the example shown in FIG. 8, the STA-4 selects CH 2 and 3 as available channels.

In response to the direct link establishment response, the STA-3 transmits an ACK to the STA-4 via the AP (⑤-1, ⑤-2). At this time, the STA-3 selects a channel for establishing a direct link among available channels included in the direct link establishment response, and includes the result information in the ACK. The selection of the channel can of course be made according to the state of the measured channel. 8 illustrates a case where STA-3 selects CH 2 as a channel for establishing a direct link.

Accordingly, since CH 2 is selected as a channel for establishing a direct link, rather than a previously operated BSS channel, STA-3 and STA-4 perform channel switching to CH 2, respectively. Now, a direct link is established through CH 2, and STA-3 and STA-4 directly transmit and receive data through CH 2 (⑥).

If, as a result of the negotiation for the direct link establishment between STA-3 and STA-4, CH 1 is determined to be a channel for direct link establishment, channel switching does not occur, and a direct link is established through CH 1 and STA-3 and STA -4 will send and receive data directly over CH 1.

In addition, if negotiation for the direct link establishment of the STA-3 and the STA-4 fails, the negotiation will be retried or the data will be transmitted and received via the AP.

Now, traffic destined for the AP occurs, and this traffic is stored in the STA-to-AP traffic buffer (ⓑ). Then, the STA-3 transmits a direct link release request to the STA-4 (⑦), and the STA-4 responds to the STA-4 by transmitting an ACK to the STA-3 (⑧), thereby releasing the direct link setting. STA-3 performs channel switching to return to CH 1 again for communication with the AP, and transmits data to the AP through CH 1.

9 is a diagram illustrating an example of a signal flow that may occur in a BSS by a direct link establishment method according to an embodiment of the present invention. In FIG. 9, as in FIG. 8, in the illustrated buffer, the left side represents an STA-to-AP traffic buffer and the right side represents an STA-to-STA traffic buffer.

Referring to FIG. 9, STA-1 and STA-2 communicate with an AP through CH 1, which is a BSS channel, respectively, or STA-1 and STA-2 establish a direct link through CH 1 and directly through CH 1. Send and receive data.

Meanwhile, STA-3 and STA-4 establish a direct link through the secondary channel CH 2 and directly transmit and receive data through CH 2 (①). Then, when traffic destined for the AP occurs in the STA-to-AP traffic buffer of the STA-3 (ⓐ), the STA-3 releases the direct link through the STA-4 and the CH 2 (②), and Switch the operating channel to CH 1 for communication. The STA-3 then transmits and receives data with the AP through CH 1 (③).

The STA-3 observes whether transmission / reception with the AP occurs during the T_staying time from the time of the last transmission / reception with the AP. On the other hand, when negotiating direct link establishment with STA-4 within at least T_staying time from the time of last data transmission and reception with the AP, the direct link is set to CH 1 and data is directly transmitted and received (④). In CH 1, transmission and reception with the AP, transmission and reception with the STA-4, and communication between the STA-1, STA-2, and AP are performed at different timings. This resource allocation is determined according to a priority defined internally between applications within STA-3, and is determined by a multiplexing scheme such as CSMA / CA between each station and AP.

After the direct link with the STA-4 is released, as shown, if no T / Staying time has elapsed and there is no data transceiving with the AP, and there is data to transmit and receive between the STA-3 and the STA-4, the direct link including the secondary channel Negotiate the configuration (⑤). As a result of the negotiation, when CH 2 is again determined to be a channel for direct link establishment, STA-3 and STA-4 switch to CH 2. And data is transmitted and received directly through CH 2 (⑥).

FIG. 10 is a diagram illustrating an example in which a direct link is established and occupied in each channel according to T_staying time by the direct link setting method according to an embodiment of the present invention described above. In FIG. 10, box BSS (AP-S #) represents a section in which station S # communicates with an AP, and box direct n is a section in which a direct connection is established. For example, direct 1 (S2-S3) is a station S2. This is a section in which the station S3 is directly connected and established. Referring to FIG. 10, the direct connection between the stations S2 and S3 (direct 1) is performed on the BSS channel (Channel 1) during the T_staying time after the station S2 has communicated with the AP. Direct connection setup may be made in channel 2.

Meanwhile, the above-described embodiments of the present invention can be written as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium. The computer-readable recording medium may be a magnetic storage medium (for example, a ROM, a floppy disk, a hard disk, etc.), an optical reading medium (for example, a CD-ROM, DVD, etc.) and a carrier wave (for example, the Internet). Storage medium).

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

1 is a reference diagram for explaining an operation of establishing a direct link between two stations in the iDLS.

2 is a reference diagram for explaining the efficiency of radio channel resources by the direct link establishment method according to the conventional DLS or the iDLS.

3 is a reference diagram for explaining a concept of further increasing the use efficiency of radio channel resources when a direct link is established using a channel other than the BSS channel.

4 is a diagram illustrating a structure of a station for an IEEE 802.11 wireless LAN environment according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a signal flow between stations and an AP or between stations according to DLS or iDLS in a WLAN environment as shown in FIG. 2.

FIG. 6 is a diagram illustrating a signal flow between stations and an AP or between stations according to an embodiment of the present invention in a WLAN environment as shown in FIG. 3.

7 is a flowchart illustrating a direct link establishment method in an IEEE 802.11 WLAN environment according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of signal flow that may occur in two stations and an AP through the processes of steps 710 to 740 of FIG. 7.

9 is a diagram illustrating an example of a signal flow that may occur in a BSS by a direct link establishment method according to an embodiment of the present invention.

10 is a diagram illustrating an example in which a direct link is established and occupied in each channel according to T_staying time by a direct link setting method according to an embodiment of the present invention.

Claims (11)

In a method for establishing a direct link at a station in an IEEE 802.11 WLAN environment, (a) Negotiation for establishing a direct link to a secondary channel, which is a radio channel other than a basic service set (BSS) channel used to communicate with an access point (AP) when traffic from the station to another station occurs. Performing with the other station; (b) switching the operating channel of the station from the BSS channel to the secondary channel if the negotiation succeeds in establishing a direct link to the secondary channel as a result of the negotiation; (c) transmitting data of the generated traffic to the other station via the secondary channel; (d) releasing direct link establishment with the other station when traffic destined for the AP is generated at the station after step (c); (e) switching an operating channel of the station from the secondary channel to the BSS channel; And (f) transmitting data of the generated traffic to the AP via the BSS channel, When the traffic to the other station occurs when a predetermined time has not elapsed since the last time of transmitting and receiving data with the AP after the step (e), the negotiation for establishing a direct link only to the BSS channel is performed. And performing with the station. The method of claim 1, In step (a), Transmitting a direct link establishment request containing information of the secondary channel to the other station via the AP; And And if receiving a direct link establishment response from the other station via the AP, sending an ACK to the other station via the AP. The method of claim 1, And if the negotiation succeeds in establishing a direct link to the BSS channel as a result of the negotiation, transmitting the data of the generated traffic to the other station through the BSS channel. delete The method of claim 1, The step (d) Sending a direct disconnect request to the other station; And And receiving an ACK from the other station. delete The method of claim 1, After the step (e), if traffic destined for the other station occurs after a predetermined time has elapsed from the time of last data transmission and reception with the AP, the other station negotiates to establish a direct link to the secondary channel. And performing the step of direct link setting. In a direct link establishment method in an IEEE 802.11 WLAN environment, (a) a basic service set (BSS) channel used by the first station and the second station to communicate with an access point (AP) when traffic destined for the other party from the first station or the second station occurs; Negotiating for establishing a direct link to a secondary channel, which is a wireless channel; (b) the first station and the second station switching an operation channel from the BSS channel to the secondary channel when the negotiation succeeds in establishing a direct link to the secondary channel as a result of the negotiation; And (c) the first station or the second station transmitting data of the generated traffic to the other party through the secondary channel; (d) when the traffic destined for the AP is generated at the first station or the second station after step (c), the first station and the second station release the direct link establishment with the other party; step; (e) switching, from the secondary channel to the BSS channel, an operating channel of the first station and the second station having traffic destined for the AP; And (f) a station having traffic destined for the AP transmitting data of the generated traffic to the AP through the BSS channel; After the step (e), when the traffic to the other station occurs when a station does not pass a certain time since the last time data was transmitted / received from the AP to the destination, the BSS channel only. And performing negotiation with a counterpart station to establish a direct link. delete delete The method of claim 8, After the step (e), if the traffic to the other station occurs after a predetermined time has elapsed since the last time data was transmitted / received from the AP at the station where the traffic was directed to the AP, the second channel directly connected to the secondary channel. And performing negotiation with a counterpart station to establish a link.

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