KR20080002296A - System and method relaying a frame in a wireless local area network - Google Patents

Abstract

A system for relaying a frame in a wireless LAN(Local Area Network) and a method thereof are provided to relay and transmit messages through the third station having a good communication environment if communication has to be performed at low speed owing to a bad communication environment between an AP(Access Point) and a station, thereby increasing data transmission efficiency. The first subscriber station(501) selects another subscriber station as a self relay subscriber station among plural subscriber stations(502-504), and transceives a data frame with an AP(500) through the relay subscriber station. The relay subscriber station receives the data frame when the data frame is transceived between the first subscriber station(501) and the AP(500), and relays/transmits the received frame to the AP(500) or the first subscriber station(501). The AP(500) transceives the data frame via the relay subscriber station when transceiving the data frame with the first subscriber station(501).

Description

SYSTEM AND METHOD RELAYING A FRAME IN A WIRELESS LOCAL AREA NETWORK}

1 is a diagram illustrating a configuration of a short range wireless communication network to which the present invention is applied.

FIG. 2 is a diagram illustrating an internal configuration of an AP or STA in FIG. 1.

3 is a diagram illustrating a data transmission method according to a communication protocol to which the present invention is applied.

4 is a diagram illustrating a difference in data rates within a basic service set to which the present invention is applied.

5 is a diagram illustrating a concept of frame relay according to a first embodiment of the present invention.

6 is a view comparing transmission efficiency in relaying according to the first embodiment of the present invention.

7 is a diagram illustrating a concept of frame relay through two subscriber stations according to the second embodiment of the present invention.

8 is a diagram illustrating data transmission during frame relay through two subscriber stations according to the second embodiment of the present invention.

9 is a diagram showing the structure of a medium access control frame to which the present invention is applied.

10 is a diagram illustrating a structure of a physical layer frame to which the present invention is applied.

11 is a flowchart illustrating an automatic setting procedure of a relay function according to an embodiment of the present invention.

12 is a signal flow diagram illustrating a procedure for transmitting a message between an AP and an STA for setting a relay function according to the first embodiment of the present invention.

13 is a signal flow diagram illustrating a procedure for relaying and transmitting a frame from an AP to an STA according to the first embodiment of the present invention.

14 is a signal flow diagram illustrating a procedure for relaying and transmitting a frame from an STA to an AP according to a first embodiment of the present invention.

15 is a signal flow diagram illustrating a procedure for transmitting a message between an AP and a STA for setting a relay function according to the second embodiment of the present invention.

16 is a signal flow diagram illustrating a procedure for relaying and transmitting a frame from an AP to an STA according to a second embodiment of the present invention.

17 is a signal flow diagram illustrating a procedure for relaying and transmitting a frame from an STA to an AP according to a second embodiment of the present invention.

FIG. 18 is a signal flowchart illustrating a procedure in which an STA in a communication impossible area joins an AP through a relay according to a third embodiment of the present disclosure; FIG.

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

100: Internet 110: Access Point

111, 201: antenna 120: subscriber station

200: access point or subscriber terminal

202: RF transceiver 203: baseband processing unit

204: microprocessor 205: network interface unit

206: data storage 207: program storage

301, 302: DIFS 303: SIFS

304: PIFS 305: Competition Zone Window

306: selected slots 400, 500, 700: access point

401, 500, 701: first subscriber station 402, 502, 702: second subscriber station

403, 503, 703: third subscriber station 404, 504, 704: fourth subscriber station

601, 613, 614, 803, 804, 805: data

602, 615, 616, 806, 807, 808: Ack message

611, 801: RTS message 612, 802: CTS message

900: media access control frame 910: frame control field

911: type field 912: subtype field

1000: physical layer message 1001: preamble

1002: PLCP header 1003: MAC header

1004: Payload 1005: CRC

The present invention relates to a data transmission system and method in a short range wireless communication network. In particular, when a data transmission speed is too slow or communication is not possible depending on the distance to an access point, the transmission speed is improved and the communication is performed using a relay terminal. A system and method for realizing area expansion.

Local area network (hereinafter, referred to as "WLAN" protocol) Among the standards defining protocols, IEEE 802.11 is Medium Access Control (hereinafter referred to as "MAC" for implementing WLAN). This standard defines standards of layer protocol and physical layer (PHY), and commercial products implemented according to this standard are widely used.

The specification is limited to the LAN, and although the maximum communication distance is not specifically stated, it is generally recognized to cover a short distance of about 100 meters. This means that in unlicensed bands, countries use public frequencies in the 2.4 GHz band, called the Industrial Scientific Medical (ISM) band, or the 5 GHz band, called the Unlicensed National Information Infrastructure (U-NII) band. This is because the output is limited to a small size.

On the other hand, the data transmission rate defined by the IEEE 802.11 standard is divided into several stages from 1Mbps to 54Mbps according to the modulation and demodulation method, and a plurality of data rates are used simultaneously. This means that each data packet can be transmitted at a different speed. In general, the transmission speed and distance are inversely proportional, so when the destination is near, the transmission speed is high and the distance is low speed.

Therefore, a subscriber station (Station (hereinafter, referred to as "STA") that is far from an access point (hereinafter referred to as "AP") or has an obstacle in a radio path is always slow. Data is transmitted and received at a speed, and an STA which is in close proximity transmits and receives data at a high speed, thereby causing an unfair situation. In addition, as well as other terminals in the service area (service area) must also be rested while transmitting and receiving data between any two terminals (ie, STA or AP).

Even worse, the STA is placed in a location where the AP cannot communicate with the AP even at the lowest data rate. Even in a single office or building, the STA is located due to obstacles between the AP and the STA. Serious problems arise that can't be done.

Accordingly, there is an urgent need for a method for effectively communicating even when the communication environment between the AP and the STA is bad and the STA needs to communicate at a low speed and when the STA is in a position where communication with the AP is impossible.

Accordingly, an object of the present invention is to increase the data transmission efficiency by relaying and transmitting a message through a third STA having a good communication environment in case a communication environment between the AP and the STA is bad due to a bad communication environment in a short range wireless communication network. A system and method for relaying a frame in a short range wireless communication network is provided.

In addition, an object of the present invention is to provide a short-range wireless communication network when the STA is in a position where communication with the AP is not possible by relaying and transmitting a message through a third STA having a good communication environment. A system and method for relaying frames in a wireless communication network are provided.

In addition, an object of the present invention is to communicate at a low speed because the communication environment between the AP and STA in a short-range wireless communication network or when the STA is in a position where communication with the AP is impossible through a plurality of STAs having a good communication environment The present invention provides a system and method for relaying frames in a short-range wireless communication network for increasing data transmission efficiency by relaying and transmitting a message in multiple times.

The system of the present invention for achieving the above object; In a short-range wireless communication network in which one access point communicates with a plurality of subscriber stations at a plurality of transmission speeds through a wireless channel, the access point transmits and receives a frame with one of the plurality of subscriber stations. A first subscriber station for selecting a subscriber station other than itself from among the plurality of subscriber stations as its relay subscriber station, and transmitting and receiving a data frame with the access point through the relay subscriber station, and the first subscriber station. When transmitting and receiving a data frame between the terminal and the access point, the relay subscriber terminal receiving the data frame transmitted from the first subscriber terminal or the access point and relays the data frame to the access point or the first subscriber terminal. And an access point for transmitting and receiving the data frame via the relay subscriber terminal when transmitting and receiving the data frame with the first subscriber station.

The first method of the present invention for achieving the above object; In a short-range wireless communication network in which one access point communicates with a plurality of subscriber stations at a plurality of transmission speeds through a wireless channel, the access point transmits a data frame to one of the plurality of subscriber stations. In the first subscriber station, selecting a subscriber station other than itself among the plurality of subscriber stations as its relay subscriber terminal, the process of approving the relay service by the relay subscriber terminal in the access point and And transmitting a data frame from the access point to the relay subscriber station, and transmitting a data frame received from the access point to the first subscriber station.

The second method of the present invention for achieving the above object; In a short-range wireless communication network in which one access point communicates with a plurality of subscriber stations at a plurality of transmission speeds through a wireless channel, a method of transmitting data frames from one subscriber station of the plurality of subscriber stations to the access point. In the first subscriber station, selecting a subscriber station other than itself among the plurality of subscriber stations as its relay subscriber terminal, the process of approving the relay service by the relay subscriber terminal in the access point and And transmitting a data frame from the first subscriber station to the relay subscriber station, and transmitting the data frame received from the first subscriber station to the access point. do.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in describing the present invention, when 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.

As described above, STAs that are far away from the AP in the short range wireless communication network or where obstacles exist in the wireless path always transmit and receive data at a slow speed, and STAs that are close to each other transmit and receive data at a high speed. In addition, since the other terminals in the service area must also be rested while transmitting and receiving data between any two terminals, the transmission efficiency of the entire network is degraded when there are many STAs having a slow transmission rate. In addition, when the STA is placed in a position where communication with the AP is not possible even at the lowest data rate, the STA may not be placed at the position due to obstacles between the AP and the STA even in one office or building.

Accordingly, the present invention provides the above two cases, namely, 1) when the communication environment between the AP and the STA is bad and communication is performed at low speed, and 2) when the STA is in a position where communication with the AP is impossible. In the case of 1), a third STA (relay STA; hereinafter referred to as 'R-STA') having a good environment relays the data packet to increase data transmission efficiency and In case of 2), it is possible to expand the service area.

Meanwhile, the present invention relates to a MAC protocol in a communication network in which data is exchanged wirelessly between one base station (ie, AP) and a plurality of terminals (ie, STAs), and all devices to which the IEEE 802.11 WLAN (Wireless LAN) standard is applied. It is directly related to and can be applied to Wireless Metropolitan Area Network (WMAN) or Wireless Wide Area Network (WAN) and similar applications.

Hereinafter, the concept of the IEEE 802.11 WLAN to which the present invention is applied, a system structure and a structure of a transmission frame will be described first to help understand the present invention before describing the present invention.

APs and STAs that comply with the IEEE 802.11 WLAN standard are already widespread and the user base is very thick, and demand is expected to increase more rapidly in the future. Currently, the most popular type is an IEEE 802.11b device using the 2.4 GHz band, and a data rate of 1 Mbps to 11 Mbps is possible. The following is an IEEE 802.11a type of 5GHz band, increasing the transmission rate from 6Mbps to 54Mbps. In addition, IEEE 802.11g type uses 2.4GHz band but supports 1Mbps to 54Mbps by mixing existing 11b and 11a methods, but it is just beginning to spread, but the market will grow rapidly as many manufacturers pay attention. watching.

When the 802.11g standard equipments are widely used, STAs having a data rate of up to 54 times can be associated with one AP. Accordingly, if the data rate of a certain STA is low, it may be because it is an 11b device, but the 11g device may be due to a bad communication environment due to a long distance from an AP or an obstacle. In this case, not only the unfair transmission rate is lower than that of the STA close to the AP, but also the performance of the entire network is reduced.

Accordingly, in the present invention, even if there is an STA having a low data rate due to a long distance or an obstacle from the AP, when there is an R-STA having a good communication environment between the AP and the STA with a low data rate, the R-STA is When data is relayed, communication between the AP and the STA can be relayed at high speed. In addition, a method of allowing a STA at a location where communication with the AP is not communicated with the AP can communicate with the AP through the R-STA as described above.

1 is a diagram illustrating a configuration of a short range wireless communication network to which the present invention is applied. Referring to FIG. 1, an IEEE 802.11 WLAN is composed of an access point (AP) 110 and a plurality of STAs 120. As described above, a small network centered on one AP 110 provided with the antenna 111 is referred to as a basic service set (hereinafter, referred to as a 'BSS'). The STAs 120 in the BSS communicate with the wired network (eg, the Internet 100) or another STA 120 in the BSS through the AP 110.

FIG. 2 is a diagram illustrating an internal configuration of the AP 110 or the STA 120 in FIG. 1. Referring to FIG. 2, the AP 110 or the STA 120 is largely composed of an RF module, a baseband processor 203, and a microprocessor, which are composed of an antenna 201 and an RF transceiver 202. (Micro-processor; 204), network interface unit 205, data storage unit 206 and program storage unit 207 may be divided into a MAC processing unit. The implementation of the MAC processing unit may use the microprocessor 204 as shown, or may be implemented as an independent hardware module.

In the meantime, the MAC module to which the present invention is applied processes the MAC part of the IEEE 802.11 standard. In this case, the IEEE 802.11 MAC uses a communication protocol called Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA). This is because when a plurality of wireless terminals use a shared medium (hereinafter, referred to as 'WM') as a space, 1) check whether the WM is occupied before transmitting data, and 2) the media is idle. In this case, the medium is approached after random backoff to avoid collision, and 3) MAC-level acknowledgment and retransmission are preferred. At this time, the time interval between the data frames occupying the WM should comply with the specification.

3 is a diagram illustrating a data transmission method according to a communication protocol to which the present invention is applied. In the 802.11 standard, the time interval is referred to as an inter-frame space (IFS), and a short inter-frame space (SIFS) 303, a PCF inter-frame space (PIFS) 304, and a DIFS (DCF Inter) according to the length of the interval. -Frame Space (301, 302) and EIFS (Extended Inter-Frame Space).

Meanwhile, among the IFSs, the SIFS 303 is an interval used when a receiver (RA) of a frame is itself and requires a response immediately to a transmitter (TA), and is preferred to other WMs. It has the effect of occupying. A representative example in which the SIFS 303 is used is a case in which the RA receives a MAC Protocol Data Unit (MPDU) frame set as its own and responds to the TA as an ACK frame. A time interval between the data frame and the ACK frame is equal to SIFS. .

In this case, for collision avoidance, a CCA (Clear Channel Assessment) detection function that determines whether a medium is busy by sensing a carrier and a header part of a transmitted frame A network allocation location (NAV) setting function for reserving a channel is used by specifying a medium occupation duration. The latter (NAV setup function) is an important feature to solve the hidden node problem.

4 is a diagram illustrating a difference in data rates within a basic service set to which the present invention is applied. Referring to FIG. 4, when the STA3 403 does not detect the CCA when the STA2 402 transmits data to the AP 400, the STA3 403 may be a hidden node. In this case, since the STA3 403 does not know that the STA2 402 transmits, the STA3 403 may transmit data considering that the channel is idle, and if so, the STA2 402 transmits the data to the AP 400. Both frames are broken because they collide with the frames sent.

In particular, when the STA2 402 sends long data, the time for transmitting the data is long, and thus the probability of collision increases. Therefore, in this case, the STA2 402 may send a frame called a short Request to Send (RTS) to the AP 400 before sending the long data.

The RTS frame includes duration information until the long data is transmitted and the ACK is received. The STA receiving the RTS frame configures NAV by using the interval information. In this case, the NAV value means that a channel is already reserved by another STA / AP. Therefore, the STA does not access a channel until the NAV value expires.

Usually, the RTS frame is sent at a lower data rate than when sending data, so STA3 403 is likely to detect it. If the STA3 403 does not detect the RTS, the AP 400 receiving the RTS sends a clear to send (CTS) to the STA2 402, so that the STA3 403 includes duration information included in the CTS frame. You can use it to know how long the channel is busy. On the other hand, since the RTS / CTS is a very short frame, the probability that the STA3 403 sends data during this period becomes low.

<Unbalanced distribution of bands depending on the location of the STA>

4 illustrates an example of a BSS centered around one AP 400, and thus, the farther away from the AP 400, the lower the transmission rate is. Of course, according to the shape of obstacles such as walls and furniture in the real environment, the rate-specific areas will appear irregularly. In addition, FIG. 4 is a conceptual diagram of a very simple type of transmission rate. To describe all transmission rates available in the actual IEEE 802.11g standard, 1, 2, 5.5, 11, 6, 9, 12, 18, 24, 36, 48 and 54 Mbps.

In FIG. 4, the STA1 401 may communicate with the AP 400 at 36 Mbps, the STA2 402 may be 6 Mbps, the STA3 403 may be up to 1 Mbps, and the STA4 404 may be in a position where communication is impossible. It can be seen. At this time, if the place of the BSS is one office, and each STA is arranged in a fixed place, each STA can not change their location arbitrarily, so the radio path with the AP 400 is not good. STA3 403 lacks fairness because the bandwidth is always lower than that of STA1 401 where it is not.

In addition, since the AP 400 cannot communicate with other STAs while the STA3 403 communicates with the AP 400, network performance of the entire BSS is also reduced. In addition, there is a problem in that communication itself is impossible because the AP 400 is not connected at the same location as the STA4 404. In addition, even when communication is not possible, the STA may periodically attempt to access the channel, and the neighbor STAs (the STA3 403 and the STA1 401 in FIG. 4) communicate with the AP 400. It can adversely affect

Therefore, in the present invention, by providing a relay function to the STA1 401, high-speed data transmission from the STA3 403 to the AP 400 is possible. Hereinafter, a concept of a method for relaying data by setting an STA having a relay function according to the present invention will be described with reference to FIG. 5.

<If STA with Relay function exists>

5 is a diagram illustrating the concept of frame relay according to a first embodiment of the present invention. Referring to FIG. 5, the rate-specific region when the STA1 401 in the BSS of FIG. 4 has a relay function is shown. In FIG. 5, the STA1 501 is in a position capable of 36 Mbps communication with the AP 500, the STA2 502 is in a position capable of 6 Mbps communication with the AP 500, and the STA3 503 is connected with the STA1 501. It can be seen that the 36Mbps communication position and the STA4 504 is in a position where communication with the AP 500 is impossible. Therefore, if the STA 5001 relays when the AP 500 communicates with the STA3 503 according to the first embodiment of the present invention, the AP 500 may transmit and receive data at 36Mbps instead of 1Mbps.

However, in the case where the STA1 501 relays in this way, the path for transmitting data from the AP 501 to the STA3 503 and the STA3 503 sending an ACK to the AP 500 becomes long and complicated, so that the gain in the transmission rate is low. But you lose money in the process. Therefore, it is necessary to determine beforehand whether relaying via the STA1 501 is a gain. To describe the conclusion first, it is advantageous to use the STA1 501 as a relay terminal of the AP 500 and the STA3 503 in FIG. 5. Referring to Fig. 6, how the transmission efficiency in this case is improved will be described.

6 is a view comparing transmission efficiency in relaying according to the first embodiment of the present invention.

In FIG. 6, A shows a process in which the AP 500 directly sends one data frame to STA3 503 and receives an ACK from STA3 503, and B uses STA2 502 as a relay terminal proposed in the present invention. In this case, a process of transmitting one frame and receiving an ACK is shown.

When calculating the time required for the A and B sequence (Sequence) in Figure 6, respectively, it can be calculated as shown in Equation 1 and Equation 2.

In Equation 1, it is calculated when Data / Ack Rate = 1Mbps, Data Length = 1500Bytes, Ack Length = 14Bytes, and SIFS = 10μsec.

In Equation 2, it is calculated assuming Data Rate = 36Mbps, Rts / Cts Length = 14Bytes, and Rts / Cts / Ack Rate = 24Mbps.

Referring to <Equation 1> and <Equation 2>, it took a total of 12,122μsec for A, 686μsec for B. That's an improvement of about 18 times. Of course, even in the same environment, the degree of efficiency improvement may vary depending on the length of the data frame to be transmitted. In the above calculation example, the length of the data frame is 1500 bytes. This is a typical length of a data frame that appears when a large bandwidth such as a large file transfer is required. Ethernet encapsulation (RFC) 894)) is the maximum data length.

Meanwhile, referring to FIG. 6, the transceiver of each frame is as follows. A detailed description thereof will be described later with reference to FIG. 13.

601: AP transmits data to STA3

602: STA sends ACK to AP

611: RTS transmission to STA1 whose AP is an R-STA

612: STA1 sends CTS response to RTS to AP

613: AP transmits data to STA1

614: STA1 sends data to STA3

615: STA3 sends an ACK to STA1

616: STA1 forwards the ACK to the AP

On the other hand, the STA4 504 of FIG. 5 described above is in a state in which it is impossible to connect to the network because it is outside the communicable area of the AP 500. Even in such a case, if the STAs that act as relays exist in the communication range, the AP may be connected to the AP as shown in FIG. 7.

7 illustrates a concept of frame relay through two subscriber stations according to the second embodiment of the present invention. Referring to FIG. 7, the AP 700 may communicate with STA1 701 at 36 Mbps, may communicate with STA2 702 at 6 Mbps, and may communicate with STA3 703 at 1 Mbps. There is a state in which communication with 704 is impossible.

At this time, when the AP 700 wants to communicate with the STA4 704 according to the second embodiment of the present invention, if the STA1 701 and the STA3 703 relay, the data is transmitted at 6Mbps instead of in an impossible state. You can give and receive.

8 is a diagram illustrating data transmission during frame relay through two subscriber stations according to the second embodiment of the present invention. That is, FIG. 8 illustrates a process in which the AP 700 sends data to the STA4 704 through the STA1 701 and the STA3 703 and receives an ACK from the STA4 704 in the time axis. It is.

Looking at the transceiver of each frame in FIG. 8 as follows, a detailed description thereof will be described later in the description of FIG.

801: AP transmits RTS to STA1 that is R-STA

802: STA1 sends CTS response to RTS to AP

803: AP transmits data to STA1

804: STA1 sends data to STA3

805: STA3 sends data to STA4

806: STA4 sends an ACK to STA3

807: STA3 sends an ACK to STA1

808: STA1 forwards the ACK to the AP

Hereinafter, detailed configurations and operations according to embodiments of the present invention described above with reference to FIGS. 9 to 16 will be described in detail. First, a method for determining whether each STA terminal has a relay function according to the present invention will be described.

<How to find out if you have a relay function>

An AP capable of using a STA having a relay function announces the fact to information of a beacon frame that is broadcasted periodically. This may use a reserved field of capability information inserted into a beacon frame or a separate reserved information element. Such an AP will be referred to as a "relay capable AP" and a BSS configured by this AP will be referred to as a "relay capable BSS". In the present invention, it is assumed that a reserved field of capability information is used to indicate a "relay capable AP / STA (relay capable AP / STA)".

In this case, the STAs may know whether the AP is a relay capable AP by checking a capability content in a beacon frame sent by the AP. However, if the standard 802.11 STA is not a "relay capable STA" having a relay function, the relay related information in the beacon may not be interpreted.

<Frame type related to relay function>

The IEEE 802.11 MAC standard has defined a MAC frame format as shown in FIG. 9. Here, the frame control field 910 to Addr4 are referred to as MAC headers, and the detailed configuration of the frame control field 910 among the MAC headers is shown in the lower part of FIG. 9. That is, in the frame control field 910, regions of type 911 and subtype 912 are 7th bit from the second bit bit-2 of the first octet. -7) are allocated.

Table 1 below shows the types of the type 911 and the subtype 912 defined in the IEEE 802.11-1999 version. In the present invention, some bits left reserved in Table 1 are used for the relay function.

Type value b3 b2 Type description Subtype value b7 b6 b5 b4 Subtype description 00 Management 0000 Association request 00 Management 0001 Association response 00 Management 0010 Reassociation request 00 Management 0011 Reassociation response 00 Management 0100 Probe request 00 Management 0101 Probe response 00 Management 0110-0111 Reserved 00 Management 1000 Beacon 00 Management 1001 Announcement traffic indication message (ATIM) 00 Management 1010 Diassociation 00 Management 1011 Authentication 00 Management 1100 Deauthentication 00 Management 1101-1111 Reserved 01 Control 0000-1001 Reserved 01 Control 1010 PS-Poll 01 Control 1011 RTS 01 Control 1100 CTS 01 Control 1101 ACK 01 Control 1110 CF-End 01 Control 1111 CF-End + CF-Ack 10 Data 0000 Data 10 Data 0001 Data + CF-Ack 10 Data 0010 Data + CF-Poll 10 Data 0011 Data + CF-Ack + CF-Poll 10 Data 0100 Null function (no data) 10 Data 0101 CF-Ack (no data) 10 Data 0110 CF-Poll (no data) 10 Data 0111 CF-Ack + CF-Poll (no data) 10 Data 1000-1111 Reserved 11 Reserved 0000-1111 Reserved

 Frame types to be used for the relay function of Table 1 are as follows.

Type value b3 b2 Type description Subtype value b7 b6 b5 b4 Subtype description 00 Management 0110 Relay Service Request 00 Management 0111 Relay Service Response 00 Management 1101 Relay request 00 Management 1110 Relay response 11 Relayed 0000 Relayed Beacon 11 Relayed 1110 Relayed Multicast Data 11 Relayed 1111 Relayed Broadcast Data

Meanwhile, the MAC frame of FIG. 9 is physical area data 100 including a preamble 1001, a physical layer convergence procedure (PLCP) header 1002, and the like, as shown in FIG. 10 while passing through an IEEE 802.11 physical layer. ) The structure of the PLCP header 1002 differs slightly depending on the type of physical layer or the version of the 802.11 standard, but has a part called a service field in common, and the remaining bits are not used regardless of the physical layer or the version. ) Are common.

In the present invention, the first bit (bit-1), which is one of the reserved bits, is used for relaying, and the name of the bit is called a relay bit. If the relay bit of the service field is set, the modifier “relayed” is indicated before the names of all the frames of Tables 1 and 2. That is, the relay bit indicates whether the currently transmitted frame is a frame transmitted through the relay or not.

In the above description, a method of adding a frame type and using a service bit is specifically described for understanding of the present invention. However, for a relay function of a frame in a wireless medium communication, which is a basic operation of the present invention, a remaining frame type is defined. It is obvious that the present invention can be applied to any form of modification, such as writing, using reserved service fields, or using a version control field.

<How to set the relay function automatically>

The relay capable AP / STA (relay capable AP / STA) frame relay function may be set manually by a user and turned on or off. In this case, the user may set an operation plan for the STA to use the relay function of another STA, the STA to provide the relay service, and the AP, respectively. However, the manual direct relay function on / off (on / off) as described above has the advantage that the implementation is simple and the operation is clear, while there are disadvantages in use inconvenience when there are many STAs to be set.

Therefore, the present invention provides a method for automatically activating the relay function. In this section, the manual setting method, which is clearly set to be clear and unnecessary, is omitted. A method of automatically activating the relay function will be described in detail with reference to FIGS. 11 and 12.

11 is a flowchart illustrating a procedure for automatically setting a relay function according to an embodiment of the present invention, and FIG. 12 is a signal illustrating a procedure for transmitting a message between an AP and a STA for setting up a relay function according to the first embodiment of the present invention. It is a flow chart.

The start STA (activator) for activating the relay function is an STA having a slow transmission rate or no communication with the AP. In a relay capable BSS, an STA having a slow transmission rate with an AP analyzes frames transmitted from other STAs to the AP (S1101) and selects an STA that transmits the highest transmission rate of a data frame among them (S1101). S1102). This is possible by finding the STA that has transmitted the frame having the highest transmission rate among frames without the CRC error transmitted by the STAs.

On the other hand, in addition to the transmission rate, it is necessary to consider whether the STA to be used as the relay terminal operates in the power save mode (S1103). That is, since the STA operating in the power save mode has to switch to the active mode when starting the relay service, it is highly likely to reject the relay service request. to be. Therefore, when the selected STA is operating in the power saving mode, another STA is selected (S1104). The following describes the procedures in the case of communicating with the AP but using the relay function due to the low transmission rate, and will be described later when the relay is not used in communication with the AP.

For convenience of description, the case of FIG. 5 described above will be described as an example. First, the STA3 503 that wants to increase the transmission rate monitors (S1201, S1202) frames transmitted by all STAs and selects the STA1 501 (S1203). Next, since the STA1 501 has identified the maximum transmission speed that can be relayed, it is calculated whether the transmission efficiency will be better than the present time when the new transmission rate is used through the relay (S1105). On the other hand, whether the transmission efficiency is better can be calculated by the example of FIG. 6 or the like. In this case, since the degree of improvement of the transmission efficiency is changed according to the length of the frame or the relay transmission rate, a threshold for determining whether to undergo the relay function may be set.

If the STA3 503 determines to use the STA1 501 as a relay terminal (S1106), the STA3 503 may relay to the STA1 501 using a relay service request frame. It is requested (S1107, S1204). If a relay service response frame does not come in response to the response from the STA1 501 within the designated time (S1108, S1109), the STA1 501 determines that the STA is not relay capable and determines another. The STA is searched for (S1104).

If the STA1 501 is a relay capable STA, the STA1 501 informs the STA3 503 of the relay using a relay service response frame (S1205). In this case, the relay service request frame specifies the relay requirement, that is, the maximum order of the required relay. For example, if the relaying STA wants to go less than 2 hops from the AP, that is, only one relay, it is designated as primary, and if it is to allow up to two relays, it is specified as secondary. Since these request and response frames do not require the involvement of the AP, they communicate directly between the two STAs without passing through the AP.

In this case, if the STA1 501 is a relay capable STA, the relay service response frame must be sent as described above, and a status code is inserted into the frame body to reject the relay. Specify whether or not to do so. If STA1 501 is the secondary relay terminal and STA3 503 requests the primary relay, the relay service response frame specifies rejection and the reason for rejection, that is, status code. A value indicating "Requested hop count can not be satisfied" is recorded. In this case, the STA3 503 may alleviate the relay condition and transmit a relay service request frame to the STA1 501 again (S1111).

On the other hand, if the STA1 (501) has approved the relay (S1110), the STA3 (503) can use the relay function of the STA1 (501). That is, when the STA1 501 transmits a relay service response frame to the STA3 503 and receives an ACK from the STA3 503 (S1206), the STA1 501 relays the STA3 503 to the AP 500. In step S1112 and S1207, the AP 500 transmits a relay response frame to the STA1 501 to transmit the relay request frame requesting to operate as an STA (R-STA) (S1208). ).

The content of the relay request frame sent from the STA1 501 to the AP 500 specifies that the STA3 503 is to be relayed. When the AP 500 receives the ACK for the relay response frame from the STA1 501 (S1113 and S1209), the relay service is started (S1114 and S1210), and the STA3 (the STA 3 All frames destined for the 503 and all frames destined for the AP 500 from the STA3 503 are transmitted via the STA1 501.

In the example of the present invention, in order to facilitate understanding, one STA has been described as performing a relay function for one STA. However, in order for one STA to perform a relay service for two or more STAs, it is possible to include more information in a body frame of the above-described request / response frames.

Meanwhile, in the above description, since one R-STA is simplified to relay service to only one STA, in this case, after the STA receives a relay service request message from any other STA, a third STA is used. A relay denial of service message should be sent for a relay service request requested by the agent.

Hereinafter, <Table 3>, <Table 4>, <Table 5> and <Table 6> show the body contents of frames used in the activation process of the relay function, and <Table 7> shows the relay A status code table of associated response frames.

Order Information Notes One Max hop count Max Hop Count should be at least 2. A value of 2 means that up to one relay will pass. 2 Purpose 1 = increase transmission efficiency 2 = subscribe and communicate

Order Information Notes One Status Code Processing result code.

Order Information Notes One Relay destination This is the MAC address of the STA of the relay destination, that is, the STA that sent the relay service request. 2 Purpose 1 = increase transmission efficiency 2 = subscribe and communicate

Order Information Notes One Status Code Processing result code for Relay Request.

Status Code Meaning 000 Successful 001 Requested hop count can not be satisfied 010 Already serving a relay function for other STA 011 Already serving a relay function for requesting STA 100 Can not change power save mode 101 Relay service not allowed 110 Release relay service

Meanwhile, the above-described relay function activation procedure can be applied to various modified procedures. In addition, a case in which one STA performs a relay function for two or more STAs can be easily implemented by extending the above-described present invention function.

<Data transfer sequence through relay>

Immediately after the AP 500 receives the ACK for the relay response frame from the STA1 501, the AP 500 manages all data and management frames transmitted to the STA3 503. Send to STA1 501 to allow STA1 501 to relay. In FIG. 6, a process of transferring one data frame to STA3 503 via the STA1 501 has been described on the time axis. Hereinafter, the delivery process will be described in more detail with reference to FIGS. 6 and 13.

13 is a signal flow diagram illustrating a procedure for relaying and transmitting a frame from an AP to an STA according to the first embodiment of the present invention.

1. When the AP 500 generates data or a management frame to be transmitted to the STA3 503, the AP 500 transmits an RTS frame to the STA1 501 (S1301). As shown in FIG. 6, the RTS frame includes time information during the entire sequence from the end of the RTS frame to the end of the last ACK frame, and thus can be relayed. By allocating the NAV to all STAs in the BSS including the standard STA, the radio channel is reserved during the non-standard frame sequence.

2. The STA1 501 receiving the RTS transmits the CTS to the AP 500 (S1302). In the duration field of the CTS frame, the time required from the end of the CTS frame to the end of the last ACK frame shown in FIG. 6 is recorded. At this time, other STAs that do not receive the RTS sent by the AP 500 by the CTS frame sent by the STA1 501 also set a NAV (S1303).

3. The AP 500 transmits data or management frame to STA1 to STA1 (S1304). At this time, the relay bit of the service field of the PLCP header is set to relay and transmitted. In this way, the data of which the relay bit of the service field is set and the frame of the management type will be referred to as "relay data and relay management" type, respectively. Meanwhile, the MAC address of the STA3 503, that is, the "Addr1" field in which the RA (Receiver Address) is recorded, is replaced with the address of the STA1 501 and transmitted.

4. When the STA1 501 receives the relay frame (relay frame (frame in which the relay bit of the service field is 1)) of which the RA is itself, the STA1 501 does not transmit an ACK frame for the relay frame because it operates as a relay STA. The RA of the received frame is transmitted to STA3 by replacing the TA (Transmitter Address), that is, the "Addr2" field with its own address (S1305).

5. When the STA3 503 receives a relay frame in which the RA is itself, the STA3 503 transmits a relayed ACK frame (S1306) for the relay frame because the STA3 503 does not operate as a relay STA. The frame is converted to the address of the AP and processed.

6. When the STA1 501 receives the relayed ACK frame from the STA3 503, the STA1 501 replaces the RA with the address of the AP and transmits the RA to the AP 500 (S1307).

7. When the AP 500 receives the ACK from the STA1 501, the AP 500 processes the transmission of the relayed frame as being completed. If the ACK is not received even after a predetermined time elapses after the relay data or the relay management frame is sent, the AP 500 retransmits according to the 802.11 standard. At this time, the "AckTimeOut" value for the relay of the frame should be set to a value larger than the time of the entire relayed frame sequence.

8. The interval between each frame of these entire sequences is SIFS.

Hereinafter, a process of transmitting a frame to the AP 500 by the STA3 503 via the STA1 501 will be described with reference to FIG. 14. 14 is a signal flowchart illustrating a procedure for relaying and transmitting a frame from an STA to an AP according to a first embodiment of the present invention.

The STA3 503 does not transmit data or management frame to the STA1 501 even though it receives an approved relay service response message from the STA1 501, and directly transmits the AP to the STA (501) as before. After communicating with the 500 and receiving one or more relayed frames from the AP 500 via the STA1 501, the STA1 501 is used as a relay STA. This means that the STA1 501 sends a relayed frame to the STA1 501 after confirming that the STA1 501 is completely set as its relay STA. Meanwhile, when the STA1 501 is used as a relay STA, the following process is performed when the STA3 503 attempts to transmit data or a management frame to the AP 500.

1. First, the STA3 503 transmits an RTS frame to the STA1 501 (S1401). The duration value of the RTS frame is a time from the end of the RTS frame to the end of the last ACK.

2. The STA1 501 responds to the STA3 503 with the CTS (S1402, S1403). In this case, the duration value of the CTS frame is a value obtained by subtracting "SIFS + CTS transmission time" from the duration value of the received RTS frame.

3. The STA3 503 receiving the CTS transmits data or management frame to be sent to the STA1 501 after the SIFS has elapsed (S1404). At this time, the frame sets the relay bit in the service field of the PLCP header to change the relay data or the relay management type, and sets the RA to STA1 (501).

4. The STA1 501 transmits the RA of the relayed frame to the AP and the TA to the AP 500 (S1405).

5. The AP 500 transmits a TA, that is, an ACK relayed to the STA1 501, with respect to the received relayed frame (S1406), and the TA of the received frame is the first transmitter, that is, the STA1 501. Is replaced with the address of STA3 503 which is used as the relay STA.

6. The STA1 501 replaces the RA of the relayed ACK frame sent by the AP 500 with the STA3 503 and transmits the STA to the STA3 503 (S1407).

7. The STA1 501 retransmits according to the 802.11 standard if there is no ACK until the expected time after transmitting the relay data or the relay management frame.

8. The interval between each frame of these entire sequences is SIFS.

<Multi relay operation method>

As described above, after the STA1 501 becomes the relay STA (R-STA) of the STA3 503, the STA3 503 may be the relay STA (R-STA) of another STA. Hereinafter, a case in which the STA4 704 intends to use the STA3 703 as a relay will be described with reference to FIGS. 7 and 15.

First, the STA4 704 transmits a relay service request frame to the STA3 703 (S1501). Since the STA3 703 is a relay capable STA, the STA3 703 transmits a relay service response frame to the STA4 704 (S1502). When the STA4 704 transmits an ACK to the STA3 703 (S1503), the STA3 703 transmits a relay request frame to the AP 700 through RTS / CTS handshaking (S1504, S1505). )do.

In this case, since the relay request frame goes to the AP 700 via the STA1 701, the relay bit of the service field must be set, and the AP 700 transmits the relay response frame to the STA1 701. (S1506, S1507) is transmitted to the STA3 (703) via. When the AP 700 receives the ACK from the STA3 703 (S1508 and S1509), data or management frames transmitted from the AP 700 to the STA4 704 thereafter are passed through the STA1 701 and the STA3 703. The ACK, which is delivered to the STA4 704 and responded by the STA4 704, is also transmitted to the AP 700 via the relay STAs to initiate the relay service (S1510).

In FIG. 8, a process of transferring one data frame to STA4 704 via STA1 701 and STA3 703 has been described on the time axis. Hereinafter, the delivery process will be described in more detail with reference to FIGS. 8 and 16.

16 is a signal flow diagram illustrating a procedure for relaying and transmitting a frame from an AP to an STA according to the second embodiment of the present invention.

1. When the AP 700 generates data or a management frame to be transmitted to the STA4 704, the AP 700 transmits an RTS frame to the STA1 701 (S1601). As shown in FIG. 8, the RTS frame includes time information during the entire sequence from the end of the RTS frame to the end of the last ACK frame, and thus can be relayed. By allocating the NAV to all STAs in the BSS including the standard STA, the radio channel is reserved during the non-standard frame sequence.

2. The STA1 701 receiving the RTS transmits the CTS to the AP 700 (S1602). In the duration field of the CTS frame, the time required from the end of the CTS frame to the end of the last ACK frame shown in FIG. 8 is recorded. At this time, other STAs that do not receive the RTS sent by the AP 700 by the CTS frame sent by the STA1 701 also set NAVs (S1603 and S1604).

3. The AP 700 transmits data or management frame to STA1 to STA1 (S1605). At this time, the relay bit of the service field of the PLCP header is set to relay and transmitted. In this way, the data of which the relay bit of the service field is set and the frame of the management type will be referred to as "relay data and relay management" type, respectively. On the other hand, the MAC address of the original STA4 (703), that is, the "Addr1" field in which the RA (Receiver Address) is recorded is replaced with the address of the STA1 701 and transmitted.

4. When the STA1 701 receives the relay frame field (the relay frame of which the relay bit is 1) in which the RA is itself, the STA1 701 does not transmit an ACK frame for it because it operates as a relay STA. The RA of the received frame is replaced with STA3, and the TA (Transmitter Address), that is, the "Addr2" field is replaced with its own address (S1606).

5. When the STA3 703 receives the relay frame field (the relay frame of which the relay bit is 1) in which the RA is itself, the STA3 703 does not transmit an ACK frame for the STA because it operates as a relay STA. The RA of the received frame is replaced with STA4, and the TA (Transmitter Address), that is, the "Addr2" field is replaced with its own address (S1607).

6. When the STA4 704 receives the relay frame in which the RA is itself, the STA4 704 transmits a relayed ACK frame (S1608) for the relay frame since the STA4 704 does not operate as the relay STA. The frame is converted to the address of the AP and processed.

7. When the STA3 703 receives the relayed ACK frame from the STA4 704, the STA3 703 replaces the RA with the address of the STA1 701 and transmits the RA to the STA1 701 (S1609).

8. When the STA1 701 receives the relayed ACK frame from the STA3 703, the STA1 701 replaces the RA with the address of the AP and transmits the RA to the AP 700 (S1610).

9. When the AP 700 receives the ACK from the STA4 704, the AP 700 processes the transmission of the relayed frame as being completed. If the ACK is not received even after a predetermined time elapses after transmitting the relay data or the relay management frame, the AP 700 performs retransmission according to the 802.11 standard. At this time, the "AckTimeOut" value for the relay of the frame should be set to a value larger than the time of the entire relayed frame sequence.

10. The interval between each frame of these entire sequences is referred to as SIFS.

Hereinafter, the process of the STA4 704 transferring the frame to the AP 700 via the STA3 703 and the STA1 701 will be described with reference to FIG. 17. 17 is a signal flowchart illustrating a procedure for relaying and transmitting a frame from an STA to an AP according to a second embodiment of the present invention.

Even if the STA4 704 receives an approved relay service response message from the STA3 703, the STA4 704 does not transmit data or a management frame to the AP 700 to the STA3 703. After communicating with the 700 and receiving one or more relayed frames from the AP 700 via the STA1 701 and the STA3 703, the STA3 703 is used as the relay STA. This means that the STA3 703 sends a relayed frame to the STA3 703 after confirming that the STA3 703 is completely set as its relay STA. Meanwhile, when the STA1 701 and the STA3 703 are used as the relay STA, the STA4 704 follows the following procedure when the STA4 704 attempts to transmit data or a management frame to the AP 700.

1. First, the STA4 704 transmits an RTS frame to the STA3 703 (S1701). The duration value of the RTS frame is a time from the end of the RTS frame to the end of the last ACK.

2. The STA3 703 responds to the STA4 704 with the CTS (S1702, S1703, S1704). In this case, the duration value of the CTS frame is a value obtained by subtracting "SIFS + CTS transmission time" from the duration value of the received RTS frame.

3. The STA4 704 receiving the CTS transmits data or management frame to be sent to the STA3 703 after SIFS (S1705). At this time, the frame sets the relay bit in the service field of the PLCP header to change the relay data or the relay management type, and sets the RA to STA3 (703).

4. The STA3 703 transmits the RA of the relayed frame to STA1 and replaces the TA with the STA1 to the STA1 701 (S1706).

5. The STA1 701 transmits the RA of the relayed frame to the AP and the TA to the AP 700 (S1707).

6. The AP 700 transmits a TA, that is, an ACK relayed to the STA1 701, with respect to the received relayed frame (S1708), and the TA of the received frame is the first transmitter, that is, the STA1 703. Is replaced with the address of the STA4 704 using the relay STA for processing.

7. The STA1 701 replaces the RA of the relayed ACK frame sent by the AP 700 with the STA3 703 and transmits it to the STA3 703 (S1709).

8. The STA3 703 replaces the RA of the relayed ACK frame sent by the STA1 701 with the STA4 704 and transmits it to the STA4 704 (S1710).

9. The STA1 701 and the STA3 703 retransmit according to the 802.11 standard if there is no ACK until the expected time after transmitting the relay data or the relay management frame.

10. The interval between each frame of these entire sequences is referred to as SIFS.

<How STA in Non-Communication Area Joins AP via Relay>

In FIG. 5 or FIG. 7, the STA4 704 exists outside the radio coverage area of the AP 700 to directly receive all frames including a beacon frame periodically transmitted by the AP 700. In this case, it is very unlikely that a frame transmitted by the STA4 704 is properly received by the AP 700. According to the IEEE 802.11 standard, in order for an STA to join an AP, the STA receives a beacon frame transmitted by the AP or the STA sends a probe request message to receive a probe response message from the AP in response thereto. Hereinafter, in this case, a procedure of subscribing to the AP 700 using the STA4 704 of FIG. 5 or 7 will be described.

1. First, the STA4 704 scans each frequency channel (S1801) to receive a beacon or probe response frame according to the 802.11 standard, and eventually fails to scan because no frame is received.

2. At this time, if the user requests, for example, "relay search and relay communication", the STA4 704 receives all error-free frames for a certain period of time for the channels set by the user so that the highest transmission rate and power saving mode ( A STA other than the power save mode is selected (S1802) to transmit a relay service request frame (S1803). The purpose field of the relay service request frame body is designated as 2, " subscription and communication. &Quot; Here, it will be assumed that the STA is STA3 (703).

3. The STA3 703 transmits a relay service response message to the STA4 704 (S1804) and receives an ACK for the STA4 (704). Then, the STA3 703 transmits a relay request frame to the AP 700. (S1806, S1807). On the other hand, the STA4 704 waits until it receives the relayed probe response frame from the STA3 703.

4. The AP 700 transmits a relay response frame to the STA3 703 (S1808 and S1809) and receives an ACK from the STA3 703 (S1810 and S1811). The AP 700 responds to the relay probe response to the STA4 704 again. (relay probe response) The frame is transmitted (S1812, S1813, S1814). This frame is via the STA3 703. Of course, the first sender of every relayed frame must do RTS / CTS handshaking before that.

5. The STA4 704 transmits an ACK for the probe response frame to the AP 700 via the relay STAs (S1815, S1816, and S1817), analyzes the received probe response frame, and analyzes the received probe response frame. It is determined whether to join the BSS (S1818).

6. If the STA4 704 decides to join the BSS through the STA3 703, it starts to transmit the relayed authentication request frame to the AP 700 (S1819, S1920, S1821). Accordingly, the AP 700 is joined to the AP 700 through an authentication procedure with the AP 700 and through an association procedure (S1822, S1823, S1824).

As described above, the STA4 704 that successfully completes the association exchanges all data and management frames with the AP 700 through the STA3 703 to initiate a relay service (S1825). However, since the STA4 704 cannot receive the beacon frame transmitted by the AP 700 in a short period, the STA4 704 cannot synchronize the MAC level with the AP 700, so that the operation may be performed even if the beacon is not properly received. It must be dealt with. For example, it is desirable that the power save mode, which is only possible if the correct synch is met, is not set in this case.

<Multicast / Broadcast frame delivery method through relay>

In BSS networks centered on APs, multicast and broadcast frames of 802.11 MAC levels are basically transmitted only by APs except for probe request frames. It describes only the case of transmitting. However, since the relay capable STA receives these frames and processes them regardless of the origin, the same may be handled even when the general STA transmits such frames.

The relay capable AP transmits multicast and broadcast frames according to the 802.11 standard without transmitting as “relayed” even though there are STAs operating as relays in the BSS. In this case, all STAs capable of directly communicating with the AP within the BSS receive these frames immediately, but STAs participating in the BSS using the relay for the purpose of "subscription and communication" do not receive these frames. Therefore, the STA in charge of relaying with the STA, which cannot directly communicate with the AP, must relay all multicast and broadcast data frames except beacons and probe request frames.

There are two ways to relay multicast and broadcast frames. One is to change the type to "relayed" like other directional frames and transmit it immediately after SIFS time. The other is to store the received multicast frame and then to the contention method defined by 802.11 standard, DCF ( Distributed Coordination Function) A method of transmitting according to a rule.

When receiving the frame and transmitting it immediately after SIFS, there is an advantage that it is efficient and simple to implement. However, if the same type of relay STA is in close proximity, the two STAs transmit to relay the multicast frame at the same time, so a collision occurs. Will be broken. Therefore, this method should be used only when it is confirmed that there is no relay STA that plays the same role as itself, and otherwise, the second method is to be used.

When relaying a multicast or broadcast data frame according to the second method described above, a separate frame type reserved in the standard is used. In the present invention, "Relayed Multicast Data" and "Relayed Broadcast Data" types are defined in Table 2 as an example. At this time, with the modification of the frame type, the RA is replaced with the address of the STA which is the relay service beneficiary, and the original RA is put in the position of Addr3 where the BSSID is located. This has the effect of blocking errors that can be made by other STAs in the BSS recognizing this frame as multicast or broadcast.

<STA and Beacon Frame in Unreachable Area>

The beacon frame is a management type packet periodically broadcasted by the AP in order to synchronize time and network information with all STAs in the BSS. Therefore, if an STA has not received a beacon for a long time, it means that it is out of communication area with the AP or the AP has stopped service. What changes in every beacon in the beacon frame is a timestamp value and TIM information, which determine when and when the STAs awake when operating in power save mode. Used. Other information includes capability information, network name called SSID, and information about supported transmission rates, which are used with almost fixed values.

Therefore, if the STA will not operate in a power save mode, it is not necessary to receive all beacon frames transmitted by the AP. Of course, the relay STA may relay all beacons, but in this case, there is a burden of receiving and buffering and sending later, as shown in the above-described multicast or broadcast frame relay method.

In addition, since the relay STA changes the timestamp value inside the beacon frame or the last received STA must process the timestamp in a manner different from the standard, the implementation is complicated, and the beacon frame is at least 100 msec. Because it comes out every time, the media share of relaying it is high, which can be a factor that degrades the overall network performance. Therefore, the beacon frame is not relayed every time, and relaying is determined by the relay STA when the network configuration information except for a timestamp and a TIM is changed or at regular intervals.

Meanwhile, when relaying the beacon, the 'Relayed beacon type' of Table 2 is used, and the values of Addr1, 2, and 3 are used in the same manner as the multicast frame relay method described above.

<Change and release of relay-Change and release by requester of relay service>

The STA using the relay service may release the relay service when 1) it is not available to communicate with the AP, or 2) it is changed from a low transmission rate with the AP to a high environment, or 3) withdraws from the BSS. Can be.

The release of the relay service does not determine a separate frame type, and processes the disassociation, de-authentication or re-association frame defined in the 802.11 standard using the standard. That is, if the STA using the relay service wants to directly communicate with the AP without going through the relay anymore, the STA simply sends a re-association request frame to the AP and receives a response from the AP.

In addition, if you want to leave, send a disassociation or de-authentication request frame to the AP. The STA providing the relay service stops the relay service by detecting a re-association or disassociation or de-authentication frame sent by the service user or the AP to the service user. The AP deletes the STA that has sent the re-association message from the relay user list and processes the STA in the same manner as the general STA.

If the STA providing the relay service misses a re-association or disassociation or de-authentication frame sent by the user, or the relay user suddenly disappears due to a failure or power off, etc. If the relay response frame is received from the AP and 'Release relay service' is specified in the status code field, the relay service is stopped.

On the other hand, when the AP tries to remove any STA from the subscriber list while aging the subscriber, if the STA receives the relay service, the AP sends a relay response frame to the relay STA of the STA. send. At this time, 'Release relay service' is used as a status code. If the STA providing the relay service receives a frame other than the relay data or the relay management type from the STA receiving the relay service, the relay service is stopped even in this case.

<Change and release of relay-Change and release by relay STA>

If the STA providing the relay service needs to change its power management mode to a power save mode or withdraws from the network, the relay service is released. In this case, the relay service user is similar to the release method described above. That is, when the relay STA transmits a re-association or disassociation or de-authentication request frame to the AP, the AP no longer recognizes the relay STA.

Meanwhile, the STA receiving the relay service of the STA immediately releases the relay use mode when receiving the frames sent by the relay STA. In this case, the STA using the relay to directly improve the transmission rate is directly communicated with the AP again, and the STA using the relay for the purpose of 'subscription and communication' is treated as being withdrawn from the AP.

If the AP sends a disassociation or de-authentication request frame to the relay STA, the relay STA must deliver it to the relay service user STA.

If the relay service user does not receive the re-association or disassociation or de-authentication message of the relay STA, the relay service is recognized as being released from the moment the AP receives a frame directly sent to the relay STA. If the AP first sends a frame to the AP before sending the frame to itself (the relay service using STA), the ACK is not received for the frame.

If the relay STA does not operate suddenly due to a failure or power off, communication between the AP and the relay service user STA will not be performed for a while. In this case, the aging function of the relay user STA and the AP may not be applied. Reconnect after withdrawal.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

According to the present invention, when the communication environment between the AP and the STA needs to be communicated at a low speed in a short range wireless communication network, the data transmission efficiency can be increased by relaying and transmitting a message through a third STA having a good communication environment. There is this.

In addition, when the STA is in a position where communication with the AP is impossible in the short range wireless communication network, the service area may be extended by relaying and transmitting a message through a third STA having a good communication environment.

In addition, when a communication environment between the AP and the STA needs to communicate at a low speed in a short range wireless communication network or when the STA is in a position where communication with the AP is impossible, the message may be relayed through multiple STAs having a good communication environment. There is an advantage that can be increased by transmitting the data transmission efficiency.

Claims (42)

In a short-range wireless communication network in which one access point communicates with a plurality of subscriber stations at a plurality of transmission speeds through a wireless channel, the access point transmits and receives a frame with one of the plurality of subscriber stations. In A first subscriber station selecting a subscriber station other than itself among the plurality of subscriber stations as its relay subscriber station, and transmitting and receiving a data frame with the access point through the relay subscriber station; When a data frame is transmitted and received between the first subscriber station and the access point, a relay subscriber that receives and transmits the data frame transmitted from the first subscriber station or the access point to the access point or the first subscriber station. With the terminal. And an access point for transmitting and receiving the data frame via the relay subscriber terminal when transmitting and receiving a data frame with the first subscriber station. The method of claim 1, wherein the first subscriber station, And a subscriber station having the highest transmission rate among the plurality of subscriber stations as its relay subscriber station. The method of claim 2, wherein the first subscriber station, And when another subscriber station having the highest transmission rate is in a power saving mode, selecting another subscriber station as a relay subscriber station. The method of claim 1, wherein the first subscriber station, Frame transmission and reception system, characterized in that for determining the use of the relay function by calculating the transmission efficiency according to the relay transmission through the relay subscriber terminal. The method of claim 1, wherein the first subscriber station, And transmitting a relay service request message including the selection information on the relay subscriber terminal to the access point through the relay subscriber terminal to request the relay service through the relay subscriber terminal. The method of claim 1, wherein the first subscriber station, And receiving a data frame from the access point through the relay subscriber terminal, and transmitting a reception response message to the access point through the relay subscriber terminal. The method of claim 1, wherein the access point, And transmitting an RTS frame including a channel occupation vector to the relay subscriber station in order to secure a transmission interval for transmitting the data frame to the first subscriber station. The method of claim 7, wherein the relay subscriber terminal, And receiving the RTS frame from the access point, and then transmitting the CTS frame to a wireless channel space. The method of claim 1, wherein the first subscriber station, And transmitting an RTS frame including a channel occupation vector to the relay subscriber station in order to secure a transmission interval for transmitting a data frame to the access point. The method of claim 9, wherein the relay subscriber terminal, And receiving the RTS frame from the first subscriber station and transmitting a CTS frame to a radio channel space. The method of claim 1, wherein the relay subscriber terminal, When the first subscriber station uses the relay service for the purpose of "subscription and communication", if it is determined that there is no other relay subscriber station in the vicinity, the multicast or broadcast data frame is received and the SIFS time elapses as described above. And transmitting the same to the first subscriber station by transmitting again after substitution. The method of claim 1, wherein the relay subscriber terminal, When the first subscriber station uses the relay service for the purpose of "subscription and communication", if it is determined that there is another relay subscriber station in the vicinity, it receives and stores the multicast or broadcast data frame, and occupies the WM through competition. Frame transmission and reception system, characterized in that when transmitting to the first subscriber station. The system of claim 1, wherein the system is And a plurality of relay subscriber stations, and transmitting and receiving data sequentially through the plurality of relay subscriber terminals when data frames are transmitted and received between the access point and the first subscriber station. The method of claim 1, wherein the access point, And transmitting information including information indicating that the access point is an access point capable of relaying service in a beacon frame broadcasted periodically by the access point. The method of claim 1, wherein the frame, And indicating that the frame is a relay related frame at an arbitrary position of a header of a physical layer or a frame of a media access control layer. The method of claim 1, wherein the frame, A frame transmitting / receiving system, characterized in that an unused remaining type, subtype, or extended type value of type and subtype information configured in a frame control field of a medium access control layer is used for relay service. In a short-range wireless communication network in which one access point communicates with a plurality of subscriber stations at a plurality of transmission speeds through a wireless channel, the access point transmits a data frame to one of the plurality of subscriber stations. To Selecting a subscriber station other than itself among the plurality of subscriber stations as the relay subscriber station from the first subscriber station; Approving a relay service by the relay subscriber terminal in the access point; Transmitting a data frame from the access point to the relay subscriber terminal; And transmitting the data frame received from the access point to the first subscriber station in the relay subscriber station. The method of claim 17, wherein the transmitting of the data frame from the access point to the relay subscriber terminal comprises: And transmitting a delimiter for distinguishing 'relay' at a service field included in the PLCP header of the data frame or any position within the frame. The method of claim 18, wherein the transmitting of the data frame from the relay subscriber terminal to the first subscriber terminal comprises: If it is determined that the received data frame is a relay data frame by checking the relay delimiter, the destination address of the received data frame is converted into the first subscriber station, and the destination address is converted into its own address. And transmitting the data frame. The method of claim 17, wherein the first subscriber station, The method of claim 1, wherein the subscriber station having the highest transmission rate among the plurality of subscriber stations is selected as its relay subscriber station. The method of claim 20, wherein the first subscriber station, And when the subscriber station with the highest transmission rate is in a power saving mode, selecting another subscriber station as a relay subscriber station. The method of claim 17, wherein the first subscriber station, The frame transmission method characterized in that the use of the relay function is determined by calculating the transmission efficiency according to the relay transmission through the relay subscriber station. The method of claim 17, wherein after the relay subscriber station selection process, Transmitting, by the first subscriber station, a relay service request message including selection information about the relay subscriber station to the relay subscriber station; Receiving, at the relay subscriber terminal, a relay service request message from the first subscriber terminal and determining whether the relay service is available; And transmitting a relay service response message from the relay subscriber terminal to the first subscriber terminal when the relay service is available as a result of the determination. The method of claim 23, wherein after the relay service response message transmission process, Transmitting a reception response message from the first subscriber station to the relay subscriber station; Transmitting a relay request message including the information of the first subscriber station from the relay subscriber station receiving the reception response message from the first subscriber station to the access point; And transmitting a relay response message from the access point receiving the relay request message from the relay subscriber terminal to the relay subscriber terminal. The method of claim 17, wherein before the data frame is transmitted from the access point, Transmitting an RTS frame including a channel occupation vector from the access point to the relay subscriber station; And transmitting the CTS frame to the radio channel space by the relay frame terminal receiving the RTS frame from the access point. The method of claim 17, wherein the method And a plurality of relay subscriber stations, and transmitting and receiving data sequentially through the plurality of relay subscriber stations when data frames are transmitted from the access point to the first subscriber station. The method of claim 17, wherein the access point, And transmitting information including information indicating that the access point is an access point capable of relaying service in a beacon frame broadcasted periodically by the access point. The method of claim 17, wherein the frame, And indicating that the frame is a relay related frame within a header of a physical layer or any frame that does not harm the standard. The method of claim 17, wherein the frame, The remaining type, subtype, or extended type value, which is not used, among the type and subtype information configured in the frame control field of the medium access control layer is set and used for the relay service. In a short-range wireless communication network in which one access point communicates with a plurality of subscriber stations at a plurality of transmission speeds through a wireless channel, a method of transmitting data frames from one subscriber station of the plurality of subscriber stations to the access point. To Selecting a subscriber station other than itself among the plurality of subscriber stations as the relay subscriber station from the first subscriber station; Approving a relay service by the relay subscriber terminal in the access point; Transmitting a data frame from the first subscriber station to the relay subscriber station; And transmitting the data frame received from the first subscriber station to the access point in the relay subscriber station. The method of claim 30, wherein the transmitting of the data frame from the first subscriber station to the relay subscriber station comprises: And transmitting the relay related bits of the service field included in the PLCP header of the data frame as relay data. The method of claim 31, wherein the transmitting of the data frame to the access point by the relay subscriber terminal comprises: If it is determined that the received data frame is a relay data frame by checking the relay data setting of the relay related bits, the destination address of the received data frame is converted into the access point, and the destination address is converted into its own address. And transmitting the data frame after conversion. The method of claim 30, wherein the first subscriber station, The method of claim 1, wherein the subscriber station having the highest transmission rate among the plurality of subscriber stations is selected as its relay subscriber station. The method of claim 33, wherein the first subscriber station, And when the subscriber station with the highest transmission rate is in a power saving mode, selecting another subscriber station as a relay subscriber station. The method of claim 30, wherein the first subscriber station, The frame transmission method characterized in that the use of the relay function is determined by calculating the transmission efficiency according to the relay transmission through the relay subscriber station. The method of claim 30, wherein after the relay subscriber station selection process, Transmitting, by the first subscriber station, a relay service request message including selection information about the relay subscriber station to the relay subscriber station; Receiving, at the relay subscriber terminal, a relay service request message from the first subscriber terminal and determining whether the relay service is available; And transmitting a relay service response message from the relay subscriber terminal to the first subscriber terminal when the relay service is available as a result of the determination. The method of claim 36, wherein after the relay service response message transmission process, Transmitting a reception response message from the first subscriber station to the relay subscriber station; Transmitting a relay request message including the information of the first subscriber station from the relay subscriber station receiving the reception response message from the first subscriber station to the access point; And transmitting a relay response message from the access point receiving the relay request message from the relay subscriber terminal to the relay subscriber terminal. The method of claim 30, wherein before the process of transmitting the data frame in the first subscriber station, Transmitting an RTS frame including a channel occupation vector from the first subscriber station to the relay subscriber station; And transmitting a CTS frame to a radio channel space by the relay frame terminal receiving the RTS frame from the first subscriber station. The method of claim 30, wherein the method is And a plurality of relay subscriber stations, and transmitting and receiving data sequentially through the plurality of relay subscriber stations when data frames are transmitted from the first subscriber station to the access point. The method of claim 30, wherein the access point, And transmitting information including information indicating that the access point is an access point capable of relaying service in a beacon frame broadcasted periodically by the access point. The method of claim 30, wherein the frame, And a frame indicating that the frame is a relay related frame in a header of a physical layer. The method of claim 30, wherein the frame, A method of transmitting a frame, characterized by setting an unused residual type, subtype, or extended type value of a type and subtype information configured in a frame control field of a medium access control layer for a relay service.

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