Communication equipment and communication methods

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] This disclosure relates to communication devices and communication methods. [Background technology]

[0002] As a successor to the IEEE 802.11ax standard (hereinafter referred to as "11ax"), a Task Group (TG) is currently working on developing the technical specifications for 802.11be (hereinafter referred to as "11be"). [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 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, there is room for further investigation into methods to improve the accuracy of channel estimation in wireless communication.

[0005] Non-limiting embodiments of this disclosure contribute to the provision of communication devices and communication methods that improve channel estimation accuracy 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 regarding an additional reference signal for each destination device in a control signal, and a transmission circuit that transmits the control signal.

[0007] These general or specific aspects may be implemented in a system, device, method, integrated circuit, computer program, or recording medium, or may be implemented in any combination of a system, device, method, integrated circuit, computer program, and recording medium.

Advantages of the Invention

[0008] According to an embodiment of the present disclosure, the channel estimation accuracy in wireless communication can be improved.

[0009] Further advantages and effects in an embodiment of the present disclosure will be clarified from the specification and drawings. Such advantages and / or effects are provided by several embodiments and the features described in the specification and drawings, respectively, but not all of them are necessarily provided in order to obtain one or more identical features.

Brief Description of the Drawings

[0010] [Figure 1] A diagram showing an example of the Extremely High Throughput Physical Layer Convergence Procedure Protocol Data Unit (EHT PPDU) format [Figure 2] A diagram showing an example of the 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] A diagram showing an example of the U-SIG and EHT-SIG formats when the number of destination users of the EHT MU PPDU is more than one (MU-MIMO) [Figure 4]Figure showing an example of the number of Very High Throughput - Long Training Field (VHT - LTF) for each spatial stream number [Figure 5] Figure showing an example of the HT - SIG2 format of IEEE 802.11n [Figure 6] Figure showing an example of the relationship between the number of spatial streams in the data part and the number of LTFs [Figure 7] Figure showing an example of the relationship between the extended spatial stream number and the number of HT - extended LTF (HT - ELTF) [Figure 8] Sequence diagram showing an operation example of the wireless communication system according to Embodiment 1 [Figure 9] Block diagram showing a configuration example of a part of the downlink wireless transmission device according to an embodiment of the present disclosure [Figure 10] Block diagram showing a configuration example of a part of the downlink wireless reception device according to an embodiment of the present disclosure [Figure 11] Block diagram showing a configuration example of the downlink wireless transmission device according to Embodiment 1 [Figure 12] Block diagram showing a configuration example of the downlink wireless reception device according to Embodiment 1 [Figure 13] Figure showing an example of the EHT - SIG format including the Extra - LTF subfield [Figure 14] Figure showing 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] Figure showing an example of a method for using a plurality of P - matrices obtained from the number of LTFs determined based on the total number of spatial streams [Figure 16] Figure showing an example of the EHT - SIG format when notifying the presence or absence of Extra - LTF in each user information [Figure 17] Figure showing an example of the EHT - SIG format when notifying the number of Extra - LTFs in each user information [Figure 18]This diagram shows an example of the EHT-SIG format when notifying the number of Extra-Ltfs (EHT-LTFs) in multiples of the initial EHT-LTF count for each user's information. [Figure 19] This diagram shows an example of the EHT-SIG format when notifying the allocation of Extra-LTF using a Bitmap in common information. [Figure 20] This diagram shows an example of the EHT-SIG format used when notifying whether user information includes Extra-LTF information in common information. [Figure 21] This figure shows 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) mode. [Figure 22] This figure shows an example of an MCS table with a combination of higher-order modulation and Extra-LTF added for Multi-User (MU) mode. [Figure 23] This diagram shows an example of the Trigger frame User Info format when notifying Extra-LTF information in user information. [Figure 24] Block diagram showing an example configuration of a downlink wireless transmission device according to Embodiment 2. [Figure 25] Block diagram showing an example configuration of a downlink wireless receiver according to Embodiment 2. [Figure 26] A diagram showing an example of the EHT-SIG format including an Extra P-matrix. [Figure 27] This diagram shows an example of the EHT-SIG format when notifying the row index of the Extra P-matrix in each user's information. [Figure 28] This diagram shows an example of LTF when two users are each assigned one spatial stream, and one of the two users is assigned an additional administrative portion of the P-matrix. [Figure 29] This diagram shows an example of the Trigger frame User Info format when notifying Extra-LTF information for each user's information. [Figure 30]A diagram showing an example of a trigger frame type for instructing Extra-LTF. [Figure 31] This diagram shows an example of a Common Info format for triggering Extra-LTF notifications using a Bitmap in common information. [Figure 32] This diagram shows an example of a Common info format for trigger frames used to notify whether or not user information includes Extra-LTF information in common information. [Figure 33] This diagram shows an example of the PPDU format when used in conjunction with Extra-LTF and Midamble. [Figure 34] A diagram showing an example of a link adaptation control information format. [Modes for carrying out the invention]

[0011] Each embodiment of this disclosure will be described in detail below with reference to the drawings.

[0012] In 11be, one of the objectives is to improve channel estimation accuracy, and a method has been discussed for transmitting an Extreme High Throat - 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 from the number of spatial streams (SS) (for example, Non-Patent Documents 1, 2).

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

[0014] Figure 2 shows an example of the U-SIG and EHT-SIG format when the destination user of the EHT MU PPDU is one (referred to as non-Multi-User Multiple-Input Multiple-Output (MU-MIMO) or SU (single user)). Figure 3 shows an example of the U-SIG and EHT-SIG format when the destination user of the EHT MU PPDU is more than one (referred to as MU-MIMO).

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

[0016] In 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 indicated by the subfield (denoted as ) or the Spatial Configuration subfield.

[0017] On the other hand, in 11be, EHT PPDU transmission includes, for example, the Number of EHT-LTF Symbols subfield (hereinafter referred to as N) included in U-SIG. EHT-LTF The number of EHT-LTF symbols included in the EHT PPDU is notified. In EHT PPDU, the number of EHT-LTFs included in the EHT PPDU can be determined based on the number of spatial streams, similar to 11ax. Also, in EHT PPDU, N EHT-LTF By notifying a number of EHT-LTF symbols that is greater than the number of EHT-LTFs determined from the number of spatial streams, it is possible to create an EHT PPDU that contains more EHT-LTFs than a normal EHT PPDU.

[0018] When transmitting more EHT-LTF than usual, an access point (AP, also called a "base station") may allocate twice the number of EHT-LTF to each terminal (STA), which is determined based on the number of spatial streams. For example, if two STAs, STA1 and STA2, are allocated the number of spatial streams as [2,1] respectively, the number of EHT-LTF may be allocated as [4,2].

[0019] When an STA receives a signal containing more EHT-LTF than HE-LTF, for example, N EHT-LTF The number of EHT-LTFs notified by the subfield, and N STS The number of spatial streams indicated by the subfield or Spatial Configuration subfield is compared to determine whether the EHT-LTF includes additional LTFs, and channel estimation is performed using the EHT-LTF.

[0020] Note N EHT-LTFIt may be included in the Common field of the EHT-SIG as an excess subfield of the U-SIG.

[0021] Also, in IEEE 802.11n (hereinafter referred to as "11n"), there is a sounding PPDU transmitted to estimate the channel between a transmitter and a receiver. Fig. 5 shows an example of the HT-SIG2 format in 11n. In 11n, when the Not sounding subfield included in the HT-SIG2 = 0, it is transmitted as a sounding PPDU.

[0022] The sounding PPDU may include, for example, an LTF (referred to as Data LTF (DLTF)) determined based on the number of spatial streams, and an LTF (referred to as Extention LTF (ELTF)) for transmitting additional spatial streams (extended spatial streams, or Extention spatial stream (ESS)). Figs. 6 and 7 show an example of the relationship between the number of spatial streams (N STS / N ESS ) and the number of LTFs (N HT-DLTF / N HT-ELTF ). Note that the total value of the number of spatial streams and the number of extended spatial streams may be required to be, for example, 4 or less and less than or equal to the number of transmitting antennas.

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

[0024] In one embodiment of this disclosure, for example, channel estimation accuracy is improved by including (or setting) a field (or information) relating to an additional user-specific LTF (referred to as Extra-LTF) in a control signal having a common field (or common information) and a user field (or user information).

[0025] For example, channel estimation accuracy can be improved by determining the allocation of Extra-LTF for each user according to the channel estimation accuracy required by that user, and by combining multiple channel estimation values ​​by maximum ratio. By improving channel estimation accuracy, signal errors can be reduced, for example, thereby improving wireless communication quality.

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

[0027] For example, in Down Link (DL) communication, the AP corresponds to the "downlink wireless transmitter," and the STA corresponds to the "downlink wireless receiver." Similarly, in Up Link (UL) communication, the AP corresponds to the "uplink wireless receiver," and the STA corresponds to the "uplink wireless transmitter." The STA may also be referred to as the "user device" or simply the "user." The "downlink wireless receiver" can be positioned as the destination device in DL communication.

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

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

[0030] An example of the operation of AP and STA in this embodiment 1 will be described. Figure 8 is a sequence diagram showing an example of the operation of a wireless communication system in which the AP transmits an EHT PPDU, including the Extra-LTF, to the STA in 11be.

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

[0032] Capabilities related to Extra-LTF may include, for example, 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 transmissions, and at least one of the maximum number of LTFs that can be received in multi-user transmissions.

[0033] For example, the AP selects an STA capable of transmitting Extra-LTF based on the capability obtained from a Capability request received from the STA, and schedules frequency resources (referred to as Recourse Units (RUs)), spatial multiplexing methods, and modulation methods (S103). The AP also generates an EHT PPDU containing Extra-LTF based on the scheduling information (S104). At this time, the AP may include information notifying the allocation of Extra-LTF (hereinafter sometimes referred to as "Extra-LTF information") in the EHT PPDU and send it to the STA (S105).

[0034] The STA, having received Extra-LTF information from the AP, performs, for example, reception processing of the EHT PPDU containing the Extra-LTF information (S106). For example, the STA obtains N from the preamble portion of the EHT PPDU. STS and N EHT-LTF Based on the value and Extra-LTF information, it is determined whether Extra-LTF is assigned to the EHT PPDU, and channel estimation is performed using the LTF.

[0035] Furthermore, based on the acquired channel estimate, the STA performs, for example, equalization processing on the data portion of the EHT PPDU and demodulates and decodes the data portion. The STA also sends a response signal (Acknowledge (ACK)) to the AP according to the error detection result of the decoded data signal (S107).

[0036] Although the above example described an EHT PPDU containing Extra-LTF, the above example of operation may also be applied to an EHT NDP PPDU containing Extra-LTF.

[0037] Figure 9 is a block diagram showing a partial configuration example of a downlink wireless transmitter (e.g., AP) 100 according to one embodiment of the present disclosure. In the AP 100 shown in Figure 9 (e.g., corresponding to a communication device), the control unit (e.g., corresponding to a control circuit) may set information regarding additional reference signals (e.g., Extra-LTF) for each destination device (e.g., STA) in the control signal. The transmitting unit (e.g., corresponding to a transmitting circuit) transmits the control signal.

[0038] Figure 10 is a block diagram showing a partial configuration example of a downlink wireless receiver (e.g., STA) 200 according to one embodiment of the present disclosure. In the STA 200 shown in Figure 10 (e.g., corresponding to a communication device), the receiving unit (e.g., corresponding to a receiving circuit) receives a control signal that includes information about additional reference signals (e.g., Extra-LTF) for each destination device (e.g., STA). The control unit (e.g., corresponding to a control circuit) may determine an additional reference signal to be used for channel estimation based on the information about the additional reference signal.

[0039] [Downstream Wireless Transmitter of Embodiment 1] Figure 11 is a block diagram showing an example configuration of a downlink wireless transmitter according to this first embodiment. The downlink wireless transmitter (e.g., AP) 100 shown in Figure 11 may include, for example, a wireless receiving unit 101, a received signal decoding unit 102, a scheduling unit 103, a data generation unit 104, a data encoding unit 105, a data modulation unit 106, a preamble generation unit 107, and a wireless transmission unit 108.

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

[0041] The wireless receiver 101 receives signals transmitted from a downlink wireless receiver (e.g., STA) 200 (see Figure 10) via an antenna, for example, and performs wireless reception processing such as downconversion and analog-to-digital (A / D) conversion. The wireless receiver 101 then divides the received signal after wireless reception processing into a preamble section (also called a preamble signal) and a data section (also called a data signal) and outputs them to the received signal decoding section 102.

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

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

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

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

[0046] The reception quality information may include, for example, information such as Packet Error Rate (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 generation unit 104, the data coding unit 105, the data modulation unit 106, and the preamble generation unit 107.

[0047] The data generation unit 104 generates a data sequence to be transmitted to the downlink wireless receiver 200 based on scheduling information output from the scheduling unit 103, and outputs the data sequence to the data encoding unit 105.

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

[0049] The data modulation unit 106 performs modulation and an inverse Fast Fourier Transform (IFFT) based, for example, the encoded data output from the data encoding 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 wireless transmission unit 108.

[0050] The preamble generation unit 107 generates a preamble signal that includes Extra-LTF or control information related to Extra-LTF (e.g., Extra-LTF allocation information) based on scheduling information output from the scheduling unit 103. The preamble signal may be modulated and processed with IFFT in the preamble generation unit 107 and output to the wireless transmission unit 108.

[0051] The wireless transmission unit 108 generates a wireless frame (also called a packet signal) by, for example, adding a preamble signal output from the preamble generation unit 107 to the data signal output from the data modulation unit 106. The wireless transmission unit 108 also performs wireless transmission processing on the wireless frame, such as digital-to-analog (D / A) conversion and upconversion to the carrier frequency, and transmits the processed signal to the downstream wireless receiver 200 via the antenna.

[0052] [Downstream wireless receiver according to Embodiment 1] Figure 12 is a block diagram showing an example configuration of a downlink wireless receiver according to Embodiment 1. The downlink wireless receiver (e.g., STA) 200 shown in Figure 12 may include, for example, a wireless receiver 201, a preamble demodulation unit 202, an Extra-LTF discrimination unit 203, a channel estimation unit 204, a data demodulation unit 205, a data decoding unit 206, a transmission signal generation unit 207, and a wireless transmission unit 208.

[0053] At least one of the preamble demodulation unit 202, the Extra-LTF discrimination 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 the control unit shown in Figure 10, for example. The wireless receiving unit 201 may be included in the receiving unit shown in Figure 10, for example.

[0054] The wireless receiver 201 may, for example, receive a signal transmitted from a downlink wireless transmitter (e.g., AP) 100 via an antenna and perform wireless reception processing such as downconversion and A / D conversion. The wireless receiver 201 may also, for example, output a data signal extracted from the received signal after wireless reception processing to a data demodulation unit 205 and output a preamble signal to a preamble demodulation unit 202.

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

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

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

[0058] Furthermore, the channel estimation unit 204 combines the channel estimates estimated using, for example, Original LTF and Extra-LTF, by their maximum ratio, 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 to correct the power difference between the combined channel estimate and the data unit. Also, if Extra-LTF is not allocated, the channel estimation unit 204 does not need to perform channel estimation using Extra-LTF.

[0059] The data demodulation unit 205 performs a process such as a Fourier transform (e.g., FFT) on the data signal output from the wireless receiver unit 201, and demodulates the data signal using the control information output from the preamble demodulation unit 202 and the channel estimate output from the channel estimation unit 204. The demodulated data signal may be output to the data decoding unit 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 information, which is the result of the detection, to the transmission signal generation unit 207.

[0061] The transmission signal generation unit 207 generates a response signal (ACK or Block ACK (referred to as BA)) based, for example, on error detection information output from the data decoding unit. The transmission signal generation unit 207 also generates a wireless frame by adding a preamble signal to the data signal, for example, and outputs it to the wireless transmission unit 208.

[0062] The wireless transmission unit 208 performs wireless transmission processing on the wireless frame output from the transmission signal generation unit 207, such as D / A conversion and upconversion to the carrier frequency, and transmits the processed signal to the downstream wireless transmission device 100 via the antenna.

[0063] [Example of operation] Next, an example of the operation of the downlink wireless transmitter (e.g., AP) 100 and the downlink wireless receiver (e.g., STA) 200 in this embodiment 1 will be described.

[0064] In one embodiment of this disclosure, the control signal (also called control information) transmitted from the downlink wireless transmitter 100 to the downlink wireless receiver 200 may include common information that is common to multiple users and user information that is specific to each of the multiple users.

[0065] The control signal may include, for example, user-specific Extra-LTF information for the user (e.g., downlink wireless receiver 200). The control information may be, for example, the SIG field (U-SIG or EHT-SIG) of the EHT PPDU or the trigger frame. The Extra-LTF information may also include, for example, information or parameters indicating at least one of the presence or absence of an Extra-LTF allocation and the number of Extra-LTF allocations.

[0066] [Method 1] In Method 1, for example, each user's information may include a subfield for notifying Extra-LTF information. For example, as shown in Figure 13, each user field in the EHT-SIG may include an Extra-LTF subfield for notifying the allocation of Extra-LTF. The notification method using the Extra-LTF subfield will be described later in specific examples 1 to 3 of Method 1.

[0067] In EHT-LTF, for example, a mapping matrix (called a P-matrix) is added to multiplex multiple EHT-LTF symbols, regardless of whether or not there are Extra-LTFs. 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 ). In 11n, for example, P 4×4 The P-matrix of P is used. 4×4 This can be expressed, for example, by equation (2). The column components of the P-matrix correspond to each LTF symbol. On the other hand, the row components of the P-matrix correspond to spatial streams, and the row components are multiplexed to each LTF symbol.

[0068]

number

[0069]

number

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

[0071] Figure 14 shows an example of a P-matrix to be added to the EHT-LTF when two spatial streams are assigned to STA1 and STA2, and two Extra-LTFs are assigned to STA1. In this case, AP is, for example, a 6x6 P-matrix(P 6×6 The elements of row 1-4, column 1-4 (called) are added to the Original LTF, P 6×6 The elements in rows 1-4 and columns 5-6 are added to the Extra-LTF.

[0072] STA1 performs a maximum ratio synthesis of channel estimates obtained from the Original LTF and channel estimates obtained from the Extra-LTF, and uses this for equalization of the data portion.

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

[0074] In this case, AP is, for example, a 4x4 P-matrix(P 4×4 In addition to adding (called) to the Original LTF, another P-matrix P 4×4 Add this to Extra-LTF.

[0075] STA1 performs a maximum ratio synthesis of channel estimates obtained from the Original LTF and two channel estimates obtained from the Extra-LTF, and uses this for equalization of the data section.

[0076] As in Method 1, by assigning Extra-LTF to specific users, it becomes possible to perform channel estimation using more LTF than before, thereby improving the accuracy of channel estimation through maximum ratio synthesis.

[0077] [Specific example of Method 1, Part 1] In specific example 1 of Method 1, Extra-LTF information, for example, notifies whether or not Extra-LTF exists. Figure 16 shows an example of the EHT-SIG format when notifying whether or not Extra-LTF exists in each user's information.

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

[0079] In specific example 1 of Method 1, the first STA may determine the number of Extra-LTFs addressed to the first STA by referring to, for example, user information addressed to the other second STA. For example, Figure 16 shows an example where one spatial stream is assigned to 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 are determined from the Spatial Configuration subfield to have one spatial stream allocated to each of them (in other words, they are determined to have a total of 2 spatial streams allocated).

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

[0082] On the other hand, STA2 identifies that Extra-LTF has been assigned to STA1, for example, based on the Extra-LTF in STA1's User field. Also, STA2 calculates the EHT-LTF index assigned to STA1 from the difference between the number of EHT-LTF and the total spatial stream, similar to STA1, and derives the EHT-LTF index (4) that STA2 refers to.

[0083] [Specific example of Method 1, part 2] In specific example 2 of Method 1, Extra-LTF information, for example, notifies the number of Extra-LTFs. Figure 18 shows an example of the EHT-SIG format when the number of Extra-LTFs is notified in each user's information. Figure 18 shows an example where one spatial stream is assigned to STA1 and STA2, and two Extra-LTFs are assigned to STA1.

[0084] In this case, the method for notifying the number of Extra-LTFs may be, for example, by notifying the number of Extra-LTFs through each Extra-LTF subfield. Alternatively, the method for notifying the number of Extra-LTFs may be to limit the number of available Extra-LTFs (for example, the number of Extra-LTFs may be selected from [0, 2, 4, 8]).

[0085] [Specific example of Method 1, part 3] In specific example 3 of Method 1, a multiple of the initial (or Original) LTF number is notified as Extra-LTF information. Figure 19 shows an example of the EHT-SIG format when the number of Extra-LTFs is notified as a multiple of the initial EHT-LTF number in each user's information. Figure 19 shows an example where one spatial stream is assigned to STA1 and STA2, and one Extra-LTF is assigned to STA1.

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

[0087] Furthermore, 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 increased to 3 times, 4 times, or more by increasing the number of bits in the Extra-LTF subfield.

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

[0089] For example, if the transmitted signal includes one or more users who have been assigned Extra-LTF, the notification "Extra-LTF present=1" is sent; if it does not include any users who have been assigned Extra-LTF, the notification "Extra-LTF present=0" is sent. The presence or absence of Extra-LTF may be notified by any of the specific examples 1 to 3 of Method 1.

[0090] As in Method 2, by switching the configuration of the EHT-SIG depending on whether or not the transmitted signal includes users who have been assigned Extra-LTF, the signaling overhead when Extra-LTF is not used can be reduced.

[0091] [Specific example of Method 2, Part 1] In specific example 1 of Method 2, if the transmitted signal includes users assigned Extra-LTF, 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 transmitted signal does not include users assigned Extra-LTF, the common information does not need to include an Extra-LTF bitmap.

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

[0093] The Extra-LTF bitmap may be a variable-length bitmap determined, for example, based on the number of user information entries in the EHT-SIG. Alternatively, the Extra-LTF bitmap may be a fixed-length bitmap based, for example, on the maximum number of concurrent users in MU-MIMO.

[0094] The Extra-LTF bitmap may, for example, use 1 bit to indicate the presence or absence of Extra-LTF for each user, as in Specific Example 1 of Method 1, or it may use up to 3 bits to indicate the number of Extra-LTF for each user, as in Specific Example 2 of Method 1. Alternatively, as in Specific Example 3 of Method 1, it may use N STS Alternatively, a single bit may be used to indicate that an LTF (Longest Time Stream) equal to a multiple of the number of spatial streams notified should be allocated.

[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, it is not necessary to refer to the user information of other users), thus reducing processing time.

[0096] [Specific example of Method 2, part 2] In specific example 2 of Method 2, for instance, if a user assigned Extra-LTF is included in the transmitted signal, Extra-LTF information is added to the user information, and the presence or absence of Extra-LTF for each user is notified. Figure 21 shows an example of the EHT-SIG format when notifying whether Extra-LTF information is included in the user information in the common information.

[0097] For example, if a user has been assigned Extra-LTF to their transmission signal, an Extra-LTF subfield is added to each user's information to notify them of the Extra-LTF information. In other words, if a user has not been assigned Extra-LTF to their transmission signal, the Extra-LTF subfield does not need to be included in each user's information.

[0098] According to specific example 2 of Method 2, when the number of destination users is small, signaling overhead can be reduced compared to notifying Extra-LTF allocation by bitmap as in specific example 1 of Method 2.

[0099] [Specific example 3 of Method 2] In specific example 3 of Method 2, the method of notifying Extra-LTF is changed depending on the number of destination users. For example, consider a case where the common information includes a fixed-length Extra-LTF Bitmap based on the maximum number of concurrent users for MU-MIMO. In this case, if the number of destination users of the transmitted signal containing Extra-LTF is equal to the maximum number of concurrent users for 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 the transmitted signal containing Extra-LTF is less than the maximum number of concurrent users for MU-MIMO, the presence or absence of Extra-LTF may be notified in the user information for each user, as in specific example 2 of Method 2.

[0100] According to specific example 3 of Method 2, by changing the notification method for 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 is notified by combining Extra-LTF information and MCS information using user information. When notifying by combining Extra-LTF and MCS, 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 single-user (SU) transmission, a combination of low-order modulation and Extra-LTF may be added to the MCS table separately from Example 1 and Example 2, as shown in Figure 22. In the case of multi-user (MU) transmission, a combination of high-order modulation and Extra-LTF may be added to the MCS table separately from Example 1 and Example 2, as shown in Figure 23, for example.

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

[0104] As shown in Method 3, by combining Extra-LTF information with MCS, notification of Extra-LTF information can be achieved without increasing the signaling for notifying Extra-LTF information.

[0105] [Embodiment 2] Embodiment 1 describes an example of how to assign users to different time symbols of an LTF, including an Extra-LTF. Embodiment 2 describes an example of how to assign multiple row components of a P-matrix to a single spatial stream using code multiplexing, for example.

[0106] [Downstream Wireless Transmitter of Embodiment 2] Figure 24 is a block diagram showing an example configuration of a downlink wireless transmitter according to Embodiment 2. The downlink wireless transmitter (for example, AP) 100 illustrated in Figure 24 may include, for example, a wireless receiving 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 wireless transmission unit 108a.

[0107] At least one of the received signal decoding unit 102a, scheduling unit 103a, data generation unit 104a, data encoding unit 105a, data modulation unit 106a, and preamble generation unit 107a may be included in the control unit shown in Figure 9, for example. The wireless transmission unit 108a may be included in the transmission unit shown in Figure 9, for example.

[0108] The wireless receiver 101a receives signals transmitted from the downlink wireless receiver (e.g., STA) 200 via an antenna, for example, and performs wireless reception processing such as downconversion and A / D conversion. The wireless receiver 101a then splits the received signal after wireless reception processing into a preamble section and a data section and outputs them to the received signal decoding section 102a.

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

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

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

[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 generation unit 104a, the data coding unit 105a, the data modulation unit 106a, and the preamble generation unit 107a.

[0113] The data generation unit 104a generates a data sequence to be transmitted to the downlink wireless receiver 200 based on 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, for example, the data sequence output from the data generation unit 104a and the scheduling information (e.g., error correction encoding method or MCS) output from the scheduling unit 103a. The encoded data may be output to, for example, the data modulation unit 106a.

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

[0116] The preamble generation unit 107a adds a P-matrix and a spatial weight matrix, generated based on scheduling information output from the scheduling unit 103a, to the LTF. The preamble generation unit 107a also generates a preamble signal that includes information about the P-matrix added to the LTF (referred to as P-matrix information), modulates and processes the preamble signal using IFFT, and outputs the modulated and IFFT processed preamble signal to the wireless transmission unit 108a.

[0117] The wireless transmission unit 108a generates a wireless frame (also called a packet signal) by adding a preamble signal output from the preamble generation unit 107a to the data signal output from the data modulation unit 106a. The wireless transmission unit 108a also performs wireless transmission processing on the wireless frame, such as D / A conversion and upconversion to the carrier frequency, and transmits the processed signal to the downstream wireless receiver 200 via the antenna.

[0118] [Downstream wireless receiver according to Embodiment 2] Figure 25 is a block diagram showing an example configuration of a downlink wireless receiver according to Embodiment 2. The downlink wireless receiver (e.g., STA) 200 illustrated in Figure 25 may include, for example, a wireless receiver unit 201a, a preamble demodulation unit 202a, a P-matrix discrimination unit 203a, a channel estimation unit 204a, a data demodulation unit 205a, a data decoding unit 206a, a transmission signal generation unit 207a, and a wireless transmission unit 208a.

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

[0120] The wireless receiver 201a may, for example, receive a signal transmitted from a downlink wireless transmitter (e.g., AP) 100 via an antenna and perform wireless reception processing such as downconversion and A / D conversion. The wireless receiver 201a may also, for example, output a data signal extracted from the received signal after wireless reception processing to the data demodulation unit 205a and output a preamble signal to the preamble demodulation unit 202a.

[0121] The preamble demodulation unit 202a extracts control signals used for demodulation and decoding of the data section by performing demodulation processing, such as a Fourier transform (e.g., FFT), on the preamble signal output from the wireless receiver unit 201a. These control signals may include information or parameters such as BW, MCS, 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 discrimination unit 203a, and the channel estimation unit 204a.

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

[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 a single spatial stream assigned to a received signal has multiple P-matrix row vectors attached to it, the channel estimation unit 204a performs channel estimation using each row vector and outputs the channel estimate obtained by combining the maximum ratios to the data demodulation unit 205a. On the other hand, if a single spatial stream assigned to a received signal does not have multiple P-matrixes attached to it (in other words, if each row vector of the P-matrix corresponds to a separate spatial stream), the channel estimation unit 204a performs channel estimation using, for example, the row vector and outputs the channel estimate to the data demodulation unit 205a.

[0125] The data demodulation unit 205a performs processing such as FFT on the data signal output from the wireless receiver unit 201a, demodulates the data signal using the control information output from the preamble demodulation unit 202a and the channel estimate 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 the 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 error detection information output from the data decoding unit 206a, for example. The transmission signal generation unit 207a also generates a wireless frame by adding a preamble signal to the data signal, for example, and outputs it to the wireless transmission unit 208a.

[0128] The wireless transmission unit 208a performs wireless transmission processing, such as D / A conversion and upconversion to the carrier frequency, on the wireless frame output from the transmission signal generation unit 207a, and transmits the processed signal to the downstream wireless transmission device 100 via the antenna.

[0129] [Specific example of Embodiment 2] In a specific example of Embodiment 2, as shown in Figure 26, for example, each user field of the EHT-SIG includes a subfield (referred to as Extra P-matrix) that notifies P-matrix information (e.g., allocation information for additional P-matrix row components). For example, as shown in Figure 27, if Extra P-matrix subfield ≠ 0, the Extra P-matrix subfield notifies the row index of the additional P-matrix to be allocated. Extra P-matrix subfield = 0 notifies that no additional P-matrix will be allocated.

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

[0131] For example, in 11ax / 11ac, if the number of LTFs is 4, the P-matrix to be added to the LTFs refers to equation (1) shown in Embodiment 1, and P 4×4 We decide to use . On the other hand, in the specific example of Embodiment 2, the number of LTFs (N EHT-LTF ) = 4, and the number of row indices (N) of the Extra P-matrix. ex-P index If (represented as) = ​​1, the P-matrix to be added to the LTF is given by referring to equation (3) below, P 6×6 We decide to use it.

[0132]

number

[0133] Furthermore, to assign multiple P-matrix row components to a single spatial stream, a spatial weight matrix (called a Q-matrix) is used, for example. In 11ax / 11ac, the Q-matrix is ​​a weight matrix consisting of the number of transmitting antennas × the number of spatial streams, and spatial division multiplexing is realized by adding it to the LTF and data section.

[0134] However, in the specific example of Embodiment 2, the Q-matrix is ​​the number of transmitting antennas × (number of spatial streams + N) ex-P index This is a matrix consisting of ). Therefore, when using the Extra P-matrix, the N of EHT-SIG 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 equals the number of spatial streams, whereas when using the Extra P-matrix, the number of columns in the Q-matrix equals (number of spatial streams + N_(ex-P index)).

[0135] To assign multiple P-matrix row components to a single spatial stream, for example, a Q-matrix with multiple "1" components in the column vector corresponding to that spatial stream can be used. Figure 28 shows an example where one spatial stream is assigned to STA1 and STA2, and one additional P-matrix row component is assigned to STA1.

[0136] In this case, STA1 contains P 4×4 The first row is assigned, and STA2 is P 4×4 The second line is assigned as the original P-matrix (referred to as Original P-matrix components). STA1 uses the Extra P-matrix index information contained in the User field addressed to STA1 to determine the P 4×4 Identify that the third row is allocated as an additional row component, P 4×4 Using the first and third rows, channel estimation is performed on each, and the obtained channel estimates are combined. Based on the Extra P-matrix index information contained in the User field addressed to STA2, STA2 determines that no additional P-matrix has been assigned, and P 4×4 Channel estimation is performed using the second line of the following.

[0137] According to a specific example of Embodiment 2, additional channel estimation is possible using the row components of an additional P-matrix in the Extra P-matrix subfield, thereby improving the channel estimation accuracy by combining the maximum ratio of multiple channel estimates.

[0138] [Supplementary information for the whole] Embodiment 1 shows an example of notifying Extra-LTF information using an EHT PPDU, but it is also possible to instruct the transmission of a Trigger base (TB) PPDU containing Extra-LTF using a Trigger frame.

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

[0140] Alternatively, for example, as shown in Figure 30, a trigger frame type for indicating Extra-LTF may be defined. When using a trigger frame for indicating Extra-LTF, as in Specific Example 1 of Method 2, the trigger dependent common info may be replaced with an Extra-LTF bitmap to notify each user of the presence or absence of Extra-LTF. An example of the common info format of the trigger frame in this case is shown in Figure 31.

[0141] Alternatively, as shown in example 2 of Method 2, an Extra-LTF present subfield can be added to the Common Info of the Trigger frame, and the presence or absence of Extra-LTF can be notified in each User Info. An example of the Trigger frame format in this case is shown in Figure 32.

[0142] In Equation (1) of Embodiment 1 and Equation (3) of Embodiment 2, a method for determining the type of P-matrix based on the number of LTFs when the number of LTFs is 8 or less was shown. However, the number of LTFs is not limited to 8 or less. For example, in 11be, the type of P-matrix may be determined based on the number of LTFs when the number of LTFs is 16 or less.

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

[0144] Furthermore, the AP may determine the allocation of Extra-LTF based on the number of receiving antennas of the STA. For example, if the AP identifies, based on the STA's capability, that the STA has more than a predetermined number of receiving antennas, it may send a signal to the STA with a number of spatial streams less than the number of receiving antennas of the STA.

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

[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. Figure 34 shows an example of the link adaptation control information format. For example, the STA may combine the Extra-LTF information and the MCS as in Method 3 and request the AP to transmit a signal including Extra-LTF using the HE-MCS field illustrated in Figure 34.

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

[0148] (Other embodiments) While the above-described embodiments explain the operation in DL communication, one embodiment of this disclosure is not limited to DL communication, but may also be applied to UL communication or sidelinks, for example.

[0149] This disclosure can be implemented in software, hardware, or software in conjunction with hardware. Each functional block used in the description of the above embodiments may be implemented in part or in whole as an integrated circuit (LSI), 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. An LSI may consist of individual chips, or it may consist of a single chip that includes some or all of the functional blocks. An LSI may have data inputs and outputs. Depending on the degree of integration, LSIs may be referred to as ICs, system LSIs, super LSIs, or ultra LSIs.

[0150] The method of integration is not limited to LSIs; it may also be implemented using dedicated circuits, general-purpose processors, or dedicated processors. Furthermore, FPGAs (Field Programmable Gate Arrays) that can be programmed after LSI manufacturing, or reconfigurable processors that allow for the reconfiguration of the connections and settings of circuit cells within the LSI, may also be used. This disclosure may be implemented as digital or analog processing.

[0151] Furthermore, if advancements in semiconductor technology or other derived technologies lead to the emergence of integrated circuit technologies that replace LSIs, then naturally, it would be possible to use those technologies to integrate functional blocks. The application of biotechnology, for example, is a possibility.

[0152] This disclosure is applicable to all types of devices, systems, and equipment having communication capabilities (collectively referred to as communication equipment). Communication equipment may include a radio transceiver and a processing / control circuit. A radio transceiver may include a receiver and a transmitter, or both as functions. A radio transceiver (transmitter, receiver) may include an RF (Radio Frequency) module and one or more antennas. The RF module may include an amplifier, an RF modulator / demodulator, or similar. Non-exclusive examples of communication devices include telephones (mobile phones, smartphones, etc.), tablets, personal computers (PCs) (laptops, desktops, notebooks, etc.), cameras (digital still / video cameras, etc.), digital players (digital audio / video players, etc.), wearable devices (wearable cameras, smartwatches, tracking devices, etc.), game consoles, digital book readers, telehealth / telemedicine devices, vehicles or mobile transport with communication capabilities (cars, airplanes, ships, etc.), and combinations of the above-mentioned devices.

[0153] Communication devices are not limited to portable or movable devices, but also include all kinds of non-portable or fixed devices, devices, and systems, such as smart home devices (appliances, lighting equipment, smart meters or measuring instruments, control panels, etc.), vending machines, and any other "things" that may exist on an IoT (Internet of Things) network.

[0154] Communication includes data communication via cellular systems, wireless LAN systems, and communication satellite systems, as well as data communication using combinations of these.

[0155] Furthermore, the communication device also includes devices such as controllers and sensors that are connected to or linked to a communication device that performs the communication functions described in this disclosure. For example, this includes controllers and sensors that generate control signals and data signals used by the communication device that performs the communication functions of the communication device.

[0156] Furthermore, communication equipment includes infrastructure facilities such as base stations, access points, and any other devices, devices, and systems that communicate with or control the aforementioned non-limited types of equipment.

[0157] A communication device according to one embodiment of the present disclosure includes a control circuit that sets information regarding additional reference signals for each destination device in the 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 a plurality of destination devices and individual information specific to each destination device, and the control circuit may set a field in the individual information that notifies information regarding the additional reference signal.

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

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

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

[0162] In a communication device according to one embodiment of the present disclosure, the control circuit may switch the configuration of the control signal depending on the presence or absence of the additional reference signal.

[0163] In a communication device according to one embodiment of the present disclosure, if the additional reference signal is present, the control circuit may set a bitmap in the common information common to the multiple destination devices in the control signal that indicates whether or not the additional reference signal is present for each destination device.

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

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

[0166] In a communication device according to one embodiment of the present disclosure, the control circuit may set information indicating a combination of the additional reference signal and the Modulation and Coding Scheme (MCS) in the individual information for each of the 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, in the control signal, individual information for each of the multiple destination devices, assignment information for the row components of the mapping matrix to be added to the additional reference signal.

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

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

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

[0171] All disclosures in the specification, drawings, and abstract contained in the Japanese application 2021-005046, filed on January 15, 2021, are incorporated herein by reference. [Industrial applicability]

[0172] One embodiment of this disclosure is useful for wireless communication systems. [Explanation of symbols]

[0173] 100 Downlink Wireless Transmitter 101, 101a, 201, 201a Wireless receiver 102,102a Received signal decoding section 103,103a Scheduling section 104,104a Data generation unit 105,105a Data encoding section 106,106a Data modulation section 107,107a Preamble generation section 108, 108a, 208, 208a Wireless Transmitter 200 Downlink Wireless Receiver 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 Unit 207,207a Transmit signal generation unit

Claims

1. A control circuit generates an extremely high throughput physical layer convergence procedure protocol data unit (EHT PPDU), the EHT PPDU comprising a U-SIG and an EHT-SIG including a Common field, the Common field including a field as a surplus subfield of the U-SIG indicating a first number of EHT-LTF symbols, the first number being greater than a second number of EHT-LTF symbols determined based on the number of spatial streams, and A transmitting circuit that transmits the aforementioned EHT PPDU, Equipped with, Communication device.

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 additional number of 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. A process to generate an extremely high throughput physical layer convergence procedure protocol data unit (EHT PPDU), wherein the EHT PPDU includes a U-SIG and an EHT-SIG containing a Common field, the Common field including a field representing a first number of the EHT-LTF as a surplus subfield of the U-SIG, the first number being greater than a second number of the EHT-LTF determined based on the number of spatial streams, The process of transmitting the aforementioned EHT PPDU, A communication method that includes this.

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

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