KR20160019354A - Method for transmitting frame using selective beamforming and apparatus for performing the method - Google Patents

Abstract

Disclosed are a method for transmitting a frame using selective beamforming, and a communications apparatus for performing the same. The disclosed communications apparatus operates the following operations of: determining a beamforming matrix in accordance with classification information in which a plurality of sub-carriers used for communications are classified by a plurality of frequency units; mapping an LTF sequence to the beamforming matrix; transmittng BA-T including the mapped LTF sequence; receiving feedback information generated based on the reception intensity of BA-T from a plurality of user terminals which received the BA-T; assigning the frequency units to data frames to be transmitted to the user terminals in accordance with the feedback information; and transmitingt the data frames using the assigned frequency units, wherein the reception intensity of BA-T may be determined by each frequency unit in each of the user terminals. The purpose of the present invention is to prevent the increase of feedback overhead according to the number of transmitting antennas of the communications apparatus and the number of receiving antennas of the user terminal, as the user terminal feeds back the reception intensity of a signal received from the communications apparatus.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a frame transmission method using selective beamforming, and a communication apparatus performing the method. [0002]

The following description relates to a frame transmission method using selective beamforming and a communication apparatus performing the method. More specifically, a frame is transmitted using a beamforming matrix determined regardless of channel information between a communication apparatus and user terminals And more particularly,

Local Area Network (LAN), which is a local area network, is divided into a wired LAN and a wireless LAN (WLAN). A wireless LAN is a method of performing communication on a network using radio waves without using a cable. The emergence of wireless LANs has become an alternative to solve the difficulties of installation, maintenance, and movement due to cabling, and the need for wireless LANs is increasing due to the increase of mobile users.

The wireless LAN system is composed of an access point (AP) and a user terminal (STA). An access point is a device that transmits radio waves so that user terminals can access the Internet or use the network within a service range.

The basic building block of the wireless LAN system defined in IEEE 802.11 is a basic service set (BSS). The types of BSS include an independent BSS (independent BSS) in which user terminals in the BSS communicate directly with each other, an infrastructure BSS in which an access point participates in the process of a user terminal communicating with user terminals inside and outside the BSS, And an extended service set for extending a service area by connecting different BSSs.

As the number of user terminals included in one BSS increases, the feedback overhead for communication between the access point and user terminals also increases. Therefore, there is a need for a communication method that can efficiently reduce feedback overhead in a situation where user terminals performing communication with the access point are in many situations.

The present invention can provide a method and apparatus for preventing feedback overhead from increasing according to the number of transmission antennas of a communication apparatus and the number of reception antennas of a user terminal by feeding back the reception strength of a signal received from a communication apparatus by a user terminal have.

The present invention can provide a method and apparatus for effectively reducing feedback overhead between a communication device and a user terminal by transmitting a BF-T using a beamforming matrix determined irrespective of channel information between a communication device and a plurality of user terminals have.

The present invention relates to a method and apparatus for generating feedback information in a user terminal by not generating a feedback matrix using a channel matrix in a user terminal and not determining a beamforming matrix according to a feedback matrix in a communication apparatus, A method and apparatus for effectively reducing the complexity of the determined process can be provided.

A method of transmitting a frame of a communication apparatus communicating with a plurality of user terminals according to an embodiment includes determining a beamforming matrix according to classification information that classifies a plurality of subcarriers used for the communication into a plurality of frequency units ; Mapping an LTF sequence to the beamforming matrix and transmitting BA-T comprising the mapped LTF sequence; Receiving feedback information generated based on the reception strength of the BA-T from a plurality of user terminals receiving the BA-T; And assigning a frequency unit to data frames to be transmitted to a plurality of user terminals according to the feedback information and transmitting data frames using the allocated frequency unit, May be determined for each of the plurality of frequency units in each of the plurality of user terminals.

In the frame transmission method according to an exemplary embodiment, the step of determining the beamforming matrix may determine the beamforming matrix regardless of channel information between the communication device and the plurality of user terminals.

In the frame transmission method according to an exemplary embodiment, the reception strength of the BA-T may be determined based on a Signal to Interference and Noise Ratio (SINR), a Signal to Noise Ratio (SNR), or an MSC Modulation and Coding Scheme).

The transmitting of data frames using the allocated frequency unit in the frame transmission method according to an exemplary embodiment may include transmitting at least one frequency unit having a reception intensity higher than a predetermined threshold intensity among a plurality of frequency units through feedback information And allocates the identified at least one frequency unit to a data frame corresponding to the feedback information.

The transmitting of data frames using the assigned frequency unit in the frame transmission method according to an exemplary embodiment of the present invention includes mapping data to at least one subcarrier corresponding to the allocated frequency unit, By mapping to a beamforming matrix according to a frequency unit, a data frame can be transmitted.

The transmitting of the data frames using the allocated frequency unit in the frame transmission method according to an exemplary embodiment of the present invention may include transmitting first allocation information on a frequency unit allocated to the plurality of user terminals, Frame to the plurality of user terminals.

In the frame transmission method according to an exemplary embodiment, the first allocation information may sequentially include information on frequency units allocated for each data frame.

In the frame transmission method according to an exemplary embodiment, the first allocation information may sequentially include information on data frames allocated for each frequency unit.

The transmitting of the data frames using the assigned frequency unit in the frame transmission method according to an exemplary embodiment may include transmitting second allocation information for the frequency unit allocated to the target user terminal receiving the data frame in a beam- May be included in the data frame and transmitted to the target user terminal.

In the frame transmission method according to an exemplary embodiment, the frequency unit may correspond to at least one subcarrier to which the same beamforming matrix is applied.

A communication apparatus according to an exemplary embodiment includes a communication unit for performing communication with a plurality of user terminals; And a processor for controlling the communication unit, wherein the processor determines a beamforming matrix according to classification information that classifies a plurality of subcarriers used for the communication into a plurality of frequency units, and adds the LTF sequence Transmits BA-T including the mapped LTF sequence, receives feedback information generated based on the reception strength of the BA-T from a plurality of user terminals receiving the BA-T, Assigning a frequency unit to data frames to be transmitted to a plurality of user terminals according to the feedback information, and transmitting data frames using the allocated frequency unit, For each of the plurality of frequency units.

According to an embodiment of the present invention, feedback strength of a signal received from a user equipment terminal is fed back so that feedback overhead can be prevented from increasing according to the number of transmission antennas of a communication device and the number of receiving antennas of a user equipment have.

According to an embodiment of the present invention, a feedback overhead between a communication apparatus and a user terminal can be effectively reduced by transmitting a BF-T using a beamforming matrix determined regardless of channel information between a communication apparatus and a plurality of user terminals have.

According to an embodiment of the present invention, a feedback matrix is not generated using a channel matrix at a UE, and a feedback information is generated at a user terminal by not determining a beamforming matrix according to a feedback matrix at a communication apparatus. The complexity of the process of determining the beamforming matrix in the communication apparatus can be effectively reduced.

1 is a diagram illustrating a communication environment including a plurality of user terminals in a BSS according to an exemplary embodiment of the present invention.
2 is a diagram for explaining a process of performing communication according to an explicit feedback scheme according to an embodiment.
3 is an illustration of an example BF-T of a PPDU structure transmitted in a communication device in accordance with one embodiment.
4 is a diagram illustrating a process of transmitting a HEW Training Field of a BF-T in a communication apparatus according to an exemplary embodiment of the present invention.
5 is a diagram illustrating a process of receiving a HEW Training Field of a BF-T in a user terminal according to an embodiment.
6 and 7 are diagrams illustrating an example of a data frame of a PPDU structure transmitted from a communication apparatus according to an embodiment.
Figure 8 is an illustration of an example of a frequency unit assigned to a user terminal in accordance with one embodiment.
9 is a diagram for explaining a process of transmitting a HEW-SIG-A in a communication apparatus according to an embodiment.
FIG. 10 is a diagram illustrating a process of receiving a HEW-SIG-A from a user terminal according to an embodiment.
11 is a diagram for explaining a process of transmitting a HEW-SIG-B in a communication apparatus according to an embodiment.
12 is a diagram illustrating a process of receiving a HEW-SIG-B from a user terminal according to an embodiment.
13 is a diagram illustrating a process of transmitting HEW-Data in a communication apparatus according to an embodiment.
FIG. 14 is a diagram illustrating a process of receiving HEW-Data in a user terminal according to an embodiment.
15 is a diagram illustrating a communication scheme according to an implicit feedback scheme according to another embodiment.
16 is a diagram for explaining communication between a communication device and a user terminal according to an embodiment.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The specific structural or functional descriptions below are illustrated for purposes of illustration only and are not to be construed as limiting the scope of the embodiments to those described in the text. Those skilled in the art will appreciate that various modifications and changes may be made thereto without departing from the scope of the present invention. In addition, the same reference numerals shown in the drawings denote the same members, and the well-known functions and structures are omitted.

1 is a diagram illustrating a communication environment including a plurality of user terminals in a BSS according to an exemplary embodiment of the present invention.

A Wireless Local Area Network (WLAN) system may include one or more Basic Service Sets (BSSs). The basic service set may comprise an access point (AP) and one or more user terminals.

An access point is a functional entity that provides a connection to a distribution system via a wireless medium for a user terminal associated with the access point. The access point may communicate with one or more user terminals 120-1, 120-2, ..., 120-N on a downlink at any given moment.

The downlink is the communication link from the access point to the user terminals, and the uplink is the communication link from the user terminals to the access point.

For example, the access point may also be referred to as a different name, such as a central controller, a base station (BS), a node-B, or a base transceiver system (BTS) .

A user terminal may be a mobile terminal, a wireless device, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS) (Mobile Subscriber Unit) or simply as a User, and may be implemented as such.

The access point may simultaneously transmit data to a user terminal group including at least one user terminal among a plurality of user terminals associated with the access point. Here, the coincidence may mean the same in time or within a predetermined error range.

The wireless LAN system supports multi-user multi-input multi-output (MU-MIMO) communication. In the MU-MIMO communication system, an access point can transmit a plurality of spatial streams to a plurality of user terminals using multiple antennas. In addition, if the access point uses multiple transmit antennas, the access point may transmit data frames to the user terminals using beamforming techniques to improve transmission performance. The access point may be referred to as a communication device, and for convenience of description, the present invention may be described by a combination of an access point and a communication device.

The wireless transmission environment of the wireless LAN system shown in FIG. 1 includes a basic service set (hereinafter, referred to as " basic service set ") 120 consisting of a plurality of user terminals 120-1, 120-2, 100). The communication device 110 may transmit a data frame to a plurality of user terminals 120-1, 120-2, ..., 120-N using a beamforming technique.

The frequency band used for communication between the communication device 110 and the plurality of user terminals 120-1, 120-2, ..., 120-N may be composed of a plurality of subcarriers . The communication apparatus 110 may classify a plurality of subcarriers into a plurality of frequency units and may classify the subcarriers based on information fed back from the plurality of user terminals 120-1, 120-2, ..., 120-N And selectively allocates a plurality of frequency units to data frames to be transmitted to the plurality of user terminals 120-1, 120-2, ..., 120-N. The communication device 110 transmits data frames to a plurality of user terminals 120-1, 120-2, ..., 120-N using selectively assigned frequency units.

At this time, the communication apparatus 110 determines a beamforming matrix irrespective of channel information with respect to the plurality of user terminals 120-1, 120-2, ..., 120-N, and determines a determined beamforming matrix , 120-2,..., 120-N using the training frames. Each of the plurality of user terminals 120-1, 120-2, ..., 120-N generates a feedback signal based on the reception strength of the received training frame and feeds back the feedback signal to the communication device 110. [ The communication apparatus 110 allocates a frequency unit to data frames to be transmitted to the plurality of user terminals 120-1, 120-2, ..., 120-N based on the feedback information, Unit to transmit data frames to a plurality of user terminals 120-1, 120-2, ..., 120-N.

2 is a diagram for explaining a process of performing communication according to an explicit feedback scheme according to an embodiment.

According to an embodiment, the communication apparatus and the user terminals can perform communication by exchanging frames of a PHY Protocol Data Unit (PPDU) structure according to an explicit feedback method.

The communication device transmits a Beamforming Announcement (BF-A) including information for feedback to user terminals. For example, the communication apparatus may include (i) information about user terminals for which feedback information is required (for example, a user terminal list) and (ii) a BF including classification information for classifying a plurality of subcarriers into a plurality of frequency units -A to the user terminals. Here, the plurality of sub-carriers may constitute a frequency band used for communication between the communication apparatus and the user terminals.

The communication device transmits BF-T (Beamforming Training) for multi-antenna channel estimation to user terminals. The BF-T includes a High Efficiency WLAN (WLAN) modulated field transmitted in a non-beamformed state and a HEW modulated field transmitted in a beamformed state. The communication apparatus determines the beamforming matrix according to the classification information, maps the determined beamforming matrix to the HEW modulated field, and transmits the BF-T.

Each of the user terminals determines the reception strength of BF-T for each of a plurality of frequency units. The user terminal can identify a plurality of frequency units classified into a plurality of subcarriers based on classification information. The user terminal determines the feedback information based on the reception strength of the BA-T, and can sequentially transmit the High Efficiency WLAN-FeedBack Information (HEW-FBInfo) including the feedback information to the communication device.

If the channel information exchange interval and the data transmission interval do not correspond to the same TxOP (Transmit Opportunity), the communication device transmits a Request to Send (RTS) to user terminals and clears the CTS Send. ≪ / RTI > Then, the communication apparatus can transmit data frames (DATA1 to DATA3) to be transmitted to the user terminals. The user terminals receiving the data frame can transmit a BA (Block Ack).

3 is an illustration of an example BF-T of a PPDU structure transmitted in a communication device in accordance with one embodiment.

The BF-T of the PPDU structure is divided into a Pre-HEW Modulated Field that is transmitted without beamforming and a HEW Modulated Field that is transmitted by beamforming. The pre-HEW modulated field may indicate a portion transmitted without being beamformed so as to be received by a user terminal performing communication through 802.11a / n / ac. The HEW Modulated Field may indicate a portion to which a beamforming matrix according to a user terminal receiving the BF-T is applied.

The Pre-HEW Modulated Field includes Legacy Training Field, Legacy SIG Field (Legacy Signal Field) and HEW SIG Field 1. The Legacy Training Field and the Legacy SIG Field may include information for a Legacy STA capable of receiving the NON_HT format. HEW SIG Field 1 may contain information on the configuration of the LTF (Long Training Field) included in the HEW Training Field and classification information on the frequency unit included in the BF-A.

HEW Modulated Field includes HEW Training Field and HEW SIG Field 2. The HEW Training Field may include an LTF sequence consisting of (i) Short Training Field (STF) and (ii) one or more LTFs. The STF includes information for automatic gain control (AGC) and signal detection of a user terminal, and the LTF may include information for channel estimation and frequency error estimation of a user terminal.

The process of transmitting the HEW Training Field will be described later with reference to FIG.

4 is a diagram illustrating a process of transmitting a HEW Training Field of a BF-T in a communication apparatus according to an exemplary embodiment of the present invention.

The LTF sequence generator 410 may generate a predetermined LTF sequence according to the bandwidth for transmitting the BF-T. The LTF sequence may consist of one or more LTFs. The LTF Mapper 420 can output the LTF sequence for each stream according to the transmission antenna of the communication apparatus by mapping the LTF sequence to a mapping code determined according to the number of symbols and the number of transmission streams N _sts (Number of Space Time Streams). The LTF sequence output for each stream according to the transmission antenna may be transmitted to the spatial mapper 450 by applying CSD (Cyclic Shift Delay).

The V subcarriers used for communication between the communication device and the user terminals may be classified into M frequency units. At this time, the beamforming matrix generator 440 can determine the beamforming matrix W _m according to classification information that classifies V subcarriers into M frequency units. Specifically, the beamforming matrix generator 440 may determine a beamforming matrix applied to subcarriers corresponding to the same frequency unit. For example, the sub-carrier 0 through sub-carrier 3 may be determined in the same frequency unit 0, and therefore, the same beam-forming matrix W ₀ can be applied. As a result, the beamforming matrix generator 440 can determine the beamforming matrix regardless of channel information between the communication apparatus and the user terminals.

The Spatial Mapper 450 may map the LTF sequence received from the CSD 430 to the beamforming matrix determined in the beamforming matrix generator 440. The LTF sequence to which the beamforming matrix is mapped is applied with an IDFT (Inverse Discrete Fourier Transform) 460, a GI (Guard Interval) addition / windowing process 470, (480) and transmitted to the user terminal through RF (Radio Frequency).

5 is a diagram illustrating a process of receiving a HEW Training Field of a BF-T in a user terminal according to an embodiment.

The signal received at the user terminal (e.g., the LTF sequence included in the HEW Training Field) is A / D converted 510, the GI 520 is removed, and a Discrete Fourier Transform (DFT) And may be delivered to the LTF Demapper 540.

The LTF demapper 540 can LTF demap the LTF sequence input by stream according to the transmission antenna of the communication apparatus. The LTF Estimator 550 may perform channel estimation using the LTF demapped LTF sequence.

The Signal Strength Calculator 560 calculates the reception strength of BA-T using channel estimation. The Signal Strength Calculator 560 can determine the reception strength of BA-T for each of a plurality of frequency units. The Signal Strength Calculator 560 may determine the reception strength of BA-T for each transmission stream received from the communication device.

The Signal Strength Calculator 560 may calculate Signal to Interference and Noise Ratio (SINR), Signal to Noise Ratio (SNR), or Modulation and Coding Scheme (MCS) as the reception strength of BA-T. For example, when the SINR is calculated as the reception strength of BA-T, the Signal Strength Calculator 560 can calculate SINR, SNR, or MCS of BA-T for each of a plurality of frequency units.

Feedback information generator 570 may generate feedback information based on the received strength of BA-T determined by Signal Strength Calculator 560. [ The generated feedback information can be included in the HEW-FBInfo and transmitted to the communication device.

6 and 7 are diagrams illustrating an example of a data frame of a PPDU structure transmitted from a communication apparatus according to an embodiment.

The data frame of the PPDU structure shown in FIG. 6 is divided into a Pre-HEW Modulated Field that is transmitted in a state where beamforming is not performed and a HEW Modulated Field that is transmitted in a beamformed state. The pre-HEW modulated field may indicate a portion transmitted without being beamformed so as to be received by a user terminal performing communication through 802.11a / n / ac. The HEW Modulated Field may indicate a portion to which a beamforming matrix according to a user terminal receiving a data frame is applied.

For example, the data frame shown in FIG. 6 can be represented by a data frame of the HEW PPDU structure shown in FIG. 6, Legacy SIG Field corresponds to L-SIG (Legacy Signal Field) in FIG. 7, and HEW SIG Field 1 corresponds to HEW-SIG-A (High Efficiency WLAN-Signal Field-A) In FIG. 6, HEW SIG Field 2 corresponds to HEW-SIG-B (High Efficiency WLAN-Singal Field-B) in FIG.

Figure 8 is an illustration of an example of a frequency unit assigned to a user terminal in accordance with one embodiment.

The communication apparatus can allocate a frequency unit to data frames to be transmitted based on feedback information included in the HEW-FBInfo received from the user terminals.

The communication apparatus can identify the frequency unit having a strong reception intensity among a plurality of frequency units by data frame and allocate the frequency unit to the corresponding data frame using the feedback information. Accordingly, even when two or more data frames are transmitted to the same user terminal, the communication apparatus confirms frequency units having relatively strong reception strength among a plurality of frequency units by data frame, assigns different frequency units to data frames can do. For example, the communication apparatus can determine at least one frequency unit having a reception intensity higher than a preset threshold strength among a plurality of units as a frequency unit having a relatively strong reception intensity among a plurality of frequency units.

8 illustrates a frequency unit assigned to data frames according to one embodiment. FIG. 8 shows frequency units assigned when a communication device transmits three data frames to two user terminals and can be displayed as shown in Table 1 below.

Data frame Frequency unit index Data frame 1 0, 2, 7, 8, 10, 11, 14, 15 Data frame 2-1 3, 4, 9, 7, 13 Data frame 2-2 1, 2, 4, 5, 6, 9, 10, 11

In Table 1, data frame 1 represents a data frame transmitted to user terminal 1, data frame 2-1 represents a first data frame transmitted to user terminal 2, and data frame 2-2 represents a data frame transmitted to user terminal 2 Th data frame. As shown in Table 1, the communication device may assign the same frequency unit to different data frames based on the feedback information.

For example, the communication apparatus can determine allocation information for a frequency unit allocated to data frames on a data frame basis as shown in Table 2 below.

Data frame Assignment information for frequency unit Data frame 1 1010_0001_1011_0011 Data frame 2-1 0001_1001_0100_0100 Data frame 2-2 0110_1110_0111_0000

In the allocation information in Table 2, "1" indicates the frequency unit allocated to the corresponding data frame, and "0" indicates the frequency unit not allocated to the corresponding data frame.

For example, the allocation information of data frame 1 may include {1010_0001_1011_0011}. The first bit value "1" of the allocation information indicates that frequency unit 0, which is the first frequency unit, is allocated to data frame 1, and "0", which is the second bit value, Lt; / RTI >

Similarly, the allocation information of the data frame 2-1 includes {0001_1001_0100_0100}, and the allocation information of the data frame 2-2 may include {0110_1110_0111_0000}.

In another example, the communication device may determine allocation information for a frequency unit assigned to data frames on a frequency unit basis. When the allocation information according to FIG. 8 is represented by frequency units, the allocation information may include {100_001_101_010_011_001_001_110_100_011_101_101_000_010_100_100}.

In another example, the communication device may determine allocation information for a frequency unit allocated to data frames for each user terminal. In other words, when data frames are transmitted through a plurality of transmission streams to a specific user terminal, allocation information for frequency units allocated to data frames can be combined. For example, when the allocation information according to FIG. 8 is displayed for each user terminal, the allocation information of the user terminal 1 includes {1010_0001_1011_0011}, and the allocation information of the user terminal 2 includes {0111_1111_0111_0100}.

The embodiments have been described in which the allocation information is determined for each data frame, for each frequency unit, or for each user terminal. However, this description does not limit or limit the embodiment of the allocation information determined by the communication apparatus. In addition to the methods described above, the communication device may use various methods to determine allocation information for frequency units assigned to data frames.

The communication device may transmit the allocation information to the user terminal. For example, the communication apparatus may include the allocation information in the HEW-SIG-A of the Pre-HEW modulated field to the user terminal. In another example, the communication device may include the allocation information in the HEW-SIG-B of the HEW modulated field to the user terminal. The process in which the allocation information is transmitted from the communication device to the user terminal will be described later with reference to Figs. 9 to 12. Fig.

9 is a diagram for explaining a process of transmitting a HEW-SIG-A in a communication apparatus according to an embodiment.

The communication apparatus according to an embodiment may transmit the allocation information to the user terminal by including it in the HEW-SIG-A of the Pre-HEW modulated field. In this case, the allocation information may be information represented by data frames, information represented by frequency units, or information represented by user terminals. The allocation information included in the HEW-SIG-A may include allocation information for a frequency unit allocated to data frames transmitted from the communication apparatus.

Specifically, in the communication apparatus, the HEW-SIG-A generator 910 can generate HEW-SIG-A including allocation information.

The channel encoder 920 can perform channel encoding on the HEW-SIG-A. Interleaver 930 may interleave the channel encoded HEW-SIG-A. The Constellation Mapper 940 is configured by a HEW (Interleaved HEW) using various modulation schemes such as Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), 16QAM (Quadrature Amplitude Modulation), 64QAM, 128QAM, 256QAM, 512QAM, -SIG-A can be modulated. The modulated HEW-SIG-A is applied to the IDFT 950, the CSD 960, the GI addition / windowing process 970, the D / A conversion 980, .

FIG. 10 is a diagram illustrating a process of receiving a HEW-SIG-A from a user terminal according to an embodiment.

The HEW-SIG-A received at the user terminal is A / D converted 1010, the GI is removed 1020, and the DFT 1030 is applied to the channel estimator and detector 1040.

The channel estimator and detector 1040 can perform channel estimation and detect a signal using the LTF. If the user terminal has a plurality of receive antennas, the Channel Estimator and Detector 1040 may combine the detected signals.

The deinterleaver 1050 can deinterleave the detected signals. The channel decoder 1060 can channel-decode the deinterleaved signal. The HEW-SIG-A Detector 1070 can determine the allocation information included in the HEW-SIG-A transmitted from the communication apparatus using the channel decoded signal.

The user terminal can demodulate the HEW-SIG-B and the HEW-data received from the communication apparatus based on the allocation information.

11 is a diagram for explaining a process of transmitting a HEW-SIG-B in a communication apparatus according to an embodiment.

The communication apparatus according to an exemplary embodiment may transmit the allocation information to the user terminal by including it in the HEW-SIG-B of the HEW modulated field. In this case, the HEW-SIG-B included in the HEW modulated field may include different information for each user terminal. The allocation information included in the HEW-SIG-B may include allocation information corresponding to a specific user terminal receiving the HEW modulated field.

In FIG. 11, a process of transmitting HEW-SIG-B corresponding to a user terminal among a plurality of user terminals will be mainly described. However, this is for the sake of convenience of explanation, and can be similarly applied to the transmission of HEW-SIG-B corresponding to another user terminal.

Specifically, in the communication apparatus, the HEW-SIG-B generator 1100 can generate the HEW-SIG-B corresponding to the user terminal 1 (STA1). The HEW-SIG-B generated by the HEW-SIG-B Generator 1100 may include allocation information on the frequency unit allocated to the data frame received by the user terminal 1 (STA 1).

For example, assuming that frequency units are allocated as shown in FIG. 8, the HEW-SIG-B generator 1100 can generate HEW-SIG-B including allocation information of {1010_0001_1011_0011}. The other HEW-SIG-B Generator generates HEW-SIG-B corresponding to the user terminal 2. More specifically, HEW-SIG-B including allocation information of {0001_1001_0100_0100} and {0110_1110_0111_0000} is generated can do. Here, {0001_1001_0100_0100} indicates a frequency unit allocated to the data frame 2-1 transmitted to the user terminal 2, and {0110_1110_0111_0000} indicates a frequency unit assigned to the data frame 2-2 transmitted to the user terminal 2 have.

The channel encoder 1110 can perform channel encoding on the HEW-SIG-B. Interleaver 1120 may interleave the channel encoded HEW-SIG-B. The Constellation Mapper 1130 can modulate the interleaved HEW-SIG-B using various modulation schemes such as BPSK, QPSK, 16QAM, 64QAM, 128QAM, 256QAM, 512QAM, and 1024QAM. The modulated HEW-SIG-B may be passed to the Spatial Mapper 1160 by applying the CSD 1140.

The beamforming matrix generator 1150 may generate a beamforming matrix according to the allocation information. For example, the beamforming matrix generator 1150 may include a plurality of beamforming matrices corresponding to a plurality of frequency units. The Beamforming Matrix Generator 1150 can identify the frequency unit assigned to the data frame including the HEW-SIG-B and select a beamforming matrix corresponding to the frequency unit assigned to the data frame from among the plurality of beamforming matrices .

The Spatial Mapper 1160 can map the HEW-SIG-B received from the CSD 430 to the beamforming matrix determined in the beamforming matrix generator 1150. [ At this time, the Spatial Mapper 1160 can map the HEW-SIG-B to the beamforming matrix of the frequency unit allocated to the corresponding data frame.

The HEW-SIG-B to which the beamforming matrix is mapped is applied to the IDFT 1170, the GI addition / windowing process 1180, the D / A 1190 transform, and transmitted to the user terminal via the RF.

12 is a diagram illustrating a process of receiving a HEW-SIG-B from a user terminal according to an embodiment.

The HEW-SIG-B received at the user terminal is A / D converted 1210, the GI is removed 1220, and the DFT 1230 is applied to the channel estimator and detector 1240.

The channel estimator and detector 1240 can perform channel estimation using the LTF and detect the HEW-SIG-B. The deinterleaver 1250 can deinterleave the detected HEW-SIG-B. Specifically, the deinterleaver 1250 can perform deinterleaving in consideration of a bit repetition included in the detected HEW-SIG-B. The channel decoder 1260 can channel-decode the deinterleaved HEW-SIG-B. The HEW-SIG-B Detector 1270 can determine allocation information included in the HEW-SIG-B transmitted from the communication apparatus using the channel-decoded HEW-SIG-B. The HEW-SIG-B Detector 1270 can confirm the allocation information corresponding to the user terminal from the HEW-SIG-B.

The user terminal can demodulate the HEW-Data received from the communication device based on the allocation information.

13 is a diagram illustrating a process of transmitting HEW-Data in a communication apparatus according to an embodiment.

The communication apparatus according to an exemplary embodiment may transmit data to be transmitted to each user terminal by including the data to be transmitted for each user terminal in the HEW-Data. The communication device can process data to be transmitted in the PHY layer.

13, the process of transmitting the HEW-Data to be transmitted to one of the plurality of user terminals will be mainly described. However, this is for convenience of explanation, and can be applied to the transmission of HEW-Data to be transmitted to another user terminal as well.

More specifically, the PHY padder 1301 may apply PHY padding to the HEW-Data to be transmitted by the communication apparatus. Scrambler 1302 can perform scrambling on PHY padded HEW-Data. The channel encoder 1303 can perform channel encoding on the scrambled HEW-Data. The stream parser 1304 can separate the channel-encoded HEW-Data by the number of transmission streams to be transmitted to the user terminal. The interleaver 1305 can interleave the separated HEW-Data for each transmission stream. Constellation Mapper 1306 can modulate the interleaved HEW-Data using various modulation schemes such as BPSK, QPSK, 16QAM, 64QAM, 128QAM, 256QAM, 512QAM and 1024QAM.

The FU Mapper (Frequency Unit Mapper) 1307 can map the modulated HEW-Data to sub-carriers according to the allocation information. The allocation information includes information on the frequency units allocated to the corresponding HEW-Data. Thus, the FU Mapper 1307 can map the corresponding HEW-Data to the sub-carriers corresponding to the allocated frequency units. In FIG. 13, the FU Mapper 1307 is shown as being located after the Constellation Mapper 1306, but this corresponds to only one embodiment, and may be located after the Interleaver 1305 in some cases. That is, the embodiment that can be applied to the position of FU Mapper 1307 is not limited or limited to the above description.

The HEW-Data mapped to the subcarrier may be transmitted to the Spatial Mapper 1310 by applying the CSD 1308.

The beamforming matrix generator 1309 may generate a beamforming matrix according to the allocation information. The beamforming matrix generator 1309 can determine the beamforming matrix using the frequency unit allocated to the data frame including the HEW-Data. For example, the beamforming matrix generator 1309 may include a plurality of beamforming matrices corresponding to a plurality of frequency units. The beamforming matrix generator 1309 can identify the frequency unit allocated to the data frame through the allocation information and select the beamforming matrix corresponding to the frequency unit allocated to the data frame among the plurality of beamforming matrices.

The Spatial Mapper 1310 can map the HEW-Data received from the CSD 1308 to the beamforming matrix determined in the beamforming matrix generator 1309. [ At this time, the Spatial Mapper 1310 can map the HEW-Data to the beamforming matrix corresponding to the frequency unit allocated to the corresponding data frame.

The HEW-Data to which the beamforming matrix is mapped is applied to the IDFT 1311, the GI addition / windowing process 1312, the D / A 1313, and transmitted to the user terminal through the RF.

FIG. 14 is a diagram illustrating a process of receiving HEW-Data in a user terminal according to an embodiment.

The received HEW-Data is A / D-converted 1410, GI is removed 1420, and DFT 1430 is applied to FU Demapper 1440.

The FU Demapper 1440 performs frequency unit demapping on the HEW-Data based on the allocation information received via the HEW-SIG-A or HEW-SIG-B and outputs the result to the channel estimator and detector 1450 . The channel estimator and detector 1450 can perform channel estimation using the LTF and detect HEW-Data. The deinterleaver 1460 can deinterleave the detected HEW-Data. Specifically, the deinterleaver 1460 can perform deinterleaving in consideration of bit repetition included in the detected HEW-Data. Stream Deparser 1470 may apply stream de-parsing to deinterleaved HEW-Data to combine streams received at the user terminal. The channel decoder 1480 can channel-decode the de-parsed HEW-Data. Descrambler 1490 descrambles the channel-decoded HEW-Data, and then transmits the descrambled HEW-Data to a MAC layer (Media Access Control Layer), which is an upper layer.

15 is a diagram illustrating a communication scheme according to an implicit feedback scheme according to another embodiment.

According to another embodiment, the communication apparatus and the user terminals can perform communication by exchanging frames of the PPDU structure according to an implicit feedback scheme based on channel reciprocity.

The communication device transmits BF-A containing information for feedback to the user terminals. For example, the communication apparatus may include (i) information about user terminals for which feedback information is required (for example, a user terminal list) and (ii) a BF including classification information for classifying a plurality of subcarriers into a plurality of frequency units -A to the user terminals.

The user terminals may transmit BF-T, which is a PPDU for multi-antenna channel estimation, to the communication device. The BF-T includes a High Efficiency WLAN (WLAN) modulated field transmitted in a non-beamformed state and a HEW modulated field transmitted in a beamformed state.

The communication apparatus may determine a beamforming matrix for multi-user transmission using the BF-T received from the user terminals, and may assign a frequency unit to a data frame to be transmitted to user terminals. The communication device may transmit the data frames (DATA1 to DATA3) using the determined beamforming matrix and the assigned frequency unit.

If the channel information exchange interval and the data transmission interval do not belong to the same Transmit Opportunity (TxOP), the communication apparatus transmits a Request to Send (RTS) to user terminals and clears CTS Send. ≪ / RTI > Then, the communication apparatus can transmit data frames (DATA1 to DATA3) to be transmitted to the user terminals.

The above-described matters are applied to the communication process shown in FIG. 15 through FIG. 1 to FIG. 14, so that detailed description will be omitted.

16 is a diagram for explaining communication between a communication device and a user terminal according to an embodiment.

Each of the steps shown in Fig. 16 may be performed by a processor included in the communication device or the user terminal. The frame exchange between the communication apparatus and the user terminals may be performed by a communication unit or a communication unit provided in the user terminal.

At step 1610, the communication device sends a Beamforming Announcement (BF-A) containing information for feedback to the user terminals. For example, the communication apparatus may include (i) information about user terminals for which feedback information is required (for example, a user terminal list) and (ii) a BF including classification information for classifying a plurality of subcarriers into a plurality of frequency units -A to the user terminals.

In step 1620, the communication device transmits Beamforming Training (BF-T) for multi-antenna channel estimation to user terminals. The BF-T includes a High Efficiency WLAN (WLAN) modulated field transmitted in a non-beamformed state and a HEW modulated field transmitted in a beamformed state. The communication apparatus determines the beamforming matrix according to the classification information, maps the determined beamforming matrix to the HEW modulated field, and transmits the BF-T.

In step 1630, each of the user terminals may calculate the received strength of the received BA-T. The user terminal can determine the reception strength of BA-T for each of a plurality of frequency units. Then, the user terminal may determine the reception strength of BA-T for each transmission stream received from the communication apparatus. For example, the user terminal may calculate SINR, SNR or MCS as the reception strength of BA-T.

Each of the user terminals can generate feedback information based on the calculated reception strength of BA-T. The generated feedback information may include information on SINR, SNR or MCS in a plurality of frequency units.

In step 1640, each of the user terminals may include feedback information in the HEW-FBInfo and transmit it to the communication device.

In step 1650, the communication device may assign the frequency unit based on the feedback information contained in the HEW-FBInfo. The communication apparatus may allocate a frequency unit to data frames to be transmitted to a plurality of user terminals according to feedback information. For example, the communication apparatus can confirm at least one frequency unit having a reception intensity higher than a predetermined threshold intensity among a plurality of units for each data frame through the feedback information. The communication device may allocate at least one identified frequency unit to the corresponding data frame.

In step 1660, the communications device may transmit data frames using the assigned frequency unit.

The steps described above with reference to FIG. 1 through FIG. 15 are applied to each step shown in FIG. 16, so that a detailed description will be omitted.

The embodiments described above may be implemented in hardware components, software components, and / or a combination of hardware components and software components. For example, the devices, methods, and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, such as an array, a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced. Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (20)

A frame transmission method of a communication apparatus communicating with a plurality of user terminals,
Determining a beamforming matrix according to classification information that classifies a plurality of subcarriers used for the communication into a plurality of frequency units;
Mapping an LTF sequence to the beamforming matrix and transmitting BA-T comprising the mapped LTF sequence;
Receiving feedback information generated based on the reception strength of the BA-T from a plurality of user terminals receiving the BA-T; And
Assigning a frequency unit to data frames to be transmitted to a plurality of user terminals according to the feedback information, and transmitting data frames using the assigned frequency unit
Lt; / RTI >
Wherein the reception strength of the BA-T is determined for each of the plurality of frequency units in each of the plurality of user terminals. The method according to claim 1,
Wherein determining the beamforming matrix comprises:
Wherein the beamforming matrix is determined regardless of channel information between the communication device and the plurality of user terminals. The method according to claim 1,
The reception strength of the BA-
Wherein the information includes information on SINR (Signal to Interference and Noise Ratio), SNR (Signal to Noise Ratio), or MSC (Modulation and Coding Scheme) of the BA-T in the plurality of frequency units. The method according to claim 1,
Wherein transmitting the data frames using the assigned frequency unit comprises:
The method comprising: identifying at least one frequency unit having a reception intensity higher than a predetermined threshold intensity among a plurality of frequency units through feedback information, and assigning the identified at least one frequency unit to a data frame corresponding to the feedback information; Transmission method. The method according to claim 1,
Wherein transmitting the data frames using the assigned frequency unit comprises:
Wherein the data frame is transmitted by mapping data to at least one subcarrier corresponding to the allocated frequency unit and mapping the mapped data to a beamforming matrix according to the allocated frequency unit. The method according to claim 1,
Wherein transmitting the data frames using the assigned frequency unit comprises:
Wherein the first allocation information for frequency units allocated to the plurality of user terminals is included in a data frame in a non-beamformed state and is transmitted to the plurality of user terminals. The method according to claim 6,
Wherein the first allocation information includes:
And sequentially includes information on frequency units allocated for each data frame. The method according to claim 6,
Wherein the first allocation information includes:
And sequentially includes information on a data frame allocated to each frequency unit. The method according to claim 1,
Wherein transmitting the data frames using the assigned frequency unit comprises:
Wherein the second allocation information for the frequency unit allocated to the target user terminal receiving the data frame is included in the data frame in the beamformed state and transmitted to the target user terminal. The method according to claim 1,
Wherein the frequency unit corresponds to at least one subcarrier to which the same beamforming matrix is applied. A computer-readable recording medium on which a program for executing the method according to any one of claims 1 to 10 is recorded. A communication unit for communicating with a plurality of user terminals; And
A processor
Lt; / RTI >
The processor comprising:
Determining a beamforming matrix according to classification information obtained by classifying a plurality of subcarriers used for the communication into a plurality of frequency units,
Mapping an LTF sequence to the beamforming matrix, transmitting a BA-T containing the mapped LTF sequence,
Receiving feedback information generated based on the reception strength of the BA-T from a plurality of user terminals receiving the BA-T,
Assigning a frequency unit to data frames to be transmitted to a plurality of user terminals according to the feedback information, transmitting data frames using the assigned frequency unit,
Wherein the reception strength of the BA-T is determined for each of the plurality of frequency units in each of the plurality of user terminals. 13. The method of claim 12,
The processor comprising:
And determines the beamforming matrix independently of channel information between the communication device and the plurality of user terminals. 13. The method of claim 12,
The reception strength of the BA-T may include information on SINR (Signal to Interference and Noise Ratio), SNR (Signal to Noise Ratio), or Modulation and Coding Scheme (MSC)) of the BA-T in the plurality of frequency units The communication device. 13. The method of claim 12,
The processor comprising:
Wherein at least one frequency unit having a reception intensity higher than a predetermined threshold intensity among a plurality of frequency units is identified through feedback information and the at least one frequency unit is assigned to a data frame corresponding to the feedback information, Device. 13. The method of claim 12,
The processor comprising:
And maps the data to at least one subcarrier corresponding to the allocated frequency unit and maps the mapped data to a beamforming matrix according to the allocated frequency unit. 13. The method of claim 12,
The processor comprising:
Wherein the first allocation information for frequency units allocated to the plurality of user terminals is included in a data frame in a non-beamformed state and is transmitted to the plurality of user terminals. 18. The method of claim 17,
Wherein the first allocation information includes:
And sequentially includes information on frequency units allocated for each data frame. 18. The method of claim 17,
Wherein the first allocation information includes:
And sequentially includes information on data frames allocated for each frequency unit. 13. The method of claim 12,
The processor comprising:
And transmits the second allocation information for the frequency unit allocated to the target user terminal receiving the data frame to the target user terminal in a data frame in a beamformed state.

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