Master access point (AP), communication method and integrated circuit

Abstract

To appropriately transmit a reference signal in cooperative communication.SOLUTION: A master AP includes, in operation, a circuit for generating a frame indicating cyclic shift information for a reference signal used in multi-access point (AP) coordinated transmission, and a transmitter for transmitting the frame to at least one slave AP, in operation, and the slave AP transmits the reference signal in the multi-AP coordinated transmission on the basis of the cyclic shift information.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] The Institute of Electrical and Electronics Engineers (IEEE) is currently working on developing technical specifications for 802.11be (hereinafter referred to as "11be") as the successor standard to 802.11ax (hereinafter referred to as "11ax"), the 802.11 standard.

[0003] In 11be, the application of cooperative communication is being considered, in which multiple wireless communication control devices (e.g., access points (AP) or base stations) on the data sending side cooperate to transmit data to a wireless communication device (e.g., a station (STA) or terminal) on the receiving side. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] IEEE 802.11-19 / 0448r1, Multi-AP Transmission Procedure, 2019-03-11 [Non-Patent Document 2] IEEE 802.11-19 / 1535r0, Sounding for AP Collaboration, 2019-09-16 [Non-Patent Document 3] A Study of the Next WLAN Standard IEEE 802.11ac Physical Layer Section 3.3.1 [Non-Patent Document 4] IEEE Std 802.11-2016 [Non-Patent Document 5] IEEE P802.11ax / D4.0, February 2019 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method of transmitting a reference signal in cooperative communication has not been fully considered.

[0006] Non-limiting examples of the present disclosure contribute to providing a radio communication control device and a radio communication control method capable of appropriately transmitting a reference signal in cooperative communication. [Means for solving the problem]

[0007] A wireless communication control device according to one embodiment of the present disclosure includes a first wireless communication control device, the first wireless communication control device including a control circuit that makes a waveform of a reference signal transmitted to a wireless communication device in cooperation with a second wireless communication control device different from the waveform of the reference signal transmitted to the wireless communication device by the second wireless communication control device in at least one of the frequency domain and the time domain, and a transmission circuit that transmits the reference signal.

[0008] 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. Effect of the Invention

[0009] According to an embodiment of the present disclosure, a reference signal can be appropriately transmitted in cooperative communication.

[0010] 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 description of the drawings]

[0011] [Figure 1] A diagram showing an example of a cooperative communication method [Diagram 2] A diagram showing an example of the Multi-AP Null Data Packet (MAP NDP) format [Diagram 3] A diagram showing an example of frequency allocation for the Extreme High Throughput Long Training Field (EHT-LTF) [Figure 4] FIG. 1 is a block diagram showing an example of the configuration of a portion of a wireless communication control device; [Diagram 5] FIG. 1 is a block diagram showing a configuration example of a wireless communication control device; [Figure 6] FIG. 1 is a diagram showing an example of frequency allocation of an Extreme High Throughput Short Training Field (EHT-STF) according to method 1. [Figure 7] FIG. 13 is a diagram showing an example of frequency allocation of EHT-STF and EHT-LTF according to method 2. [Figure 8] FIG. 13 is a diagram showing another example of frequency allocation of EHT-STF and EHT-LTF according to method 2. [Figure 9] FIG. 13 is a diagram showing an example of frequency allocation of EHT-STF according to method 3. [Figure 10] FIG. 13 is a diagram showing an example of the amount of cyclic shift with respect to the total number of transmit chains. [Figure 11] FIG. 13 is a diagram showing an example of a probability distribution of the power difference between EHT-STF and EHT-LTF. [Figure 12] FIG. 13 is a diagram showing an example of a timing detection result according to method 2. [Figure 13] FIG. 13 is a diagram showing an example of a timing detection result according to method 3. [Figure 14] FIG. 13 shows a comparison example of the power difference and timing detection results between EHT-STF and EHT-LTF. [Figure 15] A diagram showing an example of the Association Request format DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0013] [Cooperative communication method] In 11be, for example, application of DL Multi-AP coordination (hereinafter referred to as "downlink coordinated communication") is being considered, in which multiple wireless communication control devices on the signal transmission side transmit data to a wireless communication device on the reception side in a coordinated manner. Note that the wireless communication control device is also called, for example, an "access point (AP)" or a "base station," and the wireless communication device is also called, for example, a "terminal" or a "station (STA)."

[0014] In downlink cooperative communication, the AP selects a cooperative communication method or acquires beamforming information based on information (hereinafter referred to as "reception quality information") on the reception quality of signals (including, for example, reference signals or known signals) received by each STA from each of the multiple APs. For example, the STA measures the reception quality based on the signal (including, for example, reference signals or known signals) received from the AP, and transmits (in other words, feeds back) the reception quality information to the AP.

[0015] For example, the STA measures the reception quality for the source AP based on a preamble reference signal transmitted from the AP. The preamble reference signal is, for example, a reference signal included (in other words, placed) in the preamble. In the 11be downlink cooperative communication, a preamble reference signal for 11be that is an extension of the preamble reference signal specified in 11ax is being considered. The preamble reference signal for 11ax is also called, for example, "high efficiency short training field (HE-STF)" and "high efficiency long training field (HE-LTF)", and the preamble reference signal for 11be is also called, for example, "EHT-STF" and "EHT-LTF".

[0016] Also, for example, APs performing downlink cooperative communication include an AP that controls the cooperative communication (e.g., also called a "Master AP" or "M-AP"), and an AP that receives a control signal transmitted by the Master AP and performs cooperative control (e.g., also called a "Slave AP" or "S-AP").

[0017] Fig. 1 shows an example of a cooperative communication method. Fig. 1 shows an example in which three Slave APs (e.g., Slave AP1, Slave AP2, and Slave AP3) that cooperate under the control of a Master AP transmit signals (e.g., MAP NDP) including preamble reference signals to STA a and STA b.

[0018] For example, in FIG. 1, the Master AP transmits a trigger (e.g., MAP Trigger) for starting downlink cooperative communication to the Slave AP1, Slave AP2, and Slave AP3. By transmitting the MPA trigger, the Slave AP is notified of a control signal and transmission timing for cooperatively transmitting a packet (e.g., MAP NDP) including a preamble reference signal (e.g., EHT-STF and EHT-LTF) to the Slave AP. In FIG. 1, the Slave AP1, Slave AP2, and Slave AP3 transmit, for example, a packet including control information for the STA (e.g., MAP NDP announcement (MAP NDPA)) and the MAP NDP to the STA a and STA b. The STA a and STA b measure the reception quality between the STA and the Slave AP based on, for example, the preamble reference signal included in the MAP NDP transmitted from each Slave AP, and transmit reception quality information to the Slave AP (not shown).

[0019] For example, in 11be downlink cooperative communication, a method has been proposed in which the frequency resources allocated to the EHT-LTF used for channel estimation in STAs among the preamble reference signals for 11be are divided among the cooperating APs (in other words, the EHT-LTF is frequency divided), and each AP transmits the EHT-LTF at the same timing (for example, see non-patent document 1).

[0020] As an example, Fig. 2 shows a format of a time domain signal (e.g., physical protocol data unit (PPDU)) when EHT-LTF in the MAP NDP is frequency-divided in the three Slave APs shown in Fig. 1. Fig. 2 shows an example of the format of an EHT single user PPDU (EHT SU PPDU) and an EHT multi user PPDU (EHT MU PPDU).

[0021] Also, Fig. 3 shows an example of frequency allocation of EHT-LTF. Fig. 3 shows, as an example, an example of EHT-LTF allocation when there is no frequency division, and an example of EHT-LTF frequency allocation when EHT-LTF is frequency divided for the three Slave APs shown in Fig. 1.

[0022] As shown in FIG. 2 and FIG. 3, the EHT-LTF is assigned to different subcarriers (also called tones) for each Slave AP in the frequency domain.

[0023] In addition to frequency division, methods based on code division (e.g., code division using a P-matrix) have also been proposed as a method of dividing an EHT-LTF among multiple APs (e.g., Slave APs) (see, for example, Non-Patent Document 2).

[0024] In addition, in 11ax, HE-STF is inserted into packets to reduce automatic gain control (AGC) distortion in HE-LTF or to detect timing (see, for example, Non-Patent Document 3). In 11be, EHT-STF can be inserted into packets for the same purpose as in 11ax (for example, FIG. 2). For example, in 11be downstream cooperative communication, as shown in FIG. 2, EHT-LTF is frequency-divided, whereas EHT-STF is not frequency-divided, and the same signal can be transmitted between APs.

[0025] However, in downlink cooperative communication, when multiple APs transmit preamble reference signals (e.g., EHT-STF) with the same waveform at the same timing, the received signals at the STA may be added in phase or out of phase depending on the phase relationship of the propagation path, and the received power may vary significantly. The fluctuation in the received power at the STA may cause, for example, deterioration of the AGC performance.

[0026] Therefore, a non-limiting embodiment of the present disclosure describes a method for suppressing the fluctuation of the reception power of a preamble reference signal in a STA, for example, suppressing deterioration of AGC performance. For example, in one embodiment of the present disclosure, the fluctuation of the reception power in the STA is suppressed by transmitting a preamble reference signal with a different waveform in each AP included in the downlink cooperative communication.

[0027] [Wireless communication system configuration] A wireless communication system according to an embodiment of the present disclosure includes at least two transmission sources (e.g., STAs (including APs)) and one STA. In downlink cooperative communication, for example, at least two transmission sources (e.g., Slave APs) may cooperatively transmit preamble reference signals (e.g., EHT-STF and EHT-LTF) to the STA.

[0028] In the following description, for example, a "wireless communication control device" corresponds to an AP, and a "wireless communication device" corresponds to a STA.

[0029] Fig. 4 is a block diagram showing a configuration example of a part of the radio communication control device 10. In the radio communication control device 10 shown in Fig. 4, a control unit 11 makes the waveform of a reference signal transmitted to a radio communication device (e.g., STA) in cooperation with another radio communication control device different from the waveform of a reference signal transmitted to a radio communication device by the other radio communication control device in at least one of the frequency domain and the time domain. A transmission unit 12 transmits the reference signal.

[0030] [Configuration of wireless communication control device] Fig. 5 is a block diagram showing a configuration example of a radio communication control device 100 according to this embodiment. In Fig. 5, the radio communication control device 100 has a reference signal generating unit 101, a waveform converting unit 102, a transmission packet generating unit 103, a radio transmitting / receiving unit 104, and a received packet decoding unit 105.

[0031] The radio communication control device 100 shown in Fig. 5 corresponds to an example of the radio communication control device 10 shown in Fig. 4. Moreover, the reference signal generating unit 101, the waveform converting unit 102, and the transmission packet generating unit 103 in Fig. 5 correspond to an example of the control unit 11 in Fig. 4, and the radio transmitting / receiving unit 104 in Fig. 5 may correspond to an example of the transmitting unit 12 in Fig. 4. Moreover, the radio communication control device 100 is, for example, a Master AP or a Slave AP in cooperative communication.

[0032] The reference signal generating unit 101 generates a reference signal (for example, a preamble reference signal). The preamble reference signal may include at least one of EHT-STF, EHT-LTF, Legacy-STF (L-STF), and L-LTF. The reference signal generating unit 101 outputs the generated reference signal to the waveform converting unit 102.

[0033] The waveform conversion unit 102 converts the waveform of the reference signal input from the reference signal generation unit 101. For example, when the radio communication control device 100 is a slave AP, the waveform conversion unit 102 may convert the waveform of the reference signal based on control information input from the received packet decoding unit 105 (for example, control information transmitted from the master AP). Note that "waveform conversion" may mean processing or control for making two signal waveforms different from each other, or processing or control for generating signals with different waveforms from each other.

[0034] For example, the control information transmitted from the Master AP may include information for identifying the Slave AP (e.g., Slave AP number) and information on waveform conversion of the reference signal (hereinafter, referred to as "waveform conversion parameters"). The waveform conversion unit 102 outputs the reference signal after the waveform conversion to the transmission packet generation unit 103.

[0035] The transmission packet generation unit 103 generates a transmission packet including the reference signal and transmission data input from the waveform conversion unit 102. The generated transmission packet may include at least one of the MAP Trigger, NDPA, and NDP shown in FIG. 1. The transmission packet generation unit 103 outputs the generated transmission packet to the wireless transmission / reception unit 104.

[0036] The wireless transceiver 104 performs wireless transmission processing on the transmission packets and converts them into wireless transmission signals, which are then transmitted from an antenna.

[0037] Moreover, the wireless transmission / reception unit 104 receives a wireless reception signal from the antenna. The wireless transmission / reception unit 104 performs wireless reception processing on the received wireless transmission / reception signal to obtain a reception packet. The reception packet may include, for example, control information (for example, MAP Trigger (for example, FIG. 1)) transmitted from the Master AP, and may include a signal (for example, including reception quality information) transmitted from the wireless communication device 200 (not shown; for example, a STA). The wireless transmission / reception unit 104 outputs the reception packet to the reception packet decoding unit 105.

[0038] The received packet decoding unit 105 decodes the received packet and acquires the received data. For example, when the radio communication control apparatus 100 is a slave AP, the received packet decoding unit 105 may extract a slave AP number and a waveform conversion parameter from a MAP Trigger included in the received packet and output the extracted data to the waveform conversion unit 102.

[0039] An example of the configuration of the radio communication control apparatus 100 has been described above.

[0040] The wireless communication device 200 (for example, an STA) receives a packet (for example, a MAP NDP) transmitted from the wireless communication control device 100. For example, the wireless communication device 200 may control reception of the MAP NDP based on a MAP NDPA transmitted before the MAP NDP, as shown in Fig. 1. When the received packet includes a MAP NDP, the wireless communication device 200 extracts a reference signal such as EHT-STF or EHT-LTF (for example, a reference signal for a preamble).

[0041] The wireless communication device 200 may perform timing detection and AGC processing based on the extracted reference signal, for example. Also, the wireless communication device 200 may measure reception quality (in other words, channel estimation) based on the extracted reference signal, for example, and transmit (or feed back) reception quality information related to the measured reception quality to the wireless communication control device 100.

[0042] [Reference signal transmission method] An example of a method of transmitting a reference signal in the radio communication control apparatus 100 (eg, a method of converting a waveform) will be described below.

[0043] The radio communication control device 100 (e.g., a Slave AP in cooperative communication) transmits a reference signal at the same timing in cooperative communication, for example. In this embodiment, the reference signals (e.g., EHT-STF) transmitted by multiple Slave APs in cooperative communication have different waveforms between the multiple Slave APs. For example, reference signals with different waveforms are generated between the multiple Slave APs by allocating different subcarriers in the frequency domain or different delays (in other words, cyclic shifts) in the time domain between the multiple Slave APs (an example will be described later).

[0044] In addition, the subcarrier interval to which the reference signal is allocated (in other words, arranged or mapped) may be the same (in other words, common) among multiple transmission sources (e.g., Slave APs) in the cooperative communication. For example, the subcarrier interval to which the EHT-STF is allocated may be a fixed value (e.g., 8 subcarriers or 16 subcarriers) or a variable value.

[0045] In addition, the method of dividing the resources to which the EHT-LTF included in the transmission packet (e.g., MAP NDP) is assigned for each of multiple Slave APs may be frequency division as shown in FIG. 2 or FIG. 3, code division, or a division method that combines frequency division and code division.

[0046] Below, methods 1 to 7 for transmitting (or converting the waveform of) a reference signal will be described respectively.

[0047] <Method 1> In method 1, a preamble reference signal (e.g., EHT-STF) is frequency-divided for multiple transmission sources (e.g., slave APs). In other words, the frequency resource (e.g., subcarrier) to which the EHT-STF is assigned in an AP that is a certain transmission source is different from the frequency resource to which the EHT-STF is assigned in an AP that is another transmission source.

[0048] Fig. 6 shows an example of frequency allocation in EHT-STF. In Fig. 6, for example, three Slave APs, Slave AP1, Slave AP2, and Slave AP3, perform cooperative communication.

[0049] As shown in Fig. 6, when the EHT-STF is not divided into frequencies, the EHT-STF is allocated at intervals of 8 subcarriers in the frequency domain. Note that the subcarrier interval at which the EHT-STF is allocated is not limited to 8 subcarriers, and may be other intervals (for example, 16 subcarriers).

[0050] In method 1, as shown in Fig. 6, subcarriers to which EHT-LTF transmitted from each Slave AP is assigned are different from each other. In Fig. 6, a plurality of subcarriers with 8 subcarrier intervals are assigned to each EHT-STF of three Slave APs performing cooperative communication. In other words, in Fig. 6, frequency resources with 24 subcarrier intervals are assigned to the EHT-STF of each Slave AP. With this resource allocation, for example, as shown in Fig. 6, the EHT-STF assigned with 8 subcarrier intervals is transmitted from any one of the three Slave APs, and is not transmitted from the remaining AP.

[0051] Here, as an example, the subcarrier spacing of EHT-STF without frequency division is "numSC", the number of Slave APs communicating cooperatively is "numAP", the Slave AP number of each Slave AP is "iAP" (iAP = 0, 1, 2 ... numAP-1), and the subcarrier number assigned to the EHT-STF of each Slave AP is "noSC(iAP,n)" (n = 0, 1, 2 ... number of EHT-STFs assigned to each Slave AP - 1).

[0052] In this case, the subcarrier number noSC(iAP,n) assigned to the EHT-STF of each Slave AP may be calculated according to the following formula. For n=0: noSC(iAP, n) = numSC × iAP If n ≠ 0: noSC(iAP, n) = noSC(iAP, n-1) + numSC × numAP

[0053] For example, FIG. 6 shows an example of frequency division of the EHT-STF when numSC=8 and numAP=3.

[0054] For example, in cooperative communication, the Master AP may transmit a MAP Trigger (FIG. 1) including numAP (in other words, a waveform conversion parameter) to the Slave AP. Similarly, numSC may be notified from the Master AP to the Slave AP, or may be specified in a standard.

[0055] The Master AP may also include the Slave AP number iAP in the MAP Trigger and transmit it to the Slave AP. Alternatively, the Slave AP may determine the iPA based on the order of the Slave APs specified in the MAP Trigger.

[0056] Each Slave AP may determine frequency resources (eg, subcarriers) to be allocated to the EHT-STF of each Slave AP based on, for example, waveform conversion parameters notified by the Master AP or defined parameters.

[0057] In method 1, as shown in Fig. 6, the subcarriers to which the EHT-STF of each Slave AP is assigned are different. In other words, in Fig. 6, the signal waveforms in the frequency domain of the EHT-STF transmitted by each Slave AP are different from each other. Therefore, according to method 1, in a STA (for example, wireless communication device 200), it is possible to reduce the fluctuation in the received power between the EHT-STF transmitted from a plurality of Slave APs, and improve the AGC performance.

[0058] <Method 2> In method 2, similar to method 1, the EHT-STF is frequency-divided for multiple transmission sources (eg, Slave APs).

[0059] Also, in method 2, the EHT-LTF is, for example, frequency-divided for the Slave AP. In other words, the frequency resource (e.g., subcarrier) to which the EHT-LTF is assigned in a certain Slave AP is different from the frequency resource to which the EHT-LTF is assigned in another Slave AP.

[0060] Furthermore, in method 2, for example, in each of a plurality of slave APs, the subcarriers allocated to the EHT-LTF overlap with a portion of the subcarriers allocated to the EHT-STF.

[0061] Fig. 7 shows an example of frequency allocation for EHT-STF and EHT-LTF. In Fig. 7, for example, three Slave APs, Slave AP1, Slave AP2, and Slave AP3, perform cooperative communication.

[0062] As shown in Fig. 7, when the EHT-STF is not frequency-divided, the EHT-STF is allocated at intervals of 8 subcarriers in the frequency domain. Note that the subcarrier interval at which the EHT-STF is allocated is not limited to 8 subcarriers, and may be another interval (for example, 16 subcarriers).

[0063] Furthermore, as shown in Fig. 7, when the EHT-LTF is not frequency-divided, the EHT-LTF is allocated at intervals of four subcarriers in the frequency domain. Note that the subcarrier interval at which the EHT-LTF is allocated is not limited to four subcarriers, and may be other intervals (for example, one or two subcarriers).

[0064] In method 2, similarly to method 1 (e.g., FIG. 6), multiple subcarriers spaced by 8 subcarriers are assigned to each of the EHT-STFs of three Slave APs performing cooperative communication, as shown in FIG. 7. In other words, in FIG. 7, frequency resources spaced by 24 subcarriers are assigned to the EHT-STF of each Slave AP.

[0065] In Method 2, the subcarriers to which the EHT-LTF transmitted from each Slave AP is assigned are different from each other, as shown in Fig. 7. In Fig. 7, multiple subcarriers spaced by four subcarriers are assigned to the EHT-STFs of three Slave APs that communicate cooperatively.

[0066] For example, in FIG. 7, the subcarriers to which the EHT-LTF of each Slave AP is assigned may be determined based on the number of Slave APs involved in coordinated transmission (e.g., 3 in FIG. 7). For example, the subcarrier interval to which the EHT-LTF of each Slave AP is assigned (in other words, the range of frequency resources) may be calculated by "subcarrier interval of EHT-STF x number of Slave APs". In FIG. 7, the subcarrier interval of the EHT-STF is 8 subcarriers, and the number of Slave APs is 3, so the subcarrier interval to which the EHT-LTF of each Slave AP is assigned is 24 subcarriers.

[0067] For example, in Fig. 7, the subcarrier interval of the EHT-LTF is 4 subcarriers, so that the EHT-LTF transmitted from each Slave AP is assigned 6 adjacent subcarriers in the frequency domain. With this resource allocation, for example, as shown in Fig. 7, the EHT-LTF assigned at 4 subcarrier intervals is transmitted from one of the three Slave APs for every 24 subcarriers, and is not transmitted from the remaining APs.

[0068] For example, in cooperative communication, the Master AP may transmit a MAP Trigger (FIG. 1) including the number of Slave APs (in other words, a waveform conversion parameter) to the Slave APs. In addition, the subcarrier intervals of EHT-STF and EHT-LTF may be notified to the Slave APs from the Master AP or may be specified in a standard.

[0069] The Master AP may include the Slave AP number in the MAP Trigger and transmit it to the Slave AP. Alternatively, the Slave AP may determine the Slave AP number based on the order of the Slave APs specified in the MAP Trigger.

[0070] Each Slave AP may determine frequency resources (e.g., subcarriers) to be allocated to each of the EHT-STF and EHT-LTF of each Slave AP based on, for example, waveform conversion parameters notified from the Master AP or defined parameters.

[0071] In method 2, as shown in Fig. 7, the subcarriers to which the reference signals (e.g., EHT-STF and EHT-LTF) of each Slave AP are assigned are different. In other words, in Fig. 7, the signal waveforms in the frequency domain of the reference signals (e.g., EHT-STF and EHT-LTF) transmitted by each Slave AP are different from each other. Therefore, according to method 2, in a STA (e.g., wireless communication device 200), it is possible to reduce the fluctuation in the received power between EHT-STF transmitted from multiple Slave APs, and improve the AGC performance.

[0072] In addition, in method 2, there is a relationship between EHT-STF and EHT-LTF in the reference signal of each Slave AP. For example, in each Slave AP, the frequency resource (subcarrier) to which EHT-STF is assigned and the subcarrier to which EHT-LTF is assigned partially overlap (in other words, are the same). For example, in FIG. 7, in the range of 24 subcarriers assigned to the EHT-LTF of one Slave AP, the subcarrier to which one EHT-LTF is assigned among six EHT-LTFs is the same as the subcarrier to which the EHT-STF of the Slave AP is assigned.

[0073] By this reference signal allocation, for example, the frequency characteristics of the propagation path between the Slave AP and the STA are similar in part of the EHT-STF and the EHT-LTF. Therefore, the difference in the received power caused by the frequency characteristics of the propagation path between the EHT-STF and the EHT-LTF can be reduced, so that the AGC performance in the STA can be improved.

[0074] In addition, the frequency allocation of EHT-LTF in method 2 is not limited to the example shown in FIG. 7. For example, the subcarriers (in other words, the range of frequency resources) to which the EHT-LTF of each Slave AP is allocated may be determined based on the subcarrier interval of the EHT-STF. For example, as shown in FIG. 8, when the subcarrier interval of the EHT-STF is 8 subcarriers and the subcarrier interval of the EHT-LTF is 4 subcarriers, the subcarrier interval to which the EHT-LTF of each Slave AP is allocated may be 8 subcarriers. In this case, as shown in FIG. 8, since the subcarrier interval of the EHT-LTF is 4 subcarriers, the EHT-LTF transmitted from each Slave AP is allocated two subcarriers adjacent to each other in the frequency domain. Here, as shown in FIG. 8, the subcarrier to which one EHT-LTF of two adjacent EHT-LTFs is allocated is the same as the subcarrier to which the EHT-STF is allocated. Therefore, in FIG. 8, the difference in received power caused by the frequency characteristics of the propagation path between the EHT-STF and the EHT-LTF can be reduced, so that the AGC performance in the STA can be improved.

[0075] <Method 3> In method 3, the EHT-STF is assigned to subcarriers based on a different offset for each of multiple transmission sources (eg, Slave APs).

[0076] Fig. 9 shows an example of frequency allocation in EHT-STF. In Fig. 9, for example, three Slave APs, Slave AP1, Slave AP2, and Slave AP3, perform cooperative communication.

[0077] As shown in Fig. 9, when the EHT-STF is not frequency-divided, the EHT-STF is allocated at intervals of 8 subcarriers in the frequency domain. Note that the subcarrier interval at which the EHT-STF is allocated is not limited to 8 subcarriers, and may be another interval (for example, 16 subcarriers).

[0078] In method 3, the Slave AP determines the subcarrier position to which the EHT-STF is to be allocated, for example, based on an offset to the position of the subcarrier to which the ETH-STF is allocated (in other words, the frequency position) when frequency division is not performed, which is different from the offset used by other Slave APs. For example, as shown in FIG. 9, a different offset is added for each Slave AP to the position of the subcarrier to which the EHT-STF is allocated when frequency division is not performed. For example, when the number of Slave APs is equal to or less than the subcarrier interval of the EHT-STF, the offset of each Slave AP may be set in the order of 0, 1, -1, 2, -2....

[0079] For example, in coordinated transmission, the Master AP may transmit a MAP Trigger (FIG. 1) including an offset value (in other words, a waveform transformation parameter) to the Slave AP. Also, the subcarrier interval of the EHT-STF may be notified from the Master AP to the Slave AP, or may be specified in the standard.

[0080] The Master AP may include the Slave AP number in the MAP Trigger and transmit it to the Slave AP. Alternatively, the Slave AP may determine the Slave AP number based on the order of the Slave APs specified in the MAP Trigger.

[0081] Each Slave AP may determine frequency resources (e.g., subcarriers) to be allocated to each of the EHT-STF and EHT-LTF of each Slave AP based on, for example, waveform conversion parameters notified from the Master AP or defined parameters.

[0082] For example, in Fig. 9, an offset of 0 is set for Slave AP1, an offset of +1 is set for Slave AP2, and an offset of -1 is set for Slave AP1. By setting these offsets, the subcarriers to which the EHT-LTFs of the Slave APs are assigned are different from each other, as shown in Fig. 9. In other words, in Fig. 9, the signal waveforms in the frequency domain of the EHT-STFs transmitted by the Slave APs are different from each other. Therefore, according to method 3, in a STA (for example, wireless communication device 200), it is possible to reduce the fluctuation in received power between the EHT-STFs transmitted from a plurality of Slave APs, and improve the AGC performance.

[0083] 9, the frequency resource (e.g., subcarrier) interval to which the EHT-STF of each Slave AP is assigned is the same as the subcarrier interval to which the EHT-STF is assigned when frequency division is not performed (e.g., 8 subcarrier interval). In other words, the subcarrier interval to which each Slave AP assigns the EHT-STF is the same.

[0084] For example, in method 1 (e.g., FIG. 6) and method 2 (e.g., FIG. 7 or FIG. 8), the subcarrier spacing (24 subcarriers) to which the EHT-STF of each Slave AP is assigned is the number of Slave APs times (3 times) the subcarrier spacing (8 subcarriers) to which the EHT-STF is assigned when frequency division is not performed.

[0085] Therefore, in method 3, the subcarrier interval to which the EHT-STF of each Slave AP is assigned can be narrowed compared to methods 1 and 2. As a result, in method 3, the repetition time length of the EHT-STF in the time domain can be made longer compared to methods 1 and 2, so that the timing detection performance in the STA can be improved.

[0086] Furthermore, if the offset set for each Slave AP is, for example, 0, 1, -1, 2, -2, ... (in other words, the offset shifts by one subcarrier at a time), a closer frequency (e.g., adjacent subcarriers) is assigned to the EHT-STF of each Slave AP, making it easier to maintain the periodicity of the composite wave when received at the STA.

[0087] The offset set for each Slave AP is not limited to this. For example, the interval of the offset value set for each Slave AP may be set to an interval wider than, for example, 0, 1, -1, 2, -2, ... (in other words, shifting by one subcarrier at a time). For example, the offset value may be set to a value obtained by rounding down "subcarrier interval common to Slave APs / (number of Slave APs)". For example, if the subcarrier interval common to Slave APs is 8 subcarriers and the number of Slave APs is 3, the offset value is 0, 2, -2.

[0088] For example, due to frequency offset or propagation delay, there may be a case where the subcarrier to which the EHT-STF from each Slave AP is assigned shifts in the STA. On the other hand, by setting this offset, when the shift of the subcarrier is less than the offset interval, the STA receives the EHT-STF transmitted from each Slave AP at different frequencies, so that, for example, deterioration of AGC performance can be suppressed.

[0089] <Method 4> In 11ax, Cyclic Shift Diversity (CSD) is adopted, which adds a unique cyclic shift to the signal of each transmit chain in transmission and reception by multiple transmit chains in the AP and STA (see, for example, Non-Patent Document 4). CSD can reduce the fluctuation of the received power due to the phase of the propagation path, for example.

[0090] Here, a transmit chain represents a unit of transmission and may correspond to, for example, an antenna (eg, a transmitting antenna) or a stream.

[0091] In method 4, a different cyclic shift is set for the EHT-STF for each of multiple transmission sources (e.g., Slave APs). For example, a Slave AP adds a cyclic shift amount to the EHT-STF that is different from the cyclic shift amount used by other Slave APs for the EHT-LTF. By setting the cyclic shift, an offset is added in the time domain to the EHT-STF transmitted from each of the multiple Slave APs.

[0092] 10 shows an example of a cyclic shift number n for a total number of space-time streams (see, for example, Non-Patent Document 4). The total number of transmit chains indicates, for example, the sum of the number of transmit chains in each of the Slave APs that perform cooperative communication.

[0093] As an example, when the number of Slave APs performing cooperative communication is two and each Slave AP has four transmit chains, the cyclic shift amounts of cyclic shift numbers n=1 to 4 in the row of the total number of transmit chains=8 in Fig. 10 are set to each transmit chain of AP1, and the cyclic shift amounts of cyclic shift numbers n=5 to 8 are set to each transmit chain of AP2. Note that the cyclic shift amounts set to each Slave AP are not limited to the example shown in Fig. 10.

[0094] For example, in cooperative communication, the Master AP may transmit to the Slave APs a MAP Trigger (e.g., FIG. 1) including waveform conversion parameters such as the number of transmit chains (or the total number of transmit chains) of each Slave AP and the leading cyclic shift number n of the cyclic shifts set in each Slave AP. In the example shown in FIG. 10, the MAP Trigger may include the number of transmit chains 4 (or the number of transmit chains: 8) of each of AP1 and AP2, the leading cyclic shift number n=1 of AP1, and the leading cyclic shift number n=5 of AP2. By notifying this MAP Trigger, each Slave AP can apply the cyclic shift set for each Slave AP (or for each transmit chain) to the EHT-STF.

[0095] In method 4, the amount of cyclic shift applied to the reference signal (e.g., EHT-STF) transmitted in each transmit chain of each Slave AP is different. In other words, in method 4, the time domain signal waveforms of the reference signals (e.g., EHT-STF) transmitted by each Slave AP are different from each other. Therefore, according to method 4, in a STA (e.g., wireless communication device 200), it is possible to reduce the fluctuation in received power between EHT-STF transmitted from a plurality of Slave APs, and improve the AGC performance.

[0096] In addition, according to Method 4, even if CSD for EHT-STF is applied between multiple Slave APs, each Slave AP can identify the cyclic shift to be applied to the transmit chain of each Slave AP by notification from the Master AP (e.g., MAP Trigger).

[0097] Although FIG. 10 shows an example of the amount of cyclic shift when the total number of transmit chains is up to 8, cyclic shifts for a number of transmit chains of 9 or more may be defined.

[0098] <Method 5> In method 5, for example, the format (in other words, the transmission method or waveform conversion method) of the reference signals (EHT-STF and EHT-LTF) is switched based on information on the STA or information on the AP.

[0099] For example, depending on the formats of EHT-STF and EHT-LTF, the waveforms of EHT-STF and EHT-LTF may differ, and the AGC performance or timing detection accuracy in EHT-STF and EHT-LTF may differ.

[0100] Fig. 11 shows an example of a probability distribution of the power difference [dB] between EHT-LTF and EHT-STF derived by the inventors' computer simulation. In Fig. 11, the horizontal axis shows the power difference [dB] between EHT-STF and EHT-LTF, and the vertical axis shows the cumulative distribution function (CDF).

[0101] In Fig. 11, "no division" indicates characteristics in the case of a format in which neither EHT-STF nor EHT-LTF is frequency-divided. Also, "method X" indicates characteristics in the case of a format in which EHT-STF is not frequency-divided, but EHT-LTF is frequency-divided (e.g., Fig. 2). Also, "method 2" indicates characteristics in the case of a format in which EHT-STF and EHT-LTF are frequency-divided based on the above-mentioned method 2 (e.g., Fig. 7), and "method 3" indicates characteristics in the case of a format in which EHT-STF and EHT-LTF are frequency-divided based on the above-mentioned method 3 (e.g., Fig. 9).

[0102] In Fig. 11, for example, the more the probability distribution that the power difference between EHT-STF and EHT-LTF is smaller (for example, closer to 0 dB), the better the characteristics are with respect to the fluctuation of the received power at the STA (in other words, AGC performance). For example, as shown in Fig. 11, Method 2 and Method 3 show better characteristics compared to "Method X". Also, Method 2 shows the same characteristics as "no division" and shows better characteristics compared to Method 3.

[0103] The power difference between EHT-STF and EHT-LTF shown in Fig. 11 corresponds to, for example, the fluctuation of the received power between EHT-STF and EHT-LTF, for example, AGC performance. Thus, Fig. 11 shows that Method 2 and Method 3 have better AGC performance compared to Method X. Fig. 11 also shows that Method 2 and the "no division" case have similar AGC performance, and Method 2 has better AGC performance compared to Method 3.

[0104] Next, Fig. 12 and Fig. 13 show examples of timing detection results of methods 2 and 3 obtained by computer simulation by the present inventors. Note that in Fig. 12 and Fig. 13, the characteristics when the number of APs is 1 are similar to the timing detection results in the case of "no division". Therefore, in Fig. 12 and Fig. 13, the timing detection when the number of APs is 1 is the expected value. For example, even if the number of APs increases, the more timing is detected at the same position as when the number of APs is 1, the higher the timing detection accuracy.

[0105] 12 and 13, in method 3, even if the number of APs increases, timings at positions similar to the expected values ​​are detected, and the timing detection accuracy is higher than in method 2.

[0106] In the case of "Method X", in other words, when there is no frequency division of EHT-STF, the subcarrier interval to which the EHT-STF of each Slave AP is assigned is narrower than in Method 2, as in Method 3 (e.g., FIG. 9), so the repetition time length of EHT-STF in the time domain can be lengthened and the timing detection accuracy in the STA can be improved. Therefore, for example, (Method 3 and Method X) have higher timing detection accuracy than Method 2.

[0107] FIG. 14 shows an example of a summary of the power difference between EHT-STF and EHT-LTF (in other words, the AGC performance) and the timing detection accuracy for method X, method 2, and method 3.

[0108] As shown in Fig. 14, the AGC performance and timing detection accuracy characteristics differ depending on the EHT-STF and EHT-LTF formats (in other words, the transmission method or waveform conversion method). For example, in terms of AGC performance, method 2 is more suitable than method X and method 3. On the other hand, in terms of timing detection accuracy, method X or method 3 is more suitable than method 2.

[0109] On the other hand, for example, the allowable power difference between EHT-STF and EHT-LTF in a STA may differ depending on each product. Also, for example, when a STA can detect timing using L-STF, the STA does not need to detect timing based on EHT-STF.

[0110] In this way, the format of the reference signal suitable for each STA (in other words, the waveform conversion method) may differ.

[0111] Therefore, in method 5, the EHT-STF or EHT-LTF format is determined based on the performance (in other words, the specifications or capabilities) of the STA.

[0112] For example, each STA may determine the format of EHT-STF or EHT-LTF. In other words, the format of EHT-STF or LTF may be switched in the STA.

[0113] For example, in the STA, the wider the dynamic range for the received signal, the wider the range in which the fluctuation of the received power difference can be tolerated, and the less likely the AGC performance is to deteriorate. Therefore, for example, in the STA, when the dynamic range for the received signal is wider (for example, when the dynamic range is equal to or greater than a threshold), the format of method X or method 3 with higher timing detection accuracy may be applied regardless of the performance regarding the power difference between EHT-STF and EHT-LTF in FIG. 14. On the other hand, for example, in the STA, when the dynamic range for the received signal is narrower (for example, when the dynamic range is less than a threshold), the format of method 2 or method 3 with better performance regarding the power difference between EHT-STF and EHT-LTF in FIG. 14 may be applied.

[0114] Also, for example, when the STA does not perform timing detection based on EHT-STF, the format of method 2 or method 3, which has better performance regarding the power difference between EHT-STF and EHT-LTF, may be applied in Fig. 14, regardless of the timing detection performance. On the other hand, for example, when the STA performs timing detection based on EHT-STF, the format of method X or method 3, which has higher timing detection accuracy, may be applied in Fig. 14.

[0115] As an example, the STA may determine the format of Method X (e.g., FIG. 2 or FIG. 3) when the dynamic range of the received signal is wider and timing detection based on EHT-STF is performed. Also, the STA may determine the format of Method 3 (e.g., FIG. 9) when the dynamic range of the received signal is narrower and timing detection based on EHT-STF is performed. Also, the STA may determine the format of Method 2 (e.g., FIG. 7) when timing detection based on EHT-STF is not performed regardless of the dynamic range of the received signal.

[0116] The STA may notify the AP of the determined EHT-STF format. For example, the EHT-STF format notification may use at least one of the Association Request and the Reassociation Request, or other control information. As an example, FIG. 15 shows an example of adding the EHT-STF format to the Association Request table (for example, see Non-Patent Document 5).

[0117] Although the above describes the case where the STA determines (in other words, switches or selects) the EHT-STF format, the EHT-STF format may be determined by the AP. For example, the AP may determine the format based on information on the capabilities of the STA (e.g., capability) notified by the STA. In this case, the AP may notify the STA of the selected EHT-STF format by, for example, MAP NDPA (e.g., FIG. 1).

[0118] Alternatively, the format of EHT-STF may be determined based on the number of Slave APs performing cooperative communication, for example. For example, as shown in FIG. 12, even in the format of method 2, when the number of Slave APs is small (for example, 2 or less), the timing detection accuracy is less degraded compared to when the number of Slave APs is large (for example, more than 2). Therefore, for example, the AP may determine the format of method 2 when the number of Slave APs is a threshold value (for example, 2) or less, and may determine the format of method X or method 3 when the number of Slave APs is more than the threshold value (for example, 2). The AP may notify the STA of the selected EHT-STF format, for example, by MAP NDPA (for example, FIG. 1).

[0119] In this way, according to Method 5, the EHT-STF format is determined (or switched) based on the STA performance or the number of APs, thereby improving the AGC performance and timing detection accuracy in EHT-STF and EHT-LTF.

[0120] In addition, in method 5, as shown in Fig. 14, method 2 and method 3 have been described, but the methods applied to the EHT-STF format are not limited to method 2 and method 3, and method 1 and method 4 may also be applied. For example, since method 1 and method 2 have the same EHT-STF format, the timing detection accuracy of method 1 is the same as that of method 2. Also, method 4 may be applied instead of the EHT-STF format applied in the above example.

[0121] <Method 6> For example, in methods 1 to 5, it is assumed that the time domain format of EHT-STF is one symbol. In method 6, a case where the time domain format of EHT-STF is a plurality of symbols (for example, two symbols) will be described.

[0122] As shown in FIG. 14, method X or method 3 has better timing detection performance than method 2, and method 2 has better power difference between EHT-STF and EHT-LTF (in other words, AGC performance) than method X and method 3.

[0123] Therefore, of the multiple symbols (e.g., two symbols) that make up the EHT-STF, the format of method X (or method 3) may be set to the first symbol, and the format of method 2 may be applied to the second symbol.

[0124] In other words, for example, in the first symbol of two symbols constituting the EHT-STF, the Slave AP transmits an EHT-STF with the same waveform among multiple Slave APs that communicate cooperatively. In other words, for example, in the first symbol, the Slave AP transmits an EHT-STF with the same waveform as the EHT-STF transmitted by the other Slave AP. This EHT-STF setting can improve the timing detection accuracy in the first symbol.

[0125] Also, in the second symbol, the Slave AP transmits the EHT-STF in a frequency resource that is different for each of the multiple Slave APs and overlaps with at least a part of the frequency resource (e.g., subcarrier) to which the EHT-LTF is assigned in the Slave AP. In other words, for example, in the second symbol, the Slave AP transmits the EHT-STF in a subcarrier that overlaps with at least a part of the subcarrier to which the Slave AP assigns the EHT-LTF. This EHT-STF setting can improve the AGC performance in the second symbol. Also, for example, in method 2, as shown in FIG. 7, the EHT-LTFs between multiple Slave APs are not combined, so that the fluctuation in the received power between the EHT-LTFs can be reduced and the AGC performance can be improved.

[0126] Furthermore, for example, by applying the format of method 2 to the second symbol of a two-symbol EHT-STF, which is located closer to the EHT-LTF, it is possible to improve the AGC performance in the EHT-LTF.

[0127] Therefore, according to method 6, the STA can reduce fluctuations in received power and improve timing detection accuracy, thereby improving the system improvement effect of downlink cooperative communication.

[0128] The number of symbols constituting the EHT-STF may be three or more.

[0129] Furthermore, of the two symbols constituting the EHT-STF, the first symbol may be set to a format that improves timing detection accuracy (e.g., method 3 or method 4) rather than method X. Furthermore, of the two symbols constituting the EHT-STF, the second symbol may be set to a format that improves AGC performance (e.g., method 1 or method 4) rather than method 2.

[0130] <Method 7> For example, in Fig. 10, the cyclic shift amount is defined when the total number of transmit chains is up to 8. Therefore, in order to set a different cyclic shift amount for each transmit chain even when the total number of transmit chains is 9 or more, a new definition of the cyclic shift amount corresponding to a total number of transmit chains of 9 or more (in other words, an extension of the definition) is assumed.

[0131] However, in order for the cyclic shift amount to correspond to a larger total number of transmit chains, the phase shift amount for each total number of transmit chains must be made smaller or the maximum phase shift amount must be made larger, which may reduce the effect of the cyclic shift (e.g., the effect of reducing fluctuations in received power due to the phase of the propagation path).

[0132] Therefore, in Method 7, a method of determining the EHT-STF format for a larger total number of transmit chains (for example, 9 or more) without expanding the definition of the cyclic shift amount will be described.

[0133] For example, when the total number of transmit chains (or antennas) through which EHT-STF is transmitted in multiple APs is equal to or less than a threshold (e.g., 8), the AP (e.g., Slave AP) performs waveform conversion (e.g., application of cyclic shift) according to method 4. In other words, when the total number of transmit chains is equal to or less than a threshold, the AP generates EHT-STF with different waveforms in the time domain among multiple APs.

[0134] On the other hand, when the total number of transmit chains (or antennas) through which EHT-STF is transmitted in multiple APs is greater than a threshold (e.g., 8), the AP (e.g., Slave AP) makes the waveform of the EHT-STF different from the EHT-STF transmitted by other Slave APs to STAs in both the time domain and the frequency domain. In other words, the AP uses waveform conversion in both the time domain and the frequency domain. For example, the AP may use the formats of Method 4 and Method 3 in combination.

[0135] In this case, for example, the MAP Trigger (e.g., FIG. 1) may include the "total number of transmit chains of the Slave AP" and the "first cyclic shift number" of each Slave AP in Method 4, and the "offset value" for each Slave AP in Method 3. Through this process, the Slave AP can specify the cyclic shift assigned to the transmit chain of each Slave AP and the offset value of the subcarrier to which the EHT-STF is assigned in each Slave AP by notification (e.g., MAP Trigger) from the Master AP.

[0136] According to the method 7, even if the total number of transmit chains in a plurality of APs is greater than a threshold (e.g., 8), for example, the waveforms of reference signals (e.g., EHT-STF and EHT-LTF) in at least one of the time domain and the frequency domain can be made different for each AP. Therefore, according to the method 7, even if the total number of transmit chains is 9 or more in FIG. 10, for example, in the STA (e.g., the wireless communication device 200), the fluctuation of the received power of EHT-STF and EHT-LTF transmitted from a plurality of Slave APs can be reduced, and the AGC performance can be improved.

[0137] For example, the method of waveform transformation in the frequency domain used in combination with method 4 (in other words, waveform transformation in the time domain) is not limited to method 3, but may be method 1 or method 2.

[0138] Also, for example, in cases other than multi-AP (for example, single-AP) where the total number of transmit chains is greater than a threshold (for example, 9), waveform transformation in the time domain and frequency domain may be used in combination, as in method 7.

[0139] Methods 1 to 7 have been described above.

[0140] In this manner, in this embodiment, the radio communication control device 100 (for example, AP) generates reference signals (EHT-STF or EHT-LTF) with different waveforms among the multiple radio communication control devices 100 that perform cooperative transmission to the radio communication devices 200 (for example, STAs), and transmits the reference signals. By transmitting this reference signal, for example, in downlink cooperative communication, the radio communication control device 100 can appropriately transmit the reference signal, reducing fluctuations in the received power in the radio communication devices 200 and improving AGC performance.

[0141] An embodiment of the present disclosure has been described above.

[0142] In the above embodiment, an example of waveform conversion for a preamble reference signal of an NDP has been described as an example, but an embodiment of the present disclosure may also be applied to a preamble reference signal of another packet other than an NDP (e.g., a PPDU for joint transmission containing data).

[0143] In addition, in the above-described embodiment, an example in which multiple APs perform cooperative communication with a STA has been shown, but the present disclosure is not limited thereto. For example, at least a part of multiple APs may be replaced with a STA. For example, the present disclosure may be applied to a case in which one or more APs and one or more STAs perform cooperative communication with another STA. Alternatively, the present disclosure may be applied to a case in which two or more STAs perform cooperative communication with another STA.

[0144] In the above-described embodiment, a case has been described in which reference signals of different waveforms are transmitted between multiple transmission sources (e.g., Slave APs) in cooperative communication. However, the present disclosure is not limited to this, and for example, among the multiple transmission sources, some transmission sources may have different reference signal waveforms (in other words, frequency domain allocation, offset, cyclic shift, etc.), while other transmission sources may have the same reference signal waveform. Even in this case, it is possible to suppress fluctuations in the received power at the STA and suppress AGC distortion, compared to a case in which multiple transmission sources in cooperative communication transmit reference signals of the same waveform.

[0145] Furthermore, in the above-described embodiment, the case where the number of Slave APs performing cooperative communication is three has been described, but the number of APs performing cooperative communication is not limited to three and may be another number.

[0146] In addition, a subcarrier may be called a tone. In addition, the unit of frequency resources is not limited to a subcarrier, and may be other resource units. In addition, the subcarrier interval to which the reference signal is assigned in the above-mentioned embodiment is an example, and other intervals may be used.

[0147] Furthermore, the terms used to express each signal (for example, each packet) in the above-described embodiment are merely examples, and the present disclosure is not limited to these.

[0148] In addition, the notation "... part" in the above-mentioned embodiments may be replaced with other notations such as "... circuitry," "... device," "... unit," or "... module."

[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 embodiment may be realized partially or entirely as an LSI, which is an integrated circuit, and each process described in the above embodiment may be controlled partially or entirely by one LSI or a combination of LSIs. The LSI may be composed of individual chips, or may be composed of one chip to include some or all of the functional blocks. The LSI may have input and output data. Depending on the degree of integration, the LSI may be called an IC, a system LSI, a super LSI, or an ultra LSI. The method of integration is not limited to LSI, and may be realized by a dedicated circuit, a general-purpose processor, or a dedicated processor. In addition, a field programmable gate array (FPGA) that can be programmed after LSI manufacture, or a reconfigurable processor that can reconfigure the connections and settings of circuit cells inside the LSI may be used. The present disclosure may be realized as digital processing or analog processing. Furthermore, if a new integrated circuit technology that can replace LSI appears due to the progress of semiconductor technology or a derivative technology, it is possible to integrate the functional blocks using that technology. The application of biotechnology is also a possibility.

[0150] The present disclosure may be implemented in any type of apparatus, device, or system having a communication function (collectively referred to as a communication apparatus). The communication apparatus may include a radio transceiver and processing / control circuitry. The radio transceiver may include a receiver and a transmitter, or both as functions. The radio 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, etc.), tablets, personal computers (PCs) (e.g., laptops, desktops, notebooks, etc.), cameras (e.g., digital still / video cameras), digital players (e.g., digital audio / video players), wearable devices (e.g., wearable cameras, smart watches, tracking devices, etc.), game consoles, digital book readers, telehealth and telemedicine devices, communication-enabled vehicles or mobile conveyances (e.g., cars, airplanes, boats, etc.), and combinations of the above devices.

[0151] Communications Equipment includes, but is not limited to portable or mobile equipment, non-portable or fixed equipment, devices and systems of any kind, such as smart home devices (appliances, lighting equipment, smart meters or metering devices, control panels, etc.), vending machines and any other "Things" that may exist on an Internet of Things (IoT) network.

[0152] Communications include data communications via cellular systems, wireless LAN systems, communications satellite systems, etc., as well as data communications via combinations of these.

[0153] 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.

[0154] 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.

[0155] A wireless communication control device according to one embodiment of the present disclosure includes a first wireless communication control device, the first wireless communication control device including a control circuit that makes a waveform of a reference signal transmitted to a wireless communication device in cooperation with a second wireless communication control device different from the waveform of the reference signal transmitted to the wireless communication device by the second wireless communication control device in at least one of the frequency domain and the time domain, and a transmission circuit that transmits the reference signal.

[0156] In one embodiment of the present disclosure, the reference signal includes a short training field (STF) signal, and a first frequency resource to which the STF signal is assigned in the first wireless communication control device is different from a second frequency resource to which the STF signal is assigned in the second wireless communication control device.

[0157] In one embodiment of the present disclosure, the reference signal includes a long training field (LTF) signal, a third frequency resource to which the LTF signal is assigned in the first wireless communication control device is different from a fourth frequency resource to which the LTF signal is assigned in the second wireless communication control device, and the third frequency resource overlaps with at least a portion of the first frequency resource.

[0158] In an embodiment of the present disclosure, the third frequency resource and the fourth frequency resource are determined based on the number of radio communication control devices involved in cooperative transmission.

[0159] In one embodiment of the present disclosure, the interval of the frequency resources to which the first wireless communication control device allocates the reference signal is the same as the interval of the frequency resources to which the second wireless communication control device allocates the reference signal, and the control circuit determines the second frequency position to which the reference signal is allocated based on an offset to a first frequency position of the interval that is different from the offset used by the second wireless communication control device.

[0160] In an embodiment of the present disclosure, the control circuit applies, to the reference signal, a cyclic shift amount different from a cyclic shift amount used by the second wireless communication control device for the reference signal.

[0161] In one embodiment of the present disclosure, the reference signal includes a short training field (STF) signal, and a format corresponding to the waveform of the STF signal is based on information about the wireless communication device.

[0162] In one embodiment of the present disclosure, the format is determined in the wireless communication device.

[0163] In one embodiment of the present disclosure, the control circuitry determines the format based on information regarding capabilities of the wireless communication device.

[0164] In one embodiment of the present disclosure, the reference signal includes a short training field (STF) signal, and a format corresponding to the waveform of the STF signal is based on the number of radio communication control devices involved in cooperative transmission.

[0165] In one embodiment of the present disclosure, the reference signal includes a short training field (STF) signal and a long training field (LTF) signal, and the transmitting circuit transmits, among the multiple symbols constituting the STF signal, an STF signal having the same waveform as the STF signal transmitted by the second wireless communication control device in a first symbol, and transmits the STF signal in a second symbol in a frequency resource that overlaps with at least a portion of the frequency resource to which the first wireless communication control device allocates the LTF signal.

[0166] In one embodiment of the present disclosure, the second symbol is a symbol closer to the signal of the LTF than the first symbol.

[0167] In one embodiment of the present disclosure, when the total number of antennas through which the reference signal is transmitted is greater than a threshold value, the control circuit makes the waveform of the reference signal different from the waveform of the reference signal transmitted by the second wireless communication control device to the wireless communication device in both the frequency domain and the time domain.

[0168] In a wireless communication control method according to one embodiment of the present disclosure, a first wireless communication control device, in cooperation with a second wireless communication control device, transmits a reference signal to a wireless communication device by making the waveform of the reference signal different in at least one of the frequency domain and the time domain from the waveform of the reference signal transmitted by the second wireless communication control device to the wireless communication device, and transmits the reference signal.

[0169] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2019-199720, filed on November 1, 2019, are incorporated herein by reference in their entirety. [Industrial Applicability]

[0170] One embodiment of the present disclosure is useful in wireless communication systems. [Explanation of symbols]

[0171] 10, 100 Wireless communication control device 11 Control section 12 Transmitter 101 Reference signal generation section 102 Waveform conversion section 103 Transmission packet generator 104 Radio transmitter / receiver 105 Received packet decoding unit 200 Wireless communication device

Claims

1. a circuit for generating a frame indicating cyclic shift information for a reference signal used in a multi-access point (AP) coordinated transmission, when in operation; a transmitter that, in operation, transmits the frame to at least one slave AP; The slave AP transmits the reference signal in the multi-AP coordinated transmission based on the cyclic shift information. Master AP.

2. The cyclic shift information indicates a different cyclic shift value for each AP transmitting the reference signal. The master AP according to claim 1 .

3. The cyclic shift information is an offset value between cyclic shift values. The master AP according to claim 2 .

4. The cyclic shift information indicates a cyclic shift index corresponding to a cyclic shift value. The master AP according to claim 1 .

5. The cyclic shift information is defined based on a total number of transmission chains of a plurality of APs that transmit the reference signals in the multi-AP coordinated transmission. The master AP according to claim 1 .

6. The cyclic shift information indicates the number of transmission chains of the master AP. The master AP according to claim 1 .

7. The transmitter transmits the frame to two or more slave APs that transmit the reference signal in the multi-AP coordinated transmission. The master AP according to claim 1 .

8. The frame is a multi-AP trigger frame. The master AP according to claim 7.

9. The order of the slave APs in the multi-AP trigger frame specifies a different cyclic shift value for each of the slave APs that transmit the reference signal in the multi-AP coordinated transmission. The master AP according to claim 8.

10. A communication method for a master access point (AP), comprising: generating a frame indicating cyclic shift information for a reference signal used in multi-AP coordinated transmission; transmitting the frame to at least one slave AP; The slave AP transmits the reference signal in the multi-AP coordinated transmission based on the cyclic shift information. Communication methods.

11. An integrated circuit for a master access point (AP), comprising: generating a frame indicating cyclic shift information for a reference signal used in multi-AP coordinated transmission; transmitting the frame to at least one slave AP; The slave AP transmits the reference signal in the multi-AP coordinated transmission based on the cyclic shift information. Integrated circuits.

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