KR20150007255A - Method for transmitting data in wireless local area network system and apparatus therefor - Google Patents

Abstract

Disclosed are a method and an apparatus for transmitting data in a wireless LAN system. The method of transmitting data includes: setting a relay access section, to which access of a communication object included in a relay-basic service set configured by a relay apparatus is allowed; and transmitting a main-beacon frame including relay access section information and identification information of a terminal connected to the relay apparatus. As a result, a buffer overflow in the relay device can be prevented from occurring.

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for transmitting data in a wireless local area network (WLAN)

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

With the development of information and communication technology, various wireless communication technologies are being developed. Among them, a wireless local area network (WLAN) may be a personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP), a smart phone A smart phone, a tablet PC, or the like, to wirelessly connect to the Internet in a home, an enterprise, or a specific service providing area.

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

The wireless LAN 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. When using the multiple input multiple output (OFDM) and OFDM (MIMO-OFDM) spatial stream) at a transmission rate of up to 300 Mbps. According to the IEEE 802.11n standard, the wireless LAN technology can support a channel bandwidth of up to 40 MHz, which in this case can provide a transmission speed of up to 600 Mbps.

As the spread of the wireless LAN is activated and applications using the wireless LAN have been diversified, there is an increasing need for a new wireless LAN technology that supports higher throughput than the existing wireless LAN technology. Very high throughput (VHT) Wireless LAN technology is a proposed technology to support data rates of over 1Gbps. On the other hand, in a system based on the wireless LAN technology, there is a problem that the communication efficiency is lowered as the distance between the wireless LAN devices becomes longer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a data transmission method for improving efficiency of a wireless LAN system.

It is another object of the present invention to provide a data transmission apparatus for improving the efficiency of a wireless LAN system.

According to an aspect of the present invention, there is provided a communication system based on a wireless local area network (LAN), which includes a master-access point and an end terminal, .

Here, a data transmission method performed in a main access point according to an embodiment of the present invention includes: setting a relay connection interval in which a communication entity belonging to a relay-base service set included in a relay device is allowed to be connected; Beacon frame including information on the relay connection period and identifier information of a terminal connected to the relay apparatus.

Here, the main-beacon frame may include a relay traffic indication map including the identifier information of the relay apparatus and the identifier information of the terminal.

Here, the data transmission method includes the steps of: acquiring, from the relay apparatus, an ACK frame which is a response to a PS-Poll frame or a trigger frame in the relay connection section; transmitting a data frame to the relay apparatus; And obtaining a response frame for reception of the data frame from the device.

Here, the response frame may be an ACK frame.

Here, the response frame may be the data frame transmitted from the relay apparatus to the terminal.

Here, the identifier information may be an AID.

Here, the communication entity belonging to the main-basic service set constituted by the main access point may be restricted in the relay connection period.

Here, the RTIM may be part of a traffic indication map for at least one terminal connected to the main access point.

A method of transmitting data in a relay apparatus according to another embodiment of the present invention is a method of relaying data between a relay apparatus and a relay apparatus, Generating a relay-beacon frame including information on an identifier of the terminal based on the received information and information on a connection interval in which the terminal is allowed to access; and transmitting the relay- .

Here, the data transmission method may include receiving a PS-Poll frame or a trigger frame from the terminal that has received the relay-beacon frame in a connection interval in which the connection of the terminal is allowed, The method comprising: transmitting an ACK frame to the terminal in response to the data frame; receiving a data frame from the main access point; transmitting the data frame to the terminal; And receiving the frame.

Herein, the step of transmitting the data frame to the terminal may transmit the data frame to the terminal after transmitting an ACK frame, which is a response to the reception of the data frame, to the main access point.

Here, the identifier information may be an AID.

Here, the communication entity belonging to the main-basic service set constituted by the main access point may be restricted in the relay connection period.

Here, a connection interval in which the connection of the terminal is allowed may be set within the relay connection interval.

Here, the communication entity other than the terminal indicated by the identifier information of the terminal among the communication entities belonging to the R-BSS can be restricted in the connection period in which the terminal is allowed to access.

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

1 is a block diagram illustrating one embodiment of a station performing methods in accordance with the present invention.
2 is a conceptual diagram showing 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 showing an infrastructure BSS of a wireless LAN system.
5 is a block diagram illustrating an embodiment of a hierarchical AID structure.
6 is a block diagram illustrating an embodiment of a structure of a TIM information element (IE).
7 is a block diagram illustrating an embodiment of a structure of a TIM encoded on a block basis.
8 is a flowchart showing an embodiment of a data transmission / reception process.
9 is a conceptual diagram showing a wireless LAN system including a relay apparatus.
10 is a block diagram showing a logical configuration of a relay apparatus.
11 is a conceptual diagram showing a scheduling method based on a limited connection window.
12 is a conceptual diagram illustrating a continuous RAW-based scheduling method.
13 is a conceptual diagram showing a data transmission method in a wireless LAN system including a relay apparatus.
14 is a flowchart illustrating a data transmission procedure in a wireless LAN system including a relay apparatus according to an embodiment of the present invention.
15 is a conceptual diagram illustrating a data transmission procedure in a wireless LAN system including a relay apparatus according to an embodiment of the present invention.
16 is a conceptual diagram illustrating the configuration of RTIM according to an embodiment of the present invention.
FIG. 17 is a conceptual diagram illustrating an embodiment of an RPS including information on relay connection intervals. FIG.
18 is a conceptual diagram showing another embodiment of the RPS including the information of the relay connection period.
19 is a conceptual diagram illustrating a data transmission method in a wireless LAN system including a relay apparatus according to another embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. 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 a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations 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 to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

Throughout the specification, a station is a physical layer for medium access control (MAC) and a medium access control (MAC) compliant with the IEEE 802.11 standard. Means any functional medium including an interface. A station (STA) can be divided into a station (STA) which is an access point (AP) and a station (STA) which is a non-AP. A station (STA), which is an access point (AP), may be referred to simply as an access point (AP), and a station (STA) that is a non-AP may be simply referred to as a terminal.

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

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

A terminal (i.e., a non-access point) may comprise a wireless transmit / receive unit (WTRU), user equipment (UE), a user terminal (UT), an access terminal 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 their functions.

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, such as a smart watch, a smart glass, an e-book reader, a portable multimedia player (PMP), a portable game machine, a navigation device, a digital camera, a digital multimedia broadcasting (DMB) A digital audio recorder, a digital audio player, a digital picture recorder, a digital picture player, a digital video recorder, a digital video player ) And the like.

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

Referring to FIG. 1, a station 10 may include at least one processor 11, a memory 12, and a network interface device 13 connected to and performing communication with the network 20. The station 10 may further include an input interface device 14, an output interface device 15, a storage device 16, and the like. Each of the configurations included in the station 10 may be connected by a bus 17 and communicate with each other.

The processor 11 may execute program instructions stored in the memory 12 and / or the storage 16. The processor 11 may be a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which the methods according to the present invention are performed. The memory 12 and the storage device 16 may be composed of a volatile storage medium and / or a non-volatile storage medium. For example, the memory 12 may be comprised of read only memory (ROM) and / or random access memory (RAM).

The embodiments of the present invention are applied to a wireless LAN system according to IEEE 802.11, and can be applied to other communication systems as well as a wireless LAN system according to IEEE 802.11.

For example, embodiments of the present invention may be implemented in a portable Internet such as a wireless personal area network (WPAN), a wireless body area network (WBAN), a wireless broadband internet (WiBro) or a world interoperability for microwave access (WiMax) a 3G mobile communication network such as wideband code division multiple access (WCDMA) or cdma2000, a high speed downlink packet access (HSDPA) or a high speed uplink (HSUPA) a 3.5G mobile communication network such as a packet access, a 4G mobile communication network such as LTE (Long Term Evolution) or LTE-Advanced, and a 5G mobile communication network.

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

Referring to FIG. 2, a wireless LAN system according to IEEE 802.11 may include at least one basic service set (BSS). BSS stands for a set of stations (STA 1, STA 2 (AP 1), STA 3, STA 4, STA 5 (AP 2), STA 6, STA 7, STA 8) And is not a concept of a specific area.

The BSS can be divided into an infrastructure BSS (infrastructure BSS) and an independent BSS (IBSS). Here, BSS 1 and BSS 2 denote an infrastructure BSS, and BSS 3 denotes an IBSS.

The BSS 1 includes a first STA 1, a first access point STA 2 (AP 1) providing a distribution service and a plurality of access points STA 2 (AP 1), STA 5 (AP 2) ), ≪ / RTI > In the BSS 1, the first access point STA 2 (AP 1) can manage the first STA 1.

The BSS 2 includes a third terminal STA 3, a fourth terminal STA 4, a second access point STA 5 (AP 2) for providing a distribution service and a plurality of access points STA 2 (AP 1) 5 (AP 2)). ≪ / RTI > The second access point STA 5 (AP 2) in the BSS 2 can manage the third terminal STA 3 and the fourth terminal STA 4.

BSS 3 means an IBSS operating in an ad-hoc mode. In BSS 3, there is no access point, which is a centralized management entity. That is, the terminals STA 6, STA 7 and STA 8 in BSS 3 are managed in a distributed manner. In BSS 3, all terminals (STA 6, STA 7, STA 8) can be referred to as a mobile terminal, and a self-contained network is achieved because a connection is not permitted to a distribution system (DS).

The access points STA 2 (AP 1) and STA 5 (AP 2) provide a connection to the distributed system (DS) over the wireless medium for the terminal (STA 1, STA 3, STA 4) . The communication between the terminals STA 1, STA 3 and STA 4 in the BSS 1 or BSS 2 is generally performed through the access points STA 2 (AP 1) and STA 5 (AP 2) link is established, direct communication between the terminals STA 1, STA 3 and STA 4 is possible.

A plurality of infrastructure BSSs may be interconnected via a distribution system (DS). A plurality of BSSs connected through a distribution system (DS) is referred to as an extended service set (ESS). (STA 1, STA 2 (AP 1), STA 3, STA 4, STA 5 (AP 2)) included in the ESS can communicate with each other. , STA 4) can move from one BSS to another while seamlessly communicating.

The distribution system DS is a mechanism by which one access point communicates with another access point, whereby the access point transmits a frame for terminals coupled to the BSS it manages, or moves to another BSS A frame can be transmitted for an arbitrary terminal. The access point can also transmit and receive frames to and from an external network, such as a wired network. Such a distribution system (DS) does not necessarily have to be a network, and there is no restriction on the form if 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 may be a physical structure that connects the access points to each other.

In an intra-architecture BSS, a terminal (STA) may be associated with an access point (AP). The terminal STA can transmit and receive data when it is connected to an access point (AP).

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

Referring to FIG. 3, the connection procedure of the STA in the infrastructure BSS includes a probe step for detecting an access point (AP), an authentication step for a detected access point (AP) And an association step with an access point (AP) that has performed the association process.

The terminal STA may first detect neighboring APs using a passive scanning method or an active scanning method. When the passive scanning method is used, the terminal STA can detect neighboring access points APs by overhearing the beacons transmitted by the access points APs. When using the active scanning method, the terminal STA transmits a probe request frame and receives a probe response frame, which is a response to the probe request frame from the access points APs, It can detect one of the access points APs.

The terminal STA may perform an authentication step with a detected access point (AP) when it detects neighboring access points (APs). In this case, the terminal STA can perform the authentication step with a plurality of access points APs. The authentication algorithm according to the IEEE 802.11 standard can be classified 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 terminal (STA) transmits an authentication request frame and receives an authentication response frame, which is a response to the authentication request frame, from the access point (AP) The authentication with the access point (AP) can be completed.

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

The WLAN system refers to a local area network in which a plurality of communication objects according to the IEEE 802.11 standard are wirelessly connected to and receive data.

4 is a conceptual diagram showing an infrastructure BSS of a wireless LAN system.

Referring to FIG. 4, an infrastructure BSS may include one access point (AP) and a plurality of terminals STA 1 and STA 2. An access point (AP) can transmit a beacon frame including a service set ID (SSID), which is a unique identifier, in a broadcast manner. The beacon frame can provide existence of an access point (AP) and connection information to terminals that are not connected to an access point (AP), and can notify the terminals connected to the access point (AP) You can tell.

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

A terminal that is not connected to an access point (AP) may attempt authentication with a specific access point (AP) based on connection information obtained from a beacon frame or a probe response frame. A terminal that has succeeded in authentication can transmit a connection request frame to a corresponding access point (AP), and an access point (AP) receiving a connection request frame can transmit a connection response frame including an association ID (AID) of the terminal to the terminal . Through such a procedure, the terminal can 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 can 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 index (STA index). A group to which a terminal belongs (i.e., a page group, a block group, and a sub-block group) can be identified by the information of each field.

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, a partial virtual bitmap Field. ≪ / RTI > That is, when the data to be transmitted to the terminal is buffered in the access point, the TIM IE includes information for displaying a bit corresponding to the AID of the corresponding terminal, And may be encoded into a map field.

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

Referring to FIG. 7, the TIM in the IEEE 802.11 standard can be encoded on a block-by-block basis. 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 the encoding mode of the TIM. That is, the block control field may represent a block bitmap mode, a single AID mode, an OLB (offset + length + bitmap) mode, or an inverse bitmap mode. The block offset field may indicate the offset of the encoded block. The block bitmap field may refer to a bitmap indicating the position of the sub-block where the AID bit is set. The sub-block bitmap field may refer to a bitmap that indicates the location of the AID within the sub-block.

8 is a flowchart showing an embodiment of a data transmission / reception process.

Referring to FIG. 8, an access point (AP) may transmit a beacon frame including a TIM IE in a broadcast manner. A terminal (STA) operating in the power saving mode can awaken every beacon period in which the DTIM count becomes zero, and can receive a beacon frame. When the bit corresponding to its AID is set to 1 in the TIM included in the received beacon frame, the terminal STA transmits the PS-Poll frame (or trigger frame) to the access point (AP) You can tell that you are ready. When the access point AP receives the PS-Poll frame (or the trigger frame), the access point AP can transmit the data frame to the corresponding STA.

In a wireless LAN system, communication entities (i.e., access points, terminals, etc.) share a wireless channel and compete for wireless channel access based on a carrier sense multiple access (CSMA) / collision avoidance (CA) scheme. First, the communication entity can confirm 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 scheme can be achieved through channel sensing to detect if there is more than a certain level of energy in the wireless channel. If a certain level of energy is detected by the physical channel sensing method, the terminal can determine that the wireless channel is already occupied by another terminal, and accordingly wait for a random backoff time, Sensing can be performed. On the other hand, when energy less than a predetermined level is detected by the physical channel sensing method, the terminal can determine that the wireless channel is in an idle state, and can transmit signals by accessing the corresponding wireless channel.

The virtual channel sensing method can be performed by setting a channel occupancy estimation time based on a network allocation vector (NAV) timer. In the wireless LAN system, when a frame is transmitted, the communication entity can write the time required to complete the transmission of the frame in the duration field of the frame header. The communication entity can set its own NAV timer based on the duration field value of the received frame header when a certain frame is normally received through the wireless channel. The communication entity may update the NAV timer based on the duration field value of the received new frame header when the NAV timer has received a new frame before expiration. The communication entity can determine that the occupation of the wireless channel is released when the NAV timer expires, and thus can compete with the wireless channel access.

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

Since the radio channel resources are shared between communication entities, the total capacity of the WLAN system can be increased by transmitting as much data as possible during a time period occupied by a specific communication entity. That is, the total capacity of the WLAN system can be increased when the UE transmits / receives data to / from the access point through a high-speed physical layer transmission rate. The high-speed physical layer transmission rate is possible when the distance between the access point and the terminal is short and the signal quality is sufficiently secured. If the terminals are located far away from the access point, the physical layer transmission speed is lowered and the overall capacity of the WLAN system is reduced.

In a wireless LAN system that provides communication services to a plurality of sensor terminals located over a wide area, it is possible that data can not be transmitted to the entire area only by signal output of one access point. That is, a sensor terminal that does not support the communication service may be generated. On the other hand, since the low-power sensor terminal has a low signal output, the area in which the uplink data can be transmitted in the wireless LAN system can be narrowed.

In particular, a terminal located at a coverage boundary of an access point performs communication with an access point using a low physical layer transmission rate because of poor signal quality. Therefore, the total capacity of the wireless LAN system is seriously reduced. In addition, when a low power terminal uses a low physical layer transmission rate, much power is consumed because the same data must be awake for a longer time in transmitting the same data.

9 is a conceptual diagram showing a wireless LAN system including a relay apparatus.

9, the master-access point M (master) -AP, the first relay device R1, the second relay device R2 and the fifth terminal STA 5 constitute a master BSS can do. The first relay device R1, the first terminal STA1 and the second terminal STA2 may constitute a first relay BSS. The second relay device R2, the third terminal STA3 and the fourth terminal STA4 may constitute a second relay BSS. The relay apparatuses R1 and R2 can be disposed at positions where the signal quality between the main access point M-AP and the terminals STA1, STA2, STA3 and STA4 is degraded. The first relay device R1 can relay data transmission between the primary access point (M-AP) and the first and second terminals STA1 and STA2. The second relay apparatus R2 can relay data transmission between the main access point (M-AP) and the third and fourth terminals (STA3, STA4). That is, the physical area of the primary access point (M-AP) may be extended by relay devices R1, R2.

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

10, the relay apparatus includes a relay-terminal (R-STA) acting as a terminal to a main-access point (M-AP), a relay-access point R-AP).

The relay-terminal (R-STA) can search for a primary-access point (M-AP) by receiving a beacon frame or a probe response frame transmitted from the primary-access point (M-AP) have. After that, the relay-terminal (R-STA) can sequentially perform the authentication procedure and connection procedure with the searched main-access point (M-AP).

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

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

- DA field: address of end terminal

- SA field: Note - The address of the access point (M-AP)

- TA field: Note - The address of the access point (M-AP)

- RA field: address of the relay device

The relay-terminal (R-STA) can forward the data frame received from the relay-access point (R-AP) to the main-access point (M-AP) Data frame to the relay-access point (R-AP).

When a relay-terminal (R-STA) and a main-access point (M-AP) are connected and a transmission path is ensured, the relay-access point (R- (SSID) of the beacon frame periodically. The relay-access point (R-AP) can transmit the probe response frame in response to the probe request frame of the end terminal, transmit the 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. That is, the relay-access point (R-AP) may perform the same role as the primary-access point (M-AP).

An end terminal located in the periphery of the relay device may be connected to a relay-access point (R-AP) closer to the primary-access point (M-AP) to ensure high signal quality, Data can be transmitted.

The relay-access point (R-AP) may generate a beacon frame including an indicator informing that it is a communication entity relaying data transmission between the main-access point (M-AP) and the end terminal, Lt; / RTI > Such an indicator may be defined using a bit in the beacon frame or may be defined using the address field of the primary-access point (M-AP).

The relay-access point (R-AP) can transmit the data frame using the 4-address field in the same manner as the relay-terminal (R-STA). Alternatively, the relay-access point (R-AP) may transmit the data frame using the 3-address field (SA = TA, RA, DA) if the SA field and the TA field are the same.

11 is a conceptual diagram showing a scheduling method based on a restricted access window (RAW).

Referring to FIG. 11, an access point can generate a beacon including RPS (Raw Parameter Set) information for scheduling of a UE. The RPS includes a same group indication field, a PRAW (periodic RAW) indication field, a page ID field, a RAW start AID field, a RAW end AID field, a RAW start time, Field, a RAW duration field, an access restricted to paged STA only field, a group / resource allocation frame indication field, a sounding RAW field, A slot definition field, and the like. In addition, the RPS may further include a hidden node detecting RAW field, a hidden node reporting RAW field, and the like.

The access point can define the RAW period from the RAW start time to the RAW period and allow the channel access to the terminal group specified between the RAW start AID and the RAW end AID within the page ID. The access point can divide the RAW section into a plurality of time slots according to the slot definition field, and allocate the terminals belonging to the group designated by the RAW to each time slot.

One time slot has a certain length, and at least one terminal can be allocated to one time slot. A method of allocating a terminal to a time slot may be separately defined in a slot definition field or may be used to allow a terminal to self-guess according to a predetermined rule using AID location information of the terminal.

12 is a conceptual diagram illustrating a continuous RAW-based scheduling method.

Referring to FIG. 12, an access point may generate a beacon including a plurality of RPSs (i.e., RPS 1 and RPS 2). That is, the access point can set a continuous RAW section using RPS 1 and RPS 2. In this case, the access point can indicate that the terminal group of the RPS 2 is the same as the terminal group specified by the previous RPS 1 using the same group indication field included in the RPS 2, through which the RAW start AID, the RAW end AID Can generate the omitted RPS 2.

The group / resource allocation frame indication field may indicate to receive a group / resource allocation frame (i.e., an RA frame) indicating a separate time slot allocation information at the beginning of the RAW interval. Through the RAW setting method, the access point can assign a time slot for transmission of a PS-Poll frame (or a trigger frame) to a terminal in the RAW 1 section, and transmit the PS- A time slot can be allocated only to a terminal that transmitted a Poll frame (or a trigger frame).

As described above, when terminals are scheduled to access a channel within a certain time slot, terminals simultaneously accessing the channel immediately after reception of the beacon frame are temporally dispersed, thereby alleviating the channel access competition and the frame collision problem .

13 is a conceptual diagram showing a data transmission method in a wireless LAN system including a relay apparatus.

13, the M-AP and the relay apparatus R may constitute an M-BSS and the relay apparatus R and the first terminal STA 1 may form a relay (R- BSS can be configured. When there is data to be transmitted to the first terminal STA 1 (that is, when data for the first terminal STA 1 is buffered), the access point M- A TIM including the AID information of the connected relay apparatus R can be generated. That is, the main access point (M-AP) can set the bit corresponding to the AID of the relay apparatus (R) in the TIM to one. Note - The access point (M-AP) may generate a master-beacon frame containing the TIM and may transmit the generated main-beacon frame in a broadcast manner.

Note - The relay apparatus R that has received the beacon frame transmits its own AID information to the TIM of the main-beacon frame (i.e., when the bit corresponding to its own AID is set to 1 in TIM) It can be confirmed that the data is buffered in the main access point (M-AP). The relay apparatus R can request transmission of data by transmitting a PS-Poll frame (or trigger frame) to the main-access point (M-AP). When receiving a PS-Poll frame (or a trigger frame), the access point M-AP may transmit an ACK frame to the relay apparatus R in response thereto, Lt; / RTI > The relay apparatus R can transmit an ACK frame to the main access point (M-AP) in response to the successful reception of the data frame. On the other hand, since the relay apparatus R generally operates in a wake state, the transmission process of the PS-Poll frame (or the trigger frame) can be omitted. That is, the main access point (M-AP) may transmit the data frame to the relay apparatus R after a predetermined time (for example, SIFS, etc.) has elapsed after transmitting the beacon frame.

The relay apparatus R generates a TIM including the AID information of the first terminal STA 1 when the data frame received from the main access point M-AP is a data frame to be transmitted to the first terminal STA 1 can do. That is, the relay apparatus R can set the bit corresponding to the AID of the first terminal STA 1 among the TIMs to one. The relay apparatus R may transmit the relay-beacon frame including the generated TIM in a broadcast manner.

Upon receiving the relay-beacon frame, the first STA1 transmits its own AID information to the TIM of the relay-beacon frame (i.e., when the bit corresponding to its own AID is set to 1 in the TIM) It can be confirmed that the data to be transmitted is buffered in the relay apparatus R. The first terminal STA 1 may request transmission of a data frame by transmitting a PS-Poll frame (or a trigger frame) to the relay apparatus R. [

The relay apparatus R can transmit an ACK frame to the first terminal STA 1 in response to receiving the PS-Poll frame (or trigger frame), and then transmit the data frame to the first terminal STA 1, Lt; / RTI > The first terminal STA 1 may transmit an ACK frame to the relay apparatus R in response to the successful reception of the data frame.

Meanwhile, the first terminal STA1 connected to the relay apparatus R may operate in a power saving mode. Therefore, when the first terminal STA 1 is in a doze state, the relay apparatus R can not transmit the data frame directly to the first terminal STA 1, so that the transmission of the data frame is delayed, An overflow may occur in the buffer of the relay apparatus R. [ In this case, the relay apparatus R can inform the main access point (M-AP) that it can no longer receive the data frame. For example, the relay device R may generate an empty data frame with the power saving state mode bit of the control field set to 1 and send the generated empty data frame to the primary-access point (M-AP) An abnormal data frame can not be received.

Generally, when the power saving state mode bit of the control field included in the frame is set to 1, it means that the communication entity that transmitted the frame transits to the doze state. Since the relay apparatus R always operates in the wake state, the main access point M-AP receives the frame with the power saving state mode bit set to 1 from the relay apparatus R, It can be determined that there is no remaining space in the buffer. The relay device R transmits the data frame by transmitting the PS-Poll frame (or an empty data frame with the power saving state mode bit set to 0) to the main-access point (M-AP) .

FIG. 14 is a flowchart illustrating a data transmission procedure in a wireless LAN system including a relay apparatus according to an embodiment of the present invention. FIG. 15 is a flowchart illustrating a data transmission procedure in a wireless LAN system including a relay apparatus according to an embodiment of the present invention. Fig.

14 and 15, the main access point M-AP, the relay apparatus R and the second terminal STA 2 can constitute the M-BSS, and the relay apparatus R and the first The terminal STA 1 can configure the R-BSS.

When the data to be transmitted to the first terminal STA 1 exists (i.e., the data for the first terminal STA 1 is buffered), the access point M- And a relay traffic indication map (RTIM) including the identifier information of the relay apparatus R connected to the first terminal STA 1 and the identifier information of the relay apparatus R connected to the first terminal STA 1. The RTIM may be part of a TIM for at least one terminal connected to the primary access point.

16 is a conceptual diagram illustrating the configuration of RTIM according to an embodiment of the present invention.

Referring to FIG. 16, the RTIM may include identifier information of a relay apparatus and identifier information of a terminal connected to a relay apparatus. Here, the identifier information of the relay apparatus can mean AID of the relay apparatus, and the identifier information of the terminal can mean the AID of the terminal. The AID of the relay device may refer to a value derived from the AID or AID assigned by the primary-access point. In addition to the AID of the relay device, a value derived from the MAC address or MAC address of the relay device may be included in the RTIM. The AID of the terminal may be a value derived from the AID or AID assigned by the relay device. In addition to the AID of the terminal, a value derived from the MAC address or MAC address of the terminal may be included in the RTIM. Here, the RTIM may include AID information of a plurality of relay apparatuses and AID information of at least one terminal connected to each relay apparatus.

Referring again to FIG. 14 and FIG. 15, the main access point (M-AP) can set a relay connection period in which connection of a communication entity belonging to the R-BSS constituted by the relay apparatus R is permitted. NOTE - A communication entity belonging to an M-BSS constituted by an access point (M-AP) may restrict channel access in a relay access period. Note - The access point (M-AP) may generate a primary-beacon frame containing information of the RTIM and relay connection interval. Here, the information on the relay connection interval may be included in the RPS of the main-beacon frame.

FIG. 17 is a conceptual diagram illustrating an embodiment of an RPS including information on relay connection intervals. FIG.

Referring to FIG. 17, the RPS may include a relay connection interval indication field, a RAW start time field, a RAW duration field, and the like. The Relay Connection Area Indication field may indicate that a relay connection interval in which a communication entity belonging to the R-BSS is allowed to be established is set. The RAW start time field may indicate the time duration of the relay connection period. The RAW duration field can indicate the duration of the relay connection interval.

18 is a conceptual diagram showing another embodiment of the RPS including the information of the relay connection period.

Referring to FIG. 18, the RPS may include information on a relay connection interval for a plurality of relay devices (i.e., a plurality of R-BSSs). The RPS includes a relay connection section indication field, a same group indication field, a PRAW indication field, a page ID field, a RAW start AID (relay AID) field, a RAW termination AID (relay AID) field, a RAW start time field, A restricted access field for the STA, a group / resource allocation frame indication field, a sounding RAW field, a slot definition field, and the like.

The Relay Connection Area Indication field may indicate that a relay connection interval in which a communication entity belonging to the R-BSS is allowed to be established is set. The page ID field, the RAW start AID (relay AID) field, and the RAW end AID (relay AID) field may indicate a specific R-BSS that is allowed to access the channel in the relay access period. The RAW start time field may indicate the time duration of the relay connection period. The RAW duration field can indicate the duration of the relay connection interval. The slot definition field may indicate a relay connection interval mapped in units of time slots for each R-BSS.

14 and 15, the main access point (M-AP) may transmit the main-beacon frame including the RTIM and the RPS in a broadcast manner (SlOO). The second terminal STA 2 belonging to the M-BSS can know that the channel connection is restricted in the relay connection interval indicated by the RPS when the main-beacon frame is received. Therefore, the second terminal STA 2 may not perform the channel connection in the relay connection interval indicated by the RPS.

On the other hand, when the relay apparatus R receives the main-beacon frame, it can know that the data to be transmitted to the first terminal STA 1 through the RTIM is buffered in the main-access point (M-AP) It is found that a relay connection section in which a communication entity belonging to the R-BSS constituting itself is allowed to access is established. Therefore, the relay apparatus R can generate a TIM including the identifier information (i.e., AID) of the first terminal STA 1 to notify the first terminal STA 1 that data is buffered.

The relay apparatus R can set an end terminal connection interval in which the channel connection of the first terminal STA 1 indicated by the RTIM is allowed. The relay apparatus R may generate a relay-beacon frame including information of a TIM and an end-terminal connection interval. The information of the end terminal connection section may be included in the RPS of the relay-beacon frame. That is, the RPS of the relay-beacon frame may include an end terminal connection interval indication field, a RAW start time field, a RAW duration field, and the like. Here, the end terminal connection interval indication field may indicate that an end terminal connection interval in which an end terminal can be connected is set. The RAW start time field may indicate the time duration of the end terminal connection section. The RAW duration field may indicate the duration of the end terminal connection section.

In addition, the RPS of the relay-beacon frame may include information of an end terminal connection interval for a plurality of end terminals. The RPS includes an end terminal termination indication field, a same group indication field, a PRAW indication field, a page ID field, a RAW start AID (end terminal terminal AID) field, a RAW termination AID (terminal terminal AID) Field, a restricted access field for paged STA, a group / resource allocation frame indication field, a sounding RAW field, a slot definition field, and the like. Here, the end terminal connection interval indication field may indicate that an end terminal connection interval in which an end terminal can be connected is set. A page ID field, a RAW start AID field, and a RAW end AID field may indicate a specific end terminal to which a channel connection is allowed in an end terminal access section. The RAW start time field may indicate the time duration of the end terminal connection section. The RAW duration field may indicate the duration of the end terminal connection section. The slot definition field may indicate an end terminal connection interval mapped in units of time slots for each end terminal.

The relay apparatus R can transmit the relay-beacon frame in the relay connection period in a broadcast manner (S110). The first terminal STA1 receiving the relay-beacon frame can know that the data to be transmitted to the first terminal STA1 through the TIM included in the relay-beacon frame is buffered, It can be seen that an end terminal connection section permitting connection of the terminal (i.e., the first terminal STA 1) is set.

Accordingly, the first terminal STA 1 may request the transmission of data by transmitting a PS-Poll frame (or a trigger frame) to the relay apparatus R in an end terminal connection interval (S 120). At this time, the first STA 1 sets the ACK indication bit of the SIG field included in the PS-Poll frame (or the trigger frame) to 'b00' Frame may be transmitted.

The relay apparatus R can determine that the first terminal STA 1 is woken up when the PS-Poll frame (or the trigger frame) is received and accordingly the PS-Poll frame (or the trigger frame) (STA1) in response to the ACK frame (S130). At this time, the relay apparatus R can indicate that the data frame is transmitted after the ACK frame by setting the ACK indication bit of the SIG field included in the ACK frame to 'b11'.

On the other hand, the main access point (M-AP) can not receive the PS-Poll frame (or trigger frame) transmitted from the first terminal STA 1, An ACK frame transmitted from the device R can be obtained. Therefore, when the ACK frame received from the relay apparatus R is acquired, the primary access point M-AP can determine that the first terminal STA 1 is awake, and accordingly, the relay access period (or, End terminal connection section) to the relay apparatus R (S140). At this time, the main access point (M-AP) may indicate that the ACK frame is transmitted after the data frame by setting the ACK indication field of the SIG field included in the data frame to 'b00'.

When the relay apparatus R successfully receives the data frame, the relay apparatus R may transmit the ACK frame to the M-AP in response to the data frame in the end terminal access interval (S150). At this time, the relay apparatus R may indicate that the data frame is transmitted after the ACK frame by setting the ACK indication field of the SIG field included in the ACK frame to 'b11'.

Thereafter, the relay apparatus R may transmit the data frame to the first terminal STA 1 in the terminal terminal connection interval (S 160). At this time, the relay apparatus R can indicate that the ACK frame is transmitted after the data frame by setting the ACK indication field of the SIG field included in the data frame to 'b00'. If the first terminal STA1 successfully receives the data frame, the first terminal STA1 may transmit the ACK frame to the relay apparatus R in the terminal terminal connection interval (S170). At this time, the first STA1 may indicate that the frame is not transmitted after the ACK frame by setting the ACK indication field of the SIG field included in the ACK frame to 'b10'.

19 is a conceptual diagram illustrating a data transmission method in a wireless LAN system including a relay apparatus according to another embodiment of the present invention.

19, the main access point M-AP, the relay apparatus R and the second terminal STA 2 can constitute an M-BSS, and the relay apparatus R and the first terminal STA 1) may constitute an R-BSS. Here, a transmission procedure of the main-beacon frame including the RTIM and the RPS performed in the main access point (M-AP), a transmission procedure of the relay-beacon frame including the TIM and the RPS performed in the relay apparatus (R) A transmission procedure of a PS-Poll frame (or a trigger frame) performed in the terminal STA 1 and a procedure of transmitting an ACK frame in response to a PS-Poll frame (or a trigger frame) performed in the relay apparatus R 14 and Fig. 15, respectively.

Note - The access point (M-AP) can determine that the first terminal (STA 1) has awakened when an ACK frame, which is a response to the PS-Poll frame (or trigger frame), is acquired from the relay apparatus . Thus, the primary access point (M-AP) may transmit the buffered data frame for the first terminal STA 1 to the relay apparatus R at the relay connection interval (or end terminal connection interval). At this time, the main access point (M-AP) may indicate that the data frame is transmitted after the data frame by setting the ACK indication field of the SIG field included in the data frame to 'b11'.

Note that the relay apparatus R successfully receiving the data frame from the access point (M-AP) transmits the data frame to the end terminal (M-AP) without transmitting the ACK frame since the ACK indication field included in the data frame is set to 'b11' To the first terminal STA 1 in the access period. At this time, the relay apparatus R can indicate that the ACK frame is transmitted after the data frame by setting the ACK indication field included in the data frame to 'b00'. On the other hand, when the main access point (M-AP) acquires the data frame transmitted from the relay apparatus R to the first terminal STA 1, the data frame previously transmitted from the relay apparatus R is successfully transmitted to the relay station R As shown in FIG.

The first terminal STA 1 can transmit an ACK frame to the relay apparatus R in the end terminal connection period in response to the successful reception of the data frame from the relay apparatus R. [ At this time, the first STA1 may indicate that the frame is not transmitted after the ACK frame by setting the ACK indication field of the SIG field included in the ACK frame to 'b10'.

According to the present invention, the main access point can extend the service area through the relay device. Since the terminal can secure a link of good quality through the relay apparatus, the data can be transmitted at a high speed. That is, by using the relay apparatus, the use efficiency of the radio channel can be improved and the power consumption of the terminal can be reduced.

In addition, the main access point, relay device and end terminal can minimize channel contention by transmitting frames using the ACK indication bit.

In addition, the primary access point may transmit data to the relay device only when the end terminal connected to the relay device is able to receive the data. As a result, the occurrence of a buffer overflow in the relay apparatus can be prevented.

In addition, the primary-access point, the relay device and the end terminal can quickly transmit and receive data by using a fast data transmission mode (i.e., ACK for data).

In addition, the primary-access point may restrict the communication entities belonging to the M-BSS from accessing the transmission interval for the relay apparatus by setting the transmission interval for the relay apparatus. The relay apparatus can restrict channel access of some terminals belonging to the R-BSS by setting a channel access restriction period based on the transmission period for the relay apparatus set by the main access point. This allows the main access point and the relay device to transmit data quickly.

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

The computer-readable medium may refer to a hardware device that is specifically configured to store and execute program instructions, such as a ROM, a RAM, a flash memory, and the like. A hardware device 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. A program instruction may refer to a high-level language code that may be executed on a computer based on, for example, an interpreter, as well as machine code as produced by a compiler.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims (15)

A data transmission method performed at a master-access point,
Setting a relay connection period in which a connection of a communication entity belonging to a relay-basic service set (R-BSS) constituted by the relay apparatus is permitted; And
And transmitting a master-beacon frame including information on the relay connection period and identifier information of a terminal connected to the relay apparatus. The method according to claim 1,
Wherein the main-beacon frame includes a relay traffic indication map (RTIM) configured with identifier information of the relay apparatus and identifier information of the terminal. The method according to claim 1,
The data transfer method includes:
In the relay connection section,
Obtaining an acknowledge (ACK) frame, which is a response to a power save (PS) -Poll frame or a trigger frame, from the relay device;
Transmitting a data frame to the relay device; And
Further comprising the step of obtaining a response frame for reception of the data frame from the relay apparatus. The method of claim 3,
And the response frame is an ACK frame. The method of claim 3,
Wherein the response frame is the data frame transmitted from the relay apparatus to the terminal. The method according to claim 1,
Wherein the identifier information is an association ID (AID). The method according to claim 1,
Wherein a communication entity belonging to a master-basic service set (M-BSS) of the primary access point is restricted in the relay connection period. The method of claim 2,
Wherein the RTIM is part of a traffic indication map (TIM) for at least one terminal connected to the primary access point. A data transmission method performed in a relay apparatus,
Receiving information on a relay connection period in which a communication entity belonging to a relay-basic service set (R-BSS) configured by the relay apparatus is allowed to be connected with the identifier information of a terminal connected to the relay apparatus ;
Generating a relay-beacon frame including identifier information of the terminal and information of a connection interval in which the terminal is allowed to access based on the received information; And
And transmitting the relay-beacon frame. The method of claim 9,
The data transfer method includes:
In a connection section in which connection of the terminal is allowed,
Receiving a power save (PS) -Poll frame or a trigger frame from the terminal that has received the relay-beacon frame;
Transmitting an acknowledgment (ACK) frame to the terminal in response to the PS-Poll frame or the trigger frame;
Receiving a data frame from the primary access point;
Transmitting the data frame to the terminal; And
Further comprising the step of receiving an ACK frame in response to the data frame from the terminal. The method of claim 10,
Wherein the transmitting the data frame to the terminal comprises:
And transmitting the ACK frame, which is a response to the reception of the data frame, to the main access point, and then transmitting the data frame to the terminal. The method of claim 9,
Wherein the identifier information is an association ID (AID). The method of claim 9,
Wherein a communication entity belonging to a master-basic service set (M-BSS) of the primary access point is restricted in the relay connection period. The method of claim 9,
Wherein a connection interval in which the connection of the terminal is allowed is set within the relay connection interval. The method of claim 9,
Wherein the communication entity other than the terminal indicated by the identifier information of the terminal among the communication entities belonging to the R-BSS is restricted in the connection period in which the terminal is allowed to access.

Images