Wireless communication control device and wireless communication control method

Abstract

The present invention provides a slave access point (AP) comprising: a receiver that receives a frame indicating cyclic shift information of a reference signal for multi-AP coordinated transmission; and a transmitter that transmits the reference signal in the multi-AP coordinated transmission on the basis of the cyclic shift information.

Description

[0001] This application is a divisional application of the invention patent application with the application date of September 4, 2020, application number 202080072250.X, and invention name “Wireless Communication Control Device and Wireless Communication Control Method”. Technical Field

[0002] The invention relates to a wireless communication control device and a wireless communication control method. Background Art

[0003] As a successor standard to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard 802.11ax (hereinafter referred to as "11ax"), the technical specifications of 802.11be (hereinafter referred to as "11be") are being planned and formulated.

[0004] In 11be, the application of coordinated communication is studied, that is, multiple wireless communication control devices on the sending side of the data (for example, access points (AP) or base stations) coordinate to send data to the wireless communication devices on the receiving side (for example, stations (STA) or terminals).

[0005] Prior art literature

[0006] Non-patent literature

[0007] Non-patent document 1: IEEE 802.11-19 / 0448r1, Multi-AP Transmission Procedure, 2019-03-11

[0008] Non-patent document 2: IEEE 802.11-19 / 1535r0, Sounding for AP Collaboration, 2019-09-16

[0009] Non-patent document 3: A Study of the Next WLAN Standard IEEE 802.11ac PhysicalLayer Section 3.3.1

[0010] Non-patent document 4: IEEE Std 802.11-2016

[0011] Non-patent document 5: IEEE P802.11ax / D4.0, February 2019 Summary of the invention

[0012] However, the method of transmitting a reference signal in coordinated communication has not yet been fully studied.

[0013] Non-limiting embodiments of the present invention contribute to providing a wireless communication control device and a wireless communication control method capable of appropriately transmitting a reference signal in coordinated communication.

[0014] A wireless communication control device according to one embodiment of the present invention is a first wireless communication control device, comprising: a control circuit, which makes the waveform of a reference signal sent to a wireless communication device in coordination with a second wireless communication control device different from the waveform of the reference signal sent by the second wireless communication control device to the wireless communication device in at least one of a frequency domain and a time domain; and a transmitting circuit, which sends the reference signal.

[0015] According to one embodiment of the present invention, a slave access point (AP) includes: a receiver that receives a frame indicating cyclic shift information of a reference signal for multi-AP coordinated transmission; and a transmitter that transmits the reference signal in the multi-AP coordinated transmission based on the cyclic shift information.

[0016] A communication method from an access point (AP) according to an embodiment of the present invention includes: receiving a frame indicating cyclic shift information of a reference signal for multi-AP coordinated transmission; and transmitting the reference signal in the multi-AP coordinated transmission based on the cyclic shift information.

[0017] According to one embodiment of the present invention, an integrated circuit for use from an access point (AP) includes at least one input terminal, an input electronic signal, and a control circuit, which controls: receiving a frame indicating cyclic shift information of a reference signal for multi-AP coordinated transmission; and sending the reference signal in the multi-AP coordinated transmission based on the cyclic shift information.

[0018] It should be noted that these general or specific aspects may be implemented by a system, an apparatus, a method, an integrated circuit, a computer program or a recording medium, or may be implemented by any combination of systems, apparatuses, methods, integrated circuits, computer programs and recording media.

[0019] According to one embodiment of the present invention, a reference signal can be appropriately transmitted in coordinated communication.

[0020] More advantages and effects of an embodiment of the present invention will be explained through the description and drawings. These advantages and / or effects are provided by several embodiments, and the features described in the description and drawings, but not necessarily all of them need to be provided in order to obtain one or more of the same features. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is a diagram showing an example of a cooperative communication method.

[0022] Figure 2 This is a diagram showing an example of the format of a Multi-AP Null Data Packet (MAP NDP).

[0023] Figure 3 This is a diagram showing an example of frequency allocation of Extreme High Throughput Long Training Field (EHT-LTF).

[0024] Figure 4 This is a block diagram showing a configuration example of a part of a wireless communication control device.

[0025] Figure 5 This is a block diagram showing a configuration example of a wireless communication control device.

[0026] Figure 6 This is a diagram showing an example of frequency allocation of the Extreme High Throughput Short Training Field (EHT-STF) of method 1.

[0027] Figure 7 This is a diagram showing an example of frequency allocation of EHT-STF and EHT-LTF according to method 2.

[0028] Figure 8 This is a diagram showing another example of frequency allocation of EHT-STF and EHT-LTF according to method 2.

[0029] Fig. 9 This is a diagram showing an example of frequency allocation of EHT-STF according to method 3.

[0030] Fig.10 This is a diagram showing an example of the cyclic shift amount relative to the total number of transmit chains.

[0031] Fig.11 This is a diagram showing an example of probability distribution of the power difference between EHT-STF and EHT-LTF.

[0032] Fig.12 This is a diagram showing an example of the timing detection result of method 2.

[0033] Fig.13 This is a diagram showing an example of the timing detection result of method 3.

[0034] Fig.141 is a diagram showing a comparative example of the power difference and timing detection results between EHT-STF and EHT-LTF.

[0035] Fig.15 This is a diagram showing an example of the format of an association request (Association Request). DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0037] [Coordination communication method]

[0038] In 11be, for example, the application of downlink multi-access point coordination (DL Multi-AP coordination) (hereinafter referred to as "downlink coordinated communication") in which multiple wireless communication control devices on the signal transmission side coordinate the transmission of data to the wireless communication device on the receiving side is studied. In addition, 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)".

[0039] In downlink coordinated communication, for example, based on information related to the reception quality of signals (e.g., including reference signals or known signals) received by each STA from multiple APs (hereinafter referred to as "reception quality information"), the selection of the coordinated communication method in the AP or the acquisition of beamforming information is performed. For example, the STA measures the reception quality based on the signal (e.g., reference signal or known signal) received from the AP, and sends (in other words, feeds back) the reception quality information to the AP.

[0040] For example, the STA measures the reception quality for the AP as the transmission source based on the preamble reference signal sent from the AP. In addition, the preamble reference signal is, for example, a reference signal included (in other words, configured) in the preamble. In the downlink coordinated communication of 11be, the preamble reference signal for 11be, which is an extension of the preamble reference signal specified in 11ax, is studied. 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".

[0041] In addition, for example, an AP performing downlink coordinated communication includes an AP that controls the coordinated communication (for example, also called a "Master AP" or "M-AP"), and an AP that receives a control signal sent by the master AP and performs coordinated control (for example, also called a "Slave AP" or "S-AP").

[0042] Figure 1 An example of a coordinated communication method is shown. Figure 1 , an example is shown in which three slave APs (eg, slave AP1, slave AP2, and slave AP3) coordinated under the control of the master AP transmit a signal including a preamble reference signal (eg, MAP NDP) to STA a and STA b.

[0043] For example, in Figure 1 In the example, the master AP sends a trigger (e.g., a MAP trigger) related to the start of downlink coordinated communication to slave AP1, slave AP2, and slave AP3. By sending the MAP trigger, for example, the control signal and the sending timing of the packet (e.g., MAP NDP) for coordinating the sending of the reference signal for the preamble (e.g., EHT-STF and EHT-LTF) are notified to the slave APs. Figure 1 In the embodiment, a packet (e.g., a multi-access point null data packet announcement (MAP NDP announcement, MAP NDPA)) and a MAP NDP containing control information for the STA are sent from AP1, AP2, and AP3, for example, to STA a and STA b. STA a and STA b measure the reception quality between the STA and the slave AP based on a reference signal for the preamble code contained in the MAP NDP sent by each slave AP, and send reception quality information to the slave AP (not shown).

[0044] For example, the following method has been proposed, namely, for the EHT-LTF used for channel estimation in the STA in the preamble reference signal, in the downlink coordinated communication of 11be, the frequency resources allocated with the EHT-LTF are divided between the coordinating APs (in other words, the EHT-LTF is frequency divided), and each AP sends the EHT-LTF at the same time (for example, refer to non-patent document 1).

[0045] As an example, Figure 2 Indicates for Figure 1 The three shown are time domain signal formats (eg, physical protocol data unit (PPDU)) when the AP performs frequency division on the EHT-LTF in the MAP NDP. Figure 2, an example of the format of an EHT single user PPDU (EHT SU PPDU) and an EHT multi user PPDU (EHT MU PPDU) is shown.

[0046] in addition, Figure 3 An example of frequency allocation of EHT-LTF is shown. Figure 3 As an example, an example of EHT-LTF allocation without frequency division is shown, and Figure 1 The three examples of frequency allocation of EHT-LTF when frequency division of EHT-LTF is performed from AP are shown.

[0047] like Figure 2 and Figure 3 As shown, the EHT-LTF is allocated to subcarriers (or, also called "tones") that differ from AP to AP in the frequency domain.

[0048] In addition, regarding the method of dividing EHT-LTF for multiple APs (for example, from APs), in addition to frequency division, a method based on code division (for example, code division using P-matrix) has also been proposed (for example, refer to non-patent document 2).

[0049] In addition, in 11ax, HE-STF is inserted into the packet to reduce the automatic gain control (AGC: Automatic Gain Control) distortion in HE-LTF or detect the timing (for example, refer to non-patent document 3). In 11be, EHT-STF may also be inserted into the packet for the same purpose as 11ax (for example, Figure 2 ). For example, in the downlink coordinated communication of 11be, it may be as follows Figure 2 As shown, the EHT-LTF is frequency-divided, whereas the EHT-STF is not frequency-divided and the same signal is transmitted between APs.

[0050] However, in downlink coordinated communication, if multiple APs send preamble reference signals (e.g., EHT-STF) of the same waveform at the same time, the received signals in the STA will be added in phase or in reverse phase, depending on the phase relationship of the propagation path, and the received power will fluctuate greatly. Due to the fluctuation of the received power in the STA, for example, the AGC performance may be degraded.

[0051] Therefore, a non-limiting embodiment of the present invention describes a method for suppressing the fluctuation of the received power of the preamble reference signal in the STA, thereby suppressing the degradation of the AGC performance, for example. For example, in one embodiment of the present invention, each AP included in the downlink coordinated communication sends a preamble reference signal of a different waveform, thereby suppressing the fluctuation of the received power in the STA.

[0052] [Structure of wireless communication system]

[0053] A wireless communication system according to an embodiment of the present invention includes at least two transmission sources (e.g., STA (including AP)) and one STA. In downlink coordinated communication, for example, at least two transmission sources (e.g., from AP) may coordinately send a preamble reference signal (e.g., EHT-STF and EHT-LTF) to the STA.

[0054] In the following description, for example, a “wireless communication control device” corresponds to an AP, and a “wireless communication device” corresponds to an STA.

[0055] Figure 4 1 is a block diagram showing a configuration example of a part of the wireless communication control device 10. Figure 4 In the wireless communication control device 10 shown, the control unit 11 makes the waveform of the reference signal transmitted to the wireless communication device (e.g., STA) in coordination with other wireless communication control devices different from the waveform of the reference signal transmitted to the wireless communication device by the other wireless communication control devices in at least one of the frequency domain and the time domain. The transmitting unit 12 transmits the reference signal.

[0056] [Structure of wireless communication control device]

[0057] Figure 5 is a block diagram showing a configuration example of the wireless communication control device 100 according to the present embodiment. Figure 5 In the embodiment, the wireless communication control device 100 includes a reference signal generating unit 101, a waveform converting unit 102, a transmission packet generating unit 103, a wireless transceiver unit 104 and a reception packet decoding unit 105.

[0058] Figure 5 The wireless communication control device 100 shown is equivalent to Figure 4 An example of the wireless communication control device 10 shown. In addition, it can be, Figure 5 The reference signal generating unit 101, the waveform converting unit 102 and the transmission packet generating unit 103 are equivalent to Figure 4 An example of the control unit 11, Figure 5 The wireless transceiver 104 is equivalent to Figure 4 The wireless communication control device 100 is an example of a master AP or a slave AP in cooperative communication.

[0059] The reference signal generator 101 generates a reference signal (e.g., a preamble reference signal). The preamble reference signal may include, for example, at least one of EHT-STF, EHT-LTF, legacy-STF (L-STF), or L-LTF. The reference signal generator 101 outputs the generated reference signal to the waveform converter 102.

[0060] The waveform converter 102 converts the waveform of the reference signal input from the reference signal generator 101. For example, when the wireless communication control device 100 is a slave AP, the waveform converter 102 converts the waveform of the reference signal based on the control information (for example, control information transmitted by the master AP) input from the received packet decoder 105. In addition, "waveform conversion" may refer to a process or control that makes two signal waveforms different from each other, or a process or control that generates signals with different waveforms from each other.

[0061] For example, the control information sent by the master AP may also include information for identifying the slave AP (e.g., the slave AP number) and information related to the waveform conversion of the reference signal (hereinafter referred to as "waveform conversion parameters"). The waveform converter 102 outputs the waveform-converted reference signal to the transmission packet generator 103.

[0062] 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, for example, Figure 1 The transmission packet generation unit 103 outputs the generated transmission packet to the wireless transmission / reception unit 104.

[0063] The wireless transmission and reception unit 104 performs wireless transmission processing on the transmission packet and converts it into a wireless transmission signal. The wireless transmission and reception unit 104 transmits the wireless transmission signal from the antenna.

[0064] In addition, the wireless transceiver unit 104 receives a wireless reception signal from the antenna. The wireless transceiver unit 104 performs wireless reception processing on the received wireless transmission and reception signal to obtain a reception packet. The reception packet may include, for example, control information (for example, MAP trigger (for example, Figure 1 )) and may also include a signal (including reception quality information, for example) transmitted from the wireless communication device 200 (not shown. For example, STA). The wireless transceiver unit 104 outputs the received packet to the received packet decoding unit 105.

[0065] For example, when the wireless communication control device 100 is a slave AP, the received packet decoder 105 may extract the slave AP number and waveform conversion parameters from the MAP trigger included in the received packet and output them to the waveform converter 102 .

[0066] In the above, the configuration example of the wireless communication control device 100 has been described.

[0067] The wireless communication device 200 (for example, STA) receives a packet (for example, MAP NDP) transmitted from the wireless communication control device 100. Figure 1 As shown, the wireless communication device 200 may also control the reception of the MAP NDP based on the MAP NDPA sent before the MAP NDP. For example, when the received packet includes the MAP NDP, the wireless communication device 200 extracts a reference signal such as the EHT-STF or EHT-LTF (e.g., a reference signal for the preamble).

[0068] The wireless communication device 200 may also perform timing detection and AGC processing based on the extracted reference signal, for example. In addition, the wireless communication device 200 may measure (in other words, channel estimate) the reception quality based on the extracted reference signal, for example, and send (or feed back) reception quality information related to the measured reception quality to the wireless communication control device 100.

[0069] [Method of transmitting reference signal]

[0070] Hereinafter, an example of a method of transmitting a reference signal (for example, a waveform conversion method) in the wireless communication control device 100 will be described.

[0071] The wireless communication control device 100 (for example, a slave AP in coordinated communication) sends a reference signal at the same time, for example, in coordinated communication. In this embodiment, for example, the waveforms of the reference signals (for example, EHT-STF) sent by multiple slave APs in coordinated communication are different from each other among the multiple slave APs. For example, by allocating different subcarriers in the frequency domain or allocating different delays in the time domain (in other words, cyclic shifts) among multiple slave APs, a reference signal having a different waveform among multiple slave APs is generated (an example of which will be described later).

[0072] In addition, between multiple transmission sources (e.g., from an AP) in coordinated communication, the interval of subcarriers to which reference signals are allocated (in other words, configured or mapped) is the same (in other words, common). For example, the interval of subcarriers to which EHT-STF is allocated can be a fixed value (e.g., 8 subcarriers or 16 subcarriers) or a variable value.

[0073] In addition, for multiple slave APs, a method of dividing the resources allocated with the EHT-LTF included in the transmission packet (for example, MAP NDP) by slave AP may be: Figure 2 or Figure 3 The frequency division shown may be code division, or a division method combining frequency division and code division may be used.

[0074] Hereinafter, methods 1 to 7 of transmitting (or converting the waveform of) a reference signal will be described respectively.

[0075] <Method 1>

[0076] In method 1, the preamble reference signal (e.g., EHT-STF) is frequency-divided for multiple transmission sources (e.g., from APs). In other words, the frequency resources (e.g., subcarriers) to which the EHT-STF is allocated in a certain AP as a transmission source are different from the frequency resources to which the EHT-STF is allocated in other APs as transmission sources.

[0077] Figure 6 An example of frequency allocation of EHT-STF is shown. Figure 6 For example, three slave APs, slave AP1, slave AP2 and slave AP3, coordinate communication.

[0078] like Figure 6 As shown, when EHT-STF is not frequency-divided, EHT-STF is allocated at intervals of 8 subcarriers in the frequency domain. In addition, the interval of subcarriers to which EHT-STF is allocated is not limited to 8 subcarriers, but may be other intervals (e.g., 16 subcarriers).

[0079] In method 1, if Figure 6 As shown in FIG. 1 , the subcarriers to which the EHT-LTFs transmitted from the APs are allocated are different from each other. Figure 6 In FIG, multiple subcarriers with an 8-subcarrier spacing are respectively allocated to the EHT-STFs of the three slave APs that perform coordinated communication. In other words, in Figure 6 In the example, the frequency resources with a subcarrier spacing of 24 are allocated to the EHT-STF of each slave AP. Figure 6 As shown, the EHT-STFs allocated at an interval of 8 subcarriers are transmitted in such a manner that each is transmitted by one AP among three slave APs but is not transmitted by the remaining APs.

[0080] Here, as an example, the subcarrier spacing of the EHT-STF when frequency division is not performed is set to "numSC", the number of slave APs performing coordinated communication is set to "numAP", the slave AP number of each slave AP is set to "iAP" (iAP=0, 1, 2...numAP-1), and the subcarrier number of the EHT-STF allocated to each slave AP is set to "noSC(iAP, n)" (n=0, 1, 2...the number of EHT-STFs allocated to each slave AP-1).

[0081] In this case, the subcarrier number noSC(iAP,n) allocated to the EHT-STF of each slave AP can be calculated according to the following formula.

[0082] When n=0: noSC(iAP,n)=numSC×iAP

[0083] When n≠0: noSC(iAP,n)=noSC(iAP,n-1)+numSC×numAP

[0084] For example, Figure 6 An example of frequency division of EHT-STF in the case of numSC=8 and numAP=3 is shown.

[0085] For example, in coordinated communication, the master AP may also send a MAP trigger ( numAP ) containing numAP (in other words, waveform conversion parameters) to the slave AP. Figure 1 ). In addition, numSC can also be notified by the master AP to the slave AP, or it can be specified by the standard.

[0086] In addition, the master AP may include the slave AP number iAP in the MAP trigger and send it to the slave AP. Alternatively, the slave AP may determine the iAP based on the order of the slave APs specified in the MAP trigger.

[0087] Each slave AP may determine the frequency resources (eg, subcarriers) to be allocated to the EHT-STF of each slave AP based on, for example, the waveform conversion parameters notified by the master AP or predetermined parameters.

[0088] In method 1, if Figure 6 As shown in FIG. 1 , the subcarriers to which the EHT-STF of each slave AP is allocated are different. In other words, Figure 6 In the embodiment, the signal waveforms of the EHT-STFs sent from each AP in the frequency domain are different from each other. Thus, according to method 1, in a STA (eg, wireless communication device 200), the fluctuation of the received power between the EHT-STFs sent from multiple APs can be reduced, thereby improving the AGC performance.

[0089] <Method 2>

[0090] In method 2, similarly to method 1, the EHT-STF is subjected to frequency division for a plurality of transmission sources (eg, from APs).

[0091] In addition, in method 2, EHT-LTF is subjected to frequency partitioning for slave APs, for example. In other words, frequency resources (eg, subcarriers) to which EHT-LTF is allocated in a slave AP are different from frequency resources to which EHT-LTF is allocated in other slave APs.

[0092] In addition, in method 2, for example, for each of a plurality of slave APs, a subcarrier allocated to the EHT-LTF overlaps a portion of a subcarrier allocated to the EHT-STF.

[0093] Figure 7 An example of frequency allocation of EHT-STF and EHT-LTF is shown. Figure 7 For example, three slave APs, slave AP1, slave AP2 and slave AP3, coordinate communication.

[0094] like Figure 7 As shown, when EHT-STF is not frequency-divided, EHT-STF is allocated in the frequency domain at intervals of 8 subcarriers. In addition, the interval of subcarriers to which EHT-STF is allocated is not limited to 8 subcarriers, but may be other intervals (e.g., 16 subcarriers).

[0095] In addition, if Figure 7 As shown, when EHT-LTF is not frequency-divided, EHT-LTF is allocated in the frequency domain at an interval of 4 subcarriers. In addition, the interval of subcarriers to which EHT-LTF is allocated is not limited to 4 subcarriers, but can also be other intervals (for example, 1 subcarrier or 2 subcarriers).

[0096] In method 2, the same as in method 1 (for example, Figure 6 ) Similarly, if Figure 7 As shown in FIG. 1 , multiple subcarriers with an 8-subcarrier spacing are respectively allocated to the EHT-STFs of the three slave APs for coordinated communication. Figure 7 In the example, frequency resources with a subcarrier spacing of 24 are allocated to the EHT-STF of each slave AP.

[0097] In addition, in method 2, if Figure 7 As shown in FIG. 1 , the subcarriers to which the EHT-LTFs transmitted from the APs are allocated are different from each other. Figure 7 In the embodiment, a plurality of subcarriers with a 4-subcarrier spacing are respectively allocated to the EHT-STFs of the three slave APs performing coordinated communication.

[0098] For example, in Figure 7 In the example, the number of slave APs participating in the coordinated transmission may be determined based on the number of slave APs participating in the coordinated transmission (e.g., Figure 7 For example, the interval of subcarriers of EHT-LTF allocated to each slave AP (in other words, the range of frequency resources) can be calculated by "subcarrier interval of EHT-STF × number of slave APs". Figure 7 In the example, the subcarrier spacing of EHT-STF is 8 subcarriers, and the number of slave APs is three. Therefore, the subcarrier spacing of EHT-LTF allocated to each slave AP is 24 subcarriers.

[0099] For example, in Figure 7 In the example, the subcarrier spacing of the EHT-LTF is 4 subcarriers, so each EHT-LTF sent from the AP is allocated 6 adjacent subcarriers in the frequency domain. Through this resource allocation, for example, Figure 7 As shown, the EHT-LTF allocated at intervals of 4 subcarriers is transmitted in such a manner that one of three slave APs is transmitted every 24 subcarriers, and the remaining APs are not transmitted.

[0100] For example, in coordinated communication, the master AP may also send a MAP trigger ( Figure 1 ). In addition, the subcarrier spacing of EHT-STF and EHT-LTF can be notified by the master AP to the slave AP, or can be specified by the standard.

[0101] In addition, the master AP may include the slave AP number in the MAP trigger and send 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.

[0102] Each slave AP may determine the frequency resources (eg, subcarriers) to be allocated to the EHT-STF and EHT-LTF of each slave AP, for example, based on the waveform conversion parameters notified by the master AP or predetermined parameters.

[0103] In method 2, if Figure 7 As shown in FIG. 1 , the reference signals (eg, EHT-STF and EHT-LTF) of each slave AP are allocated to different subcarriers. Figure 7 In the method 2, the signal waveforms of the reference signals (e.g., EHT-STF and EHT-LTF) sent from the AP in the frequency domain are different from each other. Therefore, according to method 2, in the STA (e.g., the wireless communication device 200), the fluctuation of the received power between the EHT-STFs sent from the AP can be reduced, and the AGC performance can be improved.

[0104] In addition, in method 2, in the reference signal of each slave AP, there is an association between the EHT-STF and the EHT-LTF. For example, for each slave AP, the frequency resource (subcarrier) to which the EHT-STF is allocated overlaps with a portion of the subcarrier to which the EHT-LTF is allocated (in other words, is the same). Figure 7 In the embodiment, within the range of 24 subcarriers to which an EHT-LTF of a slave AP is allocated, a subcarrier to which one EHT-LTF among 6 EHT-LTFs is allocated is the same as a subcarrier to which an EHT-STF of the slave AP is allocated.

[0105] By allocating the reference signal in this way, for example, the frequency characteristics in the propagation path between the AP and the STA are the same in a part of the EHT-STF and the EHT-LTF. As a result, 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, thereby improving the AGC performance in the STA.

[0106] In addition, the frequency allocation of EHT-LTF in method 2 is not limited to Figure 7 For example, the subcarriers (in other words, the range of frequency resources) allocated to the EHT-LTF of each slave AP may also be determined based on the subcarrier spacing of the EHT-STF. Figure 8 As shown in FIG. 1 , when the subcarrier spacing of EHT-STF is 8 subcarriers and the subcarrier spacing of EHT-LTF is 4 subcarriers, the subcarrier spacing of the EHT-LTF allocated to each slave AP is 8 subcarriers. Figure 8 As shown in FIG. 1 , the subcarrier spacing of the EHT-LTF is 4 subcarriers, so each EHT-LTF sent from the AP is allocated 2 adjacent subcarriers in the frequency domain. Figure 8 As shown, the subcarrier to which one of the two adjacent EHT-LTFs is allocated is the same as the subcarrier to which the EHT-STF is allocated. Figure 8 In this embodiment, the difference in received power caused by the frequency characteristics of the propagation path can be reduced between EHT-STF and EHT-LTF, thereby improving the AGC performance in STA.

[0107] <Method 3>

[0108] In method 3, EHT-STF is allocated to subcarriers based on offsets that differ by transmission source (eg, from an AP) for a plurality of transmission sources.

[0109] Fig. 9 An example of frequency allocation of EHT-STF is shown. Fig. 9For example, three slave APs, slave AP1, slave AP2 and slave AP3, coordinate communication.

[0110] like Fig. 9 As shown, when EHT-STF is not frequency-divided, EHT-STF is allocated in the frequency domain at intervals of 8 subcarriers. In addition, the interval of subcarriers to which EHT-STF is allocated is not limited to 8 subcarriers, but may be other intervals (e.g., 16 subcarriers).

[0111] In method 3, the slave AP determines the subcarrier position to which the EHT-STF is allocated based on, for example, an offset relative to the position (in other words, frequency position) of the subcarrier to which the ETH-STF is allocated when frequency division is not performed, and is an offset different from the offset used by other slave APs. Fig. 9 As shown, for the position of the subcarrier to which the EHT-STF is allocated when not subject to frequency division, an offset that differs from the AP is added. For example, when the number of slave APs is less than the subcarrier spacing of the EHT-STF, the offset of each slave AP may be set in the order of 0, 1, -1, 2, -2, etc.

[0112] For example, in coordinated transmission, the master AP may also send a MAP trigger ( Figure 1 ). In addition, the subcarrier spacing of EHT-STF can be notified by the master AP to the slave AP, or can be specified by the standard.

[0113] In addition, the master AP may include the slave AP number in the MAP trigger and send 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.

[0114] Each slave AP may determine the frequency resources (eg, subcarriers) to be allocated to the EHT-STF and EHT-LTF of each slave AP, for example, based on the waveform conversion parameters notified by the master AP or predetermined parameters.

[0115] For example, in Fig. 9 In the example, the offset is set to 0 for AP1, +1 for AP2, and -1 for AP1. Fig. 9 As shown in FIG. 1 , the subcarriers to which the EHT-LTFs of the slave APs are allocated are different from each other. Fig. 9 In the embodiment, the signal waveforms of the EHT-STFs sent from each AP in the frequency domain are different from each other. Thus, according to method 3, in a STA (eg, wireless communication device 200), the fluctuation of the received power between the EHT-STFs sent from multiple APs can be reduced, thereby improving the AGC performance.

[0116] In addition, Fig. 9 In the example, the frequency resources (e.g., subcarriers) allocated to each slave AP's EHT-STF are spaced the same as the subcarrier spacing allocated to the EHT-STF without frequency segmentation (e.g., 8 subcarrier spacing). In other words, the subcarrier spacing allocated to each slave AP's EHT-STF is the same.

[0117] For example, in method 1 (e.g., Figure 6 ) and Method 2 (e.g., Figure 7 or Figure 8 ), the subcarrier spacing (24 subcarriers) to which each slave AP's EHT-STF is allocated is several times (3 times) the subcarrier spacing (8 subcarriers) to which the EHT-STF is allocated when there is no frequency division.

[0118] Therefore, method 3 can narrow the subcarrier interval to which each slave AP's EHT-STF is allocated, compared with method 1 and method 2. Therefore, method 3 can make the repetition time length of EHT-STF in the time domain longer than method 1 and method 2, thereby improving the timing detection performance in STA.

[0119] In addition, when the offset set for each slave AP is set to, for example, 0, 1, -1, 2, -2, ... (in other words, when each is offset by 1 subcarrier), a closer frequency (for example, adjacent subcarriers) is allocated to the EHT-STF of each slave AP, so it is easy to maintain the periodicity of the combined wave during reception in the STA.

[0120] In addition, 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 a larger interval than, for example, 0, 1, -1, 2, -2, ... (in other words, each is offset by 1 subcarrier). For example, the offset value may be set to a value obtained by rounding "subcarrier interval commonly used by slave APs / (number of slave APs)". For example, when the subcarrier interval commonly used by slave APs is set to 8 subcarriers and the number of slave APs is set to three, the offset value is 0, 2, -2.

[0121] For example, due to frequency offset or propagation delay, the subcarriers to which the EHT-STF from each slave AP is allocated in the STA may sometimes be offset. In contrast, by setting the offset as described above, when the subcarrier deviation is less than the offset interval, the STA receives the EHT-STF sent by each slave AP at a different frequency, thereby, for example, being able to suppress degradation of AGC performance.

[0122] <Method 4>

[0123] In 11ax, in the transmission and reception using multiple transmission chains in the AP and STA, cyclic shift diversity (CSD) is adopted to add a unique cyclic shift to the signal of each transmission chain (for example, refer to non-patent document 4). Through CSD, for example, the fluctuation of the received power caused by the phase of the propagation path can be reduced.

[0124] Here, the transmission chain represents a unit of transmission, and for example, the transmission chain is equivalent to an antenna (eg, a transmitting antenna) or a stream.

[0125] In method 4, for multiple transmission sources (e.g., from AP), different cyclic shifts are set for EHT-STF according to the transmission source. For example, from AP, a cyclic shift amount different from the cyclic shift amount used for EHT-LTF from other APs is added to EHT-STF. By setting the cyclic shift, an offset is added to the EHT-STFs transmitted by each of the multiple slave APs in the time domain.

[0126] Fig.10 An example of a cyclic shift number n for the total number of transmission chains (total number of space-time streams) (e.g., see Non-Patent Document 4). The total number of transmission chains, for example, represents the sum of the number of transmission chains from each AP performing coordinated communication.

[0127] As an example, when there are two slave APs performing coordinated communication and each slave AP has four transmission chains, Fig.10 In the example, the cyclic shift amounts of the rows with cyclic shift numbers n=1 to 4 of the total number of transmission chains = 8 are set for each transmission chain of AP1, and the cyclic shift amounts of the rows with cyclic shift numbers n=5 to 8 are set for each transmission chain of AP2. In addition, the cyclic shift amount set for each slave AP is not limited to Fig.10 Example shown.

[0128] For example, in coordinated communication, the master AP may also send the following MAP trigger to the slave AP (eg, Figure 1 ), the MAP trigger includes waveform conversion parameters such as the number of transmission chains of each slave AP (or the total number of transmission chains) and the cyclic shift number n at the front end of the cyclic shift set for each slave AP. Fig.10In the example shown, the MAP trigger may also include the number of transmission chains of AP1 and AP2, 4 (or, the number of transmission chains: 8), the cyclic shift number n=1 of the front end of AP1, and the cyclic shift number n=5 of the front end of AP2. By notifying the MAP trigger, each slave AP can apply the cyclic shift set by the slave AP (or, by transmission chain) to the EHT-STF.

[0129] In method 4, different cyclic shift amounts are added to the reference signals (e.g., EHT-STF) sent in the transmission chain of each slave AP. In other words, in method 4, the signal waveforms of the reference signals (e.g., EHT-STF) sent by each slave AP in the time domain are different from each other. Thus, according to method 4, in a STA (e.g., a wireless communication device 200), the fluctuation of the received power between the EHT-STFs sent by multiple slave APs can be reduced, and the AGC performance can be improved.

[0130] Furthermore, according to method 4, even when CSD for EHT-STF is applied between multiple slave APs, each slave AP can determine the cyclic shift added to the transmission chain of each slave AP based on the notification from the master AP (eg, MAP trigger).

[0131] In addition, as an example, Fig.10 The cyclic shift amounts are shown up to a total number of transmission chains of 8, but cyclic shift amounts for transmission chains of 9 or more may also be defined.

[0132] <Method 5>

[0133] In method 5, for example, based on information related to the STA or information related to the AP, the format of the reference signal (EHT-STF and EHT-LTF) (in other words, the transmission method or the waveform conversion method) is switched.

[0134] For example, depending on the formats of EHT-STF and EHT-LTF, the waveforms of EHT-STF and EHT-LTF are different, and the AGC performance or timing detection accuracy in EHT-STF and EHT-LTF may be different.

[0135] Fig.11 An example of the probability distribution of the power difference [dB] between EHT-LTF and EHT-STF derived by computer simulation performed by the inventors of the present invention is shown. Fig.11 In FIG. 5 , the horizontal axis represents the power difference [dB] between EHT-STF and EHT-LTF, and the vertical axis represents the cumulative distribution function (CDF: cumulative distribution function).

[0136] exist Fig.11In the example, "undivided" indicates the characteristics when both EHT-STF and EHT-LTF are not frequency-divided. In addition, "method X" indicates the characteristics when EHT-STF is not frequency-divided and EHT-LTF is frequency-divided (for example, Figure 2 ) characteristics in the case of. In addition, "Method 2" means that the format of EHT-STF and EHT-LTF is subjected to frequency division based on the above-mentioned method 2 (for example, Figure 7 ), "Method 3" means that the EHT-STF and EHT-LTF are subjected to frequency division format based on the above-mentioned method 3 (for example, Fig. 9 ) characteristics in the case of.

[0137] exist Fig.11 For example, the following characteristics are represented, that is, the more the probability distribution of the power difference between EHT-STF and EHT-LTF is smaller (for example, closer to 0 dB), the better the fluctuation of the received power in the STA (in other words, the AGC performance). Fig.11 As shown, Method 2 and Method 3 show better characteristics than "Method X". In addition, Method 2 shows the same characteristics as the case of "undivided" and better characteristics than Method 3.

[0138] Fig.11 The power difference between the EHT-STF and the EHT-LTF shown corresponds to, for example, the fluctuation of the received power between the EHT-STF and the EHT-LTF, for example, the AGC performance. Fig.11 This indicates that methods 2 and 3 have better AGC performance than method X. In addition, Fig.11 It shows that method 2 and the “unsegmented” case show the same AGC performance, and method 2 has better AGC performance than method 3.

[0139] then, Fig.12 and Fig.13 An example of the timing detection results of Method 2 and Method 3 obtained by computer simulation performed by the inventors of the present invention is shown. Fig.12 and Fig.13 In , the characteristic of the number of APs = 1 indicates the same characteristic as the timing detection result in the case of "undivided". Fig.12 and Fig.13 In the example, the timing detection at the position where the number of APs = 1 is the expected value. For example, when the number of APs increases, the more the timing at the same position as the number of APs = 1 is detected, the higher the timing detection accuracy.

[0140] If Fig.12 and Fig.13In comparison, in method 3, even if the number of APs increases, for example, the timing of the same position as the expected value can be detected, and the timing detection accuracy is higher than that of method 2.

[0141] In addition, in the case of "method X", in other words, in the case where the frequency division of EHT-STF is not performed, for example, with method 3 (for example, Fig. 9 ) Similarly, compared with method 2, the interval of the subcarriers to which the EHT-STF of each slave AP is allocated is narrower, so the repetition time length of the EHT-STF in the time domain can be made longer, thereby improving the timing detection accuracy in the STA. Therefore, for example, the timing detection accuracy of (method 3 and method X) is higher than that of method 2.

[0142] Fig.14 An example of summarizing the power difference between EHT-STF and EHT-LTF (in other words, AGC performance) and timing detection accuracy with respect to method X, method 2, and method 3 is shown.

[0143] like Fig.14 As shown, the characteristics of AGC performance and timing detection accuracy are different depending on the format of EHT-STF and EHT-LTF (in other words, the transmission method or waveform conversion method). For example, if the AGC performance is considered, method 2 is more suitable than method X and method 3. On the other hand, if the timing detection accuracy is considered, method X or method 3 is more suitable than method 2.

[0144] On the other hand, for example, the power difference between EHT-STF and EHT-LTF allowed in STA may vary depending on each product. In addition, for example, if STA can use L-STF for timing detection, the STA does not need to detect the timing based on EHT-STF.

[0145] Thus, the format of an appropriate reference signal (in other words, a waveform conversion method) may differ depending on the STA.

[0146] Therefore, in method 5, the format of the EHT-STF or EHT-LTF is decided based on the performance (in other words, specification or capability) of the STA.

[0147] For example, the format of EHT-STF or EHT-LTF may be determined by each STA. In other words, the format of EHT-STF or LTF may be switched in the STA.

[0148] For example, in STA, the wider the dynamic range of the received signal, the wider the fluctuation range of the received power difference that can be allowed, and the less likely the AGC performance is to deteriorate. Therefore, for example, it can be that when the dynamic range of the received signal in STA is wide (for example, when the dynamic range is above the threshold), regardless of Fig.14 How is the performance related to the power difference between EHT-STF and EHT-LTF, and the application Fig.14 On the other hand, for example, when the dynamic range of the received signal in the STA is narrow (for example, when the dynamic range is less than the threshold), the application Fig.14 The format of method 2 or method 3 has better performance in terms of the power difference between EHT-STF and EHT-LTF.

[0149] In addition, for example, when the EHT-STF-based timing detection is not performed in the STA, it is irrelevant Fig.14 How is the timing detection performance in the application Fig.14 The format of method 2 or method 3 with better performance related to the power difference between EHT-STF and EHT-LTF in the STA. On the other hand, for example, when the EHT-STF-based timing detection is performed in the STA, the application Fig.14 The timing detection accuracy is higher in the method X or method 3 format.

[0150] As an example, when the dynamic range of the received signal is wide and timing detection based on EHT-STF is performed, the STA may determine the format to be the format of method X (for example, Figure 2 or Figure 3 ). In addition, when the dynamic range of the received signal is narrow and timing detection based on EHT-STF is performed, the STA may determine the format to be the format of method 3 (for example, Fig. 9 ). In addition, the STA may determine the format to be the format of method 2 (for example, Figure 7 ).

[0151] Alternatively, the STA may notify the AP of the determined EHT-STF format. For example, the EHT-STF format may be notified using at least one of an association request and a reassociation request, or other control information. Fig.15 This shows an example of adding the format of EHT-STF to the association request table (for example, refer to Non-Patent Document 5).

[0152] In the above, the case where the format of the EHT-STF is determined by the STA (in other words, switched or selected), the format of the EHT-STF may also be determined by the AP. For example, the AP may also determine the format of the EHT-STF based on information related to the capabilities of the STA (e.g., capabilities) notified by the STA. In this case, the AP may also determine the format of the EHT-STF, for example, through the MAP NDPA (e.g., Figure 1 ) and notify the STA of the selected EHT-STF format.

[0153] Alternatively, the format of the EHT-STF may be determined based on the number of slave APs performing coordinated communications. Fig.12 As shown, even with the format of method 2, when the number of slave APs is small (e.g., less than two), the degradation of timing detection accuracy is less than when the number of slave APs is large (e.g., more than two). Therefore, for example, the AP may determine the format to be the format of method 2 when the number of slave APs is less than a threshold value (e.g., two), and determine the format to be the format of method X or method 3 when the number of slave APs is greater than the threshold value (e.g., two). The AP may also determine the format to be the format of method X or method 3, for example, through MAP NDPA (e.g., Figure 1 ) and notify the STA of the selected EHT-STF format.

[0154] In this way, according to method 5, the format of EHT-STF is determined (or switched) based on STA performance or the number of APs, thereby improving the AGC performance and timing detection accuracy in EHT-STF and EHT-LTF.

[0155] In addition, in method 5, if Fig.14 As shown in the figure, method 2 and method 3 are described, but the method applied to the format of EHT-STF is not limited to method 2 and method 3, and method 1 and method 4 can also be applied. For example, regarding method 1 and method 2, since the format of EHT-STF is the same, the timing detection accuracy of method 1 is the same as that of method 2. In addition, method 4 can also be applied instead of the format of EHT-STF applied in the above example.

[0156] <Method 6>

[0157] For example, in methods 1 to 5, it is assumed that the format of the time domain of EHT-STF is 1 symbol. In method 6, the case where the format of the time domain of EHT-STF is multiple symbols (for example, 2 symbols) is described.

[0158] like Fig.14As shown, the timing detection performance of method X or method 3 is better than that of method 2, and the power difference between EHT-STF and EHT-LTF of method 2 (in other words, AGC performance) is better than that of method X and method 3.

[0159] Therefore, the format of method X (or method 3) may be set for the first symbol among multiple symbols (for example, 2 symbols) constituting the EHT-STF, and the format of method 2 may be applied to the second symbol.

[0160] In other words, for example, when it is the first symbol of the two symbols constituting the EHT-STF, the slave AP transmits an EHT-STF having the same waveform among the plurality of slave APs performing coordinated communication. In other words, when it is the first symbol, for example, the slave AP transmits an EHT-STF having the same waveform as the EHT-STF transmitted by the other slave APs. By setting this EHT-STF, it is possible to improve the timing detection accuracy when it is the first symbol.

[0161] In addition, when it is the second codeword, the slave AP sends the EHT-STF in the following frequency resources: for multiple slave APs, the frequency resources are different for each slave AP and overlap with at least a portion of the frequency resources (for example, subcarriers) allocated to the EHT-LTF in the slave AP. In other words, when it is the second codeword, for example, the slave AP sends the EHT-STF in a subcarrier that overlaps with at least a portion of the subcarrier allocated to the EHT-LTF by the slave AP. By setting the EHT-STF in this way, it is possible to improve the AGC performance when it is the second codeword. In addition, for example, in method 2, as Figure 7 As shown, the EHT-LTFs will not be synthesized between multiple slave APs, so the fluctuation of the received power between the EHT-LTFs can be reduced, thereby improving the AGC performance.

[0162] In addition, for example, by applying the format of method 2 to the second symbol in the 2-symbol EHT-STF that is closer to the EHT-LTF, the AGC performance in the EHT-LTF can be improved.

[0163] Therefore, according to method 6, in STA, the fluctuation of received power can be reduced and the timing detection accuracy can be improved, thereby improving the system improvement effect based on downlink coordinated communication.

[0164] Furthermore, the number of symbols constituting the EHT-STF may be 3 or more.

[0165] In addition, when it is the first symbol of the two symbols constituting the EHT-STF, a format for improving the timing detection accuracy (for example, method 3 or method 4) may be set without being limited to method X. In addition, when it is the second symbol of the two symbols constituting the EHT-STF, a format for improving the AGC performance (for example, method 1 or method 4) may be set without being limited to method 2.

[0166] <Method 7>

[0167] For example, in Fig.10 In the , cyclic shift amounts are defined up to a total number of transmission chains of 8. Therefore, in order to set different cyclic shift amounts for each transmission chain even when the total number of transmission chains is 9 or more, for example, it is assumed that a cyclic shift amount corresponding to a total number of transmission chains of 9 or more is newly defined (in other words, the definition is extended).

[0168] However, if the cyclic shift amount is to correspond to a larger total number of transmission chains, it is necessary to further reduce the phase offset corresponding to the total number of transmission chains, or further increase the maximum phase offset. Therefore, the effect of the cyclic shift (for example, the effect of reducing the fluctuation of the received power caused by the phase of the propagation path) may be weakened.

[0169] Therefore, in method 7, a method is described in which the format of the EHT-STF is determined for a larger total number of transmission chains (for example, 9 or more) without extending the definition of the cyclic shift amount.

[0170] For example, when the total number of transmission chains (or antennas) that transmit EHT-STF in multiple APs (e.g., from APs) is less than a threshold value (e.g., 8), the AP performs waveform conversion (e.g., applies cyclic shift) according to method 4. In other words, when the total number of transmission chains is less than the threshold value, the AP generates an EHT-STF whose waveform in the time domain is different between multiple APs.

[0171] On the other hand, when the total number of transmission chains (or antennas) that transmit EHT-STF in multiple APs (e.g., slave APs) is greater than a threshold value (e.g., 8), the AP makes the waveform of the EHT-STF different from the EHT-STF sent from other slave APs to the STA 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 also use the formats of Method 4 and Method 3 together.

[0172] In this case, for example, a MAP trigger (e.g., Figure 1) may include the "total number of transmission chains of slave APs" and the "front-end 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 determine the cyclic shift added to the transmission chain of each slave AP and the offset value of the subcarrier to which the EHT-STF is allocated in each slave AP according to the notification from the master AP (for example, MAP trigger).

[0173] According to method 7, even when the total number of transmission chains in multiple APs is greater than a threshold value (e.g., 8), for example, the waveforms of reference signals (e.g., EHT-STF and EHT-LTF) can be made different in at least one region in the time domain and the frequency domain for each AP. Thus, according to method 7, for example, even in Fig.10 When the total number of transmission chains is 9 or more, it is also possible to reduce the fluctuation of the receiving power of multiple EHT-STFs and EHT-LTFs sent from the AP in the STA (for example, the wireless communication device 200), thereby improving the AGC performance.

[0174] Furthermore, for example, the method of waveform conversion in the frequency domain used together with method 4 (in other words, waveform conversion in the time domain) is not limited to method 3, and may be method 1 or method 2.

[0175] In addition, for example, in a situation different from multi-AP (for example, in a single-AP situation), when the total number of transmission chains is greater than a threshold (for example, 9), waveform conversion in the time domain and frequency domain can be used together in the same way as method 7.

[0176] In the above, methods 1 to 7 are described respectively.

[0177] Thus, in this embodiment, the wireless communication control device 100 (e.g., AP) generates a reference signal (EHT-STF or EHT-LTF) having a waveform that is different between multiple wireless communication control devices 100 that perform coordinated transmission to the wireless communication device 200 (e.g., STA), and transmits the reference signal. By transmitting the reference signal in this manner, for example, in downlink coordinated communication, the wireless communication control device 100 can appropriately transmit the reference signal, thereby reducing the fluctuation of the received power in the wireless communication device 200 and improving the AGC performance.

[0178] In the above, one embodiment of the present invention has been described.

[0179] In addition, in the above-mentioned embodiment, as an example, an example of waveform conversion of a reference signal for a preamble code of an NDP is described, but an embodiment of the present invention can also be applied to a reference signal for a preamble code of other packets different from the NDP (for example, a PPDU for joint transmission containing data).

[0180] In addition, in the above embodiment, an example of multiple APs coordinating communication with STAs is shown, but the present invention is not limited to this. For example, at least a part of the multiple APs can be replaced by STAs. For example, the present invention can also be applied to a situation where one or more APs and one or more STAs coordinate communication with other STAs. Alternatively, the present invention can also be applied to a situation where two or more STAs coordinate communication with other STAs.

[0181] In addition, the above-mentioned embodiment describes a case where a reference signal having a different waveform is transmitted between multiple transmission sources (for example, from an AP) in coordinated communication. However, the present invention is not limited to this, and for example, the waveform of the reference signal (in other words, the allocation, offset, cyclic shift, etc. of the frequency domain) may be different in some of the transmission sources, while the waveform of the reference signal may be the same in other transmission sources. Even in this case, compared with a case where multiple transmission sources in coordinated communication all transmit reference signals of the same waveform, it is still possible to suppress the fluctuation of the received power in the STA, thereby suppressing AGC distortion.

[0182] Furthermore, in the above-described embodiment, a case has been described where the number of slave APs performing coordinated communication is three, but the number of APs performing coordinated communication is not limited to three, and may be another number.

[0183] In addition, a subcarrier is sometimes referred to as a “tone.” In addition, the unit of frequency resources is not limited to a subcarrier, and may be other resource units. In addition, the interval of subcarriers to which reference signals are allocated in the above-mentioned embodiment is an example, and may be other intervals.

[0184] In addition, the terms indicating each signal (for example, each packet) in the above-mentioned embodiment are merely examples, and the present invention is not limited thereto.

[0185] In addition, expressions such as "...part" in the above embodiments may also be replaced by other expressions such as "...circuitry", "...device", "...unit" or "...module".

[0186] The present invention can be implemented by software, hardware or software in cooperation with hardware. Each functional block used in the description of the above-mentioned embodiment is partially or entirely implemented as an LSI (Large Scale Integration) as an integrated circuit, and each process described in the above-mentioned embodiment can also be partially or entirely controlled by an LSI or a combination of LSIs. LSI can be composed of individual chips, or it can be composed of a chip in a manner that includes part or all of the functional blocks. LSI can also include the input and output of data. LSI can also be called "IC (Integrated Circuit)", "System LSI (System LSI)", "Super LSI (SuperLSI)", "Ultra LSI (Ultra LSI)" according to the different integration levels. The method of integrated circuitization is not limited to LSI, and can also be implemented by a dedicated circuit, a general-purpose processor or a dedicated processor. In addition, an FPGA (Field Programmable Gate Array) that can be programmed after LSI manufacturing, or a reconfigurable processor (Reconfigurable Processor) that can reconfigure the connection or setting of the circuit block inside the LSI can also be used. The present invention can also be implemented as digital processing or analog processing. Furthermore, if integrated circuit technology that replaces LSI emerges as semiconductor technology advances or other technologies are derived, it is of course possible to use this technology to achieve integration of functional blocks. There is also the possibility of applying biotechnology, etc.

[0187] The present invention can be implemented in all kinds of devices, equipment, and systems (collectively referred to as "communication devices") with communication functions. The communication device may also include a wireless transceiver and a processing / control circuit. The wireless transceiver may also include a receiving unit and a transmitting unit, or perform the functions of these parts. The wireless transceiver (transmitting unit, receiving unit) may also include an RF (Radio Frequency) module and one or more antennas. The RF module may also include an amplifier, an RF modulator / demodulator, or a device similar to these. Non-limiting examples of communication devices include: phones (mobile phones, smart phones, etc.), tablets, personal computers (PCs) (laptops, desktops, notebook computers, etc.), cameras (digital cameras, digital video cameras, etc.), digital players (digital audio / video players, etc.), wearable devices (wearable cameras, smart watches, tracking devices, etc.), game consoles, e-book readers, telehealth / telemedicine (telehealth / medical prescription) equipment, vehicles with communication functions or transportation vehicles (cars, airplanes, ships, etc.), and combinations of the above-mentioned various devices.

[0188] Communication devices are not limited to portable or movable devices, but also include all kinds of devices, equipment, and systems that cannot be carried or fixed. For example, they include: smart home devices (home appliances, lighting equipment, smart meters or meters, control panels, etc.), vending machines, and all other "things" that can exist on the IoT (Internet of Things) network.

[0189] The communication includes data communication performed by a cellular system, a wireless LAN (Local Area Network) system, a communication satellite system, etc., and also includes data communication performed by a combination of these systems.

[0190] In addition, the communication device also includes devices such as controllers or sensors connected or linked to the communication device that performs the communication function described in the present invention. For example, it includes a controller or sensor that generates a control signal or data signal used by the communication device that performs the communication function of the communication device.

[0191] In addition, the communication device includes infrastructure equipment that communicates with the above-mentioned non-limiting various devices or controls the above-mentioned various devices, such as base stations, access points, and all other devices, equipment, and systems.

[0192] A wireless communication control device according to one embodiment of the present invention is a first wireless communication control device, comprising: a control circuit, which makes the waveform of a reference signal sent to a wireless communication device in coordination with a second wireless communication control device different from the waveform of the reference signal sent by the second wireless communication control device to the wireless communication device in at least one of a frequency domain and a time domain; and a transmitting circuit, which sends the reference signal.

[0193] In one embodiment of the present invention, the reference signal includes a short training field, namely, an STF (Short Training Field) signal, and the first frequency resource allocated with the STF signal in the first wireless communication control device is different from the second frequency resource allocated with the STF signal in the second wireless communication control device.

[0194] In one embodiment of the present invention, the reference signal includes a long training field (LTF) signal, the third frequency resource allocated with the LTF signal in the first wireless communication control device is different from the fourth frequency resource allocated with the LTF signal in the second wireless communication control device, and the third frequency resource overlaps with at least a portion of the first frequency resource.

[0195] In one embodiment of the present invention, the third frequency resource and the fourth frequency resource are determined based on the number of wireless communication control devices participating in the coordinated transmission.

[0196] In one embodiment of the present invention, the interval at which the frequency resources of the reference signal are allocated by the first wireless communication control device is the same as the interval at which the frequency resources of the reference signal are allocated by the second wireless communication control device, and the control circuit determines the second frequency position to allocate the reference signal based on the following offset, which is an offset relative to the first frequency position having the interval and is different from the offset used by the second wireless communication control device.

[0197] In one embodiment of the present invention, the control circuit adds a cyclic shift amount to the reference signal that is different from a cyclic shift amount used by the second wireless communication control apparatus for the reference signal.

[0198] In one embodiment of the present invention, the reference signal includes a short training field (STF) signal, and a format of the STF signal corresponding to the waveform depends on information related to the wireless communication device.

[0199] In one embodiment of the present invention, the format is determined in the wireless communication device.

[0200] In one embodiment of the present invention, the control circuit determines the format based on information related to the capability of the wireless communication device.

[0201] In one embodiment of the present invention, the reference signal includes a short training field (STF) signal, and the format of the STF signal corresponding to the waveform depends on the number of wireless communication control devices participating in the coordinated transmission.

[0202] In one embodiment of the present invention, the reference signal includes a signal of a short training field, i.e., an STF, and a signal of a long training field, i.e., an LTF. Among the multiple code elements constituting the signal of the STF, when it is the first code element, the transmitting circuit transmits the signal of the STF having the same waveform as the signal of the STF transmitted by the second wireless communication control device, and when it is the second code element, the transmitting circuit transmits the signal of the STF in a frequency resource overlapping with at least a portion of the frequency resource to which the signal of the LTF is allocated by the first wireless communication control device.

[0203] In one embodiment of the present invention, the second symbol is a symbol of a signal closer to the LTF than the first symbol.

[0204] In one embodiment of the present invention, when the total number of antennas sending the reference signal is greater than a threshold, the control circuit makes the waveform of the reference signal different from the waveform of the reference signal sent by the second wireless communication control device to the wireless communication device in both the frequency domain and the time domain.

[0205] In a wireless communication control method of one embodiment of the present invention, a first wireless communication control device performs the following steps: making the waveform of a reference signal sent to a wireless communication device in coordination with a second wireless communication control device different from the waveform of the reference signal sent by the second wireless communication control device to the wireless communication device in at least one of a frequency domain and a time domain; and sending the reference signal.

[0206] The disclosure contents 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.

[0207] Industrial Applicability

[0208] One embodiment of the present invention is useful for a wireless communication system.

[0209] Description of Reference Numerals

[0210] 10.100 Wireless communication control device

[0211] 11Control Unit

[0212] 12Sending Department

[0213] 101 reference signal generating unit

[0214] 102 Waveform conversion unit

[0215] 103 Sending packet generation unit

[0216] 104 Wireless Transceiver

[0217] 105 receiving packet decoding unit

[0218] 200 Wireless communication device

Claims

1. A slave access point (AP), comprising: A receiver, receiving a frame indicating cyclic shift information of a reference signal for coordinated transmission by multiple APs; and A transmitter sends the reference signal in the multi-AP coordinated transmission based on the cyclic shift information.

2. The slave AP according to claim 1, in, The cyclic shift information indicates that a cyclic shift amount is different for each AP that transmits the reference signal.

3. The slave AP according to claim 2, in, The cyclic shift information is an offset value between the cyclic shift amounts.

4. The slave AP according to claim 1, in, The cyclic shift information indicates a cyclic shift index corresponding to a cyclic shift amount.

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

6. The slave AP according to claim 1, in, The cyclic shift information indicates the number of transmission chains of the primary AP.

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

8. The slave AP according to claim 7, in, The frame is a multi-AP trigger frame.

9. The slave AP according to claim 8, in, The order-specified cyclic shift amount of the slave APs in the multi-AP trigger frame is different for each of the slave APs that transmit the reference signal in the multi-AP coordinated transmission.

10. A method for communicating from an access point (AP), comprising: receiving a frame indicating cyclic shift information of a reference signal for coordinated transmission by multiple APs; as well as The reference signal is transmitted in the multi-AP coordinated transmission based on the cyclic shift information.

11. An integrated circuit for use with a slave access point (AP), the integrated circuit comprising: At least one input terminal for inputting electronic signals, and Control circuit, control: receiving a frame indicating cyclic shift information of a reference signal for coordinated transmission by multiple APs; and The reference signal is transmitted in the multi-AP coordinated transmission based on the cyclic shift information.

12. The integrated circuit as claimed in claim 11, in, The cyclic shift information indicates that a cyclic shift amount is different for each AP that transmits the reference signal.

13. The integrated circuit of claim 12, in, The cyclic shift information is an offset value between the cyclic shift amounts.

14. The integrated circuit of claim 11, in, The cyclic shift information indicates a cyclic shift index corresponding to a cyclic shift amount.

15. The integrated circuit of claim 11, in, The cyclic shift information is defined based on a total number of transmission chains of a plurality of APs that transmit the reference signal in the multi-AP coordinated transmission.

16. The integrated circuit of claim 11, in, The cyclic shift information indicates the number of transmission chains of the primary AP.

17. The integrated circuit of claim 11, in, The frame is transmitted to two or more slave APs, and the two or more slave APs transmit the reference signal in the multi-AP coordinated transmission.

18. The integrated circuit of claim 17, in, The frame is a multi-AP trigger frame.

19. The integrated circuit of claim 18, in, The order-specified cyclic shift amount of the slave APs in the multi-AP trigger frame is different for each of the slave APs that transmit the reference signal in the multi-AP coordinated transmission.

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