Wireless communication method and wireless communication terminal using a training signal

Abstract

The present invention relates to a wireless communication method and a wireless communication terminal using a training signal. A wireless communication terminal is disclosed. The wireless communication terminal includes: a transceiver configured to transmit / receive wireless signals; and a processor configured to control the operation of the wireless communication terminal. The transceiver transmits a training signal to the basic wireless communication terminal based on a sub-band allocated from the basic wireless communication terminal, and transmits data to the basic wireless communication terminal through the sub-band allocated from the basic wireless communication terminal. The basic wireless communication terminal allocates a plurality of sub-bands to a plurality of wireless communication terminals including the wireless communication terminal, and receives data from the plurality of wireless communication terminals based on the training signal.

Description

[0001] This application is a divisional application of the patent application with the international application date of April 20, 2016 and application number 201680022741.7 (international application number PCT / KR2016 / 004131) filed on October 19, 2017, and the invention name is "Wireless communication method and wireless communication terminal using training signals". Technical Field

[0002] The present invention relates to a wireless communication method and a wireless communication terminal for setting a broadband link. In particular, the present invention relates to a wireless communication method and a wireless communication terminal for transmitting an effective training signal for communicating with multiple terminals simultaneously. Background Art

[0003] In recent years, with the expansion of the supply of mobile devices, wireless communication technology that can provide fast wireless Internet services to mobile devices has gained attention. Wireless communication technology allows mobile devices (including smart phones, smart tablets, laptops, portable multimedia players, embedded devices, etc.) to wirelessly access the Internet at home or in a company or in a specific service provision area.

[0004] One of the most famous wireless communication technologies is wireless LAN technology. Since supporting the initial wireless LAN technology by using the frequency of 2.4GHz, the Institute of Electrical and Electronics Engineers (IEEE) 802.11 has commercialized or developed various technical standards. Initially, IEEE 802.11b supported a communication speed of up to 11Mbps when using the frequency of the 2.4GHz band. Compared with the frequency of the significantly congested 2.4GHz band, the IEEE 802.11a commercialized after IEEE802.11b uses the frequency of the 5GHz band instead of the 2.4GHz band to reduce the influence of interference, and increases the communication speed to a maximum of 54Mbps by using orthogonal frequency division multiplexing (OFDM) technology. However, the disadvantage of IEEE 802.11a is that the communication distance is shorter than that of IEEE 802.11b. In addition, IEEE 802.11g uses a frequency of the 2.4 GHz band similarly to IEEE 802.11b to achieve a communication speed of a maximum of 54 Mbps and satisfy backward compatibility, thereby becoming a focus, and further, is superior to IEEE 802.11a in terms of communication distance.

[0005] In addition, as a technical standard established to overcome the communication speed limitation pointed out as a weakness of wireless LAN, IEEE 802.11n has been provided. IEEE 802.11n is intended to increase the speed and reliability of the network and extend the operating distance of the wireless network. In more detail, IEEE 802.11n supports high throughput (HT), in which the data processing speed is a maximum of 540Mbps or faster, and further, based on multiple-input and multiple-output (MIMO) technology, in which multiple antennas are used on both sides of the transmitting unit and the receiving unit to minimize transmission errors and optimize data speed. Further, the standard can use a coding scheme that transmits multiple copies overlapping each other to increase data reliability.

[0006] As the provision of wireless LANs is activated and further, the applications using wireless LANs are diversified, the demand for a new wireless LAN system for supporting a higher throughput (very high throughput (VHT)) than the data processing speed supported by IEEE 802.11n has become a focus. Among them, IEEE 802.11ac supports a wide bandwidth (80 to 160MHz) in the 5GHz frequency. The IEEE 802.11ac standard is defined only in the 5GHz band, but the initial 11ac chipset will support operations even in the 2.4GHz band in order to have backward compatibility with existing 2.4GHz band products. Theoretically, according to the standard, the wireless LAN speed of multiple stations can reach a maximum of 1Gbps, and the maximum single link speed can reach a maximum of 500Mbps. This is achieved by extending the concept of the wireless interface accepted by 802.11n, such as a wider wireless frequency bandwidth (maximum 160MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (maximum 256QAM). Further, as a scheme for transmitting data by using the 60 GHz band instead of the existing 2.4 GHz / 5 GHz, IEEE 802.11ad has been provided. IEEE 802.11ad is a transmission standard that provides a maximum speed of 7 Gbps by using a beamforming technology, and is suitable for high bit rate motion picture streams (such as large amounts of data or uncompressed HV video). However, since the 60 GHz band cannot pass through obstacles, it is disadvantageous that the 60 GHz band can only be used in devices in a short distance space.

[0007] Meanwhile, in recent years, as the next generation wireless communication technology standard after 802.11ac and 802.11ad, discussions on providing high-efficiency, high-performance wireless communication technology in a high-density environment have been ongoing. That is, in the next generation wireless communication technology environment, in the presence of high-density terminals and base station terminals, it is necessary to provide communication with high frequency efficiency indoors / outdoors, and various technologies for implementing communication are required.

[0008] In particular, as the number of devices using wireless communication technology increases, it is necessary to effectively use a predetermined channel. Therefore, a technology capable of effectively using bandwidth by simultaneously transmitting data between a plurality of terminals and a base station side is required. Summary of the invention

[0009] Technical issues

[0010] An object of the present invention is to provide an efficient wireless communication method and a wireless communication terminal.

[0011] In particular, an object of the present invention is to provide a wireless communication method and a wireless communication terminal using a training signal.

[0012] Technical Solution

[0013] According to an embodiment of the present invention, a wireless communication terminal includes: a transceiver configured to send / receive wireless signals; and a processor configured to control the operation of the wireless communication terminal, wherein the transceiver sends a training signal to a basic wireless communication terminal based on a sub-frequency band allocated from the basic wireless communication terminal, and sends data to the basic wireless communication terminal through the sub-frequency band allocated from the basic wireless communication terminal, wherein the basic wireless communication terminal allocates multiple sub-frequency bands to multiple wireless communication terminals including the wireless communication terminal, and receives data from the multiple wireless communication terminals based on the training signal.

[0014] The transceiver may transmit a subcarrier of a training signal corresponding to a subfrequency band allocated to the wireless communication terminal by the base wireless communication terminal.

[0015] The transceiver may apply a training signal scaling value that adjusts the amplitude of the training signal when transmitting a subcarrier.

[0016] The transceiver may determine the training signal scaling value based on the number of subcarriers of the training signal corresponding to the subfrequency band allocated to the wireless communication terminal by the base wireless communication terminal.

[0017] The transceiver may determine the training signal scaling value based on the number of total subcarriers corresponding to the sub-frequency band allocated to the wireless communication terminal by the basic wireless communication terminal; and the number of total subcarriers may indicate the number of subcarriers used to send data through the sub-frequency band allocated to the wireless communication terminal by the basic wireless communication terminal.

[0018] The transceiver may determine the training signal scaling value based on a value obtained by dividing the number of subcarriers of the training signal corresponding to the subfrequency band allocated to the wireless communication terminal by the number of all subcarriers.

[0019] Subcarriers for transmitting data in a sub-frequency band allocated to the wireless communication terminal by the basic wireless communication terminal include subcarriers for transmitting data and subcarriers for transmitting pilot signals.

[0020] The transceiver may transmit additional subcarriers corresponding to a sub-frequency band adjacent to a sub-frequency band allocated from a basic wireless communication terminal but not corresponding to a sub-frequency band allocated to a plurality of wireless communication terminals.

[0021] The transceiver and another wireless communication terminal may transmit the additional subcarriers simultaneously.

[0022] The transceiver may receive signaling information about a method of transmitting the additional subcarriers, and transmit the additional subcarriers based on the signaling information.

[0023] The signaling information may be in a signaling field that signals information about each of the plurality of wireless communication terminals.

[0024] The signaling information may indicate to the wireless communication terminal that the additional subcarriers are to be transmitted.

[0025] Signaling information may be applied when sending the additional subcarriers to indicate a scaling value for adjusting the amplitude of the additional subcarriers.

[0026] According to an embodiment of the present invention, a basic wireless communication terminal includes: a transceiver configured to send / receive wireless signals; and a processor configured to control the operation of the wireless communication terminal, wherein the transceiver allocates multiple sub-frequency bands to multiple wireless communication terminals, receives a training signal from each of the multiple wireless communication terminals based on the multiple sub-frequency bands allocated to each of the multiple wireless communication terminals, and receives data from each of the multiple wireless communication terminals based on the training signal through the multiple sub-frequency bands allocated to each of the multiple wireless communication terminals.

[0027] Each of the plurality of wireless communication terminals may transmit a subcarrier of a training signal corresponding to a subband allocated to each of the plurality of wireless communication terminals by the base wireless communication terminal.

[0028] A sub-band adjacent to a sub-band allocated from a basic wireless communication terminal may be allocated to at least one of the plurality of wireless communication terminals, and additional subcarriers not corresponding to the sub-bands allocated to the plurality of wireless communication terminals may be transmitted.

[0029] The transceiver may transmit signaling information regarding a method of transmitting the additional subcarriers.

[0030] The signaling information may indicate to the wireless communication terminal that the additional subcarriers are to be transmitted.

[0031] Signaling information may be applied when sending the additional subcarriers to indicate a scaling value for adjusting the amplitude of the additional subcarriers.

[0032] According to an embodiment of the present invention, an operating method of a wireless communication terminal includes: sending a training signal to a basic wireless communication terminal based on a sub-frequency band allocated from the basic wireless communication terminal; and sending data to the basic wireless communication terminal through the sub-frequency band allocated from the basic wireless communication terminal, wherein the basic wireless communication terminal allocates multiple sub-frequency bands to multiple wireless communication terminals including the wireless communication terminal, and receives data from the multiple wireless communication terminals based on the training signal.

[0033] Beneficial Effects

[0034] An embodiment of the present invention provides an efficient wireless communication method and a wireless communication terminal.

[0035] In particular, the embodiments of the present invention provide a wireless communication method and a wireless communication terminal that effectively use a training signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a view illustrating a wireless communication system according to an embodiment of the present invention.

[0037] Figure 2 is a view illustrating a wireless communication system according to another embodiment of the present invention.

[0038] Figure 3 is a block diagram illustrating a configuration of a station according to an embodiment of the present invention.

[0039] Figure 4 is a block diagram illustrating a configuration of an access point according to an embodiment of the present invention.

[0040] Figure 5 is a view illustrating a process in which a station sets an access point and a link according to an embodiment of the present invention.

[0041] Figure 6 is a view illustrating a format of a physical frame according to an embodiment of the present invention.

[0042] Figure 7 A pattern of a short training signal according to an embodiment of the present invention is illustrated.

[0043] Figure 8 The diagram shows the reference Figure 7 The specific signal pattern of the subcarriers included in the short training signal described.

[0044] Fig. 9 The pattern of a short training signal is briefly illustrated.

[0045] Fig.10 Detailed illustration of the reference Fig. 9 Describes the pattern of the short training signal.

[0046] Fig.11 The figure illustrates physical frames sent by multiple stations when the multiple stations send data to the AP.

[0047] Fig.12 A pattern of a training signal corresponding to HE-STF-long sent by nine stations to an AP according to an embodiment of the present invention is illustrated.

[0048] Fig.13 Specifically illustrated is a pattern of a training signal corresponding to HE-STF-long sent by nine stations to an AP according to an embodiment of the present invention.

[0049] Fig.14 A pattern of a training signal corresponding to HE-STF-long sent by five stations to an AP according to an embodiment of the present invention is illustrated.

[0050] Fig.15 Specifically illustrated is a pattern of a training signal corresponding to HE-STF-long sent by five stations to an AP according to an embodiment of the present invention.

[0051] Fig.16 A pattern of a training signal corresponding to HE-STF-long sent by three stations to an AP according to an embodiment of the present invention is illustrated.

[0052] Fig.17 Specifically illustrated is a pattern of a training signal corresponding to HE-STF-long sent by three stations to an AP according to an embodiment of the present invention.

[0053] Fig.18 is a ladder diagram illustrating operations of the first wireless communication terminal and the second wireless communication terminal according to the embodiment of the present invention. DETAILED DESCRIPTION

[0054] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. However, the present invention may be embodied in different forms and should not be constructed to be limited to the embodiments described herein. Parts not relevant to the description are omitted in the accompanying drawings to clearly describe the present invention, and the same reference numerals always refer to the same elements.

[0055] Furthermore, when described as comprising (or including or having) some elements, it should be understood that it may comprise (or include or have) only those elements, or it may comprise (or include or have) other elements as well as those elements, if there is no specific limitation.

[0056] This application claims priority to and the benefit of Korean Patent Application Nos. 10-2015-0055563 and 10-2105-0062726 filed in the Korean Intellectual Property Office, and the embodiments and items described in the corresponding applications are included in the detailed description of the present application.

[0057] Figure 1 1 is a schematic diagram illustrating a wireless communication system according to an embodiment of the present invention. For ease of description, the embodiment of the present invention is described by a wireless LAN system. The wireless LAN system includes one or more basic service sets (BSSs), and a BSS represents a collection of devices that are successfully synchronized with each other to communicate with each other. Generally, a BSS can be classified into an infrastructure BSS and an independent BSS (IBSS), and Figure 1 The diagram illustrates the infrastructure BSS between BSSs.

[0058] As in Figure 1 As shown in the figure, the infrastructure BSS (BSS1 and BSS2) includes one or more stations STA1, STA2, STA3, STA_d, and STA5 as stations providing distribution services, access points PCP / AP-1 and PCP / AP-2, and a distribution system (DS) connecting multiple access points PCP / AP-1 and PCP / AP-2.

[0059] A station (STA) is a predetermined device including a media access control (MAC) that complies with the provisions of the IEEE 802.11 standard and a physical layer interface for a wireless medium, and in a broad sense, includes both a non-access point (non-AP) station and an access point (AP). Further, in this specification, the term "terminal" may be used to refer to a concept including a wireless LAN communication device (such as a non-AP STA, or an AP, or both). A station for wireless communication includes a processor and a transceiver, and according to an embodiment, may further include a user interface unit and a display unit. The processor may generate a frame to be sent via a wireless network or process a frame received via a wireless network, and in addition, performs various processes to control the station. In addition, the transceiver is functionally connected to the processor, and sends and receives frames via the wireless network of the station.

[0060] An access point (AP) is an entity that provides access to a distribution system (DS) via a wireless medium of a station associated therewith. In an infrastructure BSS, communication between non-AP stations is performed via an AP in principle, but when a direct link is configured, direct communication is possible even between non-AP stations. Meanwhile, in the present invention, an AP is used as a concept including a personal BSS coordination point (PCP), and may broadly include the following concepts, including: a centralized controller, a base station (BS), a node B, a base transceiver system (BTS), and a site controller.

[0061] A plurality of infrastructure BSSs may be connected to each other through a distribution system (DS). In this case, the plurality of BSSs connected through the distribution system is referred to as an extended service set (ESS).

[0062] Figure 2 The figure shows an independent BSS as a wireless communication system according to another embodiment of the present invention. For the convenience of description, another embodiment of the present invention is described by a wireless LAN system. Figure 2 In the embodiment of Figure 1 The same or corresponding parts of the embodiments are described repeatedly.

[0063] Because in Figure 2 The BSS3 illustrated in FIG is an independent BSS and does not include an AP, so all stations STA6 and STA7 are not connected to the AP. An independent BSS is not allowed to access a distribution system and form a self-contained network. In an independent BSS, corresponding stations STA6 and STA7 can be directly connected to each other.

[0064] Figure 3 is a block diagram illustrating a configuration of a station 100 according to an embodiment of the present invention.

[0065] As in Figure 3As illustrated in FIG. 1 , the station 100 according to an embodiment of the present invention may include a processor 110 , a transceiver 120 , a user interface unit 140 , a display unit 150 , and a memory 160 .

[0066] First, the transceiver 120 sends and receives wireless signals (such as wireless LAN packets, etc.), and the transceiver 120 can be embedded in the station 100 or provided as an external element. According to an embodiment, the transceiver 120 may include at least one transmission / reception module using different frequency bands. For example, the transceiver 120 may include transmission / reception modules with different frequency bands (such as 2.4GHz, 5GHz, and 60GHz). According to an embodiment, the station 100 may include a transmission / reception module using a 6GHz or higher frequency band and a transmission / reception module using a 6GHz or lower frequency band. The corresponding transmission / reception module can perform wireless communication with an AP or an external station according to the wireless LAN standard of the frequency band supported by the corresponding transmission / reception module. The transceiver 120 can operate only one transmission / reception module at a time or operate multiple transmission / reception modules simultaneously according to the performance and requirements of the station 100. When the station 100 includes multiple transmission / reception modules, each transmission / reception module can be implemented by an independent element, or multiple modules can be integrated into one chip.

[0067] Next, the user interface unit 140 includes various types of input / output devices provided in the station 100. That is, the user interface unit 140 may receive a user input by using various input devices, and the processor 110 may control the station 100 based on the received user input. Further, the user interface unit 140 may perform an output based on a command of the processor 110 by using various output devices.

[0068] Next, the display unit 150 outputs an image on the display screen. The display unit 150 may output various display objects such as content or a user interface executed by the processor 110 based on a control command of the processor 110, etc. Further, the memory 160 stores a control program used in the station 100 and various result data. The control program may include an access program required for the station 100 to access an AP or an external station.

[0069] The processor 110 of the present invention may execute various commands or programs and process data in the station 100. Further, the processor 110 may control the corresponding units of the station 100 and control data transmission / reception between the units. According to an embodiment of the present invention, the processor 110 may execute a program for accessing an AP stored in the memory 160 and receive a communication configuration message sent by the AP. Further, the processor 110 may read information about the priority condition of the station 100 included in the communication configuration message and request access to the AP based on the information about the priority condition of the station 100. The processor 110 of the present invention may represent a main control unit of the station 100, and according to an embodiment, the processor 110 may represent a control unit for individually controlling a certain component (e.g., transceiver 120, etc.) of the station 100. The processor 110 controls various operations of wireless signal transmission / reception of the station 100 according to an embodiment of the present invention. A detailed embodiment thereof will be described below.

[0070] exist Figure 3 The station 100 illustrated in the figure is a block diagram according to an embodiment of the present invention, wherein the individual blocks are illustrated as logically distinguished elements of the device. Therefore, the elements of the device can be installed in a single chip or multiple chips according to the design of the device. For example, the processor 110 and the transceiver 120 can be implemented when the processor 110 and the transceiver 120 are integrated into a single chip or the processor 110 and the transceiver 120 are implemented as separate chips. Further, in an embodiment of the present invention, some components of the station 100 (for example, the user interface unit 140 and the display unit 150) can be optionally set in the station 100.

[0071] Figure 4 is a block diagram illustrating a configuration of an AP 200 according to an embodiment of the present invention.

[0072] As in Figure 4 As shown in FIG. 1 , the AP 200 according to the embodiment of the present invention may include: a processor 210, a transceiver 220, and a memory 260. Figure 4 In this document, the components of AP 200 are omitted. Figure 2 Description of the same or corresponding parts of the components of the station 100 will be repeated.

[0073] Reference Figure 4 , the AP 200 according to the present invention includes a transceiver 220 for operating a BSS in at least one frequency band. Figure 3As described in the embodiment of the present invention, the transceiver 220 of the AP 200 may also include a plurality of transmission / reception modules using different frequency bands. That is, the AP 200 according to the embodiment of the present invention may include two or more transmission / reception modules in different frequency bands (e.g., 2.4 GHz, 5 GHz, and 60 GHz). Preferably, the AP 200 may include a transmission / reception module using a 6 GHz or higher frequency band and a transmission / reception module using a 6 GHz or lower frequency band. The corresponding transmission / reception module may perform wireless communication with the station according to the wireless LAN standard of the frequency band supported by the corresponding transmission / reception module. The transceiver 220 may operate only one transmission / reception module at a time or operate multiple transmission / reception modules simultaneously according to the performance and requirements of the AP 200.

[0074] Next, the memory 260 stores the control program and various result data used in the AP 200. The control program may include an access program for managing access to the station. Further, the processor 210 may control the corresponding units of the AP 200 and control data transmission / reception between the various units. According to an embodiment of the present invention, the processor 210 may execute a program for accessing a station stored in the memory 260, and send a communication configuration message of one or more stations. In this case, the communication configuration message may include information about the access priority condition of the corresponding station. Further, the processor 210 performs access configuration according to the access request to the station. The processor 210 controls various operations according to an embodiment of the present invention (such as, radio signal transmission / reception of the AP 200). A detailed embodiment thereof will be described below.

[0075] Figure 5 is a diagram schematically illustrating a process in which a STA sets up a link with an AP.

[0076] Reference Figure 5 , a link between the STA 100 and the AP 200 is generally set up through three steps of scanning, authentication, and association. First, the scanning step is a step in which the STA 100 acquires access information of the BSS operated by the AP 200. Methods for performing scanning include a passive scanning method (S101) in which the AP 200 acquires information by using a beacon message transmitted periodically, and an active scanning method in which the STA 100 transmits a probe request to the AP (S103) and acquires access information by receiving a probe response from the AP (S105).

[0077] The STA 100 that successfully receives the wireless access information in the scanning step performs an authentication step (S107b) by sending an authentication request (S107a) and receiving an authentication response from the AP 200. After performing the authentication step, the STA 100 performs an association step (S109b) by sending an association request (S109a) and receiving an association response from the AP 200.

[0078] At the same time, an authentication step (S111) based on 802.1X and an IP address acquisition step (S113) through DHCP may be additionally performed. Figure 5 In FIG. 2 , the authentication server 300 is a server that processes 802.1X-based authentication with the STA 100 and may exist in physical association with the AP 200 or as a separate server.

[0079] When data is transmitted by using Orthogonal Frequency Division Modulation (OFDMA) or Multiple Input Multiple Output (MIMO), any one wireless communication terminal can transmit data to multiple wireless communication terminals at the same time. Also, any one wireless communication terminal can receive data from multiple wireless communication terminals at the same time.

[0080] For ease of description, any one wireless communication terminal that communicates with multiple wireless communication terminals at the same time is referred to as a first wireless communication terminal, and multiple wireless communication terminals that communicate with the first wireless communication terminal at the same time are referred to as multiple second wireless communication terminals. In addition, the first wireless communication terminal may be referred to as a basic wireless communication terminal. In addition, the first wireless communication terminal may be a wireless communication terminal that allocates communication media resources and performs scheduling when communicating with multiple wireless communication terminals. Specifically, the first wireless communication terminal may perform the role of a cell coordinator. At this time, the first wireless communication terminal may be an access point 200. In addition, the second wireless communication terminal may be a station 100 associated with the access point 200. In a specific embodiment, the first wireless communication terminal may be a wireless communication terminal that allocates communication media resources and performs scheduling in an independent network (such as an ad-hoc network) that is not connected to an external distribution service. In addition, the first wireless communication terminal may be at least one of a base station, an eNB, and a transmission point TP. By Figures 6 to 18 , a method for a first wireless communication terminal and a plurality of second wireless communication terminals to communicate with each other will be described. Specifically, a method for using a training signal when a first wireless communication terminal and a plurality of second wireless communication terminals communicate with each other will be described.

[0081] Figure 6 is a view illustrating a format of a physical frame according to an embodiment of the present invention.

[0082] According to an embodiment of the present invention, a physical frame sent by a wireless communication terminal includes: a traditional preamble code for signaling information of a wireless communication terminal that does not support an embodiment of the present invention, a non-traditional preamble code for signaling information of a wireless communication terminal that supports an embodiment of the present invention, and a data frame for sending data.

[0083] The conventional preamble may include at least a portion of information that cannot be decoded by a wireless communication terminal that does not support an embodiment of the present invention. The conventional preamble may include: an L-STF field, an L-LTF field, and an L-SIG field. The L-STF field indicates a short training signal that is decoded by both a wireless communication terminal that supports an embodiment of the present invention and a wireless communication terminal that does not support an embodiment of the present invention. The training signal is a signal that assists the demodulation and decoding settings of the wireless communication terminal in order to receive a signal to be sent after sending the training signal. The short training signal is a training signal with a relatively short signal length. Specifically, the wireless communication terminal can perform automatic gain control (AGC) on the OFDM symbol including the L-LTF field and the L-SIG field based on the short training signal. Moreover, the wireless communication terminal can synchronize the timing and frequency with the OFDM symbol including the L-SIG field based on the short training signal.

[0084] The L-LTF field indicates a long training signal decoded by both a wireless communication terminal supporting an embodiment of the present invention and a wireless communication terminal not supporting an embodiment of the present invention. The long training signal is a training signal having a relatively long signal length. Specifically, the wireless communication terminal can estimate the frequency offset including the L-SIG field based on the long training signal.

[0085] The L-SIG field indicates signaling information decoded by both wireless communication terminals supporting embodiments of the present invention and wireless communication terminals not supporting embodiments of the present invention. Specifically, the L-SIG field can signal information about data rate and data length.

[0086] The non-traditional preamble code may include: HE-SIG-A field, HE-SIG-B field, HE-STF, and HE-LTF.

[0087] The HE-SIG-A field signals information commonly applied to a plurality of second wireless communication terminals.

[0088] The HE-SIG-B field signals information about each of a plurality of second wireless communication terminals.

[0089] HE-STF indicates a short training signal for decoding by a wireless communication terminal supporting an embodiment of the present invention. A wireless communication terminal supporting an embodiment of the present invention can perform automatic gain control (AGC) on an OFDM symbol including HE-LTF, HE-SIG-B field, and data in a payload based on a short training signal. In addition, a wireless communication terminal supporting an embodiment of the present invention can perform synchronization for the timing and frequency of an OFDM symbol including HE-LTF and data in a payload based on a short training signal.

[0090] HE-LTF indicates a long training signal for decoding by a wireless communication terminal supporting an embodiment of the present invention. A wireless communication terminal supporting an embodiment of the present invention can estimate the channel and frequency offset of an OFDM symbol including data in a payload based on the long training signal. Specifically, a wireless communication terminal supporting an embodiment of the present invention can estimate the channel for transmitting data based on a long training signal. In addition, a wireless communication terminal supporting an embodiment of the present invention can estimate the frequency offset of an OFDM symbol based on a long training signal. In this specification, HE-LTF may indicate HE-LTF itself or a long training signal included in HE-LTF.

[0091] The HE-SIG-A field may be indicated by an OFDM x symbol, and the HE-SIG-B may be indicated by the length of an OFDM y symbol. At this time, as the value of x increases, the number of second wireless communication terminals to which the first wireless communication terminal can send data increases. Specifically, depending on the value of x, the number of second wireless communication terminals to which the first wireless communication terminal can send data may be any one of 4, 8, 12, and 16. Moreover, a variable number of HE-LTFs may be sent according to the number of spatial streams sent by the wireless communication terminal.

[0092] exist Figure 6 In an embodiment of the present invention, the L-STF, L-LTF, L-SIG, HE-SIG-A and HE-SIG-B of the physical frame are modulated into 64 FFT-based OFDM symbols. In addition, each of the HE-STFs from the physical frame to the data frame is modulated into 256 FFT-based OFDM symbols.

[0093] Assuming the minimum data transmission rate is 6 Mbps and since the maximum length of the physical frame is 1366 symbols, the entire transmission maximum time from HE-STF to the data field can be limited to 5.464 ms.

[0094] HE-STF is divided into HE-STF-short and HE-STF-long according to the application. HE-STF-short can be used for single-user (SU) downlink transmission physical frames, multi-user (MU) downlink transmission physical frames, and SU uplink transmission physical frames. HE-STF-short can have a total length of 0.4μs, where a signal pattern with a length of 0.8μs on the time axis is repeated five times. HE-STF-long can be used for upward MU physical frames. HE-STF-long can have a total length of 8.0μs, where a signal pattern with a length of 1.6μs on the time axis is repeated five times.

[0095] HE-LTF is divided into HE-LTF-short and HE-LTF-long according to the application. HE-LTF-short can be used for indoor communication. HE-LTF-short can have a length equal to the sum of 6.4μs and the length of the guard interval. HE-LTF-long can be used for outdoor communication. HE-LTF-long can have a length equal to the sum of 12.8μs and the length of the guard interval.

[0096] Moreover, the physical frame may include a HE-SIG-C field. The HE-SIG-C field may be used for MU-MIMO transmission. Specifically, the HE-SIG-C field may indicate at least one of a modulation coding scheme (MCS) and a data length for each second wireless communication terminal. The HE-SIG-C field may have a variable length. However, according to a specific embodiment, the HE-SIG-B field may indicate at least one of an MCS for each second wireless communication terminal and a data length without a HE-SIG-C field.

[0097] Will refer to Figure 7 and Figure 8 The format of the short training signal is described in detail. Figure 7 Schematically illustrates a pattern of a short training signal according to an embodiment of the present invention. In addition, Figure 8 Detailed illustration of the reference Figure 7 Describes the pattern of the short training signal.

[0098] Specifically, Figure 7 (a) and Figure 8 (a) illustrates a short training signal modulated into 64 FFTs and transmitted through a 20 MHz frequency bandwidth.

[0099] In the case of transmitting a short training signal modulated into 64 FFTs through a 20 MHz frequency bandwidth, the short training signal includes 64 subcarriers in total. Figure 7 (a) and Figure 8In (a), the six subcarriers on the left and the five subcarriers on the right are located in the guard band. For ease of explanation, if (-a, b) is used to represent the subcarriers located between -a and b, then (-26, 26) can be used to represent Figure 7 (a) and Figure 8 In this case, the subcarriers included in the short training signal have the following values:

[0100]

[0101] exist Figure 7 (a) and Figure 8 In (a), the subcarriers transmit signals. At this time, the values ​​of the 12 subcarriers are 1+j or -1-j. Further, the subcarriers are multiplied by a scaling value for adjusting the amplitude of the short training signal. Specifically, the wireless communication terminal can transmit a short training signal with an amplitude equal to the amplitude of the long training signal. For example, in the 802.11a standard, all 52 subcarriers included in the long training signal in a 20 MHz frequency bandwidth transmit signals, and the modulation amplitude of the short training signal is Therefore, in the 802.11a standard, the scaling value applied to the short training signal is the value obtained by dividing the number of subcarriers of the transmitted signal in the long training signal by the number of subcarriers of the transmitted signal in the short training signal and further divided by the modulation amplitude of the short training signal, that is,

[0102] In another specific embodiment, the wireless communication terminal may send a short training signal whose total transmission power over the entire time axis is 1. For example, in the 802.11n standard, the modulation amplitude of the short training signal is Therefore, the wireless communication terminal must multiply So that the sum of the transmission power over the entire time axis is 1. Therefore, the scaling value applied to the short training signal in the 802.11n standard is 1.

[0103] To describe the short training signal sent over a frequency bandwidth other than 20 MHz, refer to Figure 7 (a) and Figure 8 The pattern of the short training signal described in (a) can represent the left pattern as STF_L and the right pattern as STF_R based on the DC band.

[0104] Specifically, STF_L and STF_R represent the following signal patterns:

[0105] {STF_L}={1+j,0,0,0,-1-j,0,0,0,1+j,0,0,0,-1-j,0,0,0,-1-j,0,0,0,1+j}

[0106] {STF_R}={-1-j,0,0,0,-1-j,0,0,0,1+j,0,0,0,1+j,0,0,0,1+j,0,0,0,1+j}

[0107] Moreover, for the sake of convenience, {0xn} is used to indicate that 0 is assigned to consecutive n subcarriers. Figure 7 (a) and Figure 8 The short training signal of (a) can be expressed as follows:

[0108]

[0109] Figure 7 (b) and Figure 8 (b) illustrates a short training signal modulated into 128 FFTs and transmitted through a 40 MHz frequency bandwidth.

[0110]

[0111] In the case of sending a short training signal via a 20 MHz or higher frequency bandwidth, the wireless communication terminal will Figure 7 (a) and Figure 8 The pattern of the short training signal described in (a) is used as a basic pattern, and a short training signal that repeats the basic pattern in units of 20 MHz is transmitted. At this time, the wireless communication terminal can shift the phase of the basic pattern to reduce the peak to average power ratio (PAPR). Figure 7 (b) and Figure 8 In (b), the wireless communication terminal shifts the phase of the second positioning basic pattern by j.

[0112] Figure 7 (c) and Figure 8 (c) illustrates a short training signal modulated into 256 FFTs and transmitted through an 80 MHz frequency bandwidth.

[0113] {VHT-STF_(-122,122)}=*{0,0,{STF_L},{0X7},{STF_R},{0X15},{STF_L}*(-1),{0X7},{STF_R}*(- 1),{0X15},{STF_L}*(-1),{0X7},{STF_R}*(-1),{0X15},{STF_L}*(-1),{0X7},{STF_R}*(-1),0,0}

[0114] exist Figure 7 (c) and Figure 8 In (c), the wireless communication terminal will refer to Figure 7 (a) and Figure 8The pattern of the short training signal described in (a) is used as a basic pattern, and a short training signal repeating the basic pattern in units of 20 MHz is transmitted. Furthermore, the wireless communication terminal shifts the phases of the second, third, and fourth basic patterns by -1.

[0115] Figure 7 (d) and Figure 8 (d) illustrates a short training signal modulated into 32 FFTs and transmitted through a 1 MHz frequency bandwidth.

[0116] {S1G-STF_(-13,13)}={0,0.5*(1+j),0,0,0,-1-j,0,0,0,1+j,0,0,0,0,0,0,0,-1-j,0,0,0,-1-j,0,0,0,0.5*(-1-j),0}

[0117] At this time, the pattern of the short training signal can be represented as S-STF_L on the left and S-STF_R on the right based on the DC band. Specifically, S-STF_L and S-STF_R represent the following signal patterns:

[0118] {S-STF_L}={0.5*(1+j),0,0,0,-1-j,0,0,0,1+j}

[0119] {S-STF_R}={-1-j,0,0,0,-1-j,0,0,0,0.5*(-1-j)}

[0120] By using S-STF_L and S-STF_R, Figure 7 (d) and Figure 8 The short training signal of (d) can be expressed as follows:

[0121] {SIG-STF_(-13,13)}={0,{S-STF_L},{0X7},{S-STF_R},0}

[0122] As described above, the wireless communication terminal according to the embodiment of the present invention transmits the HE-STF modulated into 256 FFTs through a 20 MHz frequency bandwidth. Therefore, when the wireless communication terminal uses the same frequency bandwidth and transmits a training signal in which a basic signal pattern having the same length as the training signal described above is repeated in the time domain, the transmission is faster than the reference signal. Figure 7 and Figure 8 Specifically, when the short training signal is sent through a 20 MHz frequency bandwidth, the wireless communication terminal sends more subcarriers than the reference signal. Figure 7 and Figure 8 The described embodiment has four times more subcarriers. Therefore, it is necessary to compare with the reference Figures 7 and 8 The patterns of the short training signals described are different from the patterns of the short training signals.

[0123] The wireless communication terminal can send a short training signal in which the interval of the subcarriers used to send the signal in the basic pattern is adjusted. At this time, the basic pattern can be the STF_L and STF_R described above. Further, the interval of the subcarriers used to send the signal can be determined based on the number of subcarriers that can be sent over the entire frequency band. Specifically, the interval of the subcarriers used to send the signal can be determined in proportion to the number of subcarriers that can be sent over the entire frequency band. For example, when the number of subcarriers that can be sent over the entire frequency band is 64, based on the four intervals of the subcarriers used to send the signal, the interval of the subcarriers for sending the signal can be determined in proportion to the number of subcarriers that can be sent over the entire frequency band. The number of subcarriers of the training signal that can be sent over the entire frequency band is determined according to the frequency bandwidth in the time domain, the FFT scheme, and the length of the basic pattern of the training signal. Reference will be made to Fig. 9 and Fig.10 To describe a specific embodiment.

[0124] Fig. 9 and Fig.10 The diagram shows a short training signal sent by HE-STF according to an embodiment of the present invention. Specifically, Fig. 9 The pattern of the short training signal is briefly illustrated. In addition, Fig.10 Detailed illustration of the reference Fig. 9 Describes the pattern of the short training signal.

[0125] Fig. 9 (a) and Fig.10 (a) illustrates the pattern of a short training signal transmitted by HE-STF-short in a 20 MHz frequency bandwidth.

[0126] As in Fig. 9 (a) and Fig.10 As shown in (a), the wireless communication terminal uses 256 FFTs in a 20MHz frequency bandwidth. At this time, the wireless communication terminal can set the interval of the subcarriers sending the short training signal sent by HE-STF-short to 16 to generate a signal repeated 16 times during the OFDM 1 symbol of 12.8μs. At this time, the basic pattern length of the short training signal of HE-STF-short in the time domain is 0.8μs. In addition, the short training signal of THE-STF-short is a signal with a length of 4μs obtained by sampling the corresponding five basic signals. For example, the pattern of the short training signal sent by HE-STF-short can be as follows:

[0127]

[0128] The pattern of the short training signal transmitted through HE-STF-short may represent the left pattern as STF_L' and the right pattern as STF_R' based on a DC band.

[0129] {STF_L'}={-1-j,{0X15},1+j,{0X15},-1-j,{0X15},1+j,{0X15},-1-j,{0X15},-1-j,{0X15},1+j}

[0130] {STF_R'}={-1-j,{0X15},-1-j,{0X15},1+j,{0X15},1+j,{0X15},1+j,{0X15},1+j,{0X15},1+j}

[0131] STF_L' and STF_R' are obtained by adjusting the interval of subcarriers for transmitting signals for STF_L and STF_R described above to 16. In addition, STF_L' and STF_R' are patterns in which signal values ​​for minimizing PAPR are added to -112 and 112 positions.

[0132] Fig. 9 (b) and Fig.10 (b) illustrates the pattern of the short training signal sent through HE-STF-long.

[0133] As in Fig. 9 (b) and Fig.10 As shown in (b), the wireless communication terminal uses 256 FFTs in a 20MHz frequency bandwidth. The wireless communication terminal can set the interval of the subcarriers that send the long training signal sent by HE-STF-long to 8 to generate a signal repeated 8 times during the OFDM 1 symbol of 12.8μs. At this time, the basic pattern length of the short training signal of HE-STF-long in the time domain is 1.6μs. In addition, the short training signal of THE-STF-long is a signal with a length of 8μs obtained by sampling the corresponding five basic signals. For example, the pattern of the short training signal sent by HE-STF-long can be as follows:

[0134] {HE-STF-long_(-122,122)}=S*{0,0,{STF-L"},{0X7},{-1-j or+1+j},{0X7},{STF-R"},{0X15},{STF-L"},{0X7},{1+j or-1-j},{0X7},{STFR"},0,0}

[0135] Here, S represents the scaling value applied to the short training signal. Fig.11 and Fig.17 The scaling value applied to the short training signal is described in detail. The pattern of the short training signal transmitted through HE-STF-short can represent the left pattern as STF_L" and the right pattern as STF_R" based on the DC band.

[0136] {STF_L"}={-1-j,{0X7},1+j,{0X7},-1-j,{0X7},1+j,{0X7},-1-j,{0X7},-1-j,{0X7},1+j}

[0137] {STF_R"}={-1-j,{0X7},-1-j,{0X7},1+j,{0X7},1+j,{0X7},1+j,{0X7},1+j,{0X7},1+j}

[0138] STF_L" and STF_R" are obtained by adjusting the interval of the subcarriers used for sending signals by STF_L and STF_R described above to 8. In addition, STF_L" and STF_R" are patterns in which signal values ​​for minimizing PAPR are added to -64 and 64. Specifically, STF_L" and STF_R" are obtained by adding -1-j and 1+j or 1+j and -1-j to the positions of -64 and 64, respectively.

[0139] As described above, the plurality of second wireless communication terminals may transmit data to the first wireless communication terminal through OFDMA. Figures 11 to 17 A training signal transmitted by a plurality of wireless communication terminals when a plurality of second wireless communication terminals communicate with a first wireless communication terminal by using OFDMA will be described.

[0140] Fig.11 The figure illustrates physical frames sent by multiple stations when the multiple stations send data to the AP.

[0141] A plurality of second wireless communication terminals may repeatedly transmit a traditional preamble for signaling information of a wireless communication terminal that does not support an embodiment of the present invention. Specifically, a plurality of second wireless communication terminals may transmit the same traditional preamble through the same frequency band. At this time, the traditional preamble may include at least one of L-STF, L-LTF, and L-SIG. Moreover, a plurality of second wireless communication terminals may repeatedly transmit a signaling field between non-traditional preambles for signaling information of wireless communication terminals that do not support an embodiment of the present invention. Specifically, a plurality of second wireless communication terminals may transmit a signaling field of the same non-traditional preamble through the same frequency band. At this time, the signaling field may be the HE-SIG-A field described above.

[0142] In another specific embodiment, multiple second wireless communication terminals may send multiplexed traditional preambles. Furthermore, multiple second wireless communication terminals may send signaling fields between non-traditional preambles in a combined form. In this case, the combination may represent a combination in a frequency band or a combination in rectangular coordinates.

[0143] When at least one second wireless communication terminal performs MIMO transmission, the number of space-time streams sent by each of the multiple second wireless communication terminals may be different from each other. The duration of the HE-LTF to be sent depends on the number of space-time streams. Therefore, when at least one second wireless communication terminal performs MIMO transmission, data, HE-STF, and HE-LTF can be sent to the first wireless communication terminal at the same time. In this case, the guard interval may be different for each sub-band in the entire frequency band to which OFDMA is applied. Therefore, the complexity of transmission and reception will increase. Therefore, the second wireless communication terminal needs to align the OFDM symbols sent from the second wireless communication terminal to the first wireless communication terminal with the OFDM symbols sent from another second wireless communication terminal to the first wireless communication terminal.

[0144] Therefore, the second wireless communication terminal can align the duration of the OFDM symbol of the training signal sent from the second wireless communication terminal to the first wireless communication terminal and the OFDM symbol of the training signal sent from another second wireless communication terminal to the first wireless communication terminal. Specifically, the second wireless communication terminal can simultaneously start HE-LTF transmission to the first wireless communication terminal as another second wireless communication terminal, and simultaneously stop HE-LTF transmission to the first wireless communication terminal as another second wireless communication terminal. Specifically, the second wireless communication terminal can send the same number of HE-LTFs as the number of HE-LTFs sent by another second wireless communication terminal to the first wireless communication terminal. For example, multiple second wireless communication terminals can send the same number of HE-LTFs as the second wireless communication terminal that requires the largest number of HE-LTFs among multiple second wireless communication terminals. To this end, the second wireless communication terminal can send an additional HE-LTF. In another specific embodiment, multiple second wireless communication terminals can send the same number of HE-LTFs as the second wireless communication terminal that requires the smallest number of HE-LTFs among multiple second wireless communication terminals. To this end, the second wireless communication terminal can send a multiplexed HE-LTF. The multiplexed HE-LTF indicates that multiple HE-LTFs are combined into an LTF of one HE-LTF. Specifically, the multiplexed HE-LTF may be a combination of multiple LTFs on the frequency axis. In another specific embodiment, the multiplexed HE-LTF may be a combination of multiple LTFs on the orthogonal code axis.

[0145] In addition, the plurality of second wireless communication terminals may transmit the training signal through a sub-frequency band allocated to each of the plurality of second wireless communication terminals.

[0146] exist Fig.11 In the embodiment of the present invention, the first to seventh stations STA_a, STA_b, STA_c, STA_d, STA_e, STA_f, and STA_g send data to the AP. At this time, the first to seventh stations STA_a, STA_b, STA_c, STA_d, STA_e, STA_f, and STA_g repeatedly send L-STF, L-LTF, L-SIG, and HE-SIG-A to the AP.

[0147] The first to seventh stations STA_a, STA_b, STA_c, STA_d, STA_e, STA_f, and STA_g send HE-STF, HE-LTF, HE-SIG-C, and data to the AP through the sub-band allocated to each of the first to seventh stations STA_a, STA_b, STA_c, STA_d, STA_e, STA_f, and STA_g.

[0148] At this time, the first to seventh stations STA_a, STA_b, STA_c, STA_d, STA_e, STA_f, and STA_g send the same number of HE-LTFs. The third station STA_c requires four HE-LTFs. Therefore, among the first to seventh stations STA_a, STA_b, STA_c, STA_d, STA_e, STA_f, and STA_g, the third station STA_c requires the largest number of HE-LTFs. Therefore, the first station STA_a sends two additional HE-LTFs. In addition, the second station STA_b sends three additional HE-LTFs. In addition, the fourth station STA_d sends two additional HE-LTFs. In addition, the fifth station STA_e sends three additional HE-LTFs. In addition, the sixth station STA_f sends two additional HE-LTFs. In addition, the seventh station STA_g sends three additional HE-LTFs.

[0149] In order for the first wireless communication terminal to receive data based on the training signal, the training signal sent from each of the multiple second wireless communication terminals must have a uniform amplitude. When each of the multiple second wireless communication terminals sends a subcarrier of a training signal with the same amplitude, the training signal sent from each of the multiple second wireless communication terminals to the first wireless communication terminal may not be uniform. Therefore, a method is needed for the second wireless communication terminal to determine a scaling value for adjusting the amplitude of the training signal. In addition, whether the second wireless communication terminal sends a subcarrier corresponding to a frequency band not allocated to the multiple second wireless communication terminals among the multiple subcarriers included in the training signal. In addition, whether the second wireless communication terminal sends a subcarrier corresponding to a frequency band not allocated to the multiple second wireless communication terminals among the multiple subcarriers included in the training signal becomes an issue. Will refer to Figures 12 to 17 To describe this.

[0150] Fig.12 A pattern of a training signal corresponding to HE-STF-long sent by nine stations to an AP according to an embodiment of the present invention is illustrated. Fig.13 Specifically illustrated is a pattern of a training signal corresponding to HE-STF-long sent by nine stations to an AP according to an embodiment of the present invention.

[0151] The second wireless communication terminal transmits a subcarrier of a training signal corresponding to a subband allocated to the second wireless communication terminal. However, when a plurality of second wireless communication terminals transmit data to a first wireless communication terminal through OFDMA, interference may occur between signals transmitted by the plurality of second wireless communication terminals. Therefore, in order to prevent interference between signals transmitted by the plurality of second wireless communication terminals, the first wireless communication terminal may allocate the remaining subbands except the guard band to the plurality of second wireless communication terminals. Therefore, a portion of the subcarriers of the training signal may correspond to a subband not allocated to the second wireless communication terminal.

[0152] If the subcarrier of the training signal corresponds to a sub-frequency band that is not allocated to the second wireless communication terminal, the plurality of second wireless communication terminals may not transmit the corresponding subcarrier.

[0153] In another specific embodiment, when the subcarrier of the training signal corresponds to a subband not allocated to the second wireless communication terminal, the second wireless communication terminal to which the subband adjacent to the frequency band in which the corresponding subcarrier is transmitted is allocated can transmit the corresponding subcarrier. For ease of explanation, the subcarrier corresponding to the subband not allocated to the second wireless communication terminal is referred to as an additional subcarrier. Specifically, a plurality of second wireless communication terminals to which the subband adjacent to the frequency band in which the additional subcarrier is transmitted is allocated can simultaneously transmit the additional subcarrier. At this time, each of the plurality of second wireless communication terminals can scale the amplitude of the signal used to transmit the additional subcarrier based on the number of the plurality of second wireless communication terminals. For example, each of the first station and the second station can transmit an additional subcarrier having a signal amplitude of 1 / 2 of the signal amplitude required for the transmission of the additional subcarrier. At this time, the subband in which the additional subcarrier is located is a subband not allocated to the second wireless communication terminal, and the subband allocated to each of the first station and the second station is adjacent to the subband in which the additional subcarrier is located.

[0154] In another specific embodiment, if the subcarrier of the training signal corresponds to a sub-frequency band not allocated to the second wireless communication terminal, any second wireless communication terminal may send the additional subcarrier. In this case, the plurality of second wireless communication terminals may be second wireless communication terminals allocated a frequency band adjacent to the sub-frequency band in which the additional subcarrier is located.

[0155] At this time, the first wireless communication terminal may send information that notifies the second wireless communication terminal that the additional subcarrier is to be sent. Specifically, the HE-SIG-B field described above may include information that notifies the second wireless communication terminal that the additional subcarrier is to be sent. The second wireless communication terminal may obtain information that notifies the second wireless communication terminal that the additional subcarrier is to be sent, and may send the additional subcarrier based on the information that notifies the second wireless communication terminal that the additional subcarrier is to be sent.

[0156] In another specific embodiment, if the subcarrier of the training signal corresponds to a subband that is not allocated to the second wireless communication terminal, the first wireless communication terminal may send information that uses a signal to notify a method of sending an additional subcarrier. At this time, the information that uses a signal to notify a method of sending an additional subcarrier may indicate which of the second wireless communication terminals is to send an additional subcarrier or whether multiple second wireless communication terminals send an additional subcarrier. Further, the information that uses a signal to notify a method of sending an additional subcarrier may indicate the second wireless communication terminal that is to send an additional subcarrier. In addition, the information that uses a signal to notify a method of sending an additional subcarrier is applied when sending an additional subcarrier to indicate a scaling value for adjusting the amplitude of a signal including an additional subcarrier.

[0157] exist Fig.12and Fig.13 In the embodiment of the present invention, the subbands corresponding to the positions of -96 and 96 are not allocated to any station. Moreover, two of the HE-STF-long subcarriers transmit signals at the positions of -96 and 96, respectively. Therefore, which station transmits the subcarriers corresponding to -96 and 96 becomes a question. Fig.12 and Fig.13 In the embodiment of the present invention, the first station STA 1 sends a subcarrier of HE-STF-long located at -96. Further, the eighth station STA 8 sends a subcarrier of HE-STF-long located at 96. At this time, the AP may send information using a signal to notify the first station STA 1 to send a subcarrier of HE-STF-long located at -96. In addition, the AP may send information using a signal to notify the eighth station STA 8 to send a subcarrier of HE--STF-long located at 96. At this time, the first station STA 1 may send a subcarrier of HE--STF-long located at -96 based on the signaling information sent by the AP. In addition, the eighth station STA 8 may send a subcarrier of HE-STF-long located at 96 based on the signaling information sent by the AP.

[0158] When a plurality of second wireless communication terminals transmit each of the subcarriers of the training signal with the same transmission power, the amplitude of the training signal received by the first wireless communication terminal from each of the plurality of second wireless communication terminals varies according to the number of subcarriers transmitted by each of the plurality of second wireless communication terminals. In this case, since the amplitude of the training signal received by the first wireless communication terminal from each of the plurality of second wireless communication terminals is not uniform, the first wireless communication terminal may not be able to perform accurate automatic gain control (AGC) based on the training signal. Moreover, the first wireless communication terminal may not be able to accurately perform frequency offset detection (FOD).

[0159] In order to solve this problem, when transmitting the subcarrier of the training signal corresponding to the subband allocated to the second wireless communication terminal, the second wireless communication terminal may apply the training signal scaling value so as to adjust the amplitude of the training signal in the frequency band allocated to the second wireless communication terminal. At this time, the second wireless communication terminal may determine the training signal scaling value based on the number of subcarriers of the training signal corresponding to the subband allocated to the second wireless communication terminal. Specifically, based on the number of all subcarriers corresponding to the subband allocated to the second wireless communication terminal and the number of subcarriers of the training signal corresponding to the subband allocated to the second wireless communication terminal, the second wireless communication terminal may determine the training signal scaling value. The number of all subcarriers corresponding to the subband allocated to the second wireless communication terminal may indicate the number of subcarriers used to send data through the subband allocated to the second wireless communication terminal. At this time, the subcarriers used to send data may include subcarriers used to send data and subcarriers used to send pilot signals. For example, based on the value obtained by dividing the number of subcarriers of the training signal corresponding to the subband allocated to the second wireless communication terminal by the number of all subcarriers corresponding to the subband, the second wireless communication terminal may determine the training signal scaling value. Specifically, the second wireless communication terminal may determine the training signal scaling value in inverse proportion to the number of subcarriers of the training signal corresponding to the sub-frequency band allocated to the second wireless communication terminal.

[0160] Moreover, the second wireless communication terminal may determine the transmission power of the training signal based on the signal drop that varies according to the relative position between the second wireless communication terminal and the first wireless communication terminal. Therefore, the second wireless communication terminal may determine the training signal scaling value. At this time, the relative position between the second wireless communication terminal and the first wireless communication terminal may be the distance between the second wireless communication terminal and the first wireless communication terminal.

[0161] exist Fig.12 and Fig.13In the embodiment of the present invention, the first station STA 1 transmits four subcarriers of the subcarriers of HE-STF-long. Moreover, the second station STA 2 transmits three subcarriers of the subcarriers of HE-STF-long. Moreover, the third station STA 3 transmits three subcarriers of the subcarriers of HE-STF-long. Moreover, the fourth station STA 4 transmits four subcarriers of the subcarriers of HE-STF-long. Moreover, the fifth station STA 5 transmits two subcarriers of the subcarriers of HE-STF-long. Moreover, the sixth station STA 6 transmits four subcarriers of the subcarriers of HE-STF-long. Moreover, the seventh station STA 7 transmits three subcarriers of the subcarriers of HE-STF-long. Moreover, the eighth station STA 8 transmits four subcarriers of the subcarriers of HE-STF-long. Moreover, the ninth station STA 9 transmits three subcarriers of the subcarriers of HE-STF-long.

[0162] At this time, the first station STA1, the fourth station STA4, the sixth station STA6, and the eighth station STA8 may determine the training signal scaling value based on a value obtained by dividing the number of subcarriers 4 transmitted by each of the first station STA1, the fourth station STA4, the sixth station STA6, and the eighth station STA8 by the number of all subcarriers 26 corresponding to the subband allocated to each of the first station STA1, the fourth station STA4, the sixth station STA6, and the eighth station STA8. At this time, the second station STA2, the third station STA3, the seventh station STA7, and the ninth station STA9 may determine the training signal scaling value based on a value obtained by dividing the number of subcarriers 3 transmitted by each of the second station STA2, the third station STA3, the seventh station STA7, and the ninth station STA9 by the number of all subcarriers 26 corresponding to the subband allocated to each of the second station STA2, the third station STA3, the seventh station STA7, and the ninth station STA9. In addition, the fifth station STA 5 may determine a training signal scaling value based on a value obtained by dividing the number 2 of subcarriers transmitted by the fifth station STA 5 by the number 26 of all subcarriers corresponding to the subband allocated to the fifth station STA 5 .

[0163] Thus, the AP can receive a short training signal with uniform amplitude from each of the first station STA 1 to the ninth station STA 9. Figures 14 to 17 A specific embodiment for determining the training signal scaling value is further described below.

[0164] Fig.14 A pattern of a training signal corresponding to HE-STF-long sent by five stations to an AP according to an embodiment of the present invention is illustrated. Fig.15 Specifically illustrated is a pattern of a training signal corresponding to HE-STF-long sent by five stations to an AP according to an embodiment of the present invention.

[0165] exist Fig.14 and Fig.15 In the embodiment of the present invention, the first station STA 1 transmits seven subcarriers of the subcarriers of HE-STF-long. Furthermore, the second station STA 2 transmits seven subcarriers of the subcarriers of HE-STF-long. Furthermore, the third station STA 3 transmits two subcarriers of the subcarriers of HE-STF-long. Furthermore, the fourth station STA 4 transmits seven subcarriers of the subcarriers of HE-STF-long. Furthermore, the fifth station STA 5 transmits seven subcarriers of the subcarriers of HE-STF-long.

[0166] At this time, the first station STA1, the second station STA2, the fourth station STA4, and the fifth station STA5 may determine a training signal scaling value based on a value obtained by dividing the number of subcarriers 7 transmitted by each of the first station STA1, the second station STA2, the fourth station STA4, and the fifth station STA5 by the number of all subcarriers 52 corresponding to the subband allocated to each of the first station STA1, the second station STA2, the fourth station STA4, and the fifth station STA5. In addition, the third station STA3 may determine a training signal scaling value based on a value obtained by dividing the number of subcarriers 2 transmitted by the third station STA3 by the number of all subcarriers 26 corresponding to the subband allocated to the third station STA3. Thus, the AP can receive a short training signal having a uniform amplitude from each of the first station STA1 to the fifth station STA5.

[0167] Fig.16 A pattern of a training signal corresponding to HE-STF-long sent by three stations to an AP according to an embodiment of the present invention is illustrated. Fig.17 Specifically illustrated is a pattern of a training signal corresponding to HE-STF-long sent by three stations to an AP according to an embodiment of the present invention.

[0168] exist Fig.16 and Fig.17 In the embodiment of the present invention, the first station STA 1 transmits 14 subcarriers of the subcarriers of HE-STF-long. Furthermore, the second station STA 2 transmits two subcarriers of the subcarriers of HE-STF-long. Furthermore, the third station STA 3 transmits 14 subcarriers of the subcarriers of HE-STF-long.

[0169] In addition, the first station STA 1 and the third station STA 3 may determine a training signal scaling value based on a value obtained by dividing the number of subcarriers 14 transmitted by each of the first station STA 1 and the third station STA 3 by the number 106 of all subcarriers corresponding to the subband allocated to the first station STA 1 and the third station STA 3. In addition, the second station STA 2 may determine a training signal scaling value based on a value obtained by dividing the number of subcarriers 2 transmitted by the second station STA 2 by the number 26 of all subcarriers corresponding to the subband allocated to the second station STA 2. Thus, the AP can receive a short training signal having a uniform amplitude from each of the first station STA 1 to the third station STA 3.

[0170] refer to Fig.12 and Fig.17 The described embodiments may be applied in addition to Figure 6 and Fig.10 A pattern of another training signal other than the pattern of the described training signal.

[0171] Fig.18 is a ladder diagram illustrating operations of the first wireless communication terminal and the second wireless communication terminal according to the embodiment of the present invention.

[0172] The first wireless communication terminal 400 allocates sub-bands to the second wireless communication terminals 500 (S1801). As described above, the first wireless communication terminal 400 and the second wireless communication terminals can communicate via OFDMA. To this end, the first wireless communication terminal 400 allocates sub-bands to the second wireless communication terminals 500.

[0173] The first wireless communication terminal 400 signals information about the sub-band allocated to each of the plurality of second wireless communication terminals 500 to each of the plurality of second wireless communication terminals 500 (S1803). The first wireless communication terminal 400 may signal information about the sub-band allocated to each of the plurality of second wireless communication terminals 500 to each of the plurality of second wireless communication terminals 500 through a trigger frame. Here, the trigger frame is a MAC frame for signaling information about the sub-band allocated to each of the plurality of second wireless communication terminals. In another specific embodiment, the first wireless communication terminal 400 may send information about the sub-band allocated to each of the plurality of second wireless communication terminals 500 to each of the plurality of second wireless communication terminals 500 through the SIG-B field described above.

[0174] The second wireless communication terminal 500 transmits a training signal based on the sub-frequency band allocated to the second wireless communication terminal 500 (S1805). Specifically, the second wireless communication terminal 500 transmits a subcarrier of the training signal corresponding to the sub-frequency band allocated to the second wireless communication terminal 500.

[0175] If the subcarrier of the training signal corresponds to a sub-frequency band that is not allocated to the second wireless communication terminal 500, the plurality of second wireless communication terminals 500 may not transmit the corresponding subcarrier.

[0176] In another specific embodiment, when the subcarrier of the training signal corresponds to a subband not allocated to the second wireless communication terminal 500, the second wireless communication terminal 500 to which a subband adjacent to the frequency band in which the corresponding subcarrier is transmitted is allocated can transmit the corresponding subcarrier. For ease of description, when the subcarrier of the training signal corresponds to a subband not allocated to the second wireless communication terminal 500, the corresponding subcarrier is referred to as an additional subcarrier. Specifically, a plurality of second wireless communication terminals 500 to which a subband adjacent to the frequency band in which the additional subcarrier is transmitted is allocated can simultaneously transmit the additional subcarrier. At this time, each of the plurality of second wireless communication terminals 500 can scale the amplitude of the signal used to transmit the additional subcarrier based on the number of the plurality of second wireless communication terminals 500. For example, each of the first station and the second station can transmit an additional subcarrier having a signal amplitude of 1 / 2 of the signal amplitude required for the transmission of the additional subcarrier. At this time, the additional subcarrier corresponds to a subband not allocated to the second wireless communication terminal, and the subband allocated to each of the first station and the second station is adjacent to the subband to which the additional subcarrier corresponds.

[0177] In another specific embodiment, any second wireless communication terminal 500 may transmit the additional subcarrier. In this case, the plurality of second wireless communication terminals 500 may be second wireless communication terminals 500 allocated with sub-bands adjacent to the sub-band where the additional subcarrier is located.

[0178] At this time, the first wireless communication terminal 400 may transmit information that signals the second wireless communication terminal 500 to transmit the additional subcarrier. Specifically, the HE-SIG-B field described above may include information that signals the second wireless communication terminal 500 to transmit the additional subcarrier. The second wireless communication terminal 500 may acquire the information that signals the second wireless communication terminal 500 to transmit the additional subcarrier, and may transmit the additional subcarrier based on the information that signals the second wireless communication terminal 500 to transmit the additional subcarrier.

[0179] In another specific embodiment, the first wireless communication terminal 400 may transmit information for signaling a method of transmitting an additional subcarrier. At this time, the information for signaling a method of transmitting an additional subcarrier may indicate which of the second wireless communication terminals 500 is to transmit an additional subcarrier or whether a plurality of second wireless communication terminals 500 transmit an additional subcarrier. Further, the information for signaling a method of transmitting an additional subcarrier may indicate the second wireless communication terminal 500 to transmit an additional subcarrier. In addition, the information for signaling a method of transmitting an additional subcarrier is applied when transmitting an additional subcarrier to indicate a scaling value for adjusting the amplitude of a signal including the additional subcarrier.

[0180] A plurality of second wireless communication terminals 500 may transmit training signals having uniform amplitudes to the first wireless communication terminal 400. To this end, when transmitting the subcarriers of the training signal corresponding to the subband allocated to the second wireless communication terminal 500, the second wireless communication terminal 500 may apply the training signal scaling value in order to adjust the amplitude of the training signal in the frequency band allocated to the second wireless communication terminal. At this time, the second wireless communication terminal 500 may determine the training signal scaling value based on the number of subcarriers of the training signal corresponding to the subband allocated to the second wireless communication terminal 500. Specifically, the second wireless communication terminal 500 may determine the training signal scaling value based on the number of all subcarriers of the subband allocated to the second wireless communication terminal 500 and the number of subcarriers of the training signal corresponding to the subband allocated to the second wireless communication terminal 500. The number of all subcarriers corresponding to the subband allocated to the second wireless communication terminal 500 may indicate the number of subcarriers used to transmit data through the subband allocated to the second wireless communication terminal 500. At this time, the subcarriers used to transmit data may include subcarriers used to transmit data and subcarriers used to transmit pilot signals. For example, the second wireless communication terminal 500 may determine the training signal scaling value based on a value obtained by dividing the number of subcarriers of the training signal corresponding to the sub-frequency band allocated to the second wireless communication terminal 500 by the number of all subcarriers of the sub-frequency band allocated to the second wireless communication terminal. In a specific embodiment, the second wireless communication terminal 500 may determine the training signal scaling value in inverse proportion to the number of subcarriers of the training signal corresponding to the sub-frequency band allocated to the second wireless communication terminal 500.

[0181] Furthermore, the second wireless communication terminal 500 may determine the transmission power of the training signal based on the signal drop that varies according to the relative position between the second wireless communication terminal 500 and the first wireless communication terminal 400. Therefore, the second wireless communication terminal 500 may determine the scaling value based on the signal drop that varies according to the relative position between the second wireless communication terminal 500 and the first wireless communication terminal 400. At this time, the relative position between the second wireless communication terminal 500 and the first wireless communication terminal 400 may be the distance between the second wireless communication terminal 500 and the first wireless communication terminal 400.

[0182] The first wireless communication terminal 400 receives data from the plurality of second wireless communication terminals 500 based on the training signal.

[0183] The training signal transmitted by the second wireless communication terminal 500 may be the short training signal described above. In another embodiment, the training signal may be the long training signal described above.

[0184] In addition, the pattern of the training signal transmitted by the second wireless communication terminal 500 may be a reference Figures 7 to 10 Any of the training signal patterns described.

[0185] In addition, as referenced Fig.11 As described, the second wireless communication terminal 500 can align the duration of the OFDM symbol of the training signal sent from the second wireless communication terminal 500 to the first wireless communication terminal 400 with the duration of the OFDM symbol sent from another second wireless communication terminal 500 to the first wireless communication terminal 400. Specifically, the second wireless communication terminal 500 can simultaneously start the long training signal transmission to the first wireless communication terminal 400 as another second wireless communication terminal 500, and simultaneously stop the long training signal transmission to the first wireless communication terminal as another second wireless communication terminal 500.

[0186] Although some specific embodiments of the present invention are described by using wireless LAN communication as an example, it is not limited thereto, and some specific embodiments of the present invention can be applied to other communication systems (such as cellular communication). In addition, although the method, device, and system of the present invention are described with respect to the specific embodiments of the method, device, and system of the present invention, some or all of the components or operations of the present invention can be implemented by using a computer system with a general hardware architecture.

[0187] The features, structures, and effects described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to one embodiment. In addition, those skilled in the art can combine or modify the features, structures, and effects shown in the various embodiments in other embodiments. Therefore, it should be understood that the content related to such combination and modification is included within the scope of the present invention.

[0188] Although the present invention is described mainly based on the above-mentioned embodiments, it is not limited thereto, and those skilled in the art will appreciate that various changes and modifications may be made without departing from the spirit and scope of the present invention. For example, the various components specifically shown in the embodiments may be modified and implemented. It should be understood that the differences associated with such modifications and applications are included in the scope of the present invention as defined in the appended claims.

Claims

1. A wireless communication terminal, comprising: a transceiver configured to transmit / receive wireless signals; and a processor configured to control the operation of the wireless communication terminal, wherein, when a plurality of wireless communication terminals including the wireless communication terminal perform orthogonal frequency division multiple access (OFDMA) transmission to a basic wireless communication terminal, the transceiver transmits the conventional preamble and the signaling field of the non-conventional preamble through a frequency band of a signaling field through which the plurality of wireless communication terminals transmit the conventional preamble and the non-conventional preamble, wherein the signaling fields of the conventional preamble and the non-conventional preamble are transmitted in units of 20 MHz, a scaling value is determined based on the number of subcarriers of a training signal corresponding to a sub-band to be transmitted for OFDMA transmission assigned by the basic wireless communication terminal to the wireless communication terminal, the amplitude of the training signal is adjusted using the scaling value, the training signal is transmitted to the basic wireless communication terminal through the sub-band, and data is transmitted to the basic wireless communication terminal through the sub-band, wherein the training signal is used by the basic wireless communication terminal for automatic gain control for receiving the data from the wireless communication terminal, wherein, in the OFDMA transmission, no wireless communication terminal transmits a training signal corresponding to a sub-band not assigned to any wireless communication terminal.

2. The wireless communication terminal according to claim 1, wherein, the transceiver adjusts the amplitude of the training signal based on the number of all subcarriers corresponding to the sub-band assigned to the wireless communication terminal; and the number of all subcarriers indicates the number of subcarriers for transmitting data through the sub-band assigned to the wireless communication terminal.

3. The wireless communication terminal according to claim 2, wherein, the transceiver adjusts the amplitude of the training signal based on a value obtained by dividing the number of subcarriers of the training signal corresponding to the sub-band assigned to the wireless communication terminal by the number of all subcarriers.

4. The wireless communication terminal according to claim 2, wherein, the subcarriers for transmitting data through the sub-band assigned to the wireless communication terminal include subcarriers for transmitting data and subcarriers for transmitting pilot signals.

5. The wireless communication terminal according to claim 1, wherein, the transceiver transmits additional subcarriers corresponding to a sub-band adjacent to the sub-band assigned to the wireless communication terminal and not corresponding to the sub-band assigned to the plurality of wireless communication terminals.

6. The wireless communication terminal according to claim 5, wherein, the transceiver and another wireless communication terminal transmit the additional subcarriers simultaneously.

7. The wireless communication terminal according to claim 5, wherein, the transceiver receives signaling information about a method of transmitting the additional subcarriers and transmits the additional subcarriers based on the signaling information.

8. The wireless communication terminal according to claim 7, wherein, The signaling information is in a signaling field for signaling information about each of the plurality of wireless communication terminals.

9. A method of operating a wireless communication terminal, the method comprising: When a plurality of wireless communication terminals including the wireless communication terminal perform orthogonal frequency division multiple access (OFDMA) transmission on a basic wireless communication terminal, transmitting, by the plurality of wireless communication terminals, signaling fields of a conventional preamble and a non-conventional preamble through a frequency band of a signaling field through which the conventional preamble and the non-conventional preamble are transmitted, wherein the signaling fields of the conventional preamble and the non-conventional preamble are transmitted in units of 20 MHz. Determining a scaling value based on a number of subcarriers of a training signal corresponding to a sub-band to be transmitted and allocated by the basic wireless communication terminal to the wireless communication terminal for the OFDMA transmission. Using the scaling value to adjust an amplitude of the training signal. Transmitting the training signal to the basic wireless communication terminal through the sub-band; and Transmitting data to the basic wireless communication terminal through the sub-band. wherein the training signal is used by the basic wireless communication terminal for automatic gain control for receiving the data from the wireless communication terminal. wherein, in the OFDMA transmission, no wireless communication terminal transmits a training signal corresponding to a sub-band not allocated to any wireless communication terminal.

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