WO2015069047A1 - Method and device for transmitting and receiving data in wireless lan system - Google Patents

Abstract

Disclosed are a method and a device for transmitting and receiving data in a wireless LAN system. A connection method performed in a terminal comprises the steps of: transmitting a probe request frame; receiving, from a main-access point, a probe response frame which is a response to the probe request frame; and transmitting, to the main-access point, an ACK frame which is a response to the probe response frame if it is determined that an operation is performed in an uplink relay mode on the basis of information included in the probe response frame. Thus, the wireless transmission efficiency of a wireless LAN system is capable of being improved.

Description

Method and apparatus for transmitting / receiving data in wireless LAN system

The present invention relates to a data transmission and reception technique in a wireless LAN system, and more particularly, to a method and apparatus for transmitting and receiving data with an end terminal in a wireless LAN system including a relay device.

With the development of information and communication technology, various wireless communication technologies are being developed. Wireless local area network (WLAN) is based on radio frequency technology, personal digital assistant (PDA), laptop computer, portable multimedia player (PMP), smart It is a technology for wirelessly accessing the Internet in a home, business, or a specific service providing area by using a portable terminal such as a smart phone or a tablet PC.

The standard for WLAN technology is being developed as an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. The WLAN technology according to the IEEE 802.11a standard operates based on orthogonal frequency division multiplexing (OFDM), and may provide a transmission rate of up to 54 Mbps in a 5 GHz band. The WLAN technology according to the IEEE 802.11b standard operates based on a direct sequence spread spectrum (DSSS) scheme and can provide a transmission rate of up to 11 Mbps in the 2.4 GHz band. The WLAN technology based on the IEEE 802.11g standard operates based on the OFDM scheme or the DSSS scheme and may provide a transmission rate of up to 54 Mbps in the 2.4 GHz band.

The WLAN technology according to the IEEE 802.11n standard operates in the 2.4 GHz band and the 5 GHz band based on the OFDM scheme, and uses four spatial streams when the multiple input multiple output OFDM (MIMO-OFDM) scheme is used. It can provide a transmission rate of up to 300Mbps for spatial streams. Wireless LAN technology according to the IEEE 802.11n standard can support a channel bandwidth (channel bandwidth) up to 40MHz, in this case can provide a transmission rate of up to 600Mbps.

As the spread of the WLAN is activated and applications using the same are diversified, there is an increasing need for a new WLAN technology that supports higher throughput than the existing WLAN technology. Very high throughput (VHT) WLAN technology is proposed to support data rates of 1Gbps or more. On the other hand, in the system based on the WLAN technology, there is a problem in that the communication efficiency is lowered as the distance between the WLAN devices increases.

An object of the present invention for solving the above problems is to provide a data transmission and reception method for improving the efficiency of a wireless LAN system.

Another object of the present invention for solving the above problems is to provide a data transmission and reception apparatus for improving the efficiency of a wireless LAN system.

According to an embodiment of the present invention for achieving the above object, the connection method performed in the terminal, transmitting a probe request frame, receiving a probe response frame that is a response to the probe request frame from the master access point And if it is determined to operate in an uplink relay mode based on the information included in the probe response frame, transmitting an ACK frame, which is a response to the probe response frame, to a relay device connected to the master access point. Include.

The connection method may further include transmitting an authentication request frame to the relay device and receiving an authentication response frame, which is a response to the authentication request frame, from the master access point.

The connection method may further include transmitting a connection request frame to the relay device and receiving a connection response frame that is a response to the connection request frame from the master access point.

Here, the probe request frame may include a field indicating whether the frame is a frame transmitted in a relay method.

Here, the probe request frame may be transmitted to the master access point through the relay device.

Here, the probe response frame may include at least one of a field indicating whether to operate in an uplink relay mode and an identifier of the relay device.

Here, the authentication request frame may be transmitted to the master access point through the relay device.

Here, the connection request frame may be transmitted to the master access point through the relay device.

Here, the connection response frame may include a field indicating whether the terminal is connected to the master access point in an uplink relay mode.

According to another embodiment of the present invention for achieving the above object, the connection method performed in the main access point, receiving a probe request frame from a relay device connected to the main access point, for the probe request frame And transmitting a probe response frame including information indicating whether to operate in an uplink relay mode in response to the terminal and receiving an ACK frame, which is a response to the probe response frame, from the relay device.

The connection method may further include receiving an authentication request frame from the relay device and transmitting an authentication response frame that is a response to the authentication request frame to the terminal.

The connection method may further include receiving a connection request frame from the relay device and transmitting a connection response frame that is a response to the connection request frame to the terminal.

Here, the probe request frame may include a field indicating whether the frame is a frame transmitted in a relay method.

Here, the probe response frame may include at least one of a field indicating whether to operate in an uplink relay mode and an identifier of the relay device.

Here, the connection response frame may include a field indicating whether the terminal is connected to the master access point in an uplink relay mode.

According to another embodiment of the present invention for achieving the above object, a connection method performed in a relay device connected to a master access point, receiving a probe request frame from a terminal and transmitting the probe request frame in a relay manner Transmitting the probe request frame to the master access point.

Here, the probe request frame may include a field indicating whether the frame is a frame transmitted in a relay method.

Here, the SSID field included in the probe request frame may be set to the SSID or any of the master access point.

According to another embodiment of the present invention for achieving the above object, a data receiving method performed in a terminal connected to a relay device, receiving a beacon frame from a master access point connected to the relay device, the beacon frame Transmitting a PS-Poll frame to the relay device when it is determined that the data to be transmitted to the terminal exists in the master access point, and transmits the data frame in response to the PS-Poll frame from the master access point. Receiving and transmitting an ACK frame, which is a response to the data frame, to the relay device.

Here, the terminal may belong to the main-basic service set formed by the main-access point and the relay-basic service set formed by the relay device.

Here, the arbitrary frame transmitted by the terminal may include information indicating the type of the frame transmitted by the communication entity receiving the arbitrary frame.

Here, the PS-Poll frame may be transmitted to the master access point through the relay device.

Here, the SIG field of the PS-Poll frame may include information indicating that an NDP response is transmitted after the PS-Poll.

Here, the SIG field of the data frame may include information indicating that a normal response is transmitted after the data frame.

Here, a period for protecting transmission of at least two ACK frames may be set in the duration field of the data frame.

Here, the ACK frame may be transmitted to the master access point through the relay device.

Here, the SIG field of the ACK frame may include information indicating that a normal response is transmitted after the ACK frame.

According to another embodiment of the present invention for achieving the above object, the data transmission method performed in the master access point connected to the relay device, the beacon frame indicating that there is data to be transmitted to the terminal connected to the relay device Transmitting, receiving a PS-Poll frame from the relay device, and transmitting a data frame to the terminal when it is determined that the terminal is capable of receiving data by the PS-Poll frame. do.

The data transmission method may further include receiving an ACK frame that is a response to the data frame from the relay device.

The data transmission method may further include retransmitting the data frame to the terminal when the ACK frame that is a response to the data frame is not received from the relay device within a preset relay ACK timeout.

Here, the relay ACK timeout may be set longer than 'SIFS + reception_start_delay + slot time'.

Here, the terminal may belong to the main-basic service set formed by the main-access point and the relay-basic service set formed by the relay device.

Here, a period for protecting transmission of at least two ACK frames may be set in the duration field of the data frame.

According to the present invention, the wireless transmission efficiency of the WLAN system can be improved.

1 is a block diagram illustrating one embodiment of a station for performing methods in accordance with the present invention.

2 is a conceptual diagram illustrating an embodiment of a configuration of a wireless LAN system according to IEEE 802.11.

3 is a flowchart illustrating a connection procedure of a terminal in an infrastructure BSS.

4 is a conceptual diagram illustrating an infrastructure BSS of a WLAN system.

5 is a block diagram illustrating an embodiment of a hierarchical AID structure.

FIG. 6 is a block diagram illustrating an embodiment of a structure of a TIM information element (IE).

FIG. 7 is a block diagram illustrating an embodiment of a structure of a TIM encoded on a block basis.

8 is a flowchart illustrating an embodiment of a method of transmitting and receiving data.

9 is a conceptual diagram illustrating an embodiment of a WLAN system including a relay device.

10 is a block diagram showing a logical configuration of a relay device.

11 is a flowchart illustrating another embodiment of a data transmission / reception method.

12 is a block diagram illustrating an embodiment of an AID designated on a page ID basis.

FIG. 13 is a block diagram illustrating an embodiment of an AID designated on a block index basis.

14 is a block diagram illustrating an embodiment of an AID designated on a sub-block index basis.

15 is a flowchart illustrating still another embodiment of a data transmission / reception method.

16 is a conceptual diagram illustrating yet another embodiment of a data transmission / reception method.

17 is a conceptual diagram illustrating another embodiment of a WLAN system including a relay device.

18 is a conceptual diagram illustrating a connection method in an uplink relay mode according to an embodiment of the present invention.

19 is a conceptual diagram illustrating another embodiment of a WLAN system including a relay device.

20 is a conceptual diagram illustrating a data transmission and reception method according to another embodiment of the present invention.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. In the following description of the present invention, the same reference numerals are used for the same elements in the drawings and redundant descriptions of the same elements will be omitted.

Throughout the specification, a station (STA) is a physical layer for medium access control (MAC) and wireless medium that conforms to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. By any functional medium that includes an interface. The station STA may be divided into a station that is an access point (AP) and a station that is a non-access point (STA). A station (STA), which is an access point (AP), may simply be called an access point (AP), and a station (STA), which is a non-AP, may simply be called a terminal.

The station STA may include a processor and a transceiver, and may further include a user interface and a display device. The processor refers to a unit designed to generate a frame to be transmitted through a wireless network or to process a frame received through the wireless network, and may perform various functions for controlling a station (STA). A transceiver is a unit that is functionally connected to a processor and is designed to transmit and receive a frame through a wireless network for a station (STA).

The access point (AP) may be a centralized controller, a base station (BS), a radio access station, a node B, an evolved node B, a relay, and a mobile MMR. multihop relay (BS) -BS, base transceiver system (BTS), or site controller, and the like, and may include some or all of their functionality.

A terminal (i.e., a non-access point) may be a wireless transmit / receive unit (WTRU), user equipment (UE), user terminal (UT), access terminal (AT), Refers to a mobile station (MS), a mobile terminal, a subscriber unit, a subscriber station (SS), a wireless device, or a mobile subscriber unit And may include some or all of the functionality thereof.

Here, the terminal may be a desktop computer, a laptop computer, a tablet PC, a wireless phone, a mobile phone, a smart phone, a smart watch capable of communication. (smart watch), smart glass, e-book reader, portable multimedia player (PMP), portable gaming device, navigation device, digital camera, digital multimedia broadcasting (DMB) player, digital voice Digital audio recorder, digital audio player, digital picture recorder, digital picture player, digital video recorder, digital video player ) May be used.

1 is a block diagram illustrating one embodiment of a station for performing methods in accordance with the present invention.

Referring to FIG. 1, the station 100 may include at least one processor 110, a memory 120, and a network interface device 130 connected to a network to perform communication. In addition, the station 100 may further include an input interface device 140, an output interface device 150, a storage device 160, and the like. Each component included in the station 100 may be connected by a bus 170 to communicate with each other.

The processor 110 may execute a program command stored in the memory 120 and / or the storage device 160. The processor 110 may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods according to the present invention are performed. The memory 120 and the storage device 160 may be configured of a volatile storage medium and / or a nonvolatile storage medium. For example, the memory 120 may be configured as read only memory (ROM) and / or random access memory (RAM).

Embodiments of the present invention are applied to a WLAN system according to IEEE 802.11, and can be applied to other communication systems as well as a WLAN system according to IEEE 802.11.

For example, embodiments of the present invention may include mobile Internet, global systems such as wireless personal area network (WPAN), wireless body area network (WBAN), wireless broadband internet (WBro) or world interoperability for microwave access (WiMax). 2G mobile networks such as for mobile communication or code division multiple access (CDMA), 3G mobile networks such as wideband code division multiple access (WCDMA) or cdma2000, high speed downlink packet access (HSDPA) or high speed uplink 3.5G mobile communication network such as packet access, 4G mobile communication network such as long term evolution (LTE) or LTE-Advanced, 5G mobile communication network and the like.

2 is a conceptual diagram illustrating an embodiment of a configuration of a wireless LAN system according to IEEE 802.11.

Referring to FIG. 2, a WLAN system according to IEEE 802.11 may include at least one basic service set (BSS). BSS means a set of stations (STA1, STA2 (AP1), STA3, STA4, STA5 (AP2), STA6, STA7, STA8) that can successfully synchronize and communicate with each other, and does not mean a specific area. .

BSS can be classified into infrastructure BSS (Independent BSS) and Independent BSS (IBSS). Here, BSS1 and BSS2 mean infrastructure BSS, and BSS3 means IBSS.

BSS1 is a distribution system connecting a first terminal STA1, a first access point STA2 (AP1) providing a distribution service, and a plurality of access points STA2 (AP1), STA5 (AP2) ( distribution system (DS). In BSS1, the first access point STA2 (AP1) may manage the first terminal STA1.

The BSS2 connects a third terminal STA3, a fourth terminal STA4, a second access point STA5 (AP2) providing a distribution service, and a plurality of access points STA2 (AP1) and STA5 (AP2). It may include a distribution system (DS). In BSS2, the second access point STA5 (AP2) may manage the third terminal STA3 and the fourth terminal STA4.

BSS3 refers to IBSS operating in ad-hoc mode. There is no access point in BSS3, which is a centralized management entity. That is, in BSS3, the terminals STA6, STA7, and STA8 are managed in a distributed manner. In BSS 3, all of the terminals STA6, STA7, and STA8 may refer to mobile terminals, and thus, are not allowed to be connected to the distribution system DS, thereby forming a self-contained network.

The access points STA2 (AP1) and STA5 (AP2) may provide access to the distributed system DS through the wireless medium for the terminals STA1, STA3, and STA4 coupled thereto. In BSS1 or BSS2, communication between terminals STA1, STA3, and STA4 is generally performed through access points STA2 (AP1) and STA5 (AP2), but when a direct link is established, the terminals ( Direct communication between STA1, STA3, and STA4 is possible.

The plurality of infrastructure BSSs may be interconnected through a distribution system (DS). A plurality of BSSs connected through a distribution system (DS) is referred to as an extended service set (ESS). The entities included in the ESS (STA1, STA2 (AP1), STA3, STA4, STA5 (AP2)) can communicate with each other, any terminal (STA1, STA3, STA4) in the same ESS while communicating seamlessly one Can move from one BSS to another BSS.

A distribution system (DS) is a mechanism for one access point to communicate with another access point, whereby the access point transmits a frame or moves to another BSS for terminals coupled to the BSS it manages. A frame may be transmitted for any terminal. In addition, the access point may transmit and receive frames with an external network such as a wired network. Such a distribution system (DS) does not necessarily need to be a network, and there is no limitation on its form as long as it can provide a predetermined distribution service defined in the IEEE 802.11 standard. For example, the distribution system may be a wireless network such as a mesh network or a physical structure that connects access points to each other.

In an intrastructure BSS, a terminal (STA) may be associated with an access point (AP). The terminal STA may transmit and receive data when connected to the access point AP.

3 is a flowchart illustrating a connection procedure of a terminal in an infrastructure BSS.

Referring to FIG. 3, a connection procedure of a STA in an infrastructure BSS is largely a probe step of detecting an access point, an authentication step with a detected access point, and an authentication procedure. It may be divided into an association step with the access point AP that performs the operation.

The STA may first detect neighboring access points (APs) using a passive scanning method or an active scanning method. When using the passive scanning method, the terminal STA may detect neighboring access points APs by overhearing the beacons transmitted by the access points APs. When using the active scanning method, the STA STA neighbors by sending a probe request frame and receiving a probe response frame which is a response to the probe request frame from the access points APs. One access point (APs) can be detected.

When the terminal STA detects neighboring APs, the terminal STA may perform an authentication step with the detected AP. In this case, the terminal STA may perform an authentication step with the plurality of access points (APs). An authentication algorithm according to the IEEE 802.11 standard may be divided into an open system algorithm for exchanging two authentication frames, a shared key algorithm for exchanging four authentication frames, and the like.

Based on the authentication algorithm according to the IEEE 802.11 standard, the STA transmits an authentication request frame and receives an authentication response frame, which is a response to the authentication request frame, from the AP. By doing so, authentication with the access point AP can be completed.

When the terminal STA completes authentication, the terminal STA may perform a connection step with the AP. In this case, the terminal STA may select one of the access points AP that has performed the authentication step with itself and may perform the connection step with the selected access point AP. That is, the STA STA transmits an association request frame to the selected access point and receives an association response frame that is a response to the association request frame from the selected access point. The connection with the selected access point may be completed.

The WLAN system refers to a local area network capable of transmitting and receiving data in a state where a plurality of communication entities in accordance with the IEEE 802.11 standard are wirelessly connected.

4 is a conceptual diagram illustrating an infrastructure BSS of a WLAN system.

Referring to FIG. 4, the infrastructure BSS may include one access point (AP) and a plurality of terminals STA1 and STA2. The AP may transmit a beacon frame including a SSID (service set ID), which is a unique identifier, in a broadcast manner. The beacon frame may provide the existence of the access point (AP) and connection information to the terminals that are not connected to the access point (AP), and the presence of data transmitted to a specific terminal to the terminals connected to the AP I can tell you.

The terminal that is not connected to the access point (AP) may detect the access point (AP) by using a passive scanning method or an active scanning method and obtain connection information from the detected access point (AP). In the case of the passive scanning method, the terminal may detect the access point (AP) by receiving a beacon frame from the access point (AP). In the case of the active scanning method, the terminal may detect the access point (AP) by transmitting a probe request frame and receiving a probe response frame, which is a response thereto, from the access point (AP).

The terminal not connected to the AP may attempt to authenticate with a specific AP based on the connection information obtained from the beacon frame or the probe response frame. After successful authentication, the terminal may transmit a connection request frame to the corresponding access point (AP), and the access point (AP) receiving the connection request frame may transmit a connection response frame including the AID of the terminal to the terminal. Through such a procedure, the terminal may be connected to an access point (AP).

5 is a block diagram illustrating an embodiment of a hierarchical AID structure.

Referring to FIG. 5, in the IEEE 802.11 standard, an AID having a hierarchical structure may be used to efficiently manage a plurality of terminals. The AID assigned to one terminal may be composed of a page ID, a block index, a sub-block index, and a terminal bit index. The group to which the UE belongs (ie, page group, block group, sub-block group) may be identified by information of each field.

FIG. 6 is a block diagram illustrating an embodiment of a structure of a traffic indication map (TIM) information element (IE).

Referring to FIG. 6, the TIM IE includes an element ID field, a length field, a DTIM count field, a DTIM period field, a bitmap control field, and a partial virtual bitmap. ) Field may be included. That is, the TIM IE includes information for indicating a bit corresponding to the AID of the terminal when data to be transmitted to the terminal is buffered in the access point, which includes a bitmap control field and a partial virtual bit. It may be encoded in a map field.

FIG. 7 is a block diagram illustrating an embodiment of a structure of a TIM encoded on a block basis.

Referring to FIG. 7, in the IEEE 802.11 standard, a TIM may be encoded in block units. One encoding block may be composed of a block control field, a block offset field, a block bitmap field, and at least one sub-block field.

The block control field may indicate an encoding mode of the TIM. That is, the block control field may indicate a block bitmap mode, a single AID mode, an OLB (offset + length + bitmap) mode, and an inverse bitmap mode. The block offset field may indicate an offset of an encoded block. The block bitmap field may mean a bitmap indicating a location of a sub-block in which an AID bit is set. The sub-block bitmap field may mean a bitmap indicating the position of the AID in the sub-block.

8 is a flowchart illustrating an embodiment of a method of transmitting and receiving data.

Referring to FIG. 8, the AP may transmit a beacon frame including a TIM IE in a broadcast manner. The terminal STA operating in the power saving mode may wake up every beacon period when the DTIM count becomes zero and receive the beacon frame. If the bit corresponding to its AID is set to 1 in the TIM included in the received beacon frame, the STA is ready to receive data by transmitting a PS-Poll frame to the AP. You can inform. When the AP receives the PS-Poll frame, the AP may transmit a data frame to the corresponding STA.

In a WLAN system, communication entities (ie, access points, terminals, etc.) share a wireless channel and compete with a wireless channel access based on a carrier sense multiple access (CSMA) / collision avoidance (CA) scheme. First, the communication entity may check the occupation state of the wireless channel by using a physical channel sensing method and a virtual channel sensing method before accessing the wireless channel.

The physical channel sensing method may be performed through channel sensing for detecting whether a certain level or more of energy exists in the wireless channel. When a certain level or more energy is detected by the physical channel sensing method, the terminal may determine that the wireless channel is already occupied by another terminal, and thus waits for a random backoff time and then returns the channel. Sensing can be performed. On the other hand, if less than a predetermined level of energy is detected by the physical channel sensing method, the terminal may determine that the wireless channel is in an idle state, thereby accessing the corresponding wireless channel and transmitting a signal.

The virtual channel sensing method may be performed by setting an estimated channel occupancy time based on a network allocation vector (NAV) timer. In the WLAN system, when a communication entity transmits a frame, the communication entity may write a time required to complete transmission of the corresponding frame in a duration field of the frame header. When the communication entity normally receives any frame through the wireless channel, the communication entity may set its own NAV timer based on the duration field value of the received frame header. If the communication entity receives a new frame before the NAV timer expires, the communication entity may update the NAV timer based on the duration field value of the received new frame header. The communication entity may determine that the radio channel occupancy is released when the NAV timer expires, and thus may compete for radio channel access.

The communication entity may support a plurality of physical layer transmission rates according to various modulation schemes and channel coding rates. In general, high physical layer transmission rates can transmit a large amount of data for short radio channel occupancy times but require high signal quality. On the other hand, a lower physical layer transmission rate can transmit data even at a lower signal quality, but requires a relatively long wireless channel occupation time.

Since wireless channel resources are shared between communication entities, the total capacity of a WLAN system may be increased by transmitting as much data as possible during a time when a specific communication entity occupies a wireless channel. That is, the total capacity of the WLAN system may be increased when the terminal transmits and receives data to and from the access point through a high physical layer transmission rate. The high physical layer transmission rate is possible when the signal quality is sufficiently secured by the distance between the access point and the terminal. Alternatively, high physical layer transmission rates are possible when the communication entity transmits signals at sufficiently high transmit power to ensure sufficient signal quality. If the terminals are located far from the access point, or if the communication entity uses limited transmission power, the physical layer transmission rate is lowered and the total capacity of the WLAN system is reduced.

In particular, when the WLAN system is applied to the sensor network, the number of sensor terminals located far from the access point may increase due to the characteristics of the sensor network supporting a wide area. In this case, there is no problem in downlink quality of the access point that can easily secure power, but a problem may occur in uplink quality of a sensor terminal designed with low power. Therefore, the sensor terminal located far from the access point uses a low uplink physical layer transmission rate in order to secure a stable uplink quality, the overall capacity of the WLAN system can be significantly reduced. In addition, when the low power terminal uses a low physical layer transmission rate, a lot of power is consumed because it needs to be awake for a longer time in transmitting the same data.

9 is a conceptual diagram illustrating an embodiment of a WLAN system including a relay device.

Referring to FIG. 9, the master access point (M (master) -AP), the first relay device R1, the second relay device R2, and the fifth terminal STA5 may include a master-basic service set mater-. basic service set (M-BSS) can be configured. The first relay device R1, the first terminal STA1, and the second terminal STA2 may configure the first relay BSS R1-BSS. The second relay device R2, the third terminal STA3, and the fourth terminal STA4 may configure a second relay BSS (R2-BSS). The relay devices R1 and R2 may be disposed at locations where signal quality between the master access point M-AP and the terminals STA1, STA2, STA3, and STA4 is degraded. The first relay device R1 may relay data transmission between the master access point (M-AP) and the first and second terminals STA1 and STA2. The second relay device R2 may relay data transmission between the master access point (M-AP) and the third and fourth terminals STA3 and STA4. That is, the physical area of the master access point (M-AP) may be extended by the relay devices (R1, R2).

10 is a block diagram showing a logical configuration of a relay device.

Referring to FIG. 10, a relay device may include a relay-terminal (R-STA) operating as a terminal for a master access point (M-AP) and a relay-access operating as an access point for an end terminal belonging to an extended area. It may consist of a point (R-AP).

The relay-terminal (R-STA) may search for the master access point (M-AP) by receiving a beacon frame or a probe response frame transmitted from the master access point (M-AP) through the same procedure as that of a normal terminal. have. Thereafter, the relay-terminal (R-STA) may sequentially perform the found main access point (M-AP), the authentication procedure, and the connection procedure.

When the relay-terminal (R-STA) is connected to the master access point (M-AP), the relay-access point (R-AP) may serve a relay BSS. That is, the relay-access point (R-AP) may transmit its own beacon frame, or may transmit a probe response frame, which is a response to the probe request frame, to an end terminal belonging to the relay BSS.

If the end terminal belonging to the relay BSS determines that it is advantageous to connect to the relay access point (R-AP) rather than the master access point (M-AP), the end-terminal belongs to the relay access point (R-AP). Can be done. On the other hand, if the terminal belonging to the relay BSS determines that it is advantageous to be connected to the main access point (M-AP) rather than the relay access point (R-AP), the authentication procedure and connection with the main access point (M-AP) The procedure can be performed.

The relay-terminal (R-STA) may relay data transmission between the master access point (M-AP) and the end terminal. In this case, the relay-terminal (R-STA) may relay data transmission using the 4-address field. The 4-address field is a destination address (DA) field indicating the final destination address of the data, a source address field (SA) indicating the address where the data is generated, and a TA (address) indicating a communication entity that physically transmits a frame including data. and a receiver address (RA) field indicating an address of a communication entity that physically receives a frame including data.

For example, when a master access point (M-AP) wants to transmit data to an end terminal via a relay device, the master access point (M-AP) may configure a header address field of a data frame as follows.

TA field: address of master access point (M-AP) (ie MAC address)

RA field: address of relay device (ie MAC address)

DA field: address of end terminal (ie MAC address)

SA field: address of master access point (M-AP) (ie MAC address)

The relay-terminal (R-STA) may transmit a data frame received from the relay-access point (R-AP) to the master access point (M-AP), and receive the received data from the master access point (M-AP). The data frame may be delivered to a relay-access point (R-AP).

When the relay-terminal (R-STA) and the main-access point (M-AP) are connected to secure a transmission path, the relay-access point (R-AP) is the same identifier as the main-access point (M-AP). The beacon frame including the SSID may be periodically transmitted. In addition, the relay-access point (R-AP) may transmit a probe response frame in response to the probe request frame of the end terminal, may transmit an authentication response frame in response to the authentication request frame of the end terminal, The connection response frame may be transmitted in response to the connection request frame of. That is, the relay-access point (R-AP) may play the same role as the master-access point (M-AP).

End terminals located in the vicinity of the relay device can be connected to the relay access point (R-AP) closer than the main access point (M-AP) to ensure a high signal quality, thereby providing data at a high physical layer transmission rate Can be transmitted.

The relay-access point (R-AP) may generate a beacon frame including an indicator indicating that the relay-access point is a communication entity relaying data transmission between the master access point (M-AP) and the end terminal. Can transmit Such an indicator may be defined using one bit in the beacon frame or may be defined using the address field of a master access point (M-AP).

The relay-access point (R-AP) may transmit a data frame to an end terminal using a 4-address field in the same manner as the relay-terminal (R-STA). Alternatively, the relay-access point (R-AP) may transmit a data frame to the end terminal using a three-address field (SA = TA, RA, DA) when the SA field and the TA field are the same. Alternatively, the relay-access point (R-AP) may transmit a data frame to the end terminal using two address fields (RA, TA). When a relay-access point (AP) receives a data frame from an end terminal through a three-address field (SA = TA, RA, DA) or a two-address field (RA, TA), the relay-access point (AP) receives the data frame from the relay-terminal ( R-STA).

11 is a flowchart illustrating another embodiment of a data transmission / reception method.

Referring to FIG. 11, the master access point (M-AP) may serve the M-BSS, and the relay device R may belong to the M-BSS. The relay device R may serve an R-BSS, and the first terminal STA1 and the second terminal STA2 may belong to the R-BSS.

When the relay device R completes an authentication process with the master access point (M-AP), the relay device R may perform an association process. That is, the relay device R may transmit a connection request frame to the master access point (M-AP) (S1100). Here, the connection request frame may include an indicator for requesting AID resource allocation for terminals belonging to the R-BSS.

When the master access point (M-AP) receives the connection request frame from the relay device (R), it may obtain an indicator included in the connection request frame, and thus, allocate an AID resource for terminals belonging to the R-BSS. You can confirm the request. Accordingly, the master access point (M-AP) may transmit a connection response frame including the reference AID used to allocate AIDs of terminals belonging to the R-BSS to the relay device R (S1110). Here, the reference AID may mean an AID of the relay device R. Meanwhile, when the AID is hierarchically configured as shown in FIG. 5 described above, the reference AID may be set in a page ID unit, a block index unit, or a sub-block index unit.

When the relay device R receives the connection response frame from the master access point (M-AP), the relay device R may include the first terminal STA1 and the second terminal (STA1) belonging to the R-BSS based on the reference AID included in the connection response frame. AID may be allocated to STA2 (S1120). For example, when the reference AID is set in units of page IDs, the relay device R is different from the first terminal STA1 and the second terminal STA2 belonging to the R-BSS within the page ID range indicated by the reference AID. AID can be assigned. When the reference AID is set in block index units, the relay device R may allocate different AIDs to the first terminal STA1 and the second terminal STA2 belonging to the R-BSS within the block index range indicated by the reference AID. Can be. When the reference AID is set in the sub-block index unit, the relay device R is different from the first terminal STA1 and the second terminal STA2 belonging to the R-BSS within the sub-block index range indicated by the reference AID. AID can be assigned.

12 is a block diagram illustrating an embodiment of an AID designated on a page ID basis.

Referring to FIG. 12, the master access point (M-AP) may designate an AID range for communication entities belonging to the R-BSS in units of page IDs. For example, the master access point (M-AP) may allocate '110 000 000 000b' as the AID of the relay device R. FIG. In this case, the relay device R may allocate an AID to terminals belonging to the R-BSS within a page ID range indicated by its AID (ie, page ID group 3 11b). That is, the relay device R may allocate an AID to terminals belonging to the R-BSS within the range of '{110 000 000 001b' to '11 11111 111 111b '. Meanwhile, the master access point (M-AP) allocates the AIDs of other communication entities (eg, relay devices, terminals, etc.) belonging to the M-BSS within page ID groups 0 to 2 (00b, 01b, and 10b). can do. Accordingly, communication entities constituting the WLAN system may be distinguished by an AID which is a unique identifier.

FIG. 13 is a block diagram illustrating an embodiment of an AID designated on a block index basis.

Referring to FIG. 13, a master access point (M-AP) may designate an AID range for communication entities belonging to an R-BSS in block index units. For example, the master access point (M-AP) may allocate '00 00001 000 000b 'as the AID of the relay device R. In this case, the relay device R may allocate an AID to terminals belonging to the R-BSS within a block index range indicated by its AID. That is, the relay device R may allocate an AID to terminals belonging to the R-BSS within a range of '00 00001 000 001b 'to '00 00001 111 111b'.

14 is a block diagram illustrating an embodiment of an AID designated on a sub-block index basis.

Referring to FIG. 14, a master access point (M-AP) may designate an AID range for communication entities belonging to an R-BSS in units of sub-block indexes. For example, the master access point (M-AP) may allocate '00 00000 001 000b 'as the AID of the relay device R. In this case, the relay device R may allocate an AID to terminals belonging to the R-BSS within a sub-block index range indicated by its AID. That is, the relay device R may allocate an AID to terminals belonging to the R-BSS within a range of '00 00000 001 001b 'to '00 00000 001 111b'.

Referring back to FIG. 11, the relay device R may transmit AID resource information allocated to terminals belonging to the R-BSS to the master access point (M-AP) (S1130). In this case, the relay device R may transmit the MAC address of the corresponding terminal to the master access point (M-AP) together with the AID resource information allocated to the terminals belonging to the R-BSS. For example, the relay device R may transmit the AID and MAC address of the first terminal STA1 to the master access point M-AP, and transmit the AID and MAC address of the second terminal STA2 to the master terminal. It can transmit to the access point (M-AP).

If there is a data frame to be transmitted to the first terminal STA1, the master access point (M-AP) may configure an address field included in the corresponding data frame as follows.

First embodiment of the address field

RA field: MAC address of relay device (R)

TA field: MAC address of master access point (M-AP)

DA field: MAC address of the first terminal STA1

SA field: MAC address of master access point (M-AP)

Second embodiment of the address field

RA field: MAC address of relay device (R)

TA field: MAC address of master access point (M-AP)

DA field: AID of first terminal STA1

SA field: MAC address of master access point (M-AP)

Third embodiment of the address field

RA field: AID of relay device R

TA field: MAC address of master access point (M-AP)

DA field: MAC address of the first terminal STA1

SA field: MAC address of master access point (M-AP)

Fourth Embodiment of Address Field

RA field: AID of relay device R

TA field: MAC address of master access point (M-AP)

DA field: AID of first terminal STA1

SA field: MAC address of master access point (M-AP)

The master access point (M-AP) may transmit a data frame including the address field configured as described above to the relay device R (S1140). When the relay device R receives the data frame from the master access point (M-AP), the relay device R may know that the final destination of the data frame is the first terminal STA1 through the address field included in the data frame. Accordingly, the relay device R may transmit a data frame to the first terminal STA1 (S1150).

Meanwhile, when the master access point (M-AP) obtains a data frame transmitted from the relay device (R) to the first terminal STA1, the master access point (M-AP) may determine that the data frame has been successfully received by the relay device (R). have. That is, the master access point (M-AP) may replace a data frame transmitted from the relay device R to the first terminal STA1 to an ACK frame for the data frame transmitted to the relay device R. have. Alternatively, the relay device R may transmit an ACK frame to the master access point (M-AP) in response to successfully receiving a data frame from the master access point (M-AP). When the first terminal STA1 successfully receives the data frame from the relay device R, the first terminal STA1 may transmit an ACK frame to the relay device R in response to the data frame (S1160).

15 is a flowchart illustrating still another embodiment of a data transmission / reception method.

Referring to FIG. 15, the master access point (M-AP) may serve the M-BSS, and the relay device R may belong to the M-BSS. The relay device R may serve an R-BSS, and the first terminal STA1 and the second terminal STA2 may belong to the R-BSS.

After the relay device R associates with the master access point (M-AP), the relay device R sends an AID resource request frame to the master access point (M-AP) to request AID resource allocation for terminals belonging to the R-BSS. (S1500). The AID resource request frame may include an indicator for requesting AID resource allocation for terminals belonging to the R-BSS and information indicating the AID resource size (or number) as shown in Table 1 below.

Table 1

When the master access point (M-AP) receives an AID resource request frame, the M-AP indicates an indicator requesting AID resource allocation for terminals belonging to the R-BSS included in the AID resource request frame and an AID resource size (or number). Information indicating can be obtained. That is, the master access point (M-AP) may check the AID resource allocation request for the UEs belonging to the R-BSS through the AID resource request frame, and may check the required AID resource size (or number). The master access point (M-AP) may generate an AID resource response frame including AID resource information for terminals belonging to the R-BSS based on the information included in the AID resource request frame, and relay the AID resource response frame. In operation S1510, the device may transmit the data to the device R.

The AID resource information for the R-BSS may be an AID range used for terminals belonging to the R-BSS. In addition, the AID resource information may be specified so as not to overlap with the AID range used for terminals belonging to the M-BSS. For example, referring to FIG. 12 described above, AID resource information may be designated in units of page IDs. In this case, the master access point (M-AP) may designate '11 00000 000 001b 'to '11 11111 111 111b' as an AID range for terminals belonging to the R-BSS. Alternatively, referring to FIG. 13 described above, AID resource information may be designated in block index units. In this case, the master access point (M-AP) may designate '00 00001 000 001b 'to '00 00001 111 111b' as an AID range for terminals belonging to the R-BSS. Alternatively, referring to FIG. 14 described above, AID resource information may be designated in a sub-block index unit. In this case, the master access point (M-AP) may designate '00 00000 001 001b 'to '00 00000 001 111b' as an AID range for terminals belonging to the R-BSS.

The AID resource response frame may include an indicator indicating allocation of AID resources for UEs belonging to the R-BSS, information indicating an AID starting point, and information indicating the size (or number) of AID resources as shown in Table 2 below. . The AID range may be defined by the AID starting point and the size (or number) of AID resources.

TABLE 2

When the relay device R receives the AID resource response frame from the master access point (M-AP), the relay device R and the first terminal STA1 belonging to the R-BSS based on the AID resource information included in the AID resource response frame are connected to each other. The AID may be allocated to the second terminal STA2 (S1520). For example, when the AID range received from the master access point (M-AP) is specified in units of page IDs, the relay device R is connected to the first terminal STA1 belonging to the R-BSS within the designated page ID range. Different AIDs may be allocated to the second terminal STA2. When the AID range received from the master access point (M-AP) is designated in units of block indexes, the relay device R may include a first terminal STA1 and a second terminal (STA1) belonging to the R-BSS within the designated block index range. Different AIDs can be allocated to STA2). When the AID range received from the master access point (M-AP) is designated in the sub-block index unit, the relay device R is connected with the first terminal STA1 belonging to the R-BSS within the designated sub-block index range. Different AIDs may be allocated to the second terminal STA2.

The relay device R may transmit AID resource information allocated to terminals belonging to the R-BSS to the master access point (M-AP) (S1530). In this case, the relay device R may transmit the MAC address of the corresponding terminal to the master access point (M-AP) together with the AID resource information allocated to the terminals belonging to the R-BSS. For example, the relay device R may transmit the AID and MAC address of the first terminal STA1 to the master access point M-AP, and transmit the AID and MAC address of the second terminal STA2 to the master terminal. It can transmit to the access point (M-AP).

 If there is a data frame to be transmitted to the first terminal STA1, the master access point (M-AP) uses the address field included in the data frame as described above in the first embodiment of the address field and the first field of the address field. Second embodiment ',' third embodiment of the address field ', or' fourth embodiment of the address field '. That is, the master access point (M-AP) may configure the DA field among the address fields included in the data frame as the AID of the first terminal STA1, and relay the RA field among the address fields included in the data frame. It can consist of AID of (R).

The master access point (M-AP) may transmit a data frame including the address field configured as described above to the relay device R (S1540). When the relay device R receives the data frame from the master access point (M-AP), the relay device R may know that the final destination of the data frame is the first terminal STA1 through the address field included in the data frame. Accordingly, the relay device R may transmit a data frame to the first terminal STA1 (S1550).

Meanwhile, when the master access point (M-AP) obtains a data frame transmitted from the relay device (R) to the first terminal STA1, the master access point (M-AP) may determine that the data frame has been successfully received by the relay device (R). have. That is, the master access point (M-AP) may replace a data frame transmitted from the relay device R to the first terminal STA1 to an ACK frame for the data frame transmitted to the relay device R. have. Alternatively, the relay device R may transmit an ACK frame to the master access point (M-AP) in response to successfully receiving a data frame from the master access point (M-AP).

When the first terminal STA1 successfully receives a data frame from the relay device R, the first terminal STA1 may transmit an ACK frame to the relay device R in response to the data frame (S1560).

16 is a conceptual diagram illustrating yet another embodiment of a data transmission / reception method.

Referring to FIG. 16, the master access point (M-AP) may serve the M-BSS, and the relay device R may belong to the M-BSS. The relay device R may serve the R-BSS, and the first terminal STA1 may belong to the R-BSS. Here, the AID of the relay device R may be allocated according to the AID allocation method described with reference to FIG. 11. The AID of the first terminal STA1 belonging to the R-BSS may be allocated according to the AID allocation method described with reference to FIG. 11 or the AID allocation method described with reference to FIG. 15.

 The master access point (M-AP) may set a bit corresponding to the AID of the first terminal STA1 of the TIM to 1 to inform the user when there is data to be transmitted to the first terminal STA1, and set the TIM. The beacon frame 1600 may be transmitted.

When the relay device R receives the beacon frame 1600 of the master access point (M-AP), the relay device R corresponds to the AID of the first terminal STA1 belonging to the R-BSS among the TIMs included in the beacon frame 1600. It can be seen that the bit is set to 1, and based on this, it can be determined that data to be transmitted to the first terminal STA1 is buffered in the master access point (M-AP). The relay device R may set a bit corresponding to the AID of the first terminal STA1 to 1 in the TIM to indicate that there is data to be transmitted to the first terminal STA1, and the beacon frame 1601 including the TIM. ) Can be sent.

When the first terminal STA1 receives the beacon frame 1601 from the relay device R, the first terminal STA1 may confirm that a bit corresponding to its own AID is set to 1 among TIMs included in the beacon frame 1601. That is, the first terminal STA1 may know that data to be transmitted to the first terminal STA1 exists. The first terminal STA1 may have a contention window according to a random backoff procedure when a channel is in an idle state during a distributed coordination function (DCFS) inter frame space (DIFS) from an end of reception of a beacon frame 1601. After the transmission, the PS-Poll frame (or trigger frame) 1602 may be transmitted to the relay device R to request data transmission. At this time, the first terminal STA1 sets the response indication deferral (RID) bit of the SIG field included in the PS-Poll frame (or trigger frame) 1602 to 'b10' to generate a PS-Poll frame (or trigger frame). After 1602, this may indicate that an ACK frame 1603, which is a normal response, is transmitted.

When the relay device R receives the PS-Poll frame (or trigger frame) 1602 from the first terminal STA1, the relay device R wakes up (ie, operates in a wake state). Response to the PS-Poll frame (or trigger frame) 1602 after a short inter frame space (SIFS) from the end of reception of the PS-Poll frame (or trigger frame) 1602. ACK frame 1603 may be transmitted. In this case, the relay device R sets the RID bit of the SIG field included in the ACK frame 1603 to 'b11' to indicate that the data frame 1604, which is a long response, is transmitted after the ACK frame 1603. Can be represented.

Meanwhile, the master access point (M-AP) cannot receive the PS-Poll frame (or trigger frame) 1602 transmitted from the first terminal STA1, but the PS-Poll frame (or trigger frame) 1602 is not received. In response to the ACK frame 1603 transmitted from the relay device (R) may be received. Accordingly, when the master access point (M-AP) receives the ACK frame 1603 transmitted from the relay device R, the master access point (M-AP) may determine that the first terminal STA1 has woken up, and accordingly, the ACK frame 1603 ), The data frame 1604 may be transmitted to the relay device R after the SIFS from the reception end time. In this case, the master access point (M-AP) may indicate that the ACK frame 1605 that is a normal response is transmitted after the data frame by setting the RID bit of the SIG field included in the data frame 1604 to 'b10'. .

When the relay device R successfully receives the data frame 1604, the relay device R receives the ACK frame 1605, which is a response to the data frame 1604 after SIFS from the reception end point of the data frame 1604, to the master access point M. -AP). In this case, the relay device R may indicate that a long response data frame 1606 is transmitted after the ACK frame 1605 by setting the RID bit of the SIG field included in the ACK frame 1605 to 'b11'. Here, the data frame 1606 may include the same information as the data frame 1604 transmitted from the master access point (M-AP).

Thereafter, the relay device R may transmit the data frame 1606 to the first terminal STA1 after SIFS from the transmission end time of the ACK frame 1605. In this case, the relay device R may indicate that the ACK frame 1607 that is a normal response is transmitted after the data frame 1606 by setting the RID bit of the SIG field included in the data frame 1606 to 'b10'. When the first terminal STA1 successfully receives the data frame 1606, the relay device R receives the ACK frame 1607 that is a response to the data frame 1606 after SIFS from the reception end time of the data frame 1606. Can be sent to. In this case, the first terminal STA1 may indicate that the frame is not transmitted after the ACK frame 1607 by setting the RID bit of the SIG field included in the ACK frame 1607 to 'b00'.

Meanwhile, the master access point (M-AP) is a relay device (R) serving R-BSS when a data frame is to be transmitted in a broadcast (or multicast) manner to terminals belonging to the R-BSS. A separate broadcast / multicast AID bit assigned to the TIM may be set. In this case, the AID assigned to the relay device R may replace the broadcast / multicast AID. The master access point (M-AP) may generate a beacon frame including the TIM in which the AID bit of the relay device R is set, and transmit the generated beacon frame. That is, the AID of the relay device R may be used as an indicator for broadcast (or multicast) transmission to terminals belonging to the R-BSS.

When the relay device R receives the beacon frame from the master access point (M-AP), the relay device R may check that its AID bit is set in the TIM included in the beacon frame, and the terminals belonging to the R-BSS are based on this. It can be seen that data to be transmitted in a broadcast (or multicast) manner is buffered in the master access point (M-AP). Accordingly, the relay device R may set the AID bits of all the terminals belonging to the R-BSS to the TIM, and generate a beacon frame including the TIM in which the AID bits of all the terminals belonging to the R-BSS are set. The beacon frame can be transmitted.

When the UEs belonging to the R-BSS receive the beacon frame from the relay device R, they can confirm that their AID bits are set in the TIM included in the beacon frame. You can see that. UEs belonging to the R-BSS may request transmission of a data frame by transmitting a PS-Poll frame (trigger frame) to the relay device (R).

When the relay device R receives the PS-Poll frame (or trigger frame) from the terminals belonging to the R-BSS, the relay device R may determine that the terminals belonging to the R-BSS have woken up, and thus the PS-Poll frame (or ACK frame may be transmitted in response to the trigger frame).

Meanwhile, the master access point (M-AP) cannot receive a PS-Poll frame (or trigger frame) transmitted from terminals belonging to the R-BSS, but relays in response to the PS-Poll frame (or trigger frame). An ACK frame transmitted from the device R may be received. Accordingly, when the master access point (M-AP) receives the ACK frame transmitted from the relay device R, the master access point (M-AP) may determine that the terminals belonging to the R-BSS have woken up, and thus the data frame is relayed to the relay device R. ) Can be sent.

When the relay device R successfully receives the data frame, the relay device R may transmit an ACK frame to the master access point (M-AP) in response to the data frame. Thereafter, the relay device R may transmit the data frame to the terminals belonging to the R-BSS in a broadcast (or multicast) manner.

17 is a conceptual diagram illustrating another embodiment of a WLAN system including a relay device.

Referring to FIG. 17, a master access point (M-AP), a first relay device R1, a second relay device R2, a first terminal STA1, a second terminal STA2, and a fourth terminal ( STA4) and the fifth terminal STA5 may configure an M-BSS. The second relay device R2, the third terminal STA3, and the fourth terminal STA4 may configure a second relay BSS (R2-BSS).

The first relay device R1 may not form its own independent relay BSS. In this case, the first relay device R1 acquires only an uplink frame transmitted by the terminals STA1 and STA2 to the master access point (M-AP) from the terminals STA1 and STA2 and receives the master access point ( M-AP). That is, the relay-access point (R-AP, see FIG. 10) function serving as an access point in the first relay device R1 may not exist or may not be used, and the relay-terminal (R-STA, FIG. 10) only a function may be used to transmit an uplink frame obtained from the terminals STA1 and STA2 to the master access point (M-AP).

Since the first relay device R1 does not form its own independent relay BSS, the first relay device R1 may not independently transmit a beacon frame or a probe response frame. Therefore, each of the terminals STA1 and STA2 may confirm the existence of the master access point (M-AP) when performing the detection procedure, but cannot confirm the existence of the first relay device R1. In addition, the first relay device R1 may not perform an authentication procedure, a connection procedure, or the like with the terminals STA1 and STA2. That is, each of the terminals STA1 and STA2 may perform an authentication procedure, a connection procedure, etc. with the master access point (M-AP).

18 is a conceptual diagram illustrating a connection method in an uplink relay mode according to an embodiment of the present invention.

Referring to FIG. 18, the master access point (M-AP) may refer to the master access point (M-AP) shown in FIG. 17, and the first relay device R1 may refer to the first relay device R1 shown in FIG. 17. 1 may refer to the relay device (R1), the first terminal STA1 may mean the first terminal STA1 shown in FIG. That is, the master access point (M-AP) may form an M-BSS. The first relay device R1 may be connected to the main access point M-AP and may not form its own independent relay BSS. The first terminal STA1 may belong to the M-BSS served by the master access point (M-AP).

The master access point (M-AP) may transmit the beacon frame 1800 in a broadcast manner. The first terminal STA1 may transmit a probe request frame 1801 to search for a neighboring access point. In this case, when the channel is in the idle state during the DIFS, the first terminal STA1 may transmit the probe request frame 1801 after the contention window according to the random backoff procedure. The probe request frame 1801 may include a field indicating whether the frame is a frame transmitted in a relay manner. For example, the first terminal STA1 may indicate that the probe request frame 1801 cannot be transmitted through any relay device by setting a field indicating whether the frame is transmitted in a relay manner to 0. In addition, the first terminal STA1 may indicate that the probe request frame 1801 may be transmitted through any relay device by setting a field indicating whether the frame is transmitted in a relay manner to 1.

The first relay device R1 may acquire the probe request frame 1801 transmitted from the first terminal STA1. When the SSID field of the probe request frame 1801 is set to the SSID or any of the master access point (M-AP), the first relay device R1 ends the reception of the probe request frame 1801. After SIFS, the probe request frame 1802 including the same information as the probe request frame 1801 may be transmitted to the master access point (M-AP).

Alternatively, the first relay device R1 may indicate that the probe request frame 1801 may be transmitted through any relay device in a field indicating whether the first relay device R1 is a frame transmitted by the relay method included in the probe request frame 1801. In this case, the probe request frame 1802 including the same information as the probe request frame 1801 may be transmitted to the master access point (M-AP) after SIFS from the reception end time of the probe request frame 1801. On the contrary, the first relay device R1 indicates that the field indicating whether the frame is transmitted by the relay method included in the probe request frame 1801 indicates that the probe request frame 1801 cannot be transmitted through any relay device. In this case, the probe request frame 1801 may not be transmitted to the master access point (M-AP).

Meanwhile, the first relay device R1 may set an address field of the probe request frame 1802 as follows.

TA field: address of first relay device (ie MAC address)

RA field: broadcast address

DA field: broadcast address

SA field: address (ie MAC address) of the first terminal

The master access point (M-AP) may not receive the probe request frame 1801 transmitted from the first terminal STA1, but may receive the probe request frame 1802 transmitted from the first relay device R1. Can be. The master access point (M-AP) is a frame transmitted from the first relay device R1 based on at least one of a field indicating whether the frame is transmitted by the relay method included in the probe request frame 1802 and an address field. It can be determined whether it is being transmitted in this relay method.

For example, when the master access point (M-AP) indicates that a field indicating whether the frame is transmitted by the relay method included in the probe request frame 1802 indicates that the frame may be transmitted through any relay device. The probe request frame 1802 may be determined to be transmitted in a relay manner. Alternatively, the master access point (M-AP) indicates that the TA field indicates the address of the first relay device R1 among the address fields included in the probe request frame 1802, and the SA field indicates the address of the first terminal STA1. If so, it may be determined that the probe request frame 1802 is being transmitted through the first relay device R1.

The master access point (M-AP) may generate a probe response frame 1803 that is a response to the probe request frames 1801 and 1802. The probe response frame 1803 may include an uplink relay mode field indicating whether to operate in an uplink relay mode. For example, when the UL relay mode field is set to 0, this may indicate that the UL relay mode field does not operate in the UL relay mode. When the uplink relay mode field is set to 1, this may indicate that the uplink relay mode field operates in the uplink relay mode. Here, the master access point (M-AP) may indicate that the primary relay access mode operates in the uplink relay mode by setting the uplink relay mode field of the probe response frame 1803 to 1.

In addition, the probe response frame 1803 may include an identifier (ie, MAC address, AID, PAID, etc.) of a relay device performing uplink relay transmission. Here, the master access point (M-AP) may generate a probe response frame 1803 including the identifier of the first relay device R1.

 The master access point (M-AP) may transmit a probe response frame 1803 including an uplink relay mode field, an identifier of the first relay device R1, and the like to the first terminal STA1. In this case, the master access point (M-AP) may transmit the probe response frame 1803 to the first terminal STA1 after SIFS from the reception end time of the probe request frame 1802.

Meanwhile, the first terminal STA1 may receive a probe response frame 1803 transmitted from the master access point (M-AP). The first terminal STA1 may acquire an uplink relay mode field included in the probe response frame 1803 and an identifier of a relay device that performs uplink relay transmission, and based on this, the master access point (M-AP) ) And the first relay device R1 operate in the uplink relay mode.

The first terminal STA1 may transmit an ACK frame 1804, which is a response to the probe response frame 1803, to the first relay device R1 after SIFS from the reception end time of the probe response frame 1803. The first relay device R1 receiving the ACK frame 1804 receives the ACK frame 1805 including the same information as the ACK frame 1804 after SIFS from the reception end time of the ACK frame 1804. -AP).

Meanwhile, since the response to the probe response frame 1803 is transmitted to the master access point (M-AP) through the first relay device R1, the master access point (M-AP) operates in the uplink relay mode. A separate relay ACK timeout may be defined for the first terminal STA1. For example, the relay ACK timeout may be set longer than an existing ACK timeout (ie, SIFS + Rx_Start_Delay + slot time) as shown in Equation 1 below. The existing ACK timeout may refer to the maximum time that the first communication entity waits to receive an ACK frame that is a response to any frame from the second communication entity after transmitting any frame to the second communication entity. .

Equation 1

Accordingly, the master access point (M-AP) receives the ACK frame 1805 which is a response to the probe response frame 1803 within the relay ACK timeout from the transmission end time of the probe response frame 1803, and then the first relay device R1. If not received from the first terminal STA1, it may be determined that the probe response frame 1803 was not successfully received. In this case, the master access point (M-AP) may retransmit the probe response frame 1803 to the first terminal STA1.

After completing the detection procedure as described above, the first terminal STA1 may perform an authentication procedure with the master access point (M-AP). The first terminal STA1 may transmit the authentication request frame 1806 to the first relay device R1 after the 'relay ACK timeout + DIFS'. The first relay device R1 receiving the authentication request frame 1806 receives an authentication request frame 1807 including the same information as the authentication request frame 1806 after SIFS from the reception end time of the authentication request frame 1806. It can transmit to the access point (M-AP). Here, each of the authentication request frames 1806 and 1807 may include an uplink relay mode field indicating whether to operate in an uplink relay mode.

The master access point (M-AP) that receives the authentication request frame (1807) removes an authentication response frame (1808) that is a response to the authentication request frame (1807) after SIFS from the reception end point of the authentication request frame (1807). It can transmit to one terminal STA1. Here, the authentication response frame 1808 may include an uplink relay mode field indicating whether to operate in an uplink relay mode.

After completing the authentication procedure as described above, the first terminal STA1 may perform a connection procedure with the master access point (M-AP). The first terminal STA1 may transmit the connection request frame 1809 to the first relay device R1 after DIFS from the reception end time of the authentication response frame 1808. The first relay device R1 receiving the connection request frame 1809 receives a connection request frame 1810 including the same information as the connection request frame 1809 after SIFS from the reception termination time of the connection request frame 1809. It can transmit to the access point (M-AP). Here, each of the connection request frames 1809 and 1810 may include an uplink relay mode field indicating whether to operate in an uplink relay mode.

After receiving the connection request frame 1810, the master access point (M-AP) may transmit the connection response frame 1811 to the first terminal STA1 after SIFS from the reception termination time of the connection request frame 1810. Here, the connection response frame 1811 may include a field indicating that the first terminal STA1 is connected to the master access point (M-AP) in an uplink relay mode, an AID of the first terminal STA1, and the like. .

The first terminal STA1 may be connected to the master access point (M-AP) through the connection procedure as described above. Next, a method of transmitting and receiving data between the master access point (M-AP) and the first terminal STA1 connected based on the uplink relay mode will be described.

19 is a conceptual diagram illustrating another embodiment of a WLAN system including a relay device.

Referring to FIG. 19, a master access point (M-AP), a first relay device R1, a second relay device R2, a first terminal STA1, a second terminal STA2, and a fourth terminal ( STA4) and the fifth terminal STA5 may configure an M-BSS. The first relay device R1, the first terminal STA1, and the second terminal STA2 may configure the first relay BSS R1-BSS. The second relay device R2, the third terminal STA3, and the fourth terminal STA4 may configure a second relay BSS (R2-BSS).

If the transmit power of the master access point (M-AP) is large enough, the frame may be transmitted through the uplink relay mode. In the uplink relay mode, in case of downlink transmission, the master access point (M-AP) may transmit a frame directly to the terminals STA1, STA2, and STA4, and in case of uplink transmission, the terminals STA1, STA2, and STA4. ) May transmit the frame to the master access point (M-AP) via the relay device (R1, R2).

All terminals connected to the relay devices R1 and R2 may operate in the uplink relay mode. Alternatively, some terminals connected to the relay devices R1 and R2 may operate in an uplink relay mode, and other terminals may operate in a general relay mode (that is, both uplink and downlink transmission through a relay). Since the first terminal STA1 and the second terminal STA2 connected to the first relay device R1 belong to the M-BSS, the first terminal STA1 and the second terminal STA2 may operate in the uplink relay mode. Since the third terminal STA3 connected to the second relay device R2 does not belong to the M-BSS, the third terminal STA3 may operate in the general relay mode instead of the uplink relay mode, and the fourth terminal connected to the second relay device R2 ( STA4) may belong to the M-BSS and thus may operate in an uplink relay mode.

Meanwhile, the start of the uplink relay mode may be started by a request of a specific terminal. For example, when the first terminal STA1 recognizes that it is located in the M-BSS, the first terminal STA1 may request the uplink relay mode operation from the first relay device R1. In this case, the first relay device R1 may inform the first terminal STA1 of the target beacon transmission time (TBTT) of the master access point (M-AP) and notify the master access point (M-AP). The first terminal STA1 may indicate that the first terminal STA1 operates in an uplink relay mode.

The master access point (M-AP) is the first terminal of the TIM included in the beacon frame to transmit data to the first terminal STA1 when the first terminal STA1 operates in an uplink relay mode. The bit corresponding to the AID of (STA1) may be set to one. The first terminal STA1 may receive a beacon frame transmitted from the master access point (M-AP) based on the TBTT of the master access point (M-AP). When the bit corresponding to its AID is set to 1 among the TIMs included in the received beacon frame, the first terminal STA1 determines that data to be transmitted to the master terminal exists in the master access point (M-AP). can do.

20 is a conceptual diagram illustrating a data transmission and reception method according to another embodiment of the present invention.

Referring to FIG. 20, the master access point (M-AP) may refer to the master access point (M-AP) shown in FIG. 19, and the first relay device R1 may refer to the first relay device R1 shown in FIG. 19. 1 may refer to a relay device (R1), the first terminal STA1 may refer to the first terminal STA1 shown in FIG. That is, the first relay device R1 may be connected to the master access point M-AP, and the first terminal STA1 may be connected to the first relay device R1. The first terminal STA1 may belong to the M-BSS served by the master access point (M-AP) and the R1-BSS served by the first relay device R. FIG.

Frame transmission and reception between the master access point (M-AP), the first relay device (R1) and the first terminal STA1 may be performed based on an uplink relay mode. In this case, if the data to be transmitted to the first terminal STA1 is buffered, the master access point M-AP may set a bit corresponding to the AID of the first terminal STA1 to 1 in the TIM, and includes the TIM. The beacon frame 2000 may be transmitted.

Since the first terminal STA1 is located in the M-BSS, the first terminal STA1 may receive the beacon frame 2000 transmitted from the master access point (M-AP). Since the bit corresponding to its AID is set to 1 among the TIMs included in the received beacon frame 2000, the first terminal STA1 buffers data to be transmitted to the master access point (M-AP). It can be judged that there is.

Accordingly, the first terminal STA1 removes the PS-Poll frame (or trigger frame) 2001 after the contention window according to the random backoff procedure when the channel is in the idle state during DIFS from the reception end time of the beacon frame 2000. 1 can be transmitted to the relay device (R1). In this case, the first terminal STA1 may set the RID bit of the SIG field included in the PS-Poll frame (or trigger frame) 2001 to 'b10' and after the PS-Poll frame (or trigger frame) 2001. It may indicate that a PS-Poll frame (or trigger frame) 2002 that is a response frame of a normal type is transmitted. Meanwhile, when the PS-Poll frame (or trigger frame) 2001 is a NDP (null data packet) type frame, the first terminal STA1 sets the RID bit of the SIG field to 'b01' so that the PS-Poll frame ( Alternatively, this may indicate that a PS-Poll frame (or trigger frame) 2002 that is an NDP type response frame is transmitted after the trigger frame) 2001. That is, any frame transmitted by the first terminal STA1 is a type of a frame transmitted by the communication entity (for example, the relay device R or the master access point M-AP) that has received the arbitrary frame. It may include a RID bit that is information indicating.

The first relay device R1 receives the PS-Poll frame (or trigger frame) 2001 from the first terminal STA1 after SIFS from the reception end time of the PS-Poll frame (or trigger frame) 2001. The PS-Poll frame (or trigger frame) 2002 may be transmitted to the master access point (M-AP). The PS-Poll frame (or trigger frame) 2002 may include the same information as the PS-Poll frame (or trigger frame) 2001 received from the first terminal STA1. In this case, the first relay device R1 may set the RID bit of the SIG field included in the PS-Poll frame (or trigger frame) 2002 to 'b11', after the PS-Poll frame (or trigger frame) 2002. This may indicate that the data frame 2003, which is a response frame of a long type, is transmitted.

When the master access point (M-AP) receives the PS-Poll frame (or trigger frame) 2002 from the first relay device R1, the first terminal STA1 may receive the frame (ie , A wake state). Accordingly, the master access point (M-AP) may transmit the data frame 2003 to the first terminal STA1 after SIFS from the reception end time of the PS-Poll frame (or trigger frame) 2002. At this time, the master access point (M-AP) sets the RID bit of the SIG field included in the data frame 2003 to 'b10', so that the ACK frame 2004 which is a normal type response frame after the data frame 2003 is present. It may indicate that this is transmitted.

On the other hand, since the response to the data frame 2003 is transmitted through the first relay device R1, the master access point (M-AP) may transmit the data frame 2003 to protect the transmission of the ACK frames 2004 and 2005. ) May be set to a duration equal to the length of the SIFS + ACK frame 2004 + the length of the SIFS + ACK frame 2005.

When the first terminal STA1 receives the data frame 2003, the first terminal STA1 receives the ACK frame 2004 that is a response to the data frame 2003 after SIFS from the reception end point of the data frame 2003. ) Can be sent. In this case, the first terminal STA1 sets the RID bit of the SIG field included in the ACK frame 2004 to 'b10' to transmit an ACK frame 2005, which is a normal response frame, after the ACK frame 2004. Can be represented.

When the first relay device R1 receives the ACK frame 2004, the first relay device R1 may transmit the ACK frame 2005 to the master access point (M-AP) after SIFS from the reception end time of the ACK frame 2004. The ACK frame 2005 may include information to be identical to the ACK frame 2004 which is a response to the data frame 2003. In this case, the first relay device R1 may indicate that the frame is not transmitted after the ACK frame 2005 by setting the RID bit of the SIG field included in the ACK frame 2005 to 'b00'. When the master access point (M-AP) receives the ACK frame 2005, the master access point (M-AP) may determine that the data frame 2003 has been successfully received at the first terminal STA1.

Meanwhile, since the response to the data frame 2003 is transmitted to the master access point (M-AP) through the first relay device R1, the master access point (M-AP) operates in the uplink relay mode. A separate relay ACK timeout may be defined for the first terminal STA1. For example, the relay ACK timeout may be set longer than the existing ACK timeout (ie, SIFS + Rx_Start_Delay + slot time) as shown in Equation 1 above. The existing ACK timeout may refer to the maximum time that the first communication entity waits to receive an ACK frame that is a response to any frame from the second communication entity after transmitting any frame to the second communication entity. .

Accordingly, the master access point (M-AP) does not receive the ACK frame 2005, which is a response to the data frame 2003, from the relay device R1 within the relay ACK timeout from the transmission end point of the data frame 2003. If not, the first terminal STA1 may determine that the data frame 2003 has not been successfully received. In this case, the master access point (M-AP) may retransmit the data frame 2003 to the first terminal STA1.

According to the present invention, the master access point may extend the service area through the relay device. Since the terminal can secure a good quality link through the relay device, the terminal can transmit data at high speed. That is, the use of the relay device can improve the use efficiency of the wireless channel and can reduce the power consumption of the terminal.

In addition, the master access point may allocate available AID resources to the relay device, and the relay device may allocate AIDs to end terminals within the AID resources allocated from the master access point. Through this, the master access point may directly manage the AID of the end terminal belonging to the R-BSS. Therefore, when the master access point transmits a data frame to the end terminal through the relay device, the AID of the end terminal can be easily set in the TIM. The relay device may easily map a reception address of the data frame in the process of transferring the data frame received from the master access point to the end terminal.

In addition, the AID of the relay device may be used as an indicator for broadcast (or multicast) transmission to end terminals belonging to the corresponding R-BSS. Accordingly, the master access point may broadcast (or multicast) a data frame to a terminal belonging to the R-BSS using the AID of the relay device.

In addition, when the master access point transmits a data frame to an end terminal through the relay device, the AID of the relay device may be used instead of the relay device's MAC address as the reception address (ie, RA field) of the data frame. The length can be reduced.

In addition, when the master access point transmits a data frame to an end terminal through a relay device, the AID of the end terminal may be used instead of the end terminal's MAC address as a receiving address (ie, a DA field) of the data frame. The length can be reduced.

In addition, according to the uplink relay mode, in the case of downlink transmission, the master access point may directly transmit a frame to the end terminal, and in the case of uplink transmission, the end terminal may transmit the frame to the master access point through the relay device. have. Therefore, when the uplink relay mode is used, radio channel resources may be used more efficiently than the general relay mode in which frames are transmitted in both directions through the relay.

Embodiments of the present invention may be implemented in the form of program instructions that may be executed by various computer means, and may be recorded in a computer readable medium. Computer-readable media may include, alone or in combination with the program instructions, data files, data structures, and the like. The program instructions recorded on the computer readable medium may be those specially designed and configured for the embodiments of the present invention, or may be known and available to those skilled in computer software.

Computer readable media may refer to hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Hardware devices may be configured to operate with at least one software module to perform operations in accordance with embodiments of the present invention, and vice versa. The program command may mean a high-level language code that can be executed in a computer based on an interpreter as well as machine code generated by a compiler.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (15)

An association method performed in a terminal, Transmitting a probe request frame; Receiving a probe response frame, which is a response to the probe request frame, from a master access point; And When it is determined to operate in an uplink relay mode based on the information included in the probe response frame, a relay connected to the master access point with an acknowledgment (ACK) frame that is a response to the probe response frame. Transmitting to the device. The method according to claim 1, The connection method, Transmitting an authentication request frame to the relay device; And Receiving an authentication response frame from the master access point that is a response to the authentication request frame. The method according to claim 1, The connection method, Transmitting an association request frame to the relay device; And Receiving an association response frame from the master access point that is a response to the association request frame. The method according to claim 1, And the probe request frame includes a field indicating whether the probe request frame is a frame transmitted in a relay manner. The method according to claim 1, And the probe response frame includes at least one of a field indicating whether to operate in an uplink relay mode and an identifier of the relay device. The method according to claim 3, The connection response frame includes a field indicating whether the terminal is connected to the master access point in an uplink relay mode. A data receiving method performed in a terminal connected to a relay device, Receiving a beacon frame from a master-access point associated with the relay device; Transmitting a power save (PS) -Poll frame to the relay device when it is determined that data to be transmitted to the terminal exists in the master access point by the beacon frame; Receiving a data frame from the master access point in response to the PS-Poll frame; And And transmitting an acknowledgment (ACK) frame that is a response to the data frame to the relay device. The method according to claim 7, The terminal, And belonging to a master-basic service set formed by said master-access point and a relay-basic service set formed by said relay device. The method according to claim 7, The arbitrary frame transmitted by the terminal includes information indicating the type of the frame transmitted by the communication entity receiving the arbitrary frame. The method according to claim 7, And the PS-Poll frame is transmitted to the master access point via the relay device. The method according to claim 7, The signal (SIG) field of the PS-Poll frame includes information indicating that a response frame of a normal type is transmitted after the PS-Poll. The method according to claim 7, The SIG field of the data frame includes information indicating that a response frame of a normal type is transmitted after the data frame. The method according to claim 7, And a period for protecting transmission of at least two ACK frames is set in a duration field of the data frame. The method according to claim 7, And the ACK frame is transmitted to the master access point via the relay device. The method according to claim 7, The SIG field of the ACK frame includes information indicating that a response frame of a normal type is transmitted after the ACK frame.

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