KR101958758B1 - Method for transmitting data frame in wireless local area network and apparatus for the same - Google Patents

Abstract

A method and apparatus for transmitting data frames in a WLAN system are provided. The data frame includes a service field and a data field. The data fields are scrambled by a scrambling sequence. The service field is determined based on the set of TXVECTOR parameters, wherein the TXVECTOR parameters include control information for the service field.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for transmitting a data frame in a wireless local area network (WLAN) system, and a device supporting the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a wireless local area network (WLAN) system, and more particularly, to a method of transmitting a data frame by a sender in a wireless LAN system and an apparatus for supporting the same.

Recently, various wireless communication technologies have been developed along with the development of information communication technologies. Among these, a wireless LAN (WLAN) is a home network, a company, or a home network using a portable terminal such as a personal digital assistant (PDA), a laptop computer, a portable multimedia player (PMP) It is a technology that enables wireless access to the Internet in the service area.

IEEE 802.11n is a relatively recently established technical standard to overcome the limitation of communication speed which is pointed out as a weak point in wireless LAN. IEEE 802.11n aims to increase the speed and reliability of the network and to extend the operating distance of the wireless network. More specifically, IEEE 802.11n supports high throughput (HT) with data rates of up to 540 Mbps or higher, and uses multiple antennas at both ends of the transmitter and receiver to minimize transmission errors and optimize data rates. It is based on Multiple Inputs and Multiple Outputs (MIMO) technology.

With the spread of WLAN and the diversification of applications using it, there is a need for a new WLAN system to support a higher throughput than the data processing rate supported by IEEE 802.11n. The next generation wireless LAN system supporting Very High Throughput (VHT) is the next version of the IEEE 802.11n wireless LAN system. To support data processing speed of 1Gbps or higher in the MAC service access point (SAP) Is one of the newly proposed IEEE 802.11 wireless LAN systems.

The next generation wireless LAN system supports transmission of MU-MIMO (Multi User Multiple Input Multiple Output) method in which a plurality of non-AP STAs simultaneously access channels in order to utilize wireless channels efficiently. According to the MU-MIMO transmission scheme, an AP can simultaneously transmit frames to one or more MIMO-paired stations (STAs).

Next-generation WLAN systems can support 80 MHz, 160 MHz (contiguous 160 MHz), non-contiguous 80 + 80 MHz (non-contiguous 80 + 80 MHz) and higher channel bandwidths to support higher throughput rates. The next generation wireless LAN system also supports the transmission and reception of duplicated data units, and can support dynamic bandwidth operation in this case. As described above, in relation to the functions that can be supported in the next generation wireless LAN system, there is a method of processing data to be transmitted by the transmitting STA and transmitting the data, a method of receiving the transmitted data normally, A device is required.

SUMMARY OF THE INVENTION The present invention provides a method for transmitting data frames in a wireless LAN system and a device supporting the same.

In one aspect, a wireless device transmitting a data frame in a wireless LAN system includes a medium access control (MAC) unit for generating a data frame, a PHY (Physical) unit for transmitting a wireless signal of the data frame, And a processor operatively coupled to the PHY unit and controlling a set of TXVECTOR parameters. The processor generates the data frame, wherein the data frame includes a data field including a service field and VHT-SIG-B, which is very high throughput (VHT) signal information, and an operating channel bandwidth Wherein the data field is scrambled by a scrambling sequence, wherein the scrambling sequence is based on an initial scrambling sequence and a generator polynomial, And the service field is determined based on the set of TXVECTOR parameters, wherein the TXVECTOR parameters include control information for the service field.

In another aspect, a method for transmitting data frames in a wireless LAN includes generating a data frame, the data frame including a service field and a data field including VHT-SIG-B, which is Very High Throughput (VHT) signal information; And transmitting the wireless signal of the data frame over an operating channel bandwidth. Wherein the data field is scrambled by a scrambling sequence, wherein the scrambling sequence is generated based on an initial scrambling sequence and a generator polynomial, the service field including a set of the TXVECTOR parameters Wherein the TXVECTOR parameters include control information for the service field.

It is possible to implement channel bandwidth related information and dynamic bandwidth operation support indication information in a next generation wireless LAN system supporting transmission in a broader bandwidth by setting a scrambling sequence without implementing it in a signal field. Therefore, it is possible to transmit and receive data frames using a wider bandwidth, transmit and receive data frames including data units of duplicated format, and the like, without allocating insufficient signal fields due to a lot of information necessary for supporting MU-MIMO, And / or dynamic bandwidth operations. The initial scrambling sequence set for this can be used in a conventional WLAN system, which can guarantee backward compatibility.

In addition, in the above-described embodiment, the transmission STA may be adapted to the frame format of the WLAN system supporting the MU-MIMO (Multi User Multiple Input Multiple Output) by additionally including information parameters related to the implementation of the service field in the transmission information parameter TXVECTOR. The service field can be accurately generated. This reduces the possibility of errors such as failure of exchange of data frames between transmitting and receiving STAs, thereby ensuring more reliable communication.

1 is a diagram illustrating a configuration of a wireless local area network (WLAN) system to which an embodiment of the present invention can be applied.
2 is a diagram illustrating a physical layer architecture of a wireless LAN system supported by IEEE 802.11.
3 is a diagram showing an example of a PPDU format used in a wireless LAN system.
4 is a block diagram illustrating a format of a data field according to an embodiment of the present invention.
5 is a diagram illustrating an example of a data unit transmission method based on a PPDU generation method according to an embodiment of the present invention.
6 is a diagram illustrating an example of scrambling according to an embodiment of the present invention.
7 is a diagram illustrating an example of an initial scrambling sequence according to an embodiment of the present invention.
8 is a diagram illustrating an example of a method of receiving a PPDU generated according to an embodiment of the present invention.
9 is a block diagram illustrating a wireless device in which embodiments of the present invention may be implemented.

1 is a diagram illustrating a configuration of a wireless local area network (WLAN) system to which an embodiment of the present invention can be applied.

A WLAN system includes one or more Basic Service Sets (BSSs). A BSS is a collection of stations (STAs) that can successfully communicate and communicate with each other. It is not a concept that points to a specific area. An infrastructure BSS is one or more non-AP stations (STAs ), An AP (Access Point) 10 for providing a distribution service, and a distribution system (DS) for connecting a plurality of APs. In the infrastructure BSS, the AP manages the non-AP STAs of the BSS.

On the other hand, an independent BSS (IBSS) is a BSS operating in an ad-hoc mode. Since the IBSS does not include APs, there is no centralized management entity in the center. That is, non-AP STAs are managed in a distributed manner in the IBSS. In the IBSS, all STAs can be made as mobile STAs, and self-contained networks are established because access to the DS is not allowed.

The STA is an arbitrary functional medium including a medium access control (MAC) conforming to IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard and a physical layer interface for a wireless medium. It includes both an AP and a non-AP station.

The non-AP STA is a non-AP STA, the non-AP STA is a mobile terminal, a wireless device, a wireless transmit / receive unit (WTRU), a user equipment (UE) May also be referred to as another name, such as a mobile station (MS), a mobile subscriber unit, or simply a user. Hereinafter, non-AP STA will be referred to as STA for convenience of explanation.

An AP is a functional entity that provides access to a DS via wireless media for an associated STA to the AP. Communication between STAs in an infrastructure BSS including an AP is performed via an AP, but direct communication is also possible between STAs when a direct link is established. The AP may be referred to as a central controller, a base station (BS), a node-B, a base transceiver system (BTS), a site controller, or the like.

A plurality of infrastructure BSSs including the BSS shown in FIG. 1 may be interconnected through a distribution system (DS). A plurality of BSSs connected through a DS is referred to as an extended service set (ESS). APs 10 and / or STAs 21, 22, 23, 24 and 30 included in the ESS can communicate with each other and the STAs can move from one BSS to another BSS while seamlessly communicating with the same ESS .

In a wireless LAN system according to IEEE 802.11, the basic access mechanism of Medium Access Control (MAC) is a CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism. The CSMA / CA mechanism is also referred to as the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC, which basically employs a "listen before talk" access mechanism. According to this type of connection mechanism, the AP and / or STA senses a wireless channel or medium prior to initiating a transmission. As a result of sensing, if it is determined that the medium is in the idle status, the frame transmission is started through the medium. On the other hand, if it is detected that the medium is occupied, the AP and / or STA sets a delay period for medium access without waiting to start its own transmission.

The CSMA / CA mechanism also includes virtual carrier sensing in addition to physical carrier sensing in which the AP and / or STA directly senses the media. Virtual carrier sensing is intended to compensate for problems that may arise from media access, such as hidden node problems. For the virtual carrier sensing, the MAC of the wireless LAN system uses a network allocation vector (NAV). The NAV is a value indicating to another AP and / or the STA that the AP and / or the STA that is currently using or authorized to use the medium has remaining time until the media becomes available. Therefore, the value set to NAV corresponds to the period in which the medium is scheduled to be used by the AP and / or the STA that transmits the frame.

In addition to DCF, the IEEE 802.11 MAC protocol is a DCF and pollination-based, synchronous access scheme that uses an HCF (Point Coordination Function) that periodically polls all receiving APs and / or STAs to receive data packets. (Hybrid Coordination Function). The HCF is a protocol that allows a provider to provide data packets to a large number of users using a competing based EDCA (Enhanced Distributed Channel Access) and a non-contention based channel approach using a polling mechanism (HCCA Access). The HCF includes a medium access mechanism for improving the quality of service (QoS) of a WLAN and can transmit QoS data in both a contention period (CP) and a contention free period (CFP).

The AP and / or the STA may perform a procedure of exchanging a Request to Send (RTS) frame and a Clear to Send (CTS) frame to indicate that the media is to be accessed. The RTS frame and the CTS frame include information indicating a time interval in which a wireless medium necessary for transmitting and receiving an acknowledgment frame (ACK frame) when an actual data frame transmission and an acknowledgment is supported is reserved do. Another STA that receives the RTS frame transmitted from the AP and / or the STA to which the frame is to be transmitted or the CTS frame transmitted from the STA to which the frame is to be transmitted, transmits the RTS frame to the STA through a time interval indicated by the information included in the RTS / It can be set not to access the medium. This can be implemented through setting the NAV during the time interval.

2 is a diagram illustrating a physical layer architecture of a wireless LAN system supported by IEEE 802.11.

The PHY architecture of IEEE 802.11 includes a PHY Layer Management Entity (PLME), a Physical Layer Convergence Procedure (PLCP) sublayer 210, and a PMD (Physical Medium Dependent) sublayer 200. PLME provides the management functions of the physical layer in cooperation with the MAC Layer Management Entity (MLME). The PLCP sublayer 210 transmits an MPDU (MAC Protocol Data Unit) received from the MAC sublayer 220 to the PMD sublayer according to an instruction of the MAC layer between the MAC sublayer 220 and the PMD sublayer 200 , And delivers the frame from the PMD sublayer 200 to the MAC sublayer 220. The PMD sublayer 200 enables the transmission / reception of a physical layer entity between two stations via a wireless medium as a PLCP lower layer. The MPDU transmitted from the MAC sublayer 220 is referred to as a physical service data unit (PSDU) in the PLCP sublayer 210. MPDUs are similar to PSDUs, but individual MPDUs and PSDUs can be different when an aggregated MPDU (aggregated MPDU) aggregating multiple MPDUs is delivered.

The PLCP sublayer 210 adds an additional field including information required by the physical layer transceiver in the process of receiving the PSDU from the MAC sublayer 220 and transferring the PSDU to the PMD sublayer 200. In this case, the added field may be a PLCP preamble, a PLCP header, a tail bit for returning the convolutional encoder to a zero state, or the like, to the PSDU. The PLCP sublayer 210 receives a TXVECTOR parameter including control information necessary for generating and transmitting a PPDU and control information necessary for the receiving STA to receive and interpret the PPDU from the MAC sublayer. The PLCP sublayer 210 uses the information included in the TXVECTOR parameter in generating the PPDU including the PSDU.

The PLCP preamble serves to prepare the receiver for the synchronization function and antenna diversity before the PSDU is transmitted. The data field may include padding bits in the PSDU, a service field including a bit sequence for initializing the scrap blur, and a coded sequence in which a bit sequence with tail bits appended thereto is encoded. In this case, the encoding scheme may be selected from Binary Convolutional Coding (BCC) encoding or Low Density Parity Check (LDPC) encoding according to the encoding scheme supported by the STA receiving the PPDU. The PLCP header includes a field including information on a PLCP Protocol Data Unit (PPDU) to be transmitted. This will be described in more detail with reference to FIG.

In the PLCP sublayer 210, the above-described field is added to the PSDU to generate a PLCP Protocol Data Unit (PPDU) and transmitted to the receiving station via the PMD sublayer. The receiving station receives the PPDU and generates a PLCP preamble, data Get and restore the information needed for restoration. The PLCP sublayer of the receiving station transmits the RXVECTOR parameter including the PLCP preamble and control information included in the PLCP header to the MAC sublayer to interpret the PPDU in the receiving state and acquire the data.

Unlike existing wireless LAN systems, next generation wireless LAN systems require higher throughputs. This is called Very High Throughput (VHT). For this purpose, the next generation wireless LAN system transmits 80MHz, 160MHz continuous (contiguous 160MHz), discontinuous 80 + 80MHz (non-contiguous 80 + 80MHz) bandwidth transmission and / I want to support. In addition, a MU-MIMO (Multi User-Multiple Input Multiple Output) transmission method is provided for higher throughput. In the next generation wireless LAN system, the AP can simultaneously transmit data frames to at least one STA paired with MIMO.

1, the AP 10 transmits data to the STA group including at least one STA among a plurality of STAs 21, 22, 23, 24, and 30 associated therewith at the same time Lt; / RTI > 1 shows that the AP 10 transmits MU-MIMO to the STAs 21, 22, 23, 24, 25 and 30, In a wireless LAN system supporting a mesh network, a STA that transmits data may transmit PPDUs to a plurality of STAs using an MU-MIMO transmission scheme. Hereinafter, the AP transmits an PPDU to a plurality of STAs according to the MU-MIMO transmission scheme.

Data transmitted to each STA may be transmitted through different spatial streams. A data frame transmitted by the AP 10 may be referred to as a PPDU generated and transmitted from a physical layer (PHY) of the wireless LAN system. In the example of the present invention, it is assumed that STA1 21, STA2 22, STA3 23 and STA4 24 are STA groups that are paired with AP 10 and MU-MIMO. At this time, since a spatial stream is not allocated to a specific STA of a transmission target STA group, data may not be transmitted. On the other hand, it is assumed that the STAa 30 is an STA that is coupled to the AP but is not included in the STA group to be transmitted.

In the wireless LAN system, an identifier may be assigned to a STA group to be transmitted, which is referred to as a group identifier (Group ID). The AP transmits a Group ID management frame including group definition information to the STAs supporting the MU-MIMO transmission, and the group ID is transmitted to the STAs supporting the MU-MIMO transmission before the PPDU transmission Lt; / RTI > One STA can be assigned a plurality of group IDs.

Table 1 below shows the information elements included in the group ID management frame.

Order Information One Category 2 VHT Action 3 Membership status 4 Spatial stream position < RTI ID = 0.0 >

The category field and the VHT action field are set so that the corresponding frame corresponds to a management frame and is a group ID management frame used in the next generation wireless LAN system. As shown in Table 1, the group definition information belongs to a specific group ID And a spatial stream position information indicating a position of a corresponding spatial stream in the STA corresponding to the corresponding group ID in a total spatial stream according to the MU-MIMO transmission. Since there are a plurality of group IDs managed by one AP, the membership status information provided to one STA needs to indicate whether each STA belongs to each group ID managed by the AP. Thus, the membership state information may exist in the form of an array of subfields indicating whether or not they belong to each group ID. The spatial stream location information indicates a location for each group ID, and therefore may exist in the form of an array of subfields indicating the location of the spatial stream set occupied by the STA for each group ID. In addition, the membership state information and the spatial stream position information for one group ID can be implemented in one subfield.

When transmitting the PPDU to the plurality of STAs through the MU-MIMO transmission scheme, the AP transmits information indicating the group ID in the PPDU as control information. When the STA receives the PPDU, the STA checks the group ID field to confirm that the STA is the member STA of the STA group to be transmitted. If it is confirmed that the STA group is a member of the STA group to which the STA is to be transmitted, it is possible to confirm how many spatial stream sets transmitted to the STA group are located among the entire spatial streams. Since the PPDU includes information on the number of spatial streams allocated to the receiving STA, the STA can receive data by searching for the spatial streams assigned to the receiving STA.

3 is a diagram showing an example of a PPDU format used in a wireless LAN system.

3, the PPDU 300 includes an L-STF 310, an L-LTF 320, an L-SIG field 330, a VHT-SIGA field 340, a VHT- STF 350, LTF 360, a VHT-SIGB field 370, and a data field 380.

The PLCP sublayer constituting the PHY adds necessary information to the PSDU received from the MAC layer and converts the data into a data field 380. The L-STF 310, the L-LTF 320, the L-SIG field 330, SIGA field 340, VHT-STF 350, VHT-LTF 360 and VHT-SIGB 370 are added to generate a PPDU 300, and one or more PMD sub- To the STA. The control information required for the PLCP sublayer to generate the PPDU is provided from the TXVECTOR parameter received from the MAC layer. On the other hand, the control information used by the receiving STA to receive and interpret the PPDU is provided from the RXVECTOR parameter based on the control information contained in the PLCP header of the PPDU.

The L-STF 310 is used for frame timing acquisition, automatic gain control (AGC) convergence, coarse frequency acquisition, and the like.

The L-LTF 320 uses channel estimation for demodulation of the L-SIG field 330 and the VHT-SIGA field 340.

The L-SIG field 330 is used by the L-STA to receive and interpret the PPDU 300 and obtain data. The L-SIG field 330 includes a rate subfield, a length subfield, a parity bit, and a tail field. The rate subfield is set to a value indicating a bit rate for the data to be currently transmitted.

The length subfield is set to a value indicating the octet length of the PSDU requesting the MAC layer to transmit to the PHY layer. The L_LENGTH parameter, which is a parameter related to the octet length information of the PSDU, is determined based on the TXTIME parameter, which is a parameter related to the transmission time. TXTIME indicates a transmission time determined by the PHY layer for transmission of a PPDU including a PSDU in response to a transmission time requested by the MAC layer for transmission of a physical service data unit (PSDU). Accordingly, since the L_LENGTH parameter is a time-related parameter, the length subfield included in the L-SIG field 330 includes information related to the transmission time.

The VHT-SIGA field 340 contains control information (or signal information) necessary for the STAs receiving the PPDU to interpret the PPDU 300. The VHT-SIGA field 340 is transmitted in two OFDM symbols. Accordingly, the VHT-SIGA field 340 can be divided into the VHT-SIGA1 field and the VHT-SIGA2 field. The VHT-SIGA1 field includes channel bandwidth information used for PPDU transmission, identification information related to whether or not Space Time Block Coding (STBC) is used, information indicating a method of transmitting a PPDU among SU or MU-MIMO, In the case of MU-MIMO, information indicating a STA group to be transmitted, which is a plurality of STAs paired with an AP and an MU-MIMO, and information on a spatial stream allocated to each STA included in the STA group to be transmitted. The VHT-SIGA2 field contains short GI (short GuardInterval) related information.

The information indicating the MIMO transmission scheme and the information indicating the STA group to be transmitted may be implemented as one MIMO indication information, and may be implemented as a group ID, for example. The group ID may be set to a value having a specific range, and a specific value in the range indicates the SU-MIMO transmission scheme. Otherwise, when the PPDU 300 is transmitted in the MU-MIMO transmission scheme, It can be used as an identifier for STA group.

If the group ID indicates that the corresponding PPDU 300 is transmitted through the SU-MIMO transmission scheme, the VHT-SIGA2 field indicates whether the coding scheme applied to the data field is Binary Convolution Coding (BCC) or Low Density Parity Check (LDPC) And modulation coding scheme (MCS) information for the channel between the sender and the receiver. Further, the VHT-SIGA2 field may include a partial AID (partial AID) including an AID of a transmission target STA of the PPDU and / or a partial bit sequence of the AID.

When the group ID indicates that the corresponding PPDU 300 is transmitted through the MU-MIMO transmission scheme, the VHT-SIGA field 300 indicates that the coding scheme applied to the data field to which transmission is intended to the MU-MIMO paired receiving STAs is BCC Coding instruction or LDPC coding. In this case, modulation coding scheme (MCS) information for each receiving STA may be included in the VHT-SIGB field 370.

The VHT-STF 350 is used to improve the performance of AGC estimation in MIMO transmission.

The VHT-LTF 360 is used by the STA to estimate the MIMO channel. Since the next generation wireless LAN system supports MU-MIMO, the VHT-LTF 360 can be set to the number of spatial streams to which the PPDU 300 is transmitted. In addition, full channel sounding is supported, and the number of VHT LTFs can be increased when it is performed.

The VHT-SIGB field 370 contains dedicated control information necessary for a plurality of MIMO paired STAs to receive the PPDU 300 and obtain the data. Therefore, the STA is designed to decode the VHT-SIGB field 370 only when the common control information included in the VHT-SIGB field 370 indicates that the PPDU 300 currently received is MU-MIMO-transmitted . Conversely, the STA may be designed not to decode the VHT-SIGB field 370 if the PPDU 300 in which the common control information is currently received indicates that it is for a single STA (including SU-MIMO).

The VHT-SIGB field 370 contains information on the modulation and coding scheme (MCS) and rate-matching for each STA. It also includes information indicating the PSDU length included in the data field for each STA. The information indicating the length of the PSDU is information indicating the length of the bit sequence of the PSDU, and can be indicated in units of an octet. The size of the VHT-SIGB field 370 may vary depending on the type of MIMO transmission (MU-MIMO or SU-MIMO) and the channel bandwidth used for PPDU transmission.

The data field 380 contains data intended for transmission to the STA. The data field 380 includes a service field for initializing a scrambler and a PLCP service data unit (PSDU) to which a MAC protocol data unit (MPDU) is transmitted in the MAC layer, a service field for initializing a convolution encoder, a tail field including a bit sequence necessary for returning the data field to a normal state, and padding bits for normalizing the length of the data field.

The STA1 21, the STA2 22 and the STA3 23 in the case where the AP 10 wants to transmit data to the STA1 21, the STA2 22 and the STA3 23 in the given wireless LAN system as shown in Fig. And the STA4 24 to the STA group. In this case, it is possible to allocate no spatial stream allocated to the STA4 24 as shown in FIG. 2, assign a specific number of spatial streams to each of the STA1 21, the STA2 22 and the STA3 23, Lt; / RTI > In the example shown in FIG. 2, it can be seen that one spatial stream is allocated to STA1 21, three spatial streams are allocated to STA2 22, and two spatial streams are allocated to STA3.

4 is a block diagram illustrating a format of a data field according to an embodiment of the present invention.

4, the data field 400 includes a service field 410, a data unit 420, padding bits 430, and a tail field 440.

The service field 410 may include a bit sequence for initializing a scrambler and a CRC (Cyclic Redundancy Check) bit sequence calculated for the corresponding VHT-SIGB field transmitted to the receiving STA. The concrete structure of the service field and the step of generating the service field by the transmission STA will be described later in detail.

Data unit 420 is a data unit carried in the MAC layer, which may be a PSDU. The length of the PSDU may be different for each receiving STA, and even if the same receiving STA is used, the length may be different according to a transmitted spatial stream. However, in transmitting a PPDU by a transmitting STA, the length of the PPDU is the same, and accordingly, it is necessary to set the length of the data field to be the same. Thus, padding bits 430 are appended to data unit 420. Meanwhile, the length of the padding bits 430 added to the data unit 420 may vary depending on the length of the data unit, and padding bits may not be added to some data units.

The tail field 440 may be included only when encoding the bit sequence constituting the data field according to the BCC encoding scheme, which may include a bit sequence used to make the BCC encoder a zero state. Since the encoding schemes that can be supported by each STA are different and encoding methods to be applied to data units transmitted to each STA may be different, a data field for a specific STA includes a tail field, and a data field for another specific STA includes a tail field May not be included. Hereinafter, an example of a data unit transmission method through PPDU generation and transmission will be described in detail.

5 is a diagram illustrating an example of a data unit transmission method based on a PPDU generation method according to an embodiment of the present invention.

Referring to FIG. 5, the MAC layer transmits the generated data unit, that is, MPDU or A-MPDU to the PLCP sublayer. In the PLCP sublayer, the MPDU or the A-MPDU is referred to as a PSDU. The PLCP sublayer transmits the PSDU to another STA through the PHY layer and adds control information necessary for another STA to receive, demodulate, and decode the corresponding PPDU to acquire data. The control information may be included in the L-SIG field, the VHT-SIGA field, and the VHT-SIGB field, and a tail field may be additionally added according to the type of the encoder (in the case of a BCC encoder). Adding the control information in the PLCP sublayer may be based on the TXVECTOR parameter transmitted from the MAC layer to the PHY layer.

The TXVECTOR parameter is an information parameter indicating a bandwidth for data unit transmission of a duplicated format applied to the PSDU and / or information indicating whether or not to support a dynamic bandwidth operation in transmitting the replicated data unit Parameter. ≪ / RTI > The bandwidth indication information parameter indicates the transmission bandwidth, and the bandwidth value can be set to 20 MHz, 40 MHz, 80 MHz, 160 MHz and / or 80 + 80 MHz. The dynamic bandwidth indication information parameter is set to indicate 'Dynamic' if dynamic bandwidth operation is supported, otherwise it can be set to indicate 'Static', which can be implemented with one bit. When the dynamic bandwidth indication information parameter is set to a value indicating " Dynamic ", the receiving STA may transmit a data unit responding to the data unit to the transmitting STA using all or a portion of the channel band in which the data unit is transmitted . On the other hand, if the value is set to a value indicating 'Static', the receiving STA can transmit to the transmitting STA a data unit responding using only the channel band in which the data unit is transmitted. Using the channel bandwidth may mean that the bandwidth indication information parameter of the TXVECTOR for the responding data unit is set to the corresponding bandwidth value.

On the other hand, the bandwidth indication information parameter and / or the dynamic bandwidth indication information parameter may be based on a procedure for generating a scrambling code for scrambling the data field. This will be described in more detail below.

Table 2 below shows the configuration of the TXVECTOR parameter.

Parameter Related primitives
(associated primitive)
Value Bandwidth indication information
(CH_BANDWIDTH_IN_NON_HT) PHY-TXSTART.request
(TXVECTOR) If present, CBW20, CBW40, CBW80, CBW160 or CBW80 + 80 Dynamic bandwidth indication information
(DYN_BANDWIDTH_IN_NON_HT) PHY-TXSTART.request
(TXVECTOR) If it is, Static or Dynamic

The transmitting STA appends a service field, a padding bit (if necessary) and a tail bit (in the case of BCC encoding) to the PSDU containing the data to be transmitted. The service field may include a bit sequence for initializing a scrambler and a CRC (Cyclic Redundancy Check) bit sequence calculated for the corresponding VHT-SIGB field transmitted to the receiving STA (but included in the VHT-SIGB field) Lt; RTI ID = 0.0 > tail bits). The format of the service field can be expressed as shown in Table 3 below.

Bits Field Description B0 to B6 Scrambler initialization
(Scrambler Initialization)
Set to 0 B7 Reserved B8 to B15 CRC The calculated CRC (excluding tail bits) for the VHT-SIGB field,

The service field for a PPDU that can be used in a next-generation WLAN system includes a CRC bit sequence calculated for the VHT-SIGB field. On the other hand, the existing WLAN system does not include the VHT-SIGB field, so the CRC bit sequence is not included in the service field. Therefore, the transmitting STA needs to generate the service field differently according to whether the PPDU format is the format used in the next generation wireless LAN system or the format used in the existing wireless LAN system, and add the service field to the PSDU. To this end, the TXVECTOR parameter includes a service field information parameter, which is an information parameter related to the service field, and the transmission STA can be implemented to generate the service field based on the information. Table 4 below shows the service field information parameters included in the TXVECTOR parameter.

parameter Condition Transmission / reception vector applied value TXVECTOR RXVECTOR Service field Format = Legacy
Scrambler initialization,
7 null bits + 9 spare bits Yes no Format = High Throughput Scrambler initialization,
7 null bits + 9 spare bits Yes no Format = Very High Throughput Scrambler initialization,
7 null bits + 1 spare bit + CRC bits for VHT-SIGB field Yes no

The transmitting STA may generate a service field having the structure as shown in Table 3 based on the service field information parameter indicating the next generation wireless LAN system, that is, indicating the ultra high throughput (VHT) format. And scrambles the PSDU. The scrambling performed by the transmitting STA is based on the scrambling code generated by the transmitting STA. The scrambling step will be described in more detail with reference to FIG. 6. FIG. 6 is a diagram illustrating an example of scrambling according to an embodiment of the present invention.

Referring to FIG. 6, Data In is a bit sequence including a service field, a PSDU, a padding bit and a tail bit, to which a transmitting STA scrambles. The transmitting STA generates a scrambling sequence based on an initial scrambling sequence and a generator polynomial. In this example, the generator polynomial S (x) can be expressed as Equation 1 below.

If the TXVECTOR does not include a bandwidth indication information parameter, the transmitting STA may set the initial scrambling sequence to a 7 bit pseudo random nonzero integer instead of a 7 bit random random number.

When the TXVECTOR includes the bandwidth indication information parameter, the initial scrambling sequence can be set as shown in FIG. 7 attached hereto.

7 is a diagram illustrating an example of an initial scrambling sequence according to an embodiment of the present invention.

7, if the bandwidth indication information parameter CH_BANDWIDTH_IN_NON_HT exists in the TXVECTOR parameter and the dynamic bandwidth indication information parameter DYN_BANDWIDTH_IN_NON_HT does not exist, the scrambling sequence is a 5-bit random random integer and a set value of the bandwidth indication information parameter . When the bandwidth indication information parameter is set to a value (CBW20) indicating 20 MHz, the 5-bit number random integer may be set to a 5-bit pseudo random nonzero integer instead of zero. When the bandwidth indication information parameter is set to a value other than the value CBW20 indicating 20 MHz, the number of 5 bits other than zero need not be a random integer.

If both the bandwidth indication information parameter and the dynamic bandwidth indication information parameter are present in the TXVECTOR parameter, the scrambling sequence includes the 4-bit number random integer, the dynamic bandwidth indication information parameter setting value, and the bandwidth indication information parameter setting value. The value of the bandwidth indication information parameter is set to a value indicating 20 MHz (CBW20), and the value of the dynamic bandwidth indication information parameter is 'Static', and the 4-bit number random integer may be set to a random integer of 4 bits instead of zero have. In other cases, it is not necessary that the number of 4 bits other than 0 is a random integer.

Table 5 and Table 6 show examples of the setting values of the bandwidth indication information parameter and the dynamic bandwidth indication information parameter.

Enumerated value Setting value CBW20 0 CBW40 One CBW80 2 CBW160 or CBW80 + 80 3

Enumerated value Setting value Static 0 Dynamic One

On the other hand, the bandwidth indication information parameter is transmitted from the LSB (Least Significant Bit) of the set value of the information parameter. For example, if the bandwidth indication information parameter is set to a value indicating CBW 80, this may be represented as '10', in which case B5 of the initial scrambling sequence is set to 0 and B6 is set to 1. Figures 6 As shown in FIG. 7, the transmitting STA can generate an initial scrambling sequence based on the bandwidth indication information parameter and the dynamic bandwidth indication information parameter of the TXVECTOR parameter, and generate a scrambling sequence based on the initial scrambling sequence and the generation polynomial. The transmitting STA performs scrambling based on the scrambling sequence. The transmitting STA scrambles the input data based on the scrambling sequence and outputs scrambled data out. Referring again to FIG. 5, the transmitting STA scrambles the scrambled padding bits and the PSDU with an encoding scheme ). BCC encoding or LDPC (Low Density Parity Check) encoding techniques may be applied to the encoding technique. A coded PSDU (Coded-PSDU) is a concept that includes scrambled and coded PSDUs and fields / bits attached thereto. The C-PSDU may be referred to as a data field.

The PLCP sublayer can further add training symbols for radio resource synchronization, timing acquisition, and antenna diversity acquisition between the transmitting end AP and / or the STA and the receiving end STA. This can be implemented by adding legacy training symbols including L-STF for L-STA, L-LTF, and VHT training symbols including VHT-STF and VHT-LTF for VHT-STA . PPDUs transmitted through radio resources are mapped to OFDM symbols and transmitted through radio resources. Here, the data field included in the PPDU and / or the PPDU mapped to the OFDM symbol may be implemented to have a specific bit size and may be implemented as a multiple of Octet through a padding bit sequence added to the PSDU. The generated PPDU may be mapped to OFDM symbols and transmitted to at least one target STAs that are MIMO-paired.

8 is a diagram illustrating an example of a method of receiving a PPDU generated according to an embodiment of the present invention.

Referring to FIG. 8, the receiving STA starts receiving the VHT training symbol and the VHT-SIGB field based on the L-SIG field and the VHT-SIGA field.

The receiving STA does not decode the VHT-SIGB field if the group ID of the VHT-SIGA field indicates SU-MIMO. On the other hand, if the MU-MIMO is instructed, the VHT-SIGB field is decoded. If the VHT-SIGB field is decoded, the receiving STA checks the CRC bit sequence in the service field to check for CRC errors.

The terminal then receives the C-PSDU and decodes and descrambles it. The decoding of the C-PSDU is performed corresponding to the encoding scheme indication information included in the VHT-SIGA field. Descrambling the C-PSDU may be performed corresponding to the applied scrambling sequence.

Meanwhile, the receiving STA may set a specific bit value of the initial scrambling sequence, which is the first 7 bits of the scrambling sequence, as the bandwidth indication information parameter and / or the dynamic bandwidth indication information parameter of the RXVECTOR, which is the reception information parameter. This may correspond to the implementation of FIG. 7, which is the relationship between the bandwidth indication information parameter of the TXVECTOR and the initial scrambling sequence with the dynamic bandwidth indication information parameter.

By decoding and descrambling the C-PSDU, a PSDU that is a data unit containing the data can be obtained. Through this, the receiving STA can normally receive the data unit.

According to the above-described embodiments, it is possible to implement channel bandwidth related information and dynamic bandwidth operation support indication information in a next-generation WLAN system that is extended to a wider bandwidth through a scrambling sequence without implementing them in a separate signal field. Therefore, it is possible to support transmission / reception using a wide bandwidth, transmission / reception of a data unit in a duplicated format, and / or dynamic bandwidth transmission / reception without using a short signal field due to a lot of information necessary for supporting MU-MIMO. Also, the initial scrambling sequence can be used in a conventional WLAN system, which can guarantee backward compatibility.

In addition, in the above-described embodiment, the TX STA can accurately generate the service field suitable for the PPDU format of the WLAN system supporting the MU-MIMO, by additionally including the information parameter related to the implementation of the service field in the TXVECTOR parameter . This reduces the possibility of errors such as failure of exchange of data units between transmitting and receiving STAs, thereby ensuring more reliable communication.

9 is a block diagram illustrating a wireless device in which embodiments of the present invention may be implemented.

9, a wireless device 900 includes a processor 910, a memory 920, and a transceiver 930. The transceiver 930 includes a physical unit 931 and a MAC unit 932 and is configured to transmit and / or receive wireless signals, including a PHY layer of IEEE 802.11, MAC layer. The processor 910 is operatively coupled to the transceiver 930 to configure the MAC layer and / or the PHY layer implementing the embodiments of the present invention shown in Figures 4-8 with respect to data unit transmission / reception through PPDU generation do. The processor 910 is also configured to control a set of TXVECTOR parameters.

The processor 910 and / or the transceiver 930 may include an application-specific integrated circuit (ASIC), other chipset, logic circuitry, and / or data processing device. When the embodiment is implemented in software, the above-described techniques may be implemented with modules (processes, functions, and so on) that perform the functions described above. The module may be stored in memory 920 and executed by processor 910. [ The memory 920 may be contained within the processor 910 and may be operatively connected to the processor 910 by various means known in the art and located separately external.

Claims (12)

As a communication method,
Generating a VHT (Very High Throughput) -SIG-A field, a VHT-SIG-B field, and a data field;
Scrambling the data field via a scrambler to generate a scrambled data field;
And transmitting the VHT-SIG-A field, the VHT-SIG-B field, and the scrambled data field,
Wherein the scrambled data field comprises a service field and a Physical Service Data Unit (PSDU)
The VHT-SIG-B field includes a first set of bits and tail bits,
Wherein the service field included in the scrambled data field includes a second set of bits, a reserved bit and a cyclic redundancy check (CRC) bits indicating a scrambler initialization state,
The CRC bits are calculated based on a portion of the VHT-SIG-B field excluding the tail bits,
The VHT-SIG-A field includes a third bit set indicating one of multi-input multi-output (MU-MIMO) transmission and single user multi-input and multi-output Gt;. ≪ / RTI >
The method according to claim 1,
Wherein the data field is scrambled based on bits obtained via at least one TXVECTOR parameter,
Wherein the VHT-SIG-A field, the VHT-SIG-B field, and the scrambled data field are transmitted on a channel bandwidth determined based on the at least one transmission vector parameter.
3. The method of claim 2,
Wherein the at least one transmission vector parameter indicates whether dynamic bandwidth is supported.
The method according to claim 1,
Wherein the second set of bits is set to zero before the data field is scrambled.
A communication device comprising:
Memory; And
A processor coupled to the memory and performing program instructions stored in the memory,
The processor comprising:
A VHT-SIG-A field, a VHT-SIG-B field, and a data field,
Scrambling the data field via a scrambler to generate a scrambled data field,
The VHT-SIG-A field, the VHT-SIG-B field, and the scrambled data field,
Wherein the scrambled data field comprises a service field and a PSDU,
The VHT-SIG-B field includes a first set of bits and tail bits,
Wherein the service field included in the scrambled data field includes a second set of bits, a reserved bit and CRC bits indicating a scrambler initialization state,
The CRC bits are calculated based on a portion of the VHT-SIG-B field excluding the tail bits,
Wherein the VHT-SIG-A field comprises a third set of bits indicating either SU-MIMO transmission and MU-MIMO transmission.
6. The method of claim 5,
Wherein the data field is scrambled based on bits obtained via at least one TXVECTOR parameter,
Wherein the VHT-SIG-A field, the VHT-SIG-B field, and the scrambled data field are transmitted on a channel bandwidth determined based on the at least one transmission vector parameter.
The method according to claim 6,
Wherein the at least one transmission vector parameter indicates whether dynamic bandwidth is supported.
6. The method of claim 5,
Wherein the second set of bits is set to zero before the data field is scrambled.
1. A communication device for an access point (AP)
Memory; And
A processor coupled to the memory and performing program instructions stored in the memory,
The processor comprising:
A VHT-SIG-A field, a VHT-SIG-B field, and a data field,
Scrambling the data field via a scrambler to generate a scrambled data field,
And controlling the AP to transmit the VHT-SIG-A field, the VHT-SIG-B field, and the scrambled data field,
Wherein the scrambled data field comprises a service field and a PSDU,
The VHT-SIG-B field includes a first set of bits and tail bits,
Wherein the service field included in the scrambled data field includes a second set of bits, a reserved bit and CRC bits indicating a scrambler initialization state,
The CRC bits are calculated based on a portion of the VHT-SIG-B field excluding the tail bits,
The VHT-SIG-A field includes a third bit set indicating one of multi-input multi-output (MU-MIMO) transmission and single user multi-input and multi-output Gt; AP, < / RTI >
10. The method of claim 9,
Wherein the data field is scrambled based on bits obtained via at least one TXVECTOR parameter,
Wherein the VHT-SIG-A field, the VHT-SIG-B field, and the scrambled data field are transmitted on a channel bandwidth determined based on the at least one transmission vector parameter.
11. The method of claim 10,
Wherein the at least one transmission vector parameter indicates whether dynamic bandwidth is supported.
10. The method of claim 9,
Wherein the second set of bits is set to zero before the data field is scrambled.

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