Communication device, and communication method

Abstract

To provide a communication device capable improving the accuracy in channel estimation in wireless communication.SOLUTION: The communication device generates EXTREMELY HIGH THROUGHPUT PHYSICAL LAYER CONVERGENCE PROCEDURE PROTOCOL DATA UNIT (EHT PPDU). The EHT-PPDU includes a U-SIG and EHT-SIG that includes a COMMON field. The COMMON field includes a field indicating the first number of EHT-LTF symbols as a surplus subfield of U-SIG. The first number includes a control circuit that is larger than the second number of EHT-LTF symbols that are determined based on the number of spatial streams and a transmission circuit that transmits the EHT PPDU.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present disclosure relates to a communication device and a communication method. [Background technology]

[0002] A task group (TG) is currently developing the technical specifications for 802.11be (hereinafter referred to as "11be") as the successor standard to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, 802.11ax (hereinafter referred to as "11ax"). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] IEEE 802.11-20 / 486r0, “Decoupling Channel Training from NSTS,”March, 2020 [Non-patent document 2] IEEE 802.11-20 / 1375r2, “EHT LTF Design,” October, 2020 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is room for improvement in the accuracy of channel estimation in wireless communication.

[0005] Non-limiting embodiments of the present disclosure contribute to providing a communication device and a communication method that improve the accuracy of channel estimation in wireless communication. [Means for solving the problem]

[0006] A communication device according to an embodiment of the present disclosure includes a control circuit that sets information about an additional reference signal for each destination device in a control signal, and a transmission circuit that transmits the control signal.

[0007] These comprehensive or specific aspects may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a recording medium, or may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. [Effects of the Invention]

[0008] According to an embodiment of the present disclosure, it is possible to improve the accuracy of channel estimation in wireless communication.

[0009] Further advantages and benefits of an embodiment of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, respectively, but not necessarily all of them may be provided to obtain one or more identical features. [Brief explanation of the drawings]

[0010] [Figure 1] An example of the Extremely High Throughput Physical Layer Convergence Procedure Protocol Data Unit (EHT PPDU) format [Figure 2] FIG. 1 shows an example of U-SIG and EHT-SIG formats when the number of destination users of the EHT MU PPDU is one (non-Multi-User Multiple-Input Multiple-Output (MU-MIMO)). [Figure 3] FIG. 1 shows an example of U-SIG and EHT-SIG formats when the number of destination users of an EHT MU PPDU is more than one (MU-MIMO). [Figure 4]An example of the number of Very High Throughput - Long Training Fields (VHT - LTF) for each number of spatial streams [Figure 5] An example of the HT-SIG2 format for IEEE 802.11n [Figure 6] FIG. 10 is a diagram showing an example of the relationship between the number of spatial streams in the data section and the number of LTFs. [Figure 7] A diagram showing an example of the relationship between the number of extended spatial streams and the number of HT-extended LTFs (HT-ELTFs). [Figure 8] FIG. 1 is a sequence diagram illustrating an example of operation of the wireless communication system according to the first embodiment. [Figure 9] FIG. 1 is a block diagram illustrating a configuration example of a portion of a downstream radio transmission device according to an embodiment of the present disclosure. [Figure 10] FIG. 1 is a block diagram illustrating a configuration example of a portion of a downstream radio receiving device according to an embodiment of the present disclosure. [Figure 11] FIG. 1 is a block diagram showing a configuration example of a downlink radio transmission device according to a first embodiment; [Figure 12] FIG. 1 is a block diagram showing a configuration example of a downlink radio receiving device according to a first embodiment; [Figure 13] A diagram showing an example of an EHT-SIG format including an Extra-LTF subfield [Figure 14] FIG. 10 shows an example of a method for determining a mapping matrix (P-matrix) from the number of LTFs obtained by adding the number of extra-LTFs to the number of LTFs determined based on the total number of spatial streams. [Figure 15] A diagram showing an example of a method of using multiple P-matrixes calculated from the number of LTFs determined based on the total number of spatial streams. [Figure 16] An example of the EHT-SIG format for notifying the presence or absence of Extra-LTF in each user information. [Figure 17] An example of the EHT-SIG format when notifying the number of Extra-LTFs in each user information [Figure 18]Figure 10 shows an example of the EHT-SIG format when notifying the number of Extra-LTFs in multiples of the initial EHT-LTF number in each user information. [Figure 19] An example of the EHT-SIG format for notifying the allocation of Extra-LTF using Bitmap in common information [Figure 20] A diagram showing an example of the EHT-SIG format when notifying whether Extra-LTF information is included in user information in common information. [Figure 21] A diagram showing an example of a Modulation and Coding Scheme (MCS) table that adds a combination of low-order modulation and Extra-LTF for Single User (SU). [Figure 22] An example of an MCS table that adds a combination of high-order modulation and Extra-LTF for Multi-User (MU) [Figure 23] An example of the Trigger frame User Info format when notifying Extra-LTF information in the user information [Figure 24] FIG. 10 is a block diagram showing a configuration example of a downlink radio transmission device according to a second embodiment. [Figure 25] FIG. 10 is a block diagram showing a configuration example of a downlink radio receiving device according to a second embodiment. [Figure 26] An example of the EHT-SIG format including the Extra P-matrix [Figure 27] An example of the EHT-SIG format when notifying the row index of the Extra P-matrix in each user information. [Figure 28] An example of LTF when two users are assigned one spatial stream each and one of the two users is assigned an additional administrative portion of the P-matrix. [Figure 29] An example of the Trigger frame User Info format when notifying Extra-LTF information in each user information [Figure 30]Figure showing an example of a trigger frame type for instructing Extra-LTF [Figure 31] An example of the Trigger frame Common Info format when notifying Extra-LTF using Bitmap in the common information [Figure 32] A diagram showing an example of the Trigger frame Common info format when notifying whether or not Extra-LTF information is included in the user information in the common information. [Figure 33] An example of PPDU format when using Extra-LTF and Midamble together [Figure 34] FIG. 1 shows an example of a link adaptation control information format. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings.

[0012] In 11be, one of the goals is to improve the accuracy of channel estimation, and a method is being discussed to transmit an Extreme High Throughput - LTF (EHT-LTF) that is greater than the High Efficient non-Legacy Long Training Field (hereinafter referred to as HE-LTF) of 11ax, which is determined by the number of spatial streams (SS) (e.g., Non-Patent Documents 1 and 2).

[0013] Fig. 1 shows an example of an EHT Physical Layer Convergence Procedure Protocol Data Unit (EHT PPDU) format for notifying an EHT-LTF. In Fig. 1, a signal (SIG) field including a U-SIG field and an EHT-SIG field is a non-limiting example of a control signal. Also, as shown in Fig. 1, one or more EHT-LTFs can be set in the EHT PPDU. The EHT-LTF is a non-limiting example of an additional reference signal.

[0014] Also, Fig. 2 shows an example of U-SIG and EHT-SIG formats when the number of destination users of the EHT MU PPDU is one (called non-Multi-User Multiple-Input Multiple-Output (MU-MIMO) or SU (single user)). Fig. 3 shows an example of U-SIG and EHT-SIG formats when the number of destination users of the EHT MU PPDU is more than one (called MU-MIMO).

[0015] 2 and 3, the EHT-SIG field includes, for example, a common field common to multiple destination users and a user field for each destination user. As shown in Fig. 2, in the case of non-MIMO, one user field is provided in the EHT-SIG field, and as shown in Fig. 3, in the case of MU-MIMO, the EHT-SIG field is provided with user fields in the number corresponding to the number of destination users.

[0016] In the IEEE 802.11ax HE PPDU transmission, for example, as shown in Figure 4, the number of spatial streams (hereinafter referred to as N) included in the user information (also called the User field) of the HE PPDUG is STSThe number of HE-LTFs included in the HE PPDU is determined based on the value of the number of spatial streams notified by the Spatial Configuration subfield or the Spatial Configuration subfield.

[0017] On the other hand, in 11be, EHT PPDU transmission, for example, the Number of EHT-LTF Symbols subfield (hereinafter referred to as N) included in the U-SIG is used. EHT-LTF ) to notify the number of EHT-LTF symbols included in the EHT PPDU. In the EHT PPDU, the number of EHT-LTF symbols included in the EHT PPDU can be determined based on the number of spatial streams, just like in 11ax. In addition, in the EHT PPDU, N EHT-LTF By notifying a number of EHT-LTF symbols greater than the number of EHT-LTFs determined from the number of spatial streams, an EHT PPDU containing more EHT-LTFs than a normal EHT PPDU can be realized.

[0018] When transmitting more EHT-LTFs than normal EHT-LTFs, an access point (AP, also called a "base station") may allocate to each terminal (also called a Station (STA)) twice the number of EHT-LTFs determined based on the number of spatial streams. For example, when the number of spatial streams allocated to two STAs 1 and 2 is [2, 1], the number of EHT-LTFs allocated may be [4, 2].

[0019] A STA receiving a signal containing more EHT-LTFs than HE-LTFs may, for example, EHT-LTF The number of EHT-LTFs signaled by the subfield, N STS The number of spatial streams signaled by the subfield or the Spatial Configuration subfield is compared to determine whether the EHT-LTF includes additional LTFs, and the EHT-LTF is used to perform channel estimation.

[0020] In addition, N EHT-LTFmay be included in the Common field of the EHT-SIG as an extra subfield of the U-SIG.

[0021] In addition, IEEE 802.11n (hereinafter referred to as "11n") has a sounding PPDU that is transmitted to estimate the channel between the transmitter and receiver. Figure 5 shows an example of the HT-SIG2 format in 11n. In 11n, if the Not Sounding subfield in HT-SIG2 is set to 0, the PPDU is transmitted as a Sounding PPDU.

[0022] The Sounding PPDU may include, for example, an LTF (called Data LTF (DLTF)) determined based on the number of spatial streams, and an LTF (called Extension LTF (ELTF)) for transmitting an additional spatial stream (called an extension spatial stream or Extension spatial stream (ESS)). STS / N ESS ) and the number of LTFs (N HT-DLTF / N HT-ELTF ) is shown below. Note that the total number of spatial streams and the number of extended spatial streams may be required to be, for example, 4 or less and the number of transmit antennas or less.

[0023] Here, in MU-MIMO, the required channel estimation accuracy may differ for each user. For example, in MU-MIMO, when the same number of spatial streams is assigned to multiple users (in other words, when the transmission power per user is equal), the modulation scheme (in other words, Modulation and Coding Scheme (MCS)) may differ significantly between destination users. When the MCS differs significantly between destination users, higher-order modulated signals are more susceptible to noise than lower-order modulated signals, and signal errors are more likely to occur.

[0024] In one embodiment of the present disclosure, for example, the accuracy of channel estimation is improved by including (or setting) a field (or information) regarding an additional LTF (called Extra-LTF) for each user in a control signal having a common field (or common information) and a user field (or user information).

[0025] For example, the channel estimation accuracy can be improved by determining the allocation of extra-LTFs for each user according to the channel estimation accuracy required by each user and performing maximum ratio combining of multiple channel estimation values. The improvement in channel estimation accuracy can reduce signal errors, for example, and therefore improve wireless communication quality.

[0026] [Wireless communication system configuration] A wireless communication system according to an embodiment of the present disclosure includes at least one access point (AP, also called a "base station") and one terminal (called a "station (STA)").

[0027] For example, in Down Link (DL) communication, an AP corresponds to a "downlink wireless transmitting device" and an STA corresponds to a "downlink wireless receiving device." Also, in Up Link (UL) communication, an AP corresponds to an "uplink wireless receiving device" and an STA corresponds to an "uplink wireless transmitting device." Note that an STA may also be referred to as a "user device" or simply a "user." The "downlink wireless receiving device" may be positioned as a destination device in DL communication.

[0028] In one embodiment of the present disclosure, the AP may transmit a PPDU including control information of Extra-LTF to a STA, for example, in DL communication.

[0029] [Embodiment 1] In the first embodiment, for example, the AP transmits a signal including an Extra-LTF to the STA. Hereinafter, as a non-limiting example, a method in which the AP transmits a signal including an Extra-LTF to the STA in 11be will be described.

[0030] An example of the operation of the AP and STA in the first embodiment will be described. FIG. 8 is a sequence diagram showing an example of the operation of a wireless communication system in which an AP transmits an EHT PPDU including an Extra-LTF to a STA in 11be.

[0031] The AP transmits a signal (capability request) requesting transmission of capability information (called Capability) related to Extra-LTF to a STA (e.g., STA1, STA2) (S101). When the STA receives the Capability request, it transmits the Capability related to Extra-LTF of the STA to the AP that sent the Capability request as, for example, a Capability response (S102).

[0032] The capability regarding Extra-LTF may include, for example, at least one of information on whether Extra-LTF is supported, the maximum number of LTFs that can be received in non-Orthogonal Frequency-Division Multiple Access (OFDMA) single-user transmission, and the maximum number of LTFs that can be received in multi-user transmission.

[0033] The AP selects STAs capable of transmitting Extra-LTF based on the capabilities acquired from the Capability Requests received from the STAs, and schedules frequency resources (called Resource Units (RUs)), spatial multiplexing methods, and modulation methods (S103). The AP also generates an EHT PPDU including Extra-LTF based on the scheduling information (S104). At this time, the AP may transmit information notifying the allocation of Extra-LTF (hereinafter sometimes referred to as "Extra-LTF information") to the STAs, for example, by including it in the EHT PPDU (S105).

[0034] The STA that has received the Extra-LTF information from the AP performs, for example, a receiving process for the EHT PPDU including the Extra-LTF information (S106). For example, the STA may receive the N acquired from the preamble part of the EHT PPDU. STS and N EHT-LTF Based on the value of and the extra-LTF information, it is determined whether extra-LTF is allocated to the EHT PPDU, and channel estimation is performed using the LTF.

[0035] Based on the acquired channel estimation value, the STA performs, for example, equalization processing on the data portion of the EHT PPDU, and demodulates and decodes the data portion. Furthermore, the STA transmits a response signal (Acknowledge (referred to as ACK)) to the AP according to, for example, the error detection result of the decoded data signal (S107).

[0036] In the above example, an EHT PPDU including an Extra-LTF has been described, but the above example of operation may also be applied to an EHT NDP PPDU including an Extra-LTF.

[0037] 9 is a block diagram illustrating a configuration example of a portion of a downlink radio transmitting device (e.g., AP) 100 according to an embodiment of the present disclosure. In the AP 100 (e.g., corresponding to a communication device) illustrated in FIG. 9, a control unit (e.g., corresponding to a control circuit) may set information regarding an additional reference signal (e.g., Extra-LTF) for each destination device (e.g., STA) in a control signal. A transmitting unit (e.g., corresponding to a transmitting circuit) transmits the control signal.

[0038] 10 is a block diagram illustrating a configuration example of a portion of a downlink radio receiving device (e.g., STA) 200 according to an embodiment of the present disclosure. In the STA 200 (e.g., corresponding to a communication device) illustrated in FIG. 10, a receiving unit (e.g., corresponding to a receiving circuit) receives a control signal including information about an additional reference signal (e.g., Extra-LTF) for each destination device (e.g., STA). A control unit (e.g., corresponding to a control circuit) may determine the additional reference signal to be used for channel estimation based on the information about the additional reference signal.

[0039] [Downstream radio transmitting device according to the first embodiment] Fig. 11 is a block diagram showing an example configuration of a downlink radio transmission device according to this embodiment 1. The downlink radio transmission device (for example, AP) 100 shown in Fig. 11 may include, for example, a radio receiving unit 101, a received signal decoding unit 102, a scheduling unit 103, a data generating unit 104, a data encoding unit 105, a data modulating unit 106, a preamble generating unit 107, and a radio transmitting unit 108.

[0040] At least one of the received signal decoding unit 102, the scheduling unit 103, the data generation unit 104, the data encoding unit 105, the data modulation unit 106, and the preamble generation unit 107 may be included in, for example, the control unit shown in Fig. 9. The radio transmission unit 108 may be included in, for example, the transmission unit shown in Fig. 9.

[0041] The radio receiving unit 101 receives a signal transmitted from a downlink radio receiving device (e.g., STA) 200 (see FIG. 10) via an antenna, for example, and performs radio receiving processing such as down-conversion and analog-to-digital (A / D) conversion. The radio receiving unit 101 divides the received signal after radio receiving processing into a preamble part (also called a preamble signal) and a data part (also called a data signal), and outputs the divided parts to the received signal decoding unit 102.

[0042] The received signal decoding unit 102 may perform demodulation processing such as Fourier transform (e.g., Fast Fourier Transform (FFT)) on each of the preamble signal and data signal input from the radio receiving unit 101, and extract control signals included in each of the preamble signal and data signal. The control signals may include information or parameters such as frequency bandwidth (BW), MCS, or encoding method.

[0043] In addition, the received signal decoding unit 102 may, for example, use a control signal and a channel estimation signal obtained from the preamble signal to channel equalize, demodulate, and decode the data signal after the Fourier transform, and perform error detection such as a Cyclic Redundancy Check (CRC).

[0044] For example, if there is no error in the data signal (in other words, a decoding error), the received signal decoding unit 102 outputs the decoded data signal and the control signal to the scheduling unit 103. On the other hand, for example, if there is an error in the data signal, the received signal decoding unit 102 does not need to output the decoded data signal.

[0045] The scheduling unit 103 may determine scheduling information for the data signal to be transmitted to the downlink radio receiving device 200, for example, based on reception quality information of the data signal output from the received signal decoding unit 102 or the capability of the downlink radio receiving device (e.g., STA) 200.

[0046] The reception quality information may include, for example, information such as a packet error rate (PER) or RSSI. The scheduling information may include, for example, information or parameters such as RU, MCS, an error correction coding method, and Extra-LTF information. The scheduling information may be output to, for example, the data generating unit 104, the data coding unit 105, the data modulating unit 106, and the preamble generating unit 107.

[0047] The data generating section 104 generates a data sequence to be transmitted to the downlink radio receiving apparatus 200 based on, for example, the scheduling information output from the scheduling section 103 , and outputs the data sequence to the data encoding section 105 .

[0048] Data encoding section 105 performs encoding based on, for example, the data sequence output from data generation section 104 and the scheduling information (for example, an error correction coding method or MCS) output from scheduling section 103. The encoded data may be output to, for example, data modulation section 106.

[0049] The data modulation unit 106 performs modulation and inverse Fourier transform (e.g., Inverse Fast Fourier Transform (IFFT)) based on, for example, the coded data output from the data coding unit 105 and the scheduling information (e.g., modulation method) output from the scheduling unit 103. The modulated data signal may be output to, for example, the radio transmission unit 108.

[0050] The preamble generating unit 107 generates a preamble signal including Extra-LTF or control information related to Extra-LTF (for example, Extra-LTF allocation information) based on, for example, the scheduling information output from the scheduling unit 103. The preamble signal may be subjected to modulation and IFFT processing in the preamble generating unit 107 and then output to the radio transmitting unit 108.

[0051] Radio transmitting unit 108 generates a radio frame (also called a packet signal) by, for example, adding the preamble signal output from preamble generating unit 107 to the data signal output from data modulating unit 106. Radio transmitting unit 108 also performs radio transmission processing, such as digital-to-analog (D / A) conversion and up-conversion to a carrier frequency, on the radio frame, and transmits the signal after the radio transmission processing to downlink radio receiving device 200 via an antenna.

[0052] [Downstream radio receiving device according to the first embodiment] Fig. 12 is a block diagram showing an example configuration of a downlink radio receiving device according to Embodiment 1. The downlink radio receiving device (for example, STA) 200 shown in Fig. 12 may include, for example, a radio receiving unit 201, a preamble demodulating unit 202, an Extra-LTF determining unit 203, a channel estimating unit 204, a data demodulating unit 205, a data decoding unit 206, a transmission signal generating unit 207, and a radio transmitting unit 208.

[0053] At least one of the preamble demodulation unit 202, the Extra-LTF determination unit 203, the channel estimation unit 204, the data demodulation unit 205, the data decoding unit 206, and the transmission signal generation unit 207 may be included in, for example, the control unit shown in Fig. 10. The wireless receiving unit 201 may be included in, for example, the receiving unit shown in Fig. 10.

[0054] The radio receiving unit 201 may receive a signal transmitted from a downlink radio transmitting device (e.g., AP) 100 via an antenna, and perform radio receiving processing such as down-conversion and A / D conversion. The radio receiving unit 201 may also output a data signal extracted from the received signal after the radio receiving processing to the data demodulating unit 205, and output a preamble signal to the preamble demodulating unit 202.

[0055] The preamble demodulation unit 202 extracts a control signal used for demodulating and decoding the data portion by, for example, performing demodulation processing such as a Fourier transform (e.g., FFT) on the preamble signal output from the radio receiving unit 201. This control signal may include information or parameters such as BW, MCS, an error correction coding method, and Extra-LTF information. The preamble demodulation unit 202 may output the extracted control information to, for example, the data demodulation unit 205, the data decoding unit 206, the Extra-LTF determination unit 203, and the channel estimation unit 204.

[0056] The Extra-LTF determination unit 203 determines whether or not an Extra-LTF is included in the preamble of the received signal, for example, based on the Extra-LTF information output from the preamble demodulation unit 202. The determined information (hereinafter sometimes referred to as Extra-LTF determination information) may be output to the channel estimation unit 204, for example.

[0057] The channel estimation unit 204 performs channel estimation using, for example, a reference signal (for example, LTF) included in the preamble. For example, when an extra-LTF is assigned based on the extra-LTF discrimination information output from the extra-LTF discrimination unit 203, the channel estimation unit 204 performs channel estimation using the extra-LTF in addition to the EHT-LTF (referred to as the original LTF) determined based on the number of spatial streams assigned to the downlink wireless receiving device.

[0058] Furthermore, the channel estimation unit 204 performs maximum ratio combining on channel estimates estimated using the original LTF and the extra-LTF, and outputs the combined channel estimate to the data demodulation unit 205. Note that a power correction value may be applied to the combined channel estimate in order to correct a power difference between the combined channel estimate and the data portion. Furthermore, if an extra-LTF is not allocated, the channel estimation unit 204 does not need to perform channel estimation using the extra-LTF.

[0059] Data demodulation section 205 performs processing such as Fourier transform (e.g., FFT) on the data signal output from radio reception section 201, and demodulates the data signal using the control information output from preamble demodulation section 202 and the channel estimation value output from channel estimation section 204. The demodulated data signal may be output to data decoding section 206, for example.

[0060] The data decoding unit 206, for example, uses the control information output from the preamble demodulation unit 202 to decode the demodulated data signal output from the data demodulation unit 205, performs error detection such as CRC, and outputs the error detection result, which is error detection information, to the transmission signal generation unit 207.

[0061] The transmission signal generation unit 207 generates a response signal (ACK or Block ACK (BA)) based on, for example, the error determination information output from the data decoding unit. Furthermore, the transmission signal generation unit 207 adds, for example, a preamble signal to the data signal to generate a radio frame, and outputs the radio frame to the radio transmission unit 208.

[0062] The radio transmitting unit 208 performs radio transmission processing, such as D / A conversion and up-conversion to a carrier frequency, on the radio frame output from the transmission signal generating unit 207, and transmits the signal after radio transmission processing to the downlink radio transmitting device 100 via an antenna.

[0063] [Example of operation] Next, an example of the operation of the downlink radio transmitting device (for example, AP) 100 and the downlink radio receiving device (for example, STA) 200 in the first embodiment will be described.

[0064] In one embodiment of the present disclosure, a control signal (also referred to as control information) transmitted from a downlink radio transmitting device 100 to a downlink radio receiving device 200 may include common information common to multiple users and user information specific to multiple users.

[0065] The control signal may include, for example, extra-LTF information specific to a user (for example, downlink radio receiving device 200). The control information may be, for example, a SIG field (U-SIG or EHT-SIG) of an EHT PPDU or a trigger frame. The extra-LTF information may include, for example, information or a parameter indicating at least one of whether or not extra-LTF is allocated and the number of extra-LTFs allocated.

[0066] [Method 1] In Method 1, for example, a subfield for notifying Extra-LTF information may be included in each piece of user information. For example, as shown in Fig. 13, an Extra-LTF subfield for notifying allocation of Extra-LTF may be included in each user field of the EHT-SIG. Notification methods using the Extra-LTF subfield will be described later in specific examples 1 to 3 of Method 1.

[0067] In EHT-LTF, for example, regardless of whether Extra-LTF is used or not, a mapping matrix (called P-matrix) is added to multiplex multiple EHT-LTF symbols. In 11ac / ax, for example, as shown in equation (1), the number of LTFs (N HE-LTF ) The P-matrix to be used is determined according to the 4×4 The P-matrix of P is used. 4×4 is expressed by, for example, equation (2). The column elements of the P-matrix correspond to each LTF symbol. On the other hand, the row elements of the P-matrix correspond to spatial streams, and the row elements are multiplexed into each LTF symbol.

[0068]

number

[0069]

number

[0070] The P-matrix to be added to the EHT-LTF including the Extra-LTF may be determined based on the number of EHT-LTFs, for example. This number of EHT-LTFs may be calculated by adding the number of Extra-LTFs to the number of EHT-LTFs determined based on the total number of spatial streams transmitted in MU-MIMO.

[0071] FIG. 14 shows an example of a P-matrix added to the EHT-LTF when two spatial streams are assigned to each of STA1 and STA2, and two Extra-LTFs are assigned to STA1. In this case, the AP creates, for example, a 6-row, 6-column P-matrix (P 6×6 The elements of rows 1 to 4 and columns 1 to 4 of the original LTF are added to P 6×6 The elements in rows 1 to 4 and columns 5 to 6 of are added to Extra-LTF.

[0072] For example, STA1 performs maximum ratio combining of the channel estimation value obtained from the Original LTF and the channel estimation value obtained from the Extra-LTF, and uses the result for equalization processing of the data portion.

[0073] The P-matrix added to the EHT-LTF including the Extra-LTF may use, for example, multiple Original LTFs determined based on the total number of spatial streams transmitted by MU-MIMO. Fig. 15 shows an example of a P-matrix added to the EHT-LTF when two spatial streams are assigned to each of STA1 and STA2, and four Extra-LTFs are assigned to STA1.

[0074] In this case, the AP is, for example, a 4-row, 4-column P-matrix (P 4×4 In addition to adding another P-matrix P 4×4 Add to Extra-LTF.

[0075] STA1 performs maximum ratio combining of, for example, a channel estimation value obtained from the Original LTF and two channel estimation values ​​obtained from the Extra-LTF, and uses the combined value for equalization of the data portion.

[0076] As in Method 1, allocating extra-LTFs to specific users enables channel estimation using more LTFs than conventional methods, thereby improving the accuracy of channel estimation through maximum ratio combining.

[0077] [Example 1 of Method 1] In Concrete Example 1 of Method 1, the Extra-LTF information indicates, for example, whether or not an Extra-LTF is provided. Fig. 16 shows an example of an EHT-SIG format when the presence or absence of an Extra-LTF is indicated in each user information.

[0078] The Extra-LTF subfield may be, for example, a 1-bit subfield. For example, Extra-LTF=1 indicates that an Extra-LTF is allocated, and Extra-LTF=0 indicates that an Extra-LTF is not allocated.

[0079] In a specific example 1 of method 1, the first STA may determine the number of extra-LTFs addressed to the first STA by also referring to user information addressed to other second STAs. For example, Figure 16 shows an example in which one spatial stream is assigned to each of STA1 and STA2, and two extra-LTFs are assigned to STA1. An example of LTF assignment in this case is shown in Figure 17.

[0080] STA1 and STA2 determine from the Spatial Configuration subfield that one spatial stream has been assigned to each of them (in other words, that the total number of spatial streams assigned is 2).

[0081] In this case, one Original LTF is allocated to each of STA1 and STA2. STA1, for example, refers to the Extra-LTF in the User field of STA2 and identifies that no Extra-LTF is allocated to STA2. STA1 also, for example, refers to the Extra-LTF in the User field of STA2 and identifies that no Extra-LTF is allocated to STA2. EHT-LTF The number of EHT-LTFs reported in the subfield (in this example, N EHT-LTF The number of Extra-LTFs allocated to STA1 is determined by subtracting the total number of spatial streams (=2) notified in the Spatial Configuration subfield from the total number of spatial streams (=4) notified in the Spatial Configuration subfield, and the EHT-LTF index (1 to 3) to be referenced is derived.

[0082] On the other hand, STA2 identifies that Extra-LTF has been allocated to STA1 based on, for example, the Extra-LTF in the User field of STA1. STA2 also calculates the EHT-LTF index allocated to STA1 from the difference between the number of EHT-LTFs and the total number of spatial streams, in the same way as STA1, and derives the EHT-LTF index (4) that STA2 refers to.

[0083] [Example 2 of Method 1] In specific example 2 of method 1, the extra-LTF information notifies, for example, the number of extra-LTFs. Fig. 18 shows an example of an EHT-SIG format when the number of extra-LTFs is notified in the user information. Fig. 18 shows an example in which one spatial stream is assigned to each of STA1 and STA2, and two extra-LTFs are assigned to STA1.

[0084] In this case, the method of notifying the number of extra-LTFs may be, for example, notifying the number of extra-LTFs by each extra-LTF subfield, or notifying the number of extra-LTFs by limiting the number of usable extra-LTFs (for example, selecting the number of extra-LTFs from [0, 2, 4, 8]).

[0085] [Example 3 of Method 1] In specific example 3 of method 1, a multiple of the initial (or original) number of LTFs is reported as extra-LTF information. Fig. 19 shows an example of an EHT-SIG format when reporting the number of extra-LTFs as a multiple of the initial EHT-LTF number in each user information. Fig. 19 shows an example in which one spatial stream is assigned to each of STA1 and STA2, and one extra-LTF is assigned to STA1.

[0086] In this case, the Extra-LTF subfield included in each user information may be a 1-bit subfield, and when Extra-LTF=1, twice the number of LTFs as the initial number of LTFs may be allocated (in other words, when Extra-LTF=0, no Extra-LTFs may be allocated).

[0087] The extra-LTF subfield is not limited to a 1-bit subfield, and the multiple of the initial LTF number to be notified may be three or four times or more by increasing the number of bits of the extra-LTF subfield.

[0088] [Method 2] In method 2, the configuration (or format) of the control information is switched depending on the presence or absence of Extra-LTF. For example, an Extra-LTF present subfield is added to the U-SIG to notify the presence or absence of Extra-LTF.

[0089] For example, if the transmission signal includes one or more users to which Extra-LTF is assigned, Extra-LTF present = 1 is notified, and if the transmission signal does not include any users to which Extra-LTF is assigned, Extra-LTF present = 0 is notified. The presence or absence of Extra-LTF may be notified by any of specific examples 1 to 3 of Method 1.

[0090] As in Method 2, by switching the EHT-SIG configuration depending on whether the transmitted signal includes a user to which Extra-LTF is assigned, it is possible to reduce the signaling overhead when Extra-LTF is not used.

[0091] [Example 1 of Method 2] In specific example 1 of method 2, if the transmission signal includes a user to which Extra-LTF is assigned, for example, an Extra-LTF bitmap may be added to the common information, and the presence or absence of Extra-LTF for each user may be notified by the Extra-LTF bitmap. In other words, if the transmission signal does not include a user to which Extra-LTF is assigned, the common information does not need to include the Extra-LTF bitmap.

[0092] FIG. 20 shows an example of the EHT-SIG format when notifying allocation of Extra-LTF by Bitmap in common information.

[0093] The Extra-LTF bitmap may be a variable-length bitmap determined based on the number of user information included in the EHT-SIG, or may be a fixed-length bitmap determined based on the maximum number of multiplexed users in MU-MIMO.

[0094] The Extra-LTF bitmap may, for example, indicate the presence or absence of an Extra-LTF for each user with one bit, as in Example 1 of Method 1, or may indicate the number of Extra-LTFs for each user with up to three bits, as in Example 2 of Method 1. Alternatively, as in Example 3 of Method 1, N STS Alternatively, it may be possible to notify by one bit that the number of LTFs to be allocated is a multiple of the number of spatial streams notified by the signal.

[0095] According to specific example 1 of method 2, the allocation of Extra-LTF to other users can be determined by referring to the Extra-LTF bitmap (in other words, there is no need to refer to the user information of other users), thereby reducing processing time.

[0096] [Example 2 of Method 2] In a specific example 2 of method 2, for example, when a transmission signal includes a user to which Extra-LTF is assigned, Extra-LTF information is added to the user information, and the presence or absence of Extra-LTF for each user is notified. Fig. 21 shows an example of an EHT-SIG format for notifying whether Extra-LTF information is included in the user information in the common information.

[0097] For example, if a transmission signal includes a user to which Extra-LTF is assigned, an Extra-LTF subfield for reporting the Extra-LTF information is added to each user information. In other words, if a transmission signal does not include a user to which Extra-LTF is assigned, the user information does not need to include an Extra-LTF subfield.

[0098] According to the second specific example of the second method, when the number of destination users is small, signaling overhead can be reduced compared to the first specific example of the second method, in which allocation of Extra-LTF is notified by bitmap.

[0099] [Example 3 of Method 2] In a specific example 3 of Method 2, for example, the method of notifying Extra-LTF is changed depending on the number of destination users. For example, assume that the common information includes an Extra-LTF Bitmap of a fixed length based on the maximum number of multiplexed users in MU-MIMO. In this case, if the number of destination users of a transmission signal including Extra-LTF is equal to the maximum number of multiplexed users in MU-MIMO, the presence or absence of Extra-LTF for each user may be notified using the Extra-LTF bitmap, as in specific example 1 of Method 2. On the other hand, if the number of destination users of a transmission signal including Extra-LTF is less than the maximum number of multiplexed users in MU-MIMO, the presence or absence of Extra-LTF may be notified in the user information, for example, as in specific example 2 of Method 2.

[0100] According to specific example 3 of method 2, by changing the notification method of Extra-LTF depending on the number of destination users of the transmitted signal including Extra-LTF, an efficient signaling method can be flexibly selected and the signaling method can be optimized.

[0101] [Method 3] In Method 3, for example, Extra-LTF information and MCS are combined and the Extra-LTF information is notified by user information. When combining Extra-LTF and MCS and notifying them, for example, the modulation method and the number of Extra-LTFs may be combined and notified for each MCS index (Example 1), or the modulation method and a multiple of the number of Original LTFs may be combined and notified for each MCS index (Example 2).

[0102] For example, in the case of transmission for a single user (SU), a combination of low-order modulation and Extra-LTF may be added to the MCS table for each of Examples 1 and 2, as shown in Fig. 22. In the case of transmission for a multi-user (MU), a combination of high-order modulation and Extra-LTF may be added to the MCS table for each of Examples 1 and 2, as shown in Fig. 23.

[0103] Note that the combinations of Extra-LTF information and MCS shown in Figure 22 (Example 1) and Figure 23 (Example 2) are non-limiting examples, and other combinations may be used. Furthermore, the combinations of Extra-LTF information and MCS may be changed depending on, for example, the number of destination users.

[0104] By combining the extra-LTF information with the MCS as in method 3, it is possible to realize notification of the extra-LTF information without increasing the signaling for notifying the extra-LTF information.

[0105] [Embodiment 2] In the first embodiment, an example of a method for allocating users to each time symbol of an LTF including an Extra-LTF has been described. In the second embodiment, an example of a method for allocating multiple row components of a P-matrix to one spatial stream using code multiplexing will be described.

[0106] [Downstream radio transmitting device according to the second embodiment] 24 is a block diagram showing a configuration example of a downlink radio transmission device according to embodiment 2. The downlink radio transmission device (for example, (for example, AP)) 100 illustrated in FIG. 24 may include, for example, a radio reception unit 101a, a received signal decoding unit 102a, a scheduling unit 103a, a data generation unit 104a, a data encoding unit 105a, a data modulation unit 106a, a preamble generation unit 107a, and a radio transmission unit 108a.

[0107] At least one of the received signal decoding unit 102a, the scheduling unit 103a, the data generating unit 104a, the data encoding unit 105a, the data modulating unit 106a, and the preamble generating unit 107a may be included in, for example, the control unit shown in Fig. 9. The radio transmitting unit 108a may be included in, for example, the transmitting unit shown in Fig. 9.

[0108] The radio receiving unit 101a receives a signal transmitted from a downlink radio receiving device (e.g., STA) 200 via an antenna, and performs radio receiving processing such as down-conversion and A / D conversion. The radio receiving unit 101a divides the received signal after the radio receiving processing into a preamble portion and a data portion, and outputs the divided portions to the received signal decoding unit 102a.

[0109] The received signal decoding unit 102a may perform demodulation processing such as Fourier transform (e.g., FFT) on the preamble signal and data signal input from the radio receiving unit 101a, and extract control signals included in the preamble signal and data signal. The control signals may include information or parameters such as BW, MCS, or an encoding method. Furthermore, the received signal decoding unit 102a may, for example, use the control signal and the channel estimation signal acquired from the preamble signal to channel equalize, demodulate and decode the data signal after the Fourier transform, and perform error detection such as CRC.

[0110] For example, if there is no error in the data signal (in other words, no decoding error), the received signal decoding unit 102a outputs the decoded data signal and control signal to the scheduling unit 103a.

[0111] The scheduling unit 103a may determine scheduling information for a data signal to be transmitted to a downlink radio receiving device (e.g., STA) 200, for example, based on reception quality information of the data signal output from the received signal decoding unit 102a or the capability of the downlink radio receiving device.

[0112] The reception quality information may include, for example, information such as PER and RSSI. The scheduling information may include, for example, information or parameters such as RU, MCS, error correction coding method, and Extra-LTF information. The scheduling information may be output to, for example, the data generating unit 104a, the data encoding unit 105a, the data modulating unit 106a, and the preamble generating unit 107a.

[0113] The data generating unit 104a generates a data sequence to be transmitted to the downlink radio receiving apparatus 200 based on, for example, the scheduling information output from the scheduling unit 103a, and outputs the data sequence to the data encoding unit 105a.

[0114] The data encoding unit 105a performs encoding based on, for example, the data sequence output from the data generation unit 104a and the scheduling information (for example, an error correction coding method and MCS) output from the scheduling unit 103a. The encoded data may be output to, for example, a data modulation unit 106a.

[0115] The data modulation unit 106a performs spatial multiplexing by, for example, adding the spatial weight matrix output from the scheduling unit 103a to the coded data output from the data coding unit 105a. The data modulation unit 106a also performs modulation and inverse Fourier transform (e.g., IFFT) on the spatially multiplexed data based on the scheduling information (e.g., modulation method) output from the scheduling unit 103a, and outputs the data signal to the radio transmission unit 108a.

[0116] The preamble generation unit 107a adds, to the LTF, a P-matrix and a spatial weighting matrix generated based on, for example, the scheduling information output from the scheduling unit 103a. The preamble generation unit 107a also generates a preamble signal including, for example, information on the P-matrix added to the LTF (referred to as P-matrix information), and outputs the preamble signal that has been modulated and subjected to IFFT processing to the radio transmission unit 108a.

[0117] The radio transmitting unit 108a generates a radio frame (also called a packet signal) by, for example, adding a preamble signal output from the preamble generating unit 107a to the data signal output from the data modulating unit 106a. The radio transmitting unit 108a also performs radio transmission processing, such as D / A conversion and up-conversion to a carrier frequency, on the radio frame, and transmits the signal after the radio transmission processing to the downlink radio receiving device 200 via an antenna.

[0118] [Downstream radio receiving device according to the second embodiment] Fig. 25 is a block diagram showing an example configuration of a downlink radio receiving device according to embodiment 2. The downlink radio receiving device (e.g., STA) 200 shown in Fig. 25 may include, for example, a radio receiving unit 201a, a preamble demodulating unit 202a, a P-matrix determining unit 203a, a channel estimating unit 204a, a data demodulating unit 205a, a data decoding unit 206a, a transmission signal generating unit 207a, and a radio transmitting unit 208a.

[0119] At least one of the preamble demodulation unit 202a, P-matrix determination unit 203a, channel estimation unit 204a, data demodulation unit 205a, data decoding unit 206a, and transmission signal generation unit 207a may be included in, for example, the control unit shown in Fig. 10. The radio reception unit 201a may be included in, for example, the reception unit shown in Fig. 10.

[0120] The radio receiving unit 201a may receive a signal transmitted from a downlink radio transmitting device (e.g., AP) 100 via an antenna, and perform radio receiving processing such as down-conversion and A / D conversion. The radio receiving unit 201a may also output a data signal extracted from the received signal after the radio receiving processing to the data demodulating unit 205a, and output a preamble signal to the preamble demodulating unit 202a.

[0121] The preamble demodulation unit 202a extracts a control signal used for demodulating and decoding the data portion by performing demodulation processing such as Fourier transform (e.g., FFT) on the preamble signal output from the radio receiving unit 201a. This control signal may include information or parameters such as BW, MCS, an error correction coding method, and P-matrix information. The preamble demodulation unit 202a may output the extracted control information to the data demodulation unit 205a, the data decoding unit 206a, the P-matrix determination unit 203a, and the channel estimation unit 204a.

[0122] The P-matrix determination unit 203a determines the type (or size) of the P-matrix added to the LTF included in the preamble of the received signal and the allocation information of the P-matrix based on, for example, the P-matrix information output from the preamble demodulation unit 202a. The determined information (hereinafter sometimes referred to as P-matrix determination information) may be output to, for example, the channel estimation unit 204a.

[0123] The channel estimation unit 204a performs channel estimation using, for example, a reference signal (e.g., LTF) included in the preamble. For example, the channel estimation unit 204a performs channel estimation using row vectors of the P-matrix corresponding to each spatial stream based on the P-matrix discrimination information output from the P-matrix discrimination unit 203a.

[0124] For example, if multiple P-matrix row vectors are attached to one spatial stream assigned to the received signal, the channel estimation unit 204a performs channel estimation using each row vector and outputs a maximum ratio combined channel estimation value to the data demodulation unit 205a.On the other hand, if multiple P-matrixes are not attached to one spatial stream assigned to the received signal (in other words, if the P-matrix row vectors correspond to the respective spatial streams), the channel estimation unit 204a performs channel estimation using, for example, the row vectors and outputs the channel estimation value to the data demodulation unit 205a.

[0125] The data demodulation unit 205a performs processing such as FFT on the data signal output from the radio receiving unit 201a, demodulates the data signal using the control information output from the preamble demodulation unit 202a and the channel estimation value output from the channel estimation unit 204a, and outputs the demodulated data signal to the data decoding unit 206a.

[0126] The data decoding unit 206a, for example, uses the control information output from the preamble demodulation unit 202a to decode the demodulated data signal output from the data demodulation unit 205a, performs error detection such as CRC, and outputs error detection information to the transmission signal generation unit 207a.

[0127] The transmission signal generation unit 207a generates a response signal (ACK or Block ACK (BA)) based on, for example, the error determination information output from the data decoding unit 206a. The transmission signal generation unit 207a also generates a radio frame by adding, for example, a preamble signal to the data signal, and outputs the radio frame to the radio transmission unit 208a.

[0128] The radio transmitting unit 208a performs radio transmission processing, such as D / A conversion and up-conversion to a carrier frequency, on the radio frame output from the transmission signal generating unit 207a, and transmits the signal after the radio transmission processing to the downlink radio transmitting device 100 via an antenna.

[0129] [Specific example of embodiment 2] In a specific example of the second embodiment, as shown in Fig. 26, each user field of the EHT-SIG includes a subfield (referred to as Extra P-matrix) for notifying P-matrix information (for example, allocation information of row elements of an additional P-matrix). As shown in Fig. 27, for example, when the Extra P-matrix subfield is not equal to 0, the Extra P-matrix subfield notifies the row index of the P-matrix to be additionally allocated. The Extra P-matrix subfield = 0 notifies that no additional P-matrix is ​​allocated.

[0130] In this case, the type of P-matrix to be added to the LTF may be determined based on the number of LTFs and the total number of row components of the P-matrix to be added. In other words, the type of P-matrix to be added to the LTF is not determined based only on the number of LTFs.

[0131] For example, in 11ax / 11ac, when the number of LTFs is 4, the P-matrix added to the LTF is calculated by referring to the formula (1) shown in the first embodiment. 4×4 On the other hand, in the specific example of the second embodiment, it is decided to use the number of LTFs (N EHT-LTF )=4, and the number of row indices of the Extra P-matrix (N ex-P index When (expressed as)=1, the P-matrix to be added to the LTF is calculated by referring to the following equation (3): 6×6 Decided to use.

[0132]

number

[0133] To assign multiple row components of a P-matrix to one spatial stream, a spatial weight matrix (referred to as a Q-matrix) is used. In 11ax / 11ac, the Q-matrix is ​​a weight matrix consisting of the number of transmit antennas multiplied by the number of spatial streams, and is added to the LTF and data portion to achieve spatial division multiplexing.

[0134] However, in the specific example of the second embodiment, the Q-matrix is ​​the number of transmitting antennas × (number of spatial streams + N ex-P index ) matrix. Therefore, when using Extra P-matrix, N STS The value of the number of spatial streams notified in the subfield or Spatial Configuration subfield may differ from the value of the number of columns included in the Q-matrix. For example, in 11ax / ac, the number of columns in the Q-matrix = the number of spatial streams, whereas when using an Extra P-matrix, the number of columns in the Q-matrix = (number of spatial streams + N_(ex-P index)).

[0135] To assign multiple row elements of a P-matrix to one spatial stream, for example, a Q-matrix is ​​used in which the column vector corresponding to the spatial stream contains multiple elements of "1." Figure 28 shows an example in which one spatial stream is assigned to each of STA1 and STA2, and one additional row element of a P-matrix is ​​assigned to STA1.

[0136] In this case, STA1 has P 4×4 The first row of STA2 is assigned to P 4×4 The second line of the P-matrix is ​​assigned as the original P-matrix (original P-matrix components). STA1 assigns the P 4×4 Identify that the third row of is assigned as an additional row component, and 4×4 STA2 performs channel estimation using the first and third lines of the message, and combines the obtained channel estimation values. Based on the Extra P-matrix index information included in the User field addressed to STA2, STA2 determines that an additional P-matrix has not been assigned, and 4×4 The second line of the following is used to perform channel estimation.

[0137] According to a specific example of the second embodiment, additional channel estimation is possible using row elements of an additional P-matrix in the Extra P-matrix subfield, and therefore, the accuracy of channel estimation can be improved by maximum ratio combining of multiple channel estimates.

[0138] [Overall supplement] In the first embodiment, an example has been shown in which Extra-LTF information is notified using an EHT PPDU, but a Trigger frame may be used to instruct transmission of a Trigger base (TB) PPDU including Extra-LTF.

[0139] For example, as in Method 1, Extra-LTF information (Extra-LTF subfield) may be added to each user information (User Info subfield) of the Trigger frame to indicate whether or not Extra-LTF is included in the TB PPDU to be transmitted to each user. Fig. 29 shows an example of the Trigger frame User Info format when Extra-LTF information is notified in each user information.

[0140] Alternatively, for example, a Trigger frame type for instructing Extra-LTF may be defined as shown in Fig. 30. When using a Trigger frame for instructing Extra-LTF, the Trigger Dependent Common info may be replaced with an Extra-LTF bitmap to notify the presence or absence of Extra-LTF for each user, as in specific example 1 of method 2. An example of the Common Info format of the Trigger frame in this case is shown in Fig. 31.

[0141] Alternatively, for example, as in specific example 2 of method 2, an Extra-LTF present subfield may be added to Common Info of the Trigger frame, and the presence or absence of Extra-LTF may be notified in each User Info. An example of the Trigger frame format in this case is shown in FIG.

[0142] Although equation (1) in embodiment 1 and equation (3) in embodiment 2 show a method of determining the type of P-matrix based on the number of LTFs when the number of LTFs is 8 or less, the number of LTFs does not have to be limited to 8 or less. For example, in 11be, when the number of LTFs is 16 or less, the type of P-matrix may be determined based on the number of LTFs.

[0143] Furthermore, when using Extra-LTF and Midamble together (for example, when channel estimation accuracy is likely to deteriorate due to channel fading), LTF including Extra-LTF may be inserted as a midamble into the data section, as shown in Fig. 33. In this case, the AP may notify the STA whether or not Midamble is included in the data section by using a Doppler field included in the preamble, similar to 11ax.

[0144] The AP may also determine the allocation of Extra-LTF based on the number of receive antennas of the STA. For example, if the AP determines that the STA has more than a predetermined number of receive antennas based on the capability of the STA, the AP may transmit to the STA a signal to which a number of spatial streams that is less than the number of receive antennas of the STA is allocated.

[0145] The more receiving antennas a STA has, the easier it becomes to accurately separate the channels between the Original LTF and the Extra-LTF at that STA. Therefore, the accuracy of channel estimation can be improved by performing maximum ratio combining of the channel estimates obtained using the Original LTF and the Extra-LTF.

[0146] Furthermore, the STA may request the AP to transmit a signal including Extra-LTF using link adaptation control information that notifies the AP of recommended transmission parameters. An example of a link adaptation control information format is shown in Figure 34. For example, the STA may combine Extra-LTF information and MCS as in Method 3 and request the AP to transmit a signal including Extra-LTF using the HE-MCS field shown in Figure 34.

[0147] The embodiments of the present disclosure have been described above.

[0148] (Other embodiments) In each of the above-described embodiments, the operation in DL communication has been described, but an embodiment of the present disclosure is not limited to DL communication and may be applied to, for example, UL communication or sidelink.

[0149] The present disclosure can be realized by software, hardware, or software linked to hardware. Each functional block used in the description of the above embodiments may be realized, in part or in whole, as an LSI, which is an integrated circuit, and each process described in the above embodiments may be controlled, in part or in whole, by a single LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of a single chip that includes some or all of the functional blocks. The LSI may have data input and output. Depending on the degree of integration, the LSI may be called an IC, system LSI, super LSI, or ultra LSI.

[0150] The integrated circuit method is not limited to LSI, but may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. Also, a field programmable gate array (FPGA) that can be programmed after LSI manufacturing, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells within the LSI, may be used. The present disclosure may be realized as digital processing or analog processing.

[0151] Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology or other derivative technologies, it is natural that such technology can be used to integrate functional blocks. The application of biotechnology is also a possibility.

[0152] The present disclosure may be implemented in any type of apparatus, device, or system (collectively referred to as a communications apparatus) that has a communications function. The communications apparatus may include a wireless transceiver and processing / control circuitry. The wireless transceiver may include a receiver and a transmitter, or both functions. The wireless transceiver (transmitter and receiver) may include a radio frequency (RF) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or the like. Non-limiting examples of communication devices include telephones (e.g., cell phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, telehealth / telemedicine devices, communication-enabled vehicles or mobile transportation (e.g., cars, airplanes, ships), and combinations of the above devices.

[0153] Communications equipment is not limited to portable or mobile equipment, but also includes non-portable or fixed equipment, devices, and systems of any kind, such as smart home devices (such as appliances, lighting equipment, smart meters or metering devices, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0154] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0155] A communications apparatus also includes devices such as controllers and sensors connected or coupled to a communications device that performs the communications functions described in this disclosure, such as controllers and sensors that generate control and data signals used by the communications device to perform the communications functions of the communications apparatus.

[0156] The communication apparatus also includes infrastructure facilities, such as base stations, access points, and any other apparatus, device, or system that communicates with or controls the various apparatuses listed above, but are not limited to these.

[0157] A communication device according to an embodiment of the present disclosure includes a control circuit that sets information about an additional reference signal for each destination device in a control signal, and a transmission circuit that transmits the control signal.

[0158] In a communication device according to one embodiment of the present disclosure, the control signal includes common information common to multiple destination devices and individual information specific to the destination device, and the control circuit may set a field in the individual information to notify information regarding the additional reference signal.

[0159] In a communication device according to an embodiment of the present disclosure, the information regarding the additional reference signal may be information indicating the presence or absence of the additional reference signal.

[0160] In a communication device according to an embodiment of the present disclosure, the information regarding the additional reference signals may be information indicating the number of the additional reference signals.

[0161] In a communication device according to an embodiment of the present disclosure, the information regarding the additional reference signals may be information indicating a multiple of the original number of the reference signals.

[0162] In the communication device according to an embodiment of the present disclosure, the control circuit may switch the configuration of the control signal depending on whether or not the additional reference signal is present.

[0163] In a communication device according to one embodiment of the present disclosure, when the additional reference signal is present, the control circuit may set a bitmap in common information common to multiple destination devices in the control signal that indicates the presence or absence of the additional reference signal for each of the destination devices.

[0164] In a communication device according to one embodiment of the present disclosure, when the additional reference signal is present, the control circuit may set information regarding the additional reference signal to individual information specific to multiple destination devices in the control signal.

[0165] In a communication device according to one embodiment of the present disclosure, the control circuit may change the method of notifying information regarding the additional reference signal using the control signal depending on the number of destination devices to which the additional reference signal is assigned.

[0166] In a communication device according to one embodiment of the present disclosure, the control circuit may set information indicating a combination of information regarding the additional reference signal and a Modulation and Coding Scheme (MCS) in individual information specific to multiple destination devices in the control signal.

[0167] In a communication device according to one embodiment of the present disclosure, the control circuit may set allocation information for row components of a mapping matrix to be added to the additional reference signal to individual information specific to multiple destination devices in the control signal.

[0168] A communication device according to one embodiment of the present disclosure includes a receiving circuit that receives a control signal including information regarding an additional reference signal for each destination device, and a control circuit that determines the additional reference signal to be used for channel estimation based on the information regarding the additional reference signal.

[0169] In a communication method according to an embodiment of the present disclosure, a communication device sets information regarding an additional reference signal for each destination device in a control signal and transmits the control signal.

[0170] In a communication method according to one embodiment of the present disclosure, a communication device receives a control signal including information regarding an additional reference signal for each destination device, and determines the additional reference signal to be used for channel estimation based on the information regarding the additional reference signal.

[0171] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2021-005046, filed on January 15, 2021, are incorporated herein by reference in their entirety. [Industrial Applicability]

[0172] One embodiment of the present disclosure is useful in wireless communication systems. [Explanation of symbols]

[0173] 100 Downstream radio transmitter 101, 101a, 201, 201a Wireless receiver 102, 102a Received signal decoding unit 103,103a Scheduling section 104, 104a Data generation unit 105, 105a Data encoding section 106, 106a Data modulation section 107,107a Preamble generation unit 108, 108a, 208, 208a Radio transmitter 200 Downstream radio receiving device 202, 202a Preamble demodulation section 203 Extra-LTF discrimination section 203a P-matrix discrimination section 204, 204a Channel estimation unit 205,205a Data demodulation section 206, 206a Data decoding section 207, 207a Transmission signal generation unit

Claims

1. a control circuit for generating an extremely high throughput physical layer convergence procedure protocol data unit (EHT PPDU), the EHT-PPDU including a U-SIG and an EHT-SIG including a Common field, the Common field including a field indicating a first number of EHT-LTF symbols as an extra subfield of the U-SIG, the first number being greater than a second number of the EHT-LTF symbols determined based on a number of spatial streams; a transmitting circuit for transmitting the EHT PPDU; Equipped with Communication equipment.

2. The EHT PPDU includes information indicating whether to add the EHT-LTF; The communication device according to claim 1 .

3. The EHT PPDU includes information indicating the number of additional EHT-LTFs; The communication device according to claim 1 .

4. The EHT PPDU includes information indicating a multiple of the initial number of the EHT-LTF. The communication device according to claim 1 .

5. generating an extremely high throughput physical layer convergence procedure protocol data unit (EHT PPDU), the EHT-PPDU including a U-SIG and an EHT-SIG including a Common field, the Common field including a field indicating a first number of the EHT-LTFs as an extra subfield of the U-SIG, the first number being greater than a second number of the EHT-LTFs determined based on a number of spatial streams; transmitting the EHT PPDU; A communication method, including:

6. controlled by an integrated circuit, The communication method according to claim 5.

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