WO2016208830A1 - Method for transmitting and receiving signal in wireless lan system and apparatus for same - Google Patents

Abstract

A method for receiving a signal by a station (STA) in a wireless LAN system according to one embodiment of the present invention, comprises: a step for receiving a multi-user (MU) frame including a SIG-B field and a SIG-A field in which M per user SIG-Bs are jointly encoded into N (<M) unit blocks; a step for decoding the SIG-B field on the basis of the SIG-A field; and a step for obtaining per user SIG-B of the station from the decoded SIG-B field, wherein a plurality of different MCS levels are set to the unit blocks, respectively, and the MCS levels set to the unit blocks are directed by the SIG-A field.

Description

Method for transmitting / receiving signal in WLAN system and apparatus therefor

The present specification relates to a WLAN system, and more particularly, to a method for transmitting or receiving a signal for multiple users in a WLAN system and a station performing the same.

The signal transmission method proposed below may be applied to various wireless communications. Hereinafter, a wireless local area network (WLAN) system will be described as an example of a system to which the present invention can be applied.

The standard for WLAN technology is being developed as an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. IEEE 802.11a and b are described in 2.4. Using unlicensed band at GHz or 5 GHz, IEEE 802.11b provides a transmission rate of 11 Mbps and IEEE 802.11a provides a transmission rate of 54 Mbps. IEEE 802.11g applies orthogonal frequency-division multiplexing (OFDM) at 2.4 GHz to provide a transmission rate of 54 Mbps. IEEE 802.11n applies multiple input multiple output OFDM (MIMO-OFDM) to provide a transmission rate of 300 Mbps for four spatial streams. IEEE 802.11n supports channel bandwidths up to 40 MHz, in this case providing a transmission rate of 600 Mbps.

The WLAN standard uses a maximum of 160MHz bandwidth, supports eight spatial streams, and supports IEEE 802.11ax standard through an IEEE 802.11ac standard supporting a speed of up to 1Gbit / s.

An object of the present invention is to provide a method for efficiently transmitting or receiving signals for multiple users in a WLAN system.

The present invention is not limited to the above-described technical problem and other technical problems can be inferred from the embodiments of the present invention.

In a wireless LAN system according to an aspect of the present invention for achieving the above-described technical problem, a method for receiving a signal from a station (STA), N individual user SIG-B (SIG-B) N is smaller than M Receiving a multi-user frame including a SIG-B field and a SIG-A field jointly encoded into unit blocks; Decoding the SIG-B field based on the SIG-A field; And acquiring an individual user SIG-B of the station from the decoded SIG-B field, wherein the unit blocks are configured with different MCS levels different from each other, and the MCS set in the unit blocks. Levels are indicated by the SIG-A field.

A station (STA) according to another aspect of the present invention for achieving the above-described technical problem is, SIG- jointly encoded with N unit blocks of M individual user SIG-B (SIG-B) smaller than M A receiver for receiving a multi-user frame including a B field and a SIG-A field; And a processor for decoding the SIG-B field based on the SIG-A field and obtaining an individual user SIG-B of the station from the decoded SIG-B field, wherein the unit blocks differ from each other. Multiple MCS levels are each set and set in the unit blocks.

In a wireless LAN system according to another aspect of the present invention for achieving the above-described technical problem, a method for transmitting an AP signal, M individual user SIG-B (per user SIG-B) than M Joint encoding into small N unit blocks; And transmitting a multi-user frame including the SIG-B field and the SIG-A field including the unit blocks, wherein the Mblocks are configured with different MCS levels different from each other. The MCS levels set in the unit blocks are indicated by the SIG-A field.

Preferably, the number of individual user SIG-Bs jointly encoded per unit block may be different from each other, but the size of the individual user SIG-Bs may be the same.

Preferably, the number of individual user SIG-Bs may be determined for each of the unit blocks such that the unit blocks in which the different MCS levels are set have a length of one symbol.

Advantageously, said multiple MCS levels may be selected from an MCS set comprising at least one fixed MCS level and at least one variable MCS level.

Advantageously, said multiple MCS levels correspond to at least one MCS level and a station having a maximum SNR corresponding to a station having a minimum signal to noise ratio (SNR) among a plurality of stations receiving said MU frame. It may include at least one MCS level.

Advantageously, the MU frame may be received on a 20 MHz, 40 MHz, 80 MHz or 160 MHz bandwidth based on orthogonal frequency divisional multiple access (OFDMA).

According to an embodiment of the present invention, when multiple MCS levels are applied to the HE-SIG-B field during MU transmission, overhead for the HE-SIG-B field may be reduced, and MU transmission and reception may be performed more efficiently. .

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description.

1 is a diagram illustrating an example of a configuration of a WLAN system.

2 is a diagram illustrating another example of a configuration of a WLAN system.

3 is a diagram illustrating an exemplary structure of a WLAN system.

4 is a view for explaining a link setup process in a WLAN system.

5 is a diagram for describing an active scanning method and a passive scanning method.

6 is a view for explaining the DCF mechanism in a WLAN system.

7 and 8 are exemplary diagrams for explaining the problem of the existing conflict resolution mechanism.

9 is a diagram for explaining a mechanism for solving a hidden node problem using an RTS / CTS frame.

FIG. 10 is a diagram for explaining a mechanism for solving an exposed node problem using an RTS / CTS frame.

11 to 13 are views for explaining the operation of the station receiving the TIM in detail.

14 to 18 are diagrams for explaining an example of a frame structure used in the IEEE 802.11 system.

19 to 21 are diagrams illustrating a MAC frame format.

22 shows a Short MAC frame format.

23A is a diagram illustrating an example of a high efficiency (HE) PPDU format.

23B shows the HE-SIG-B field structure of the HE PPDU.

23C shows the encoding structure of HE-SIG-B.

FIG. 24 is a diagram illustrating a method for performing UL MU transmission in an AP station and a non-AP station.

FIG. 25 illustrates an Aggregate-MPDU (A-MPDU) frame structure for UL MU transmission.

FIG. 26 illustrates resources available in a 20 MHz channel when transmitting a signal based on OFDMA.

27, 28 and 29 illustrate ways of applying multiple MCSs to a HE-SIG-B field in accordance with embodiments of the present invention.

30 is a flowchart illustrating a signal transmission and reception method according to an embodiment of the present invention.

31 is a block diagram illustrating an exemplary configuration of an AP device (or base station device) and a station device (or terminal device).

32 shows an exemplary structure of a processor of an AP device or a station device.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment.

Specific terms used in the following description are provided to help the understanding of the present invention, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present invention.

In some instances, well-known structures and devices are omitted or shown in block diagram form, centering on the core functions of each structure and device, in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802 system, 3GPP system, 3GPP LTE and LTE-A (LTE-Advanced) system and 3GPP2 system. That is, steps or parts which are not described to clearly reveal the technical spirit of the present invention among the embodiments of the present invention may be supported by the above documents. In addition, all terms disclosed in the present document can be described by the above standard document.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various radio access systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA).

In addition, terms such as first and / or second may be used herein to describe various components, but the components should not be limited by the terms. The terms are only for the purpose of distinguishing one component from another component, for example, without departing from the scope of rights in accordance with the concepts herein, the first component may be called a second component, and similarly The second component may also be referred to as a first component.

In addition, throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, except to exclude other components unless otherwise stated. And “…” described in the specification. unit", "… “Unit” refers to a unit that processes at least one function or operation, which may be implemented in a combination of hardware and / or software.

1 is a diagram illustrating an example of a configuration of a WLAN system.

As shown in FIG. 1, the WLAN system includes one or more basic service sets (BSSs). A BSS is a set of stations (STAs) that can successfully synchronize and communicate with each other.

A station is a logical entity that includes medium access control (MAC) and a physical layer interface to a wireless medium. The station is an access point (AP) and a non-AP station. Include. The portable terminal operated by the user among the stations is a non-AP station, which is simply referred to as a non-AP station. A non-AP station is a terminal, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile terminal, or a mobile subscriber. It may also be called another name such as a mobile subscriber unit.

The AP is an entity that provides an associated station with access to a distribution system (DS) through a wireless medium. The AP may be called a centralized controller, a base station (BS), a Node-B, a base transceiver system (BTS), or a site controller.

BSS can be divided into infrastructure BSS and Independent BSS (IBSS).

The BBS shown in FIG. 1 is an IBSS. The IBSS means a BSS that does not include an AP. Since the IBSS does not include an AP, access to the DS is not allowed, thereby forming a self-contained network.

2 is a diagram illustrating another example of a configuration of a WLAN system.

The BSS shown in FIG. 2 is an infrastructure BSS. The infrastructure BSS includes one or more stations and an AP. In the infrastructure BSS, communication between non-AP stations is performed via an AP, but direct communication between non-AP stations is also possible when a direct link is established between non-AP stations.

As shown in FIG. 2, a plurality of infrastructure BSSs may be interconnected through a DS. A plurality of BSSs connected through a DS is called an extended service set (ESS). Stations included in an ESS may communicate with each other, and a non-AP station may move from one BSS to another BSS while communicating seamlessly within the same ESS.

The DS is a mechanism for connecting a plurality of APs. The DS is not necessarily a network, and there is no limitation on the form if it can provide a predetermined distribution service. For example, the DS may be a wireless network such as a mesh network or a physical structure that connects APs to each other.

3 is a diagram illustrating an exemplary structure of a WLAN system. In FIG. 3, an example of an infrastructure BSS including a DS is shown.

In the example of FIG. 3, BSS1 and BSS2 constitute an ESS. In a WLAN system, a station is a device that operates according to MAC / PHY regulations of IEEE 802.11. The station includes an AP station and a non-AP station. Non-AP stations are typically user-managed devices, such as laptop computers and mobile phones. In the example of FIG. 3, station 1, station 3, and station 4 correspond to non-AP stations, and station 2 and station 5 correspond to AP stations.

In the following description, a non-AP station includes a terminal, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), and a mobile terminal. May be referred to as a Mobile Subscriber Station (MSS). In addition, the AP may include a base station (BS), a node-B, an evolved Node-B (eNB), and a base transceiver system (BTS) in other wireless communication fields. , A concept corresponding to a femto base station (Femto BS).

FIG. 4 is a diagram illustrating a general link setup process, and FIG. 5 is a diagram illustrating an active scanning method and a passive scanning method.

In order for a station to set up a link and transmit and receive data over a network, it first discovers the network, performs authentication, establishes an association, and authenticates for security. It must go through the back. The link setup process may also be referred to as session initiation process and session setup process. In addition, the process of discovery, authentication, association and security establishment of the link setup process may be collectively referred to as association process.

An exemplary link setup procedure will be described with reference to FIG. 4.

In step S410, the station may perform a network discovery operation. The network discovery operation may include a scanning operation of the station. In other words, in order for a station to access a network, it must find a network that can participate. The station must identify a compatible network before joining the wireless network. Network identification in a particular area is called scanning.

There are two types of scanning methods, active scanning and passive scanning. 4 exemplarily illustrates a network discovery operation including an active scanning process, but may operate as a passive scanning process.

In active scanning, a station performing scanning transmits a probe request frame and waits for a response to discover which AP exists in the vicinity while moving channels. The responder transmits a probe response frame in response to the probe request frame to the station transmitting the probe request frame. Here, the responder may be the station that last transmitted the beacon frame in the BSS of the channel being scanned. In the BSS, the AP transmits a beacon frame, so the AP becomes a responder. In the IBSS, the responder is not constant because the stations in the IBSS rotate and transmit the beacon frame. For example, a station that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 stores the BSS-related information included in the received probe response frame and stores the next channel (for example, number 2). Channel) to perform scanning (i.e., probe request / response transmission and reception on channel 2) in the same manner.

In addition, referring to FIG. 5, the scanning operation may be performed by a passive scanning method. In passive scanning, a station performing scanning waits for a beacon frame while moving channels. Beacon frame is one of the management frame (management frame) in IEEE 802.11, it is transmitted periodically to inform the existence of the wireless network, and to perform the scanning station to find the wireless network and join the wireless network. In the BSS, the AP periodically transmits a beacon frame, and in the IBSS, stations in the IBSS rotate to transmit a beacon frame. When the scanning station receives the beacon frame, the scanning station stores the information about the BSS included in the beacon frame and records beacon frame information in each channel while moving to another channel. The station receiving the beacon frame may store the BSS related information included in the received beacon frame, move to the next channel, and perform scanning on the next channel in the same manner.

Comparing active and passive scanning, active scanning has the advantage of less delay and power consumption than passive scanning.

After the station has found the network, the authentication process may be performed in step S420. This authentication process may be referred to as a first authentication process in order to clearly distinguish from the security setup operation of step S440 described later.

The authentication process includes a process in which the station transmits an authentication request frame to the AP, and in response thereto, the AP transmits an authentication response frame to the station. An authentication frame used for authentication request / response corresponds to a management frame.

The authentication frame includes an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network, and a finite cyclic group. Group) and the like. This corresponds to some examples of information that may be included in the authentication request / response frame, and may be replaced with other information or further include additional information.

The station may send an authentication request frame to the AP. The AP may determine whether to allow authentication for the corresponding station based on the information included in the received authentication request frame. The AP may provide the station with the result of the authentication process through an authentication response frame.

After the station is successfully authenticated, the association process may be performed in step S430. The association process includes the station transmitting an association request frame to the AP, and in response, the AP transmitting an association response frame to the station.

For example, the association request frame may include information related to various capabilities, beacon listening interval, service set identifier (SSID), supported rates, supported channels, RSN, mobility domain. Information about supported operating classes, TIM Broadcast Indication Map Broadcast request, interworking service capability, and the like.

For example, the association response frame may include information related to various capabilities, status codes, association IDs (AIDs), support rates, Enhanced Distributed Channel Access (EDCA) parameter sets, Received Channel Power Indicators (RCPI), Received Signal to Noise Information) such as an indicator, a mobility domain, a timeout interval (association comeback time), an overlapping BSS scan parameter, a TIM broadcast response, and a QoS map.

This corresponds to some examples of information that may be included in the association request / response frame, and may be replaced with other information or further include additional information.

After the station is successfully associated with the network, a security setup procedure may be performed at step S540. The security setup process of step S440 may be referred to as an authentication process through a Robust Security Network Association (RSNA) request / response. The authentication process of step S520 is called a first authentication process, and the security setup process of step S540 is performed. It may also be referred to simply as the authentication process.

The security setup process of step S440 may include, for example, performing a private key setup through 4-way handshaking through an Extensible Authentication Protocol over LAN (EAPOL) frame. . In addition, the security setup process may be performed according to a security scheme not defined in the IEEE 802.11 standard.

Based on the above, a collision detection technique in a WLAN system will be described.

As described above, in the wireless environment, since various factors affect the channel, the transmitter may not accurately perform collision detection. Thus, 802.11 introduced a distributed coordination function (DCF), a carrier sense multiple access / collision avoidance (CSMA / CA) mechanism.

6 is a view for explaining the DCF mechanism in a WLAN system.

The DCF performs a clear channel assessment (CCA) that senses the medium for a certain period of time (eg DIFS: DCF inter-frame space) before the stations with the data to transmit transmit the data. At this time, if the medium is idle (if available), the station can use it to transmit signals. However, if the medium is busy (unavailable), it can wait for an additional random backoff period in DIFS before sending data, assuming several stations are already waiting to use the medium. In this case, the random backoff period allows collisions to be avoided, assuming that there are several stations for transmitting data, each station has a probabilistic different backoff interval, resulting in different transmissions. Because you have time. When one station starts transmitting, the other stations will not be able to use the medium.

Briefly, the random backoff time and procedure are as follows.

When a medium changes from busy to idle, several stations start preparing to send data. In order to minimize collisions, stations wishing to transmit data each select a random backoff count and wait for the slot time. The random backoff count is a pseudo-random integer value and selects one of the uniformly distributed values in the range [0 CW]. CW stands for 'contention window'.

The CW parameter takes the CWmin value as an initial value, but if the transmission fails, the value is doubled. For example, if an ACK response for a transmitted data frame is not received, a collision can be considered. If the CW value has a CWmax value, the CWmax value is maintained until the data transmission is successful, and the data transfer succeeds and resets to the CWmin value. At this time, CW, CWmin, CWmax is preferable to maintain 2 ⁿ -1 for convenience of implementation and operation.

On the other hand, when the random backoff procedure starts, the station selects a random backoff count within the range of [0 CW] and continues to monitor the medium while the backoff slot counts down. In the meantime, if the medium is busy, it stops counting down and resumes counting down the remaining backoff slots when the medium becomes idle again.

Referring to FIG. 6, when there is data that several stations want to send, station 3 transmits a data frame immediately because the medium is idle as much as DIFS, and the other stations wait for the medium to be idle. Since the medium has been busy for some time, several stations will see the opportunity to use it. Thus, each station selects a random backoff count. In FIG. 6, the station 2, which has selected the smallest backoff count, transmits a data frame.

After the transfer of station 2 is finished, the medium is idle again and the stations resume counting down for the backoff interval that they stopped. Figure 6 shows the second random backoff count value after station 2 and station 5, which had stopped counting down briefly when the medium was busy, started transmitting data frames after counting down the remaining backoff slots, but accidentally randomized station 4 Overlap with the backoff count value shows that a collision has occurred. At this time, since both stations do not receive an ACK response, the CW is doubled and the random backoff count value is selected again.

As already mentioned, the most basic of CSMA / CA is carrier sensing. The terminal may use physical carrier sensing and virtual carrier sensing to determine whether the DCF medium is busy / idle. Physical carrier sensing is performed at the physical layer (PHY) stage and is performed through energy detection or preamble detection. For example, if it is determined that the voltage level at the receiver or the preamble is read, it can be determined that the medium is busy. Virtual carrier sensing is performed by setting a network allocation vector (NAV) to prevent other stations from transmitting data and using a value of a duration field of a MAC header. In order to reduce the possibility of collision, a robust collision detection mechanism was introduced, which can be seen in the following two examples. For convenience, it is assumed that the carrier sensing range is the same as the transmission range.

7 and 8 are exemplary diagrams for explaining the problem of the existing conflict resolution mechanism.

Specifically, FIG. 7 is a diagram for explaining hidden node issues. In this example, station A and station B are in communication, and station C has information to transmit. Specifically, when station A is transmitting information to station B, when station C carrier senses the medium before sending data to station B, it does not detect station A's signal transmission because station C is outside of station A's transmission range. It is possible that the media is idle. Eventually, station B receives the information of station A and station C at the same time, causing a collision. In this case, the station A may be referred to as a hidden node of the station C.

8 is a diagram for describing exposed node issues. Station B is currently sending data to station A. At this time, station C performs carrier sensing. Since station B is transmitting information, the medium is detected as busy. As a result, even if station C wants to send data to station D, the medium is sensed to be busy, causing an unnecessarily waiting for the medium to become idle. In other words, even though the station A is outside the CS range of the station C, there is a case where the information transmission of the station C is prevented. Station C then becomes an exposed node of station B.

In order to use the collision avoidance mechanism well in the above-mentioned situation, by introducing short signaling packets such as request to send (RTS) and clear to send (CTS), there is room for neighboring stations to overhear whether to transmit information between the two stations. You can leave That is, when the station to transmit data transmits the RTS frame to the station receiving the data, the receiving end station may inform that it will receive the data by transmitting the CTS frame to the surrounding terminals.

9 is a diagram for explaining a mechanism for solving a hidden node problem using an RTS / CTS frame.

In FIG. 9, both station A and station C attempt to transmit data to station B. FIG. Station A sends an RTS to Station B, which sends the CTS to both Station A and Station C around it. As a result, station C waits for the end of data transfer between station A and station B to avoid collisions.

FIG. 10 is a diagram for explaining a mechanism for solving an exposed node problem using an RTS / CTS frame.

By overhearing the RTS / CTS transmissions of the station A and the station B in FIG. 10, the station C can recognize that no collision occurs even if the C transmits data to another station D. FIG. That is, station B transmits the RTS to all the surrounding terminals, and only station A which has the data to send actually transmits the CTS. Since station C receives only RTS and not station A's CTS, it can be seen that station A is outside the CS range of STC C.

11 to 13 are views for explaining the operation of the station receiving the TIM in detail.

Referring to FIG. 11, the station may switch from a sleep state to an awake state to receive a beacon frame including a TIM from an AP, interpret the received TIM element, and know that there is buffered traffic to be transmitted to the AP. . The station may transmit a PS-Poll frame to request an AP to transmit a data frame after contending with other stations for medium access for PS-Poll frame transmission. The AP receiving the PS-Poll frame transmitted by the station may transmit the frame to the station. The station may receive a data frame and send an acknowledgment (ACK) frame thereto to the AP. The station may then go back to sleep.

As shown in FIG. 11, the AP operates according to an immediate response method of transmitting a data frame after a predetermined time (for example, short inter-frame space (SIFS)) after receiving a PS-Poll frame from a station. Can be. On the other hand, if the AP does not prepare a data frame to be transmitted to the station after receiving the PS-Poll frame during the SIFS time, it can operate according to the delayed response (deferred response) method, which will be described with reference to FIG.

In the example of FIG. 12, the operation of the station transitioning from the sleep state to the awake state, receiving a TIM from the AP, and transmitting a PS-Poll frame to the AP through contention is identical to the example of FIG. If the AP does not prepare a data frame during SIFS even after receiving the PS-Poll frame, the AP may transmit an ACK frame to the station instead of transmitting the data frame. When the data frame is prepared after transmitting the ACK frame, the AP may transmit the data frame to the station after performing contention. The station may send an ACK frame indicating that the data frame was successfully received to the AP and go to sleep.

13 illustrates an example in which the AP transmits a DTIM. Stations may transition from a sleep state to an awake state to receive a beacon frame containing a DTIM element from the AP. The stations may know that a multicast / broadcast frame will be transmitted through the received DTIM. The AP may transmit data (ie, multicast / broadcast frame) immediately after the beacon frame including the DTIM without transmitting and receiving the PS-Poll frame. The stations may receive data while continuing to awake after receiving the beacon frame including the DTIM, and may go back to sleep after the data reception is complete.

14 to 18 are diagrams for explaining an example of a frame structure used in the IEEE 802.11 system.

The station STA may receive a Physical Layer Convergence Protocol (PLCP) Packet Data Unit (PPDU). In this case, the PPDU frame format may include a Short Training Field (STF), a Long Training Field (LTF), a SIG (SIGNAL) field, and a Data field. In this case, as an example, the PPDU frame format may be set based on the type of the PPDU frame format.

As an example, the non-HT (High Throughput) PPDU frame format may include only a legacy-STF (L-STF), a legacy-LTF (L-LTF), a SIG field, and a data field.

In addition, the type of the PPDU frame format may be set to any one of the HT-mixed format PPDU and the HT-greenfield format PPDU. In this case, the above-described PPDU format may further include an additional (or other type) STF, LTF, and SIG fields between the SIG field and the data field.

In addition, referring to FIG. 15, a Very High Throughput (VHT) PPDU format may be set. In this case, an additional (or other type) STF, LTF, SIG field may be included between the SIG field and the data field in the VHT PPDU format. More specifically, in the VHT PPDU format, at least one or more of a VHT-SIG-A field, a VHT-STF field, VHT-LTF, and VHT SIG-B field may be included between the L-SIG field and the data field.

In this case, the STF may be a signal for signal detection, automatic gain control (AGC), diversity selection, precise time synchronization, or the like. In addition, the LTF may be a signal for channel estimation, frequency error estimation, or the like. In this case, the STF and the LTF may be referred to as a PCLP preamble, and the PLCP preamble may be referred to as a signal for synchronization and channel estimation of the OFDM physical layer.

Also, referring to FIG. 16, the SIG field may include a RATE field and a LENGTH field. The RATE field may include information about modulation and coding rate of data. The LENGTH field may include information about the length of data. In addition, the SIG field may include a parity bit, a SIG TAIL bit, and the like.

The data field may include a SERVICE field, a PLC Service Data Unit (PSDU), a PPDU TAIL bit, and may also include a padding bit if necessary.

In this case, referring to FIG. 17, some bits of the SERVICE field may be used for synchronization of the descrambler at the receiving end, and some bits may be configured as reserved bits. The PSDU corresponds to a MAC PDU (Protocol Data Unit) defined in the MAC layer and may include data generated / used in an upper layer. The PPDU TAIL bit can be used to return the encoder to zero. The padding bit may be used to adjust the length of the data field in a predetermined unit.

In addition, as an example, as described above, the VHT PPDU format may include additional (or other types of) STF, LTF, and SIG fields. In this case, L-STF, L-LTF, and L-SIG in the VHT PPDU may be a portion for the Non-VHT of the VHT PPDU. In this case, VHT-SIG A, VHT-STF, VHT-LTF, and VHT-SIG B in the VHT PPDU may be a part for the VHT. That is, in the VHT PPDU, a field for the Non-VHT and a region for the VHT field may be defined, respectively. In this case, as an example, the VHT-SIG A may include information for interpreting the VHT PPDU.

In this case, as an example, referring to FIG. 18, the VHT-SIGA may be configured of VHT SIG-A1 (FIG. 18A) and VHT SIG-A2 (FIG. 18B). In this case, the VHT SIG-A1 and the VHT SIG-A2 may be configured with 24 data bits, respectively, and the VHT SIG-A1 may be transmitted before the VHT SIG-A2. At this time, the VHT SIG-A1 may include a BW, STBC, Group ID, NSTS / Partial AID, TXOP_PS_NOT_ALLOWED field, and Reserved field. VHT SIG-A2 also includes Short GI, Short GI NSYM Disambiguation, SU / MU [0] Coding, LDPC Extra OFDM Symbol, SU VHT-MCS / MU [1-3] Coding, Beamformed, CRC, Tail and Reserved fields. It may include. Through this, it is possible to check the information on the VHT PPDU.

19 to 21 illustrate a MAC frame format.

The station may receive a PPDU based on any one of the above-described PPDU formats. In this case, the PSDU of the data portion of the PPDU frame format may include a MAC PDU. In this case, the MAC PDU is defined according to various MAC frame formats, and the basic MAC frame may be composed of a MAC header, a frame body, and a frame check sequence (FCS).

In this case, as an example, referring to FIG. 19, the MAC header may include a frame control field, a duration / ID field, an address field, a sequence control, a QoS control, and a HT control subfield. have. In this case, the frame control field of the MAC header may include control information required for frame transmission / reception. The interval / ID field may be set to a time for transmitting a corresponding frame. In addition, the address field may include identification information about the sender and the receiver, which will be described later. In addition, the Sequence Control, QoS Control, and HT Control fields may refer to the IEEE 802.11 standard document.

In this case, as an example, the HT Control field may have two forms as an HT variant and a VHT variant. In this case, the information included in the HT Control field may vary according to each type. Also, referring to FIGS. 20 and 21, the VHT subfield of the HT Control may be a field indicating whether the HT Control field is a HT variant or a VHT variant. In this case, as an example, when the VHT subfield has a value of "0", it may be in the form of HT variant, and when the VHT subfield has a value of "1", it may be in the form of VHT variant.

At this time, as an example, referring to FIG. 20, if the HT Control field is a HT variant, Link Adaptation Control, Calibration Position, Calibration Sequence, CSI / Steering, HT NDP Announcement, AC constraint, RDG / More PPDU and Reserved fields may be used. It may include. In this case, as an example, referring to b of FIG. 20, the link adaptation control field may include a TRQ, MAI, MFSI, and MFB / ASELC field. For more details, refer to the IEEE802.11 standard document.

Also, as an example, referring to FIG. 21, if the HT Control field is a VHT variant type, MRQ, MSI, MFSI / GID-LM, MFB GID-H, Coding Type, FB Tx Type, FB Tx Type, Unsolicited MFB, AC It can include constraints, RDG / More PPDUs, and Reserved fields. In this case, as an example, referring to b of FIG. 21, the MFB field may include a VHT N_STS, MCS, BW, SNR field, and the like.

22 shows a Short MAC frame format. The MAC frame may be configured in the form of a short MAC frame in order to prevent unnecessary waste of information by reducing unnecessary information. In this case, as an example, referring to FIG. 22, the MAC header of a short frame may always include a frame control field, an A1 field, and an A2 field. In addition, the Sequence Control field, the A3 field, and the A4 field may be selectively included. In this way, unnecessary information may be omitted from the MAC frame to prevent waste of radio resources.

At this time, as an example, when looking at the frame control field of the MAC header, Protocol Version, Type, PTID / Subtype, From DS, More Fragment, Power Management, More Data, Protected Frame, End of Service Period, Relayed Frame and Ack Policy fields It may include. The content of each subfield of the frame control field may refer to an IEEE 802.11 standard document.

On the other hand, the Type (Field) field of the frame control field of the MAC header is composed of 3 bits, the value 0 to 3 includes the configuration for each address information, 4-7 may be reserved. In this regard, in the present invention, new address information may be indicated through a reserved value, which will be described later.

Also, the From DS field of the control frame field of the MAC header may be configured with 1 bit.

In addition, in addition, the More Fragment, Power Management, More Data, Protected Frame, End of Service Period, Relayed Frame and Ack Policy fields may be configured as 1 bit. In this case, the Ack Policy field may be configured with 1 bit as ACK / NACK information.

In relation to stations including a frame configured in the above-described form, a VHT AP may support a non-AP VHT station operating in a TXOP (Transmit Opportunity) power save mode in one BSS. In this case, as an example, the non-AP VHT station may be operating in the TXOP power save mode as an active state. At this time, the AP VHT station may be configured to switch the non-AP VHT station to the doze state during the TXOP. In this case, as an example, the AP VHT station may indicate that the TXVECTOR parameter TXOP_PS_NOT_ALLOWED is set to a value of 0 and that the AP VHT station is switched to an inactive state by transmitting a VHT PPDU. At this time, parameters in the TXVECTOR transmitted together with the VHT PPDU by the AP VHT station may be changed from 1 to 0 during TXOP. Through this, power saving can be performed for the remaining TXOP.

On the contrary, when TXOP_PS_NOT_ALLOWED is set to 1 and power saving is not performed, the parameters in the TXVECTOR may be maintained without changing.

For example, as described above, when the non-AP VHT station is switched to inactive during TXOP in the TXOP power save mode, the following condition may be satisfied.

When the VHT MU PPDU is received and the station is not indicated as a member of the group by the RXVECTOR parameter Group_ID.

If the station has received a SU PPDU and the station does not match the partial AID of the station or the PARTIAL_AID of the RXVECTOR parameter is 0

The station determines that the RXVECTOR parameter PARTIAL_AID matches the station's partial AID, but the recipient address in the MAC header does not match the station's MAC address.

-The station is indicated as a member of the group by the RXVECTOR parameter GROUP_ID, but the NUM_STS parameter of the RXVECTOR parameter is set to 0.

If a VHT NDP Announcement frame is received and the station has the RXVECTOR parameter PARTIAL_AID set to 0 and the AIDs in the Info field of the station do not match.

When the station receives a frame in which the More Data field is set to 0, the Ack Policy subfield is set to No Ack, or sends an ACK with the Ack Policy subfield set to No Ack.

At this time, the AP VHT station may include a Duration / ID value and a NAV-SET Sequence (e.g., RTS / CTS) set to the remaining TXOP interval. In this case, the AP VHT station may not transmit a frame for the non-AP VHT station which is switched to the inactive state based on the above conditions for the remaining TXOP.

Also, as an example, if an AP VHT station transmits a VHT PPDU together with the TXVECTOR parameter TXOP_PS_NOT_ALLOWED in the same TXOP with the TXVECTOR parameter set to 0 and the station does not want to change from active to inactive, the AP VHT station sends a VHT SU PPDU. May not transmit.

Also, as an example, the AP VHT station may not transmit a frame to the VHT station which is switched to an inactive state before the NAV set when the TXOP starts.

In this case, when the AP VHT station does not receive an ACK after transmitting a frame including at least one of MSDU, A-MSDU, and MMPDU while the More Data field is set to 0, the AP VHT station may be retransmitted at least once in the same TXOP. . In this case, as an example, when ACK for retransmission is not received in the last frame of the same TXOP, the frame may be retransmitted until the next TXOP.

Also, as an example, the AP VHT station may receive a BlockAck frame from the VHT station operating in the TXOP power save mode. In this case, the BlockAck frame may be a response to the A-MPDU including the MPDU in which the More Data field is set to zero. At this time, since the AP VHT station is in an inactive state, it may not receive a response of the subsequence of the re-transmitted MPDU during the same TXOP.

In addition, the VHT station operating in the TXOP power save mode and switched to the inactive state may cause the NAV timer to operate during the inactive state. At this time, for example, when the timer is completed, the VHT station may be switched to an awake state.

In addition, the station may compete for media access when the NAV timer expires.

● HE PPDU

FIG. 23A is a diagram illustrating an example of a high efficiency (HE) PPDU format according to an embodiment of the present invention. FIG. The HE PPDU format can be used on an IEEE 802.11ax system. As described above, since the type of the PPDU format can be set in various ways, the scope of the present invention is not limited to the HE PPDU of FIG. 23A. For convenience of description, FIG. 23 illustrates a HE PPDU format set in units of 20 MHz on an 80 MHz bandwidth, but a HE PPDU may be transmitted on a 20 MHz, 40 MHz, or 160 MHz bandwidth.

Referring to FIG. 23A, the HE PPDU includes L parts (L-STF, L-LTF, L-SIG, RL-SIG) and HE parts (HE-SIG-A, HE-STF, HE-LTF, HE-SIG-). B). L-STF, L-LTF, L-SIG, RL-SIG, HE-SIG-A and HE-SIG-B are set in units of 1x symbol (3.2us), HE-STF, HE-LTF and Data are 4x It can be set in symbol (12.8us) units.

In the L part, the legacy preamble is transmitted. The L part may be transmitted in units of 20 MHz in the frequency domain. If the bandwidth is greater than 20 MHz, the L part may be transmitted in a duplication in 20 MHz units. The L-SIG includes packet length information. The RL-SIG is a field in which the L-SIG is repeatedly transmitted to improve the reliability of the L-SIG.

The HE-SIG-A may be transmitted in units of 20 MHz, similarly to the L part. If the bandwidth is greater than 20 MHz, the HE-SIG-A may be transmitted in duplication in units of 20 MHz. The HE-SIG-A may include common control information of multiple users. The content of common control information included in the HE-SIG-A may be determined according to the type of the PPDU. For example, for SU PPDU, HE-SIG-A is a format indicator, TXOP period, BSS color field, dual carrier modulation (DCM) indicator, UL / DL flag, bandwidth, Payload GI (Guard Interval), PE, MCS, coding And LTF compression, Number of Spatial Streams (NSTS), STBC, Beamforming, Cyclic Redundancy Check (CRC), and Tail fields. The MU DL PPDU may include at least one of a format indicator, a TXOP period, a BSS color field, a DCM indicator, the number of HE-SIG-B field symbols, an MCS, CRC, and Tail fields of the HE-SIG-B field. . In addition, the MU UL PPDU may include at least one of a format indicator, a TXOP period, a BSS color field, a DCM indicator, a CRC, and a tail field. Information of the above-described HE-SIG-A field may be joint encoded.

23B illustrates a HE-SIG-B field structure of a HE PPDU according to an embodiment of the present invention. 24 exemplifies 40 MHz, 80 MHz, and 160 MHz bandwidths, but is not limited thereto. The HE-SIG-B field may also be transmitted in units of 20 MHz. The number of OFDM symbols in the HE-SIG-B field is variable.

If the bandwidth is not greater than 20 MHz, one HE-SIG-B field is transmitted.

If the bandwidth is greater than 20 MHz, the 20 MHz sized channels transmit either odd type HE-SIG-B or even type HE-SIB B, respectively. For example, an odd type HE-SIG-B and an even type HE-SIG-B may be alternately transmitted. The odd 20 MHz channel transmits the odd type HE-SIG-B, and the even 20 MHz channel transmits the even type HE-SIG-B. More specifically, for 40 MHz bandwidth, the odd type HE-SIG-B is transmitted on the first 20 MHz channel and the even type HE-SIG-B is transmitted on the second 20 MHz channel. For 80 MHz bandwidth, odd type HE-SIG-B is transmitted on the first 20 MHz channel, even type HE-SIG-B is transmitted on the second 20 MHz channel, and the same odd type HE-SIG-B is third Repeated transmission on the 20 MHz channel, the same even type HE-SIG-B is repeatedly transmitted on the fourth 20 MHz channel. Similar transmission in the 160 MHz bandwidth.

As such, the HE-SIG-B may be repeatedly transmitted as the bandwidth increases. The HE-SIG-B repeatedly transmitted is 20 MHz from the 20 MHz channel to which the same type of HE-SIG-B is transmitted. Frequency hopping by size can be transmitted.

Meanwhile, the per user HE-SIG-B of each of the odd type HE-SIG-B and the even type HE-SIB B may be different. However, all odd type HE-SIG-Bs have the same per user HE-SIG-B. Similarly, even type HE-SIG-Bs all have the same per user HE-SIG-B.

According to an embodiment, the odd type HE-SIG-B includes only resource allocation information for odd 20 MHz channels, and the even type HE-SIG-B includes only resource allocation information for even 20 MHz channels. It can be set to. Alternatively, according to another embodiment of the present invention, the odd-type HE-SIG-B includes resource allocation information for at least some of the even-numbered 20 MHz channels, or the even-type HE-SIG-B is odd-numbered 20 Resource allocation information for at least some of the MHz channels may be included.

The HE-SIG-B may include user specific information. For example, the user specific information may include at least one of a station AID, resource allocation information (eg, allocation size), STA-specific MCS, NSTS, Coding, STBC, and transmit beamforming information for DL-OFDMA PPDU. It doesn't work.

More specifically, the HE-SIG-B may include a common field and a user specific field. The common field may precede the user specific field. The common field contains information about all of the STAs designated to receive the PPDU in that bandwidth. The common field may include resource unit allocation information. The user specific field may include a plurality of subfields, and the subfields may include information specific to an individual STA designated to receive a PPDU. The common field and the user specific field may be distinguished in bit units, not in OFDM symbol units.

23C illustrates an encoding structure of HE-SIG-B according to an embodiment of the present invention. Referring to FIG. 23C, information of two users is jointly encoded for each BCC block except the last binary convolution code (BCC) block in a user specific field. The information of the joint-encoded users includes STA ID, information on a single user assignment of the RU (eg, NSTS, transmit beamforming, MCS and Coding), and each user information on multiple user assignment of the RU (eg, Spatial Configuration field, MCS). , Coding) may be included, but is not limited thereto.

● MU transfer

FIG. 24 is a diagram illustrating a method for performing UL MU transmission in an AP station and a non-AP station.

As described above, the AP may acquire a TXOP capable of accessing the medium and transmit the signal by occupying the medium through competition. In this case, referring to FIG. 24, the AP station may transmit a trigger frame to a plurality of stations in order to perform UL MU transmission. In this case, as an example, the trigger frame may include information on a resource allocation position and size, station IDs, MCS, MU type (= MIMO, OFDMA), and the like as UL MU allocation information. That is, the AP station may be a frame that transmits a trigger frame to a plurality of stations so that the plurality of stations can perform uplink data transmission. In this case, as an example, the plurality of stations may transmit data to the AP after SIFS has elapsed based on the format indicated by the trigger frame. Thereafter, the AP may transmit ACK / NACK information to the station, thereby performing UL MU transmission.

FIG. 25 illustrates an Aggregate-MPDU (A-MPDU) frame structure for UL MU transmission. In the UL MU transmission, a plurality of stations may respectively receive resource allocation information for themselves and perform data transmission at the same time. For this purpose, the A-MPDU format may be used. In more detail, referring to FIG. 25A, an A-MPDU may include a plurality of A-MPDU subframe fields and an end of frame (EOF) pad field. In this case, information on each of the plurality of stations may be transmitted through each A-MPDU subframe. In this case, as an example, referring to FIG. 25B, an A-MPDU subframe may include an MPDU delimiter, an MPDU, and a PAD field. Also, as an example, referring to FIG. 25C, the MPDU delimiter field may include an EOF, MPDU length, CRC, Delimiter Signature field, and Reserved field.

For example, the EOF field may consist of 1 bit. In this case, the EOF field may be a field indicating whether the end of the frame or not. At this time, as an example, the A-MPDU subframe in which the MPDU length field is set to 0 and the EOF is set to 1 as the A-MPDU subframe cannot be located before other A-MPDUs in which the EOF is set to 0. That is, the A-MPDU subframe in which the MPDU length field is 0 and the EOF is 1 may be the last A-MPDU subframe of the frame.

In addition, the MPDU length field may be a field indicating the length of the MPDU. At this time, if the MPDU length field is set to 0, the MPDU may not exist. Also, as an example, an A-MPDU subframe in which the MPDU length field is set to 0 may be used to indicate a start or last frame.

In addition, the Delimiter Signature field may be formed in an independent pattern to search for the MPDU delimiter. That is, it may be a field used to distinguish each A-MPDU subframe.

Hereinafter, unless there is a specific limitation of the AP, the term STA may be used to mean a non-AP STA.

In IEEE 802.11ax, the AP may transmit and receive signals with multiple users based on OFDMA or MU-MIMO.

FIG. 26 illustrates resources available in a 20 MHz channel when transmitting a signal based on OFDMA. The number in the block means the number of tones (e.g., subcarriers).

Referring to FIG. 26, up to 9 STAs may be supported when transmitting signals using the smallest chunk (e.g., 26 tones), and up to 8 STAs may be supported when using MU-MIMO.

Hereinafter, the schemes for reducing the overhead of HE-SIG-B, which increases as the number of STAs increases.

● HE- SIG Multiple MCSs for -B Fields

Hereinafter, a method of using multiple MCSs for the HE-SIG-B field will be described. According to the existing WLAN system, only a single MCS (e.g., MCS0) was used in the SIG field (eg, the L-SIG field). However, according to embodiments of the present invention, by using multiple MCSs for the HE-SIG-B field, overhead of the HE-SIG-B can be reduced.

The indexes of the following embodiments are merely to aid understanding of the invention, and the scope of the present invention is not limited by the order of the indexes, and embodiments having different indices may be combined.

First Example

For convenience of description, multiple MCSs are illustrated, for example, but not limited to, MCS0, MCS1, MCS3, and MCS5. In addition, the HE-SIG-B information of an individual user included in the HE-SIG-B field is called per user HE-SIG-B. For example, one HE-SIG-B field may include a plurality of per user HE-SIG-Bs.

According to an embodiment of the present invention, the number of bits of per user HE-SIG-B may be configured in consideration of 1x symbol units of the HE-SIG-B field. In this case, even different per user HE-SIG-Bs may have the same size. As such, multiple MCSs may be applied to per user HE-SIG-Bs having the same information size.

Assuming that the information size of per user HE-SIG-Bs is the same as 26 bits and that MCS0, MCS1, MCS3, and MCS5 are used as multiple MCSs, the number of tones required per per HE-SIG-B is 52, 26, 13, (13/2).

Of the total 242 tones (e.g., subcarriers) of the 20 MHz channel, the number of available tones for the HE-SIG-B field is 52. Accordingly, as shown in FIG. 27, when transmitting the HE-SIG-B field using MCS0, MCS1, MCS3, and MCS5, 1, 2, 4, and 8 STAs are stored in one block (eg, 1 symbol), respectively. Per user HE-SIG-B can be transferred to the network. For convenience of description, it is assumed that the size of one unit block is one symbol, but the present invention is not limited thereto. As such, since per user HE-SIG-B for a plurality of STAs may be transmitted in one symbol, overhead of the HE-SIG-B field may be reduced during MU transmission.

On the other hand, assuming that per user HE-SIG-B is composed of one symbol when using MCS0 among multiple MCSs, when using MCS1, MCS3, and MCS5, per user HE-SIG-B is 1/2 symbol each. , 1/4 symbol and 1/8 symbol length. Therefore, even when supporting multiple users, the canonical HE-SIG-B field transmission structure, that is, transmission of the HE-SIG-B field in units of one symbol is possible.

The information on the multiple MCSs described above may be included in the HE-SIG-A field and transmitted. For example, if a total of four MCSs are available, each MCS may be indicated by using 2-bit in the HE-SIG-A field.

2nd Example

The maximum number of resource units (RU) available by the STA in the 20 MHz channel is nine. In this embodiment, the configuration of the MCS of the HE-SIG-B field for transmitting per user HE-SIG-B of 9 STAs corresponding to nine RUs in one symbol is proposed.

For convenience of description, MCS Set A = {MCS0, MCS1, MCS3, MCS5, MCS6} is illustrated, but is not limited thereto.

Assuming that the size of the HE-SIG-B information for one STA is 26-bit, as shown in FIG. 28, a STA that can be scheduled through one block (eg, 1 symbol) of the HE-SIG-B field The number of is 1, 2, 4, 8 and 9 for each MCS (ie, MCS0, MCS1, MCS3, MCS5, MCS6). For convenience of description, it is assumed that the size of one unit block is one symbol, but the present invention is not limited thereto.

MCS information of the HE-SIG-B field may be indicated through the HE-SIG-A field, and when MCS Set A is used, the MCS indicator transmitted through the HE-SIG-A field may be configured as 3-bit. have.

On the contrary, in order to reduce the overhead of the HE-SIG-A field, the MCS set B may be configured with four MCSs except for one of the five MCSs included in the MCS Set A. The MCS indicator for MCS Set B may be configured with 2-bits. For example, it may be configured as MCS Set B = {MCS0, MCS1, MCS3, MCS6}.

In another embodiment, MCS Set C = {MCS0, MCS1, MCS3, MCSX} may be used. MCSX of MCS Set C may be variable. For example, MCS6 or MCS7 can be used as MCSX. Whether MCS6 or MCS7 is used as the MCSX may be explicitly signaled, but may be implicitly predefined according to the radio channel situation. For example, if the reception environment of the STA is relatively good, MCS7 may be used instead of MCS6 to simultaneously support more STAs on a limited channel.

According to another embodiment, in consideration of the low SNR and the High SNR of the STAs, the AP selects two low MCSs corresponding to the low SNR among MCS0 to MCS7, and selects and uses the high MCS2 corresponding to each of the High SNRs. Can be.

The third Example

In Embodiments 1 and 2 described above, per user HE-SIG-B of 2n (n is a natural number) STAs are transmitted in one block (e.g., 1 symbol) of the HE-SIG-B field. Therefore, per user HE-SIG-B of three or five STAs may not be transmitted in one symbol. For convenience of description, it is assumed that the size of one unit block is one symbol, but the present invention is not limited thereto.

This embodiment proposes a method for transmitting per user HE-SIG-B for three or five STAs while maintaining the canonical transmission structure of the HE-SIG-B field to the maximum.

According to an embodiment of the present invention, MCS Set D = {MCS0, MCS1, MCS2, MCS3, MCS4, MCS5, MCS6} may be used. The number of per user HE-SIG-Bs of STAs included in one symbol for each MCS of MCS Set D is 1, 2, 3, 4, 6, 8, and 9, respectively, as shown in FIG. The MCS indicator for MCS Set D consists of 3 bits and can be transmitted through the HE-SIG-A field.

On the other hand, the MCS set proposed for the HE-SIG-B field in Embodiments 1, 2, and 3 described above is used as a case where the HE-SIG-B field canonically transmitted, but the present invention is not limited thereto. . For example, in addition to the case where the HE-SIG-B field canonically configured and transmitted, Embodiments 1, 2, or 3 described above may be used to transmit information on a plurality of STAs, where the MCS is determined according to the number of STAs. Can be determined.

In addition, the above-described embodiments are not limited to DL MU transmission and may also be used for UL MU transmission.

30 shows a flow of a method for transmitting and receiving a signal based on the embodiments described above. Descriptions overlapping with the above-described embodiments may be omitted. Hereinafter, it is assumed that the first STA is an AP STA and the second STA is a non-AP STA, but this is for convenience of description only, and the first STA is a non-AP STA or the second STA is an AP STA. Can be. Further, although only the first STA and the second STA are shown to avoid blurring the subject matter of the description, those skilled in the art may understand that there may be other STAs that transmit and receive MU frames.

Referring to FIG. 30, first, a first STA selects multiple MCS levels to be used for SIG-B (S3005). MCS levels may be selected from an MCS set. The MCS set may include at least one fixed MCS level and at least one variable MCS level. Meanwhile, the MCS levels include at least one MCS level corresponding to a station having a minimum signal to noise ratio (SNR) among a plurality of stations receiving an MU frame and at least one MCS level corresponding to a station having a maximum SNR. can do.

The first STA encodes the SIG-A field and the SIG-B field, respectively (S3010). For example, the first STA may jointly encode M individual user SIG-Bs into N unit blocks. Here, M may be a natural number of two or more, and N may be a natural number smaller than M. According to an embodiment, M may correspond to the total number of STAs receiving MU frames. In addition, N may be determined according to the size of the SIG-B field. As shown in FIGS. 27 to 29, one unit block may correspond to one symbol, but is not limited thereto.

In the first STA encoding the SIG-B field, multiple MCS levels different from each other may be set in the unit blocks. For example, a first MCS level may be applied to the first unit block, and a second MCS level may be applied to the second unit block.

According to an embodiment, the number of individual user SIG-Bs jointly encoded per unit block may be different from each other, but the size of the individual user SIG-Bs may be the same. In addition, the number of individual user SIG-Bs may be determined for each unit block so that unit blocks in which different MCS levels are set have a length of one symbol.

The first STA may include information on multiple MCS levels configured in the unit blocks in the SIG-A field. That is, multiple MCS levels may be indicated by the SIG-A field.

The first STA transmits an MU frame including the SIG-A and SIG-B fields (S3615). The MU frame may be transmitted on a 20 MHz, 40 MHz, 80 MHz or 160 MHz bandwidth based on orthogonal frequency divisional multiple access (OFDMA).

The second STA decodes the SIG-A field included in the MU frame (S3620). For example, the second STA may obtain information about multiple MCS levels applied to the SIG-B field by decoding the SIG-A field.

The second STA decodes the SIG-B field based on the SIG-A field (S3625). The second STA may use information obtained from the SIG-A field, for example, information on multiple MCS levels, to decode the SIG-B field.

The second STA obtains an individual user SIG-B of the second STA from the decoded SIG-B field (S3630). Since the SIG-B field includes the individual user SIG-B of another STA in addition to the individual user SIG-B of the second STA, the second STA acquires only its individual user SIG-B and discards information on other STAs. can do.

The second STA obtains data in the resource region indicated by the individual user SIG-B of the second STA.

31 is a block diagram illustrating an exemplary configuration of an AP device (or base station device) and a station device (or terminal device) according to an embodiment of the present invention.

The AP 100 may include a processor 110, a memory 120, and a transceiver 130. The station 150 may include a processor 160, a memory 170, and a transceiver 180.

The transceivers 130 and 180 may transmit / receive radio signals and may implement, for example, a physical layer in accordance with the IEEE 802 system. The processors 110 and 160 may be connected to the transceivers 130 and 180 to implement a physical layer and / or a MAC layer according to the IEEE 802 system. Processors 110 and 160 may be configured to perform operations in accordance with one or more combinations of the various embodiments of the invention described above. In addition, the modules for implementing the operations of the AP and the station according to various embodiments of the present invention described above may be stored in the memory 120 and 170, and may be executed by the processors 110 and 160. The memories 120 and 170 may be included in the processors 110 and 160 or may be installed outside the processors 110 and 160 and connected to the processors 110 and 160 by a known means.

The above descriptions of the AP device 100 and the station device 150 may be applied to a base station device and a terminal device in another wireless communication system (eg, LTE / LTE-A system).

The detailed configuration of the AP and the station apparatus as described above, may be implemented to be applied independently or the two or more embodiments described at the same time described in the various embodiments of the present invention, overlapping description is omitted for clarity do.

32 illustrates an exemplary structure of a processor of an AP device or a station device according to an embodiment of the present invention.

The processor of an AP or station may have a plurality of layer structures, and FIG. 32 intensively focuses on the MAC sublayer 3810 and the physical layer 3820 among these layers, particularly on a Data Link Layer (DLL). Represented by As shown in FIG. 32, the PHY 3820 may include a Physical Layer Convergence Procedure (PLCP) entity 3811 and a Physical Medium Dependent (PMD) entity 3822. Both the MAC sublayer 3810 and the PHY 3820 each contain management entities conceptually referred to as a MAC sublayer management entity (MLME) 3811. These entities 3811 and 3821 provide a layer management service interface on which layer management functions operate.

In order to provide correct MAC operation, a Station Management Entity (SME) 3830 exists within each station. SME 3830 is a layer-independent entity that may appear within a separate management plane or appear to be off to the side. Although the precise functions of the SME 3830 are not described in detail herein, in general, this entity 3830 collects layer-dependent states from various Layer Management Entities (LMEs) and values of layer-specific parameters. It can be seen that it is responsible for such functions as setting. SME 3830 can generally perform these functions on behalf of a generic system management entity and implement standard management protocols.

The entities shown in FIG. 32 interact in various ways. 32 shows some examples of exchanging GET / SET primitives. The XX-GET.request primitive is used to request the value of a given MIB attribute (management information based attribute information). The XX-GET.confirm primitive is used to return the appropriate MIB attribute information value if the Status is "Success", otherwise it is used to return an error indication in the Status field. The XX-SET.request primitive is used to request that the indicated MIB attribute be set to a given value. If the MIB attribute means a specific operation, this is to request that the operation be performed. And, the XX-SET.confirm primitive confirms that the indicated MIB attribute is set to the requested value when status is "success", otherwise it is used to return an error condition in the status field. If the MIB attribute means a specific operation, this confirms that the operation has been performed.

As shown in FIG. 32, MLME 3811 and SME 3830 can exchange various MLME_GET / SET primitives through MLME_SAP 3850. In addition, various PLCM_GET / SET primitives can be exchanged between PLME 3821 and SME 3830 via PLME_SAP 3860, and MLME 3811 and PLME 3870 via MLME-PLME_SAP 3870. Can be exchanged between.

Embodiments of the present invention described above may be implemented through various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

For implementation in hardware, a method according to embodiments of the present invention may include one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), and Programmable Logic Devices (PLDs). It may be implemented by field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of a module, a procedure, or a function that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable any person skilled in the art to make and practice the invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. In addition, while the preferred embodiments of the present specification have been shown and described, the present specification is not limited to the specific embodiments described above, and the technical field to which the present invention belongs without departing from the gist of the present specification claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or prospect of the present specification.

In the present specification, both the object invention and the method invention are described, and the description of both inventions may be supplementarily applied as necessary.

As described above, embodiments of the present invention can be applied to various wireless communication systems, including IEEE 802.11 systems.

Claims (15)

1. In a method for receiving a signal from a station (STA) in a wireless LAN system,

   M individual user SIG-Bs receive a multi-user frame comprising a SIG-B field and a SIG-A field jointly encoded into N unit blocks smaller than M step;

   Decoding the SIG-B field based on the SIG-A field; And

   Obtaining an individual user SIG-B of the station from the decoded SIG-B field;

   Multiple MCS levels different from each other are set in the unit blocks, and the MCS levels set in the unit blocks are indicated by the SIG-A field.
2. The method of claim 1,

   The number of the individual user SIG-Bs joint-encoded per unit block is different from each other, but the size of the individual user SIG-Bs are the same.
3. The method of claim 1,

   Wherein the number of individual user SIG-Bs is determined for each unit block such that the unit blocks for which the different MCS levels are set have a length of one symbol.
4. The method of claim 1, wherein the multiple MCS levels are:

   And a set of MCSs comprising at least one fixed MCS level and at least one variable MCS level.
5. The method of claim 1, wherein the multiple MCS levels are:

   Receiving at least one MCS level corresponding to a station having a minimum signal to noise ratio (SNR) among the plurality of stations receiving the MU frame and at least one MCS level corresponding to a station having a maximum SNR; Way.
6. The method of claim 1, wherein the MU frame,

   A signal receiving method received on a 20 MHz, 40 MHz, 80 MHz or 160 MHz bandwidth based on orthogonal frequency divisional multiple access (OFDMA).
7. In the method for transmitting an AP signal in a WLAN system,

   Joint encoding M individual user SIG-Bs into N unit blocks smaller than M; And

   Transmitting a multi-user frame including a SIG-B field and a SIG-A field including the unit blocks,

   Multiple MCS levels different from each other are set in the unit blocks, and the MCS levels set in the unit blocks are indicated by the SIG-A field.
8. The method of claim 7, wherein

   The number of jointly encoded individual user SIG-Bs per unit block is different from each other, but the size of the individual user SIG-Bs are the same.
9. The method of claim 7, wherein

   And the number of individual user SIG-Bs is determined for each unit block such that the unit blocks for which the different MCS levels are set have a length of one symbol.
10. The method of claim 7, wherein the multiple MCS levels,

    And a set of MCSs comprising at least one fixed MCS level and at least one variable MCS level.
11. The method of claim 7, wherein the multiple MCS levels,

    A signal transmission comprising at least one MCS level corresponding to a station having a minimum signal to noise ratio (SNR) among the plurality of stations receiving the MU frame and at least one MCS level corresponding to a station having a maximum SNR. Way.
12. In the station (STA),

    M individual user SIG-Bs receive a multi-user frame comprising a SIG-B field and a SIG-A field jointly encoded into N unit blocks smaller than M receiving set; And

    A processor that decodes the SIG-B field based on the SIG-A field and obtains an individual user SIG-B of the station from the decoded SIG-B field;

    Multiple MCS levels different from each other are set in the unit blocks, and the MCS levels set in the unit blocks are indicated by the SIG-A field.
13. The method of claim 12,

    Wherein the number of jointly encoded individual user SIG-Bs per unit block is different from each other, but the sizes of the individual user SIG-Bs are the same.
14. The method of claim 12,

    The number of individual user SIG-Bs is determined for each unit block such that the unit blocks for which the different MCS levels are set have a length of one symbol.
15. The method of claim 12, wherein the multiple MCS levels are:

    And a MCS set comprising at least one fixed MCS level and at least one variable MCS level.

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