Integrated circuit for first wireless station

Abstract

The present invention relates to an integrated circuit for a first wireless station, the first wireless station belonging to a basic service set (BSS), the integrated circuit comprising: a control circuit, the control circuit performing the following control: receiving a trigger frame sent from an access point (AP) belonging to an overlapping BSS (OBSS), the trigger frame requesting an uplink multi-user signal from a plurality of wireless stations belonging to the OBSS, and when the uplink multi-user signal is sent, sending the signal to a second wireless station belonging to the BSS in a spatial multiplexing operation, wherein the spatial multiplexing operation is limited based on a rank of the first wireless station, the rank indicating a received signal strength indicator (RSSI) measurement accuracy.

Description

[0001] This application is a divisional application of the Chinese patent application filed on March 14, 2017, with application number CN201780022745.X and invention name “Wireless Station and Communication Method”. Technical Field

[0002] The present invention relates to a wireless station and a communication method for performing appropriate wireless communication in an environment where interference between wireless stations occurs. Background Art

[0003] In the IEEE (the Institute of Electrical and Electronics Engineers) 802.11 Task Group (TG) ax, the formulation of the technical specifications of IEEE802.11ax (hereinafter referred to as 11ax) is being carried out as the successor standard of IEEE802.11ac.

[0004] In the IEEE 802.11 standard, BSS (Basic Service Set) is defined as a collection of wireless stations (also called stations or STAs) that constitute a basic wireless network. The BSS is composed of one access point and multiple terminals (wireless stations other than the access point) in infrastructure mode, and multiple terminals in ad hoc mode. To distinguish it from the BSS in infrastructure mode, the BSS in ad hoc mode is called IBSS (Independent BSS). The BSS other than the BSS (intra-BSS) to which the terminal (or access point) belongs is called OBSS (Overlapping BSS) or inter-BSS. In an OBSS, multiple communication cells overlap, so in communication between OBSSs, interference occurs between communication cells, and communication quality deteriorates.

[0005] In wireless communication, due to the influence of the distance between wireless stations and obstacles, etc., a state where wireless signals between wireless stations cannot reach each other may occur (radio wave environment where carrier sense does not work). As a countermeasure for such an environment, that is, an environment where hidden terminals exist, the IEEE802.11 standard provides a function to prevent collisions using NAV (Network Allocation Vector: transmission prohibition period). If the access point and the terminal receive a wireless frame for NAV setting at a level above a predetermined threshold, transmission is prohibited during the NAV period set by the duration information, except when the wireless frame for NAV setting is a frame sent to the terminal or the access point. The minimum reception sensitivity value is generally used as the threshold for determining whether to set NAV.

[0006] In addition, in 11ax, it has been agreed to introduce SR (Spatial Reuse) for reusing wireless resources used by OBSS (refer to non-patent document 1). The purpose of SR is to improve the communication performance in the wireless network by increasing the transmission opportunities of the terminal (or access point) and improving the utilization rate of wireless resources when the interference given to OBSS (hereinafter referred to as given interference) is small. A method for implementing SR, under specific conditions, sets the threshold (hereinafter referred to as OBSS_PD (Power Density)) used to determine whether to set NAV when receiving a wireless frame from OBSS to a value larger than the value of the minimum receiving sensitivity normally used.

[0007] Prior art literature

[0008] Non-patent literature

[0009] Non-patent document 1: Robert Stacey, "Specification Framework for TGax", IEEE802.11-15 / 0132r15

[0010] Non-patent document 2: Sigurd Schelstraete, “Multiple NAVs for Spatial Reuse”, IEEE 802.11-15 / 1348

[0011] Non-patent document 3: Reza Hedayat, "TXOP Considerations for Spatial Reuse," IEEE802.11-15 / 1104 Summary of the invention

[0012] However, when the given interference level to the OBSS is greater than a specified threshold, if the terminal (or access point) misestimates the size of the given interference and releases the conventional NAV, this will cause interference at a level at which the terminals (or access points) in the OBSS cannot correctly decode received signals, causing concern that the communication performance of the wireless network will be degraded.

[0013] Therefore, one aspect of the present invention provides a wireless station and a communication method that prevent inappropriate regular NAV release and improve communication performance.

[0014] A wireless station according to one embodiment of the present invention is a wireless station in a wireless network having multiple wireless stations, comprising: a receiving unit, which receives a trigger signal sent from a first wireless station belonging to an interference cell to a second wireless station belonging to the interference cell; and a transmission prohibition period control unit, which, after setting a transmission prohibition period for other wireless stations in the communication cell to which this station belongs, determines whether to release the transmission prohibition period based on the reception strength of the trigger signal when the receiving unit receives the trigger signal.

[0015] Furthermore, these general or specific methods can be implemented through systems, methods, integrated circuits, computer programs or recording media, or through any combination of systems, devices, methods, integrated circuits, computer programs and recording media.

[0016] According to one aspect of the present invention, inappropriate regular NAV release can be prevented, thereby improving the communication performance of the wireless network. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. 1 is a diagram illustrating the positional relationship between access points and terminals in the first embodiment.

[0018] Figure 2 This is a block diagram showing an example of the configuration of a terminal according to the first embodiment.

[0019] Figure 3 This is a sequence diagram showing an example of the operation of the wireless network when RTS / CTS frames are transmitted and received in the first embodiment.

[0020] Figure 4 This is a sequence diagram showing an example of the operation of the wireless network when trigger frames are transmitted and received in the first embodiment.

[0021] Figure 5 This is a diagram illustrating the positional relationship between access points and terminals constituting a wireless network according to the second embodiment.

[0022] Figure 6 This is a block diagram showing an example of the configuration of a terminal according to the second embodiment.

[0023] Figure 7 This is a diagram illustrating the positional relationship between access points and terminals constituting a wireless network according to the third embodiment.

[0024] Figure 8 This is a block diagram showing an example of the structure of a terminal according to the third embodiment.

[0025] Fig. 9 This is a sequence diagram showing an example of the operation of the wireless network when trigger frames are transmitted and received in the third embodiment.

[0026] Fig.10 This is a sequence diagram showing an example of the operation of the wireless network when trigger frames are transmitted and received in the fourth embodiment.

[0027] Fig.11 This is a diagram illustrating the positional relationship between access points and terminals constituting a wireless network according to the fifth embodiment.

[0028] Fig.12 This is a block diagram showing the structure of a terminal according to the fifth embodiment.

[0029] Fig.13 This is a sequence diagram showing an example of the operation of the wireless network when trigger frames are transmitted and received in the fifth embodiment.

[0030] Fig.14 This is a diagram illustrating the positional relationship between access points and terminals constituting a wireless network according to the sixth embodiment.

[0031] Fig.15 This is a block diagram showing an example of the structure of a terminal according to the sixth embodiment.

[0032] Fig.16 This is a sequence diagram showing an example of the operation of the wireless network when RTS / CTS frames are transmitted and received in the sixth embodiment. DETAILED DESCRIPTION

[0033] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. However, there are cases where a more detailed description than necessary, for example, a detailed description of known matters and a repeated description of substantially the same structure are omitted.

[0034] In addition, the following description and the referenced drawings are provided for those skilled in the art to understand the present invention, and are not intended to limit the scope of the claims of the present invention.

[0035] <How the Invention Was Completed>

[0036] Hereinafter, the process leading to the completion of the present invention will be briefly described.

[0037] In 11ax, it is agreed to manage NAVs differently in each of the intra-BSS and OBSS (see non-patent document 2). This avoids the situation where the NAV of the intra-BSS is released due to a NAV release request (CF-End: Contention Free-End) from the OBSS, and the NAV of the OBSS is released due to the CF-End of the intra-BSS. In 11ax, in order to simplify SR processing, when there are multiple OBSSs, the terminal (or access point) does not distinguish NAVs for each OBSS, but manages two NAVs: intra-BSS NAV and regular NAV (NAV of the OBSS, or NAV when the OBSS is not distinguished as intra-BSS).

[0038] Moreover, in 11ax, as one of the SR methods, it is proposed to release the conventional NAV even when a CF-End frame (NAV release request frame) is received except under specified conditions (non-patent document 3). In this method, the size of a given interference to the terminal (or access point) of the OBSS is estimated by using a combination of a trigger signal and a response signal, and the conventional NAV is released. In the case where the size of the given interference of the OBSS is suppressed to be less than a specified threshold value derived empirically, for example, according to this method, the effect of SR is further improved.

[0039] In the following reference non-patent document 1, it is disclosed that a terminal (or access point) releases a normal NAV when the following conditions are met. The first condition is that when an inter-BSS RTS (Request To Send) frame is received, the RSSI (Received Signal Strength Indicator) is higher than OBSS_PD (a threshold value applicable to the case where the object is OBSS). The second condition is that when an inter BSS CTS (Clear To Send) frame is received, the RSSI is lower than the prescribed NAV release threshold.

[0040] Reference Non-Patent Document 1: Reza Hedayat, “Recipient-aware Spatial Reuse,” IEEE802.11-16 / 0060

[0041] In addition, the following reference non-patent document 2 discloses that when the RSSI of the trigger frame is lower than OBSS_PD, the terminal (or access point) releases the normal NAV upon detection of the UL MU PPDU (UpLink Multi-User Physicallayer convergence Protocol Data Unit) sent in succession to the trigger frame.

[0042] Reference Non-Patent Document 2: Geonjung Ko, “Improving Spatial Reuse During OBSS ULMU Procedure”, IEEE 802.11-15 / 1338

[0043] However, in the case where the measurement accuracy of the RSSI of the terminal is low, or the distance between the terminals is close, the conventional NAV is sometimes released by mistake. As a result, interference such as OBSS_PD or above is sometimes generated for the terminal (or access point) of the OBSS, and the desired signal cannot be received correctly. From this reason, it is desired to prevent the release of inappropriate conventional NAV. In the embodiments of the present invention described below, a wireless station and a communication method for preventing the release of inappropriate conventional NAV and improving the communication performance of the wireless network are described. Furthermore, the terminal or access point in each of the following embodiments corresponds to a wireless station.

[0044] <First embodiment>

[0045] Figure 1 FIG. 1 is a diagram illustrating the positional relationship between access points and terminals constituting the wireless network 100 according to the first embodiment. Figure 1 As shown, there are access point A, terminal B, terminal C, and access point D. Access point A and terminal B belong to BSS1 (OBSS), and terminal C and access point D belong to BSS2 (intra-BSS).

[0046] [Description of structure]

[0047] Figure 2 This is a block diagram showing an example of the configuration of the terminal 200 according to the first embodiment. Figure 2 The terminal 200 illustrated in the example corresponds to Figure 1 Terminal C is shown. Furthermore, Figure 1 The structure of access points A and D and terminal B shown can also be Figure 1 The terminal 200 shown has the same structure.

[0048] like Figure 2As shown, the terminal 200 includes a transmitting and receiving antenna 201, a wireless transmitting and receiving unit 202, a transmitting signal generating unit 203, a receiving signal demodulating and decoding unit 204, an RSSI measuring unit 205, a BSS type determining unit 206, a transmitting control unit 207, a transmitting buffer 208, a MAC frame generating unit 209, a transmitting prohibited state setting unit 210, and a terminal information setting unit 211. In addition, the BSS type determining unit 206, the transmitting control unit 207, the transmitting buffer 208, the MAC frame generating unit 209, the transmitting prohibited state setting unit 210, and the terminal information setting unit 211 constitute an access control unit 212 (MAC).

[0049] The transmitting / receiving antenna 201 is at least one antenna, and performs transmission or reception of wireless signals.

[0050] When transmitting, the wireless transmission and reception unit 202 performs predetermined wireless transmission processing such as D / A conversion and up-conversion to a carrier frequency on the transmission signal input from the transmission signal generation unit 203, and transmits the transmission signal through the transmission and reception antenna 201. When receiving, the wireless transmission and reception unit 202 performs predetermined wireless reception processing such as down-conversion and A / D conversion on the wireless signal received through the transmission and reception antenna 201, and outputs the received wireless signal to the reception signal demodulation and decoding unit 204 and the RSSI measurement unit 205.

[0051] The transmission signal generating unit 203 encodes and modulates the MAC frame input from the MAC frame generating unit 209, adds a pilot signal for frequency synchronization and timing synchronization on the receiving side, and a control signal (also called a preamble) such as a channel estimation signal to generate a wireless frame (also called PPDU), and outputs it to the wireless transmitting and receiving unit 202.

[0052] The received signal demodulation and decoding unit 204 extracts the wireless frame by performing autocorrelation processing on the wireless signal after the wireless reception processing input from the wireless transmission and reception unit 202, and demodulates and decodes the wireless frame. In addition, the received signal demodulation and decoding unit 204 extracts the preamble information (control signal of the wireless frame) and the MAC frame from the wireless signal input from the wireless transmission and reception unit 202, outputs the preamble information to the BSS type determination unit 206, and outputs the MAC frame to the transmission prohibition state setting unit 210.

[0053] RSSI measurement section 205 measures RSSI based on the wireless signal after wireless reception processing input from wireless transmission and reception section 202 , and outputs RSSI information including the measurement result to transmission prohibition state setting section 210 .

[0054] The BSS category determination unit 206 extracts the identifier information of the BSS (hereinafter referred to as BSS color) included in the preamble information input from the received signal demodulation and decoding unit 204, and determines the category of the BSS to which the terminal (or access point) that has transmitted the received wireless signal belongs. The BSS category determination unit 206 determines that the BSS is an intra-BSS when the BSS color included in the preamble information is the same as the BSS color of the BSS to which the terminal 200 belongs, and determines that the BSS is an OBSS when it is not the same. The BSS category determination unit 206 outputs the determination result as BSS category information (information indicating whether it is an intra-BSS category) to the transmission prohibition state setting unit 210.

[0055] The transmission control unit 207 performs transmission control based on the transmission prohibition state information (information indicating that transmission is prohibited, that is, indicating whether NAV is set) input from the transmission prohibition state setting unit 210 and the buffer state information (information indicating whether there is transmission data) input from the transmission buffer 208. Specifically, when NAV is not set and there is transmission data in the transmission buffer 208, the transmission control unit 207 outputs a transmission data generation instruction to the transmission data generation unit.

[0056] Transmission buffer 208 stores transmission data transmitted by terminal 200 to other terminals (or access points) and outputs buffer status information indicating the presence or absence of transmission data to transmission control unit 207.

[0057] MAC frame generation section 209 performs MAC frame generation processing such as adding a MAC header to the transmission data input from transmission buffer 208 based on the transmission data generation instruction input from transmission control section 207 . MAC frame generation section 209 outputs the generated MAC frame to transmission signal generation section 203 .

[0058] The transmission prohibition state setting unit 210 sets the NAV based on the RSSI information input from the RSSI measurement unit 205, the MAC frame input from the received signal demodulation and decoding unit 204, the RSSI measurement accuracy information input from the terminal information setting unit 211, and the BSS type information input from the BSS type determination unit 206.

[0059] Specifically, transmission prohibition state setting section 210 sets NAV in the case of a MAC frame instructing NAV setting such as an RTS / CTS frame. Transmission prohibition state setting section 210 also releases NAV when the set NAV period expires or when a CF-End frame instructing NAV release is received.

[0060] Furthermore, when setting NAV, the transmission prohibition state setting unit 210 distinguishes the states of the intra-BSS NAV and the normal NAV, and performs the above-mentioned NAV setting and NAV release for each NAV. Specifically, for example, when receiving a MAC frame of the intra-BSS, the transmission prohibition state setting unit 210 performs the setting of the intra-BSS, and when receiving a MAC frame of the OBSS, the normal NAV is set.

[0061] However, the transmission prohibition state setting unit 210 uses the NAV release determination method described later to determine whether to release the NAV. In this determination, if the determination to release the NAV is made, the normal NAV is released even in the case other than the above (when the set NAV period expires or when a CF-End frame is received). The transmission prohibition state setting unit 210 outputs transmission prohibition state information related to NAV setting or NAV release to the transmission control unit 207.

[0062] The terminal information setting unit 211 outputs the RSSI measurement accuracy information of the terminal 200 to the transmission prohibition state setting unit 210. In 11ax, two types of terminal levels (also called ST level A) with different required accuracy such as RSSI measurement accuracy are supported, and the RSSI measurement accuracy information is information set based on the terminal level of the terminal 200.

[0063] According to such a structure, in the first embodiment, by setting the threshold for the release judgment of the normal NAV in consideration of the RSSI measurement accuracy, it is possible to prevent a terminal with low RSSI measurement accuracy from inappropriately releasing the NAV based on the RSSI measurement error, thereby causing a large given interference to the OBSS. A specific operation example of the wireless network 100 according to the first embodiment is described below.

[0064] [Action examples]

[0065] Figure 3 1 is a sequence diagram showing an example of the operation of the wireless network 100 when sending and receiving RTS / CTS frames in the first embodiment. Figure 3 As shown, first, terminal B performs a transmission process of an RTS (Request to Send: a trigger signal of CTS) frame for requesting CTS transmission from access point A (ST101). Terminal C performs a reception process of an RTS frame from terminal B (ST102). The RTS frame reception process includes RSSI measurement of the RTS frame. In addition, the RSSI measurement method is not particularly limited in the present invention, and a known RSSI measurement method can be used. Terminal C sets a normal NAV based on RTS (ST103).

[0066] Next, access point A responds to the RTS frame from terminal B by sending a response signal, namely a CTS (Clear to Send) frame (ST104). If terminal C receives the CTS from access point A, it measures the RSSI (ST105). Terminal C determines whether to release the normal NAV based on the RSSI of the CTS frame (ST106). The details of the method for determining whether to release the normal NAV in ST106 will be described later.

[0067] exist Figure 3 , illustrates a case where it is determined in ST106 that the normal NAV is not to be released. In this case, terminal C updates the normal NAV based on the CTS frame (ST107). Next, terminal B sends data to access point A (ST108). At this time, since the normal NAV is set in terminal C, terminal C does not send data to access point D.

[0068] on the other hand, Figure 4 1 is a sequence diagram showing an example of the operation of the wireless network 100 when trigger frame transmission and reception are performed in the first embodiment. Figure 4 In the example, it is assumed that terminal C pre-sets a conventional NAV.

[0069] like Figure 4 As shown, first, access point A performs a trigger frame transmission process for terminal B (ST201). Terminal C performs a trigger frame reception process from access point A (ST202). The trigger frame reception process includes RSSI measurement of the trigger frame. Terminal C determines whether to release the normal NAV based on the RSSI measurement result of the trigger frame (ST203). The details of the normal NAV determination method in ST203 will be described later.

[0070] exist Figure 4 , illustrates a case where it is determined in ST203 that the normal NAV is not to be released. In this case, terminal C updates the normal NAV according to the trigger frame (ST204). Next, terminal B sends data to access point A (ST205). At this time, since the normal NAV is set in terminal C, terminal C does not send data to access point D.

[0071] [NAV release determination method 1]

[0072] The following explains Figure 3 ST106 shown, or Figure 4 The details of the method for determining whether to release the normal NAV in ST203 are shown.

[0073] The NAV release determination method 1 described below corresponds to Figure 3The determination method in ST106. In NAV release determination method 1, terminal C sets the threshold for determining NAV release based on the RSSI measurement accuracy information of the terminal or the terminal class (STA Classes). Terminal C sets the threshold for the trigger signal (first threshold) and the threshold for the response signal (second threshold). Here, the trigger signal is, for example, an RTS frame, and the response signal is, for example, a CTS frame. The first threshold and the second threshold are set higher than the threshold for the intra-BSS signal.

[0074] 11ax supports two types of terminal levels with different requirements for RSSI measurement accuracy. Level A is a high-performance terminal, and the RSSI measurement accuracy is required to be within ±2dB. On the other hand, level B is a low-performance terminal, and the RSSI measurement accuracy is required to be within ±5dB. That is, in a level B terminal, a maximum RSSI measurement error of 3dB is allowed for a level A terminal.

[0075] Therefore, in order to keep the given interference to other terminals caused by the RSSI measurement error of the terminal of class B within the same level as that of class A, it is necessary to set a threshold value different from that of class A in the terminal of class B. Specifically, the first threshold value in the terminal of class B is set 3dB higher than the first threshold value in class A, and the second threshold value in the terminal of class B is set 3dB lower than the second threshold value in class A. The so-called 3dB value is a value based on the difference in RSSI measurement accuracy required for the terminal of class A and the terminal of class B. In addition, the first threshold value may be set to be greater than the second threshold value.

[0076] Then, upon receiving a trigger signal (RTS frame) from the OBSS ( Figure 3 In step ST102), terminal C measures the RSSI of the RTS frame to determine whether it is higher than the first threshold. Furthermore, terminal C measures the RSSI of the response signal (CTS frame) subsequently sent from the OBSS to determine whether it is lower than the second threshold. When the RSSI of the RTS frame is higher than the first threshold and the RSSI of the CTS frame is lower than the second threshold, terminal C releases the normal NAV. Furthermore, terminal C may not determine whether the RSSI of the RTS frame is higher than the first threshold, but may determine whether to release the normal NAV based only on the result of determining whether the RSSI of the CTS frame is lower than the second threshold.

[0077] According to such a determination method, even when terminal C is a class B terminal, that is, a terminal with relatively low RSSI measurement accuracy, a conventional NAV release determination can be made based on a threshold value set in consideration of the measurement accuracy. Therefore, even when terminal C is a class B terminal, that is, a terminal with relatively low RSSI measurement accuracy, the interference caused to the OBSS terminal (or access point) can be reduced. Therefore, inappropriate conventional NAV release can be prevented, and the communication performance of the wireless network can be improved. Furthermore, the first threshold or the second threshold in the class A terminal can be set to OBSS_PD, for example.

[0078] [NAV release determination method 2]

[0079] The NAV release determination method 2 described below corresponds to Figure 4 In the NAV release determination method 2, terminal C sets the threshold for determining NAV release based on the RSSI measurement accuracy information of the terminal or the terminal level. Terminal C sets the threshold for the trigger signal. Here, the trigger signal is, for example, a trigger frame. The threshold is set higher than the threshold for the intra-BSS signal.

[0080] In NAV release determination method 2, the aspect of using the RSSI of the trigger frame for determination is different from determination method 1. When a trigger frame is received from OBSS, terminal C determines whether the RSSI of the trigger frame is lower than a threshold. When the RSSI of the trigger frame is lower than the threshold, terminal C releases the normal NAV. Furthermore, the threshold setting method may be the same as the setting method of the second threshold in the above-mentioned NAV release determination method 1 (i.e., set to be 3dB lower than OBSS_PD), or a different setting method may be used.

[0081] According to such a determination method, similar to NAV release determination method 1, even when terminal C is a terminal with relatively low RSSI measurement accuracy, a conventional NAV release determination can be performed based on a threshold value set in consideration of measurement accuracy. Therefore, even when terminal C is a terminal with relatively low RSSI measurement accuracy, interference to the terminal (or access point) of the OBSS can be reduced. Therefore, inappropriate conventional NAV release can be prevented, and the communication performance of the wireless network can be improved.

[0082] <Second embodiment>

[0083] Hereinafter, a second embodiment will be described. Figure 5 1 is a diagram illustrating the positional relationship between access points and terminals constituting a wireless network 100' according to the second embodiment. Figure 5As shown, in the wireless network 100', the access point A and the terminal B belong to BSS1 (OBSS), and the terminal C and the access point D belong to BSS2 (intra-BSS). Figure 1 The first embodiment shown is the same, but the distance between the terminal B and the terminal C is closer than that in the first embodiment.

[0084] Thus, when the distance between terminal B and terminal C is relatively close, the RSSI of the signal transmitted from terminal C to terminal B is close to the RSSI of the signal transmitted from access point A to terminal B, and the reception quality of the signal transmitted from access point A to terminal B may be reduced due to interference from terminal C. In such a case, the possibility of failure in reception from access point A at terminal B increases. In the second embodiment, a wireless network 100' that can perform communication appropriately without reducing the communication quality even in such a case will be described.

[0085] [Description of structure]

[0086] Figure 6 This is a block diagram showing an example of the configuration of a terminal 200 ′ according to the second embodiment. Figure 6 The terminal 200′ shown in the example corresponds to Figure 5 Terminal C is shown. Furthermore, Figure 5 The structure of the access points A and D and the terminal B shown can also be the same as Figure 6 The terminal 200' shown has the same structure.

[0087] like Figure 6 As shown in the figure, the terminal 200' has a transmitting and receiving antenna 201, a wireless transmitting and receiving unit 202, a transmitting signal generating unit 203, a receiving signal demodulating and decoding unit 204, an RSSI measuring unit 205, a BSS type determining unit 206, a transmitting control unit 207, a transmitting buffer 208, a MAC frame generating unit 209, and a transmitting prohibited state setting unit 210. In addition, the BSS type determining unit 206, the transmitting control unit 207, the transmitting buffer 208, the MAC frame generating unit 209, and the transmitting prohibited state setting unit 210 constitute an access control unit 212' (MAC). That is, the terminal 200' in the second embodiment is different from the terminal 200' in the second embodiment in that the terminal information setting unit 211 is not provided. Figure 2 The configuration of the terminal 200 in the first embodiment shown is different. Also, the operation of the transmission prohibition state setting unit 210 is slightly different from that in the first embodiment.

[0088] The transmission prohibition state setting unit 210 sets NAV based on the RSSI information input from the RSSI measurement unit 205, the MAC frame input from the received signal demodulation and decoding unit 204, and the BSS type information input from the BSS type determination unit 206. In addition, when the set NAV period expires or when a CF-End frame instructing NAV release is received, the transmission prohibition state setting unit 210 releases the NAV.

[0089] Furthermore, when setting the NAV, the transmission prohibition state setting unit 210 distinguishes the states of the intra-BSS NAV and the normal NAV, and performs the above-mentioned NAV setting and NAV release for each NAV. Specifically, for example, when receiving a MAC frame of the intra-BSS, the transmission prohibition state setting unit 210 performs the setting of the intra-BSS, and when receiving a MAC frame of the OBSS, the normal NAV is set.

[0090] However, the transmission prohibition state setting unit 210 uses the NAV release determination method described later to determine whether to release the NAV. If the determination to release the NAV is made in the determination, the normal NAV is released even in addition to the above. The transmission prohibition state setting unit 210 outputs the transmission prohibition state information related to the NAV setting or NAV release to the transmission control unit 207.

[0091] [Action examples]

[0092] The operation example of the wireless network 100' in the second embodiment is similar to Figure 3 or Figure 4 The operation examples shown are the same, so the description is omitted. Figure 3 ST106, or Figure 4 The NAV release determination method in ST203 of the embodiment is slightly different from the NAV release determination methods 1 and 2 described in the first embodiment. The NAV release determination method in the second embodiment will be described below.

[0093] [NAV release determination method]

[0094] The NAV release determination method described below corresponds to Figure 3 In the NAV release determination method in the second embodiment, terminal C sets a threshold value (third threshold value) for the upper limit value of the trigger signal, a threshold value (fourth threshold value) for the lower limit value of the trigger signal, and a threshold value (second threshold value) for the response signal. Here, the trigger signal is, for example, an RTS frame, and the response signal is, for example, a CTS frame. The third threshold value, the fourth threshold value, and the second threshold value are set to be higher than the threshold value for the intra-BSS signal.

[0095] Upon receiving a trigger signal (RTS frame) from OBSS ( Figure 3 In ST102), terminal C measures the RSSI of the RTS frame, determines whether it is higher than the third threshold, and determines whether it is lower than the fourth threshold. That is, terminal C determines whether the RSSI of the RTS frame is within a specified range specified by the third threshold and the fourth threshold.

[0096] Terminal C then measures the RSSI of the response signal (CTS frame) sent from the OBSS to determine whether it is lower than the second threshold. When the RSSI of the RTS frame is within the specified range and the RSSI of the CTS frame is lower than the second threshold, terminal C releases the normal NAV.

[0097] The third threshold may be, for example, OBSS_PD. The fourth threshold may be a predetermined threshold greater than the third threshold. For example, the fourth threshold is a value obtained by adding a positive offset value to the third threshold. This can reduce the amount of signaling required for notification of the fourth threshold.

[0098] Thus, in the second embodiment, the RSSI of the trigger signal from the OBSS is within the prescribed range (a range higher than the third threshold and lower than the fourth threshold), and only when the RSSI of the response signal is lower than the second threshold, the NAV is released in the terminal C. Therefore, in the case where the distance between the access point A and the terminal C is relatively close, and when the reception quality in the terminal B is expected to be reduced due to the interference of the terminal C, by preventing the NAV release when the RSSI of the trigger signal is not within the prescribed range, the degradation of the communication performance in the wireless network 100' can be reduced. Therefore, it is possible to prevent inappropriate regular NAV release and improve the communication performance of the wireless network.

[0099] Furthermore, in the operation example of the second embodiment described above, an operation example of sending and receiving RTS / CTS frames is described, but the present invention is not limited thereto. That is, the second embodiment can also be applied to sending and receiving trigger frames.

[0100] <Third embodiment>

[0101] Hereinafter, a third embodiment will be described. Figure 7 1 is a diagram illustrating the positional relationship between access points and terminals constituting a wireless network 100" according to the third embodiment. Figure 7 As shown, in the presence of terminal E belonging to BSS1 (OBSS), Figure 1 The wireless network 100 of the first embodiment shown is different.

[0102] In such a structure, access point A sometimes sends a trigger frame requesting MU-BA (Multi-User Block Ack) transmission to multiple terminals such as terminal B and terminal E. Block Ack is specified by IEEE802.11e to respond to multiple received data in one frame. In addition, MU-BA multiplexes block Ack transmission among multiple users through MU (Multi-User) multiplexing. In addition, MU multiplexing refers to frequency multiplexing and spatial multiplexing of multiple terminals.

[0103] In such a case, the MU-BA transmission from the terminal B and the terminal E that received the trigger frame may not be received by the access point A due to interference from, for example, the terminal C. If such a situation occurs, the access point A retransmits the trigger frame requesting MU-BA transmission again to the terminal B and the terminal E, so the communication volume increases, which will reduce the communication performance of the wireless network 100". In the third embodiment, a wireless network 100" is described in which communication can be properly performed without reducing the communication quality even in such a situation.

[0104] [Description of structure]

[0105] Figure 8 This is a block diagram showing an example of the structure of a terminal 200 according to the third embodiment. Figure 8 The terminal 200" shown in the example corresponds to Figure 7 Terminal C is shown. Furthermore, Figure 7 The structures of the access points A and D and the terminals B and E shown can also be the same as Figure 8 The terminal 200" shown in FIG.

[0106] like Figure 8 As shown, the terminal 200" has a transmitting and receiving antenna 201, a wireless transmitting and receiving unit 202, a transmitting signal generating unit 203, a receiving signal demodulating and decoding unit 204, a BSS category determining unit 206, a transmitting control unit 207, a transmitting buffer 208, a MAC frame generating unit 209, a transmitting prohibited state setting unit 210, and a trigger information analyzing unit 213. In addition, the BSS category determining unit 206, the transmitting control unit 207, the transmitting buffer 208, the MAC frame generating unit 209, the transmitting prohibited state setting unit 210, and the trigger information analyzing unit 213 constitute an access control unit 212" (MAC). That is, in terms of not having an RSSI measuring unit and a terminal information setting unit 211, but having a trigger information analyzing unit 213, the terminal 200" in the third embodiment is the same as Figure 2 The configuration of the terminal 200 in the first embodiment shown is different. Also, the operation of the transmission prohibition state setting unit 210 is different between the first embodiment and the second embodiment.

[0107] The trigger information analysis unit 213 extracts trigger type information related to the trigger type from the trigger frame input from the received signal demodulation and decoding unit 204 , and outputs the information to the transmission prohibition state setting unit 210 .

[0108] The transmission prohibition state setting unit 210 sets NAV based on the MAC frame input from the received signal demodulation and decoding unit 204, the BSS type information input from the BSS type determination unit 206, and the trigger type input from the trigger information analysis unit 213. In addition, when the set NAV period expires or a CF-End frame instructing NAV release is received, the transmission prohibition state setting unit 210 releases the NAV.

[0109] Furthermore, when setting the NAV, the transmission prohibition state setting unit 210 distinguishes the states of the intra-BSS NAV and the normal NAV, and performs the above-mentioned NAV setting and NAV release for each NAV. Specifically, for example, when receiving a MAC frame of the intra-BSS, the transmission prohibition state setting unit 210 performs the setting of the intra-BSS, and when receiving a MAC frame of the OBSS, the normal NAV is set.

[0110] However, the transmission prohibition state setting unit 210 uses the NAV release determination method described later to determine whether to release the NAV. If the determination to release the NAV is made in the determination, the normal NAV is released even in addition to the above. The transmission prohibition state setting unit 210 outputs the transmission prohibition state information related to the NAV setting or the NAV release to the transmission control unit 207.

[0111] [Action examples]

[0112] Fig. 9 1 is a sequence diagram showing an example of the operation of the wireless network 100" when trigger frame transmission and reception are performed in the third embodiment. Fig. 9 In the example, it is assumed that terminal C has preset a conventional NAV.

[0113] like Fig. 9 As shown, first, the access point A transmits a trigger frame requesting MU-BA transmission to the terminal B and the terminal E (ST301).

[0114] When receiving the trigger frame from access point A, terminal C identifies the trigger type (ST302). Terminal C determines whether to release the normal NAV based on the identification result in ST302 (ST303). The details of the normal NAV determination method in ST303 will be described later.

[0115] exist Fig. 9In FIG. 1 , a case where it is determined in ST303 that the normal NAV is not to be released is illustrated. In this case, terminal C continues the normal NAV and maintains the transmission prohibition state.

[0116] Next, the terminal B and the terminal E perform MU-BA transmission to the access point A (ST304 and ST305). At this time, since the normal NAV is set in the terminal C, the terminal C does not perform transmission to the access point D.

[0117] [NAV release determination method]

[0118] The following explains Fig. 9 The details of the method of determining whether to release the normal NAV in ST303 are shown.

[0119] In 11ax, MU-BA is sent in UL MU PPDU. As mentioned above, when receiving MU-BA from multiple terminals, if the reception on the access point A side fails due to interference, the communication volume increases due to the retransmission of the trigger frame and MU-BA, and the communication performance of the wireless network 100" decreases. Therefore, it is expected that no interference will be generated. In addition, the PPDU length in MU-BA is shorter, so the effect of conventional NAV release is small.

[0120] Therefore, in the third embodiment, when receiving a trigger frame, terminal C extracts the trigger type information and determines the trigger type, and does not release the normal NAV if the trigger type is MU-BAR (Multi-User Block Ack Request) requesting MU-BA transmission.

[0121] Thus, in the third embodiment, whether to release the normal NAV is determined based on the trigger type, and the normal NAV is not released when the trigger type is MU-BAR. Thus, MU-BA is sent and received preferentially, and a decrease in the communication performance of the wireless network 100" caused by the retransmission of the trigger frame and MU-BA can be prevented, and the effect of SR can be maintained. Furthermore, when it is determined that the received trigger frame is a trigger type other than MU-BAR, terminal C can maintain the effect of SR by performing the NAV control as before. Therefore, inappropriate release of the normal NAV can be prevented, and the communication performance of the wireless network can be improved.

[0122] Furthermore, in the third embodiment, the case where access point A, terminal B, and terminal E belong to the OBSS and access point A sends a trigger frame including MU-BAR to terminal B and terminal E is described, but the present invention is not limited to this. For example, even if more terminals belong to the OBSS and access point A sends MU-BAR to these terminals, the third embodiment can also be applied.

[0123] <Fourth embodiment>

[0124] The fourth embodiment will be described below. The positional relationship between the access points and the terminals constituting the wireless network 100" of the fourth embodiment is as follows: Figure 7 The same is true for the wireless network 100" of the third embodiment illustrated in FIG.

[0125] exist Figure 7 In a wireless network 100" as illustrated in the figure, if the number of terminals that perform SR-based multiplexing with access point A (MU multiplexing number) is large, the probability of reception failure due to SR increases due to the influence of the positional relationship between the terminals and the RSSI measurement accuracy. In addition, if the multiplexing number is large, the noise increases and the influence of interference caused by terminal C becomes larger. Therefore, in the fourth embodiment, a wireless network 100" is described in which communication can be properly performed without reducing the communication quality even in the case of a large number of multiplexing numbers.

[0126] [Description of structure]

[0127] The structure of the terminal 200" in the fourth embodiment is also the same as Figure 8 The terminal 200" of the third embodiment shown is the same. However, the operations of the transmission prohibition state setting unit 210 and the trigger information analysis unit 213 are slightly different from those of the third embodiment.

[0128] The trigger information analyzing section 213 extracts the multiplexing number information related to the MU multiplexing number included in the trigger frame input from the received signal demodulating and decoding section 204 , and outputs the extracted information to the transmission prohibition state setting section 210 .

[0129] The transmission prohibition state setting unit 210 sets NAV based on the MAC frame input from the received signal demodulation and decoding unit 204, the BSS type information input from the BSS type determination unit 206, and the multiplexing number information input from the trigger information analysis unit 213. In addition, when the set NAV period expires or when a CF-End frame instructing NAV release is received, the transmission prohibition state setting unit 210 releases the NAV.

[0130] Furthermore, when setting the NAV, the transmission prohibition state setting unit 210 distinguishes the states of the intra-BSS NAV and the normal NAV, and performs the above-mentioned NAV setting and NAV release for each NAV. Specifically, for example, when receiving a MAC frame of the intra-BSS, the transmission prohibition state setting unit 210 performs the setting of the intra-BSS, and when receiving a MAC frame of the OBSS, the normal NAV is set.

[0131] However, the transmission prohibition state setting unit 210 uses the NAV release determination method described later to determine whether to release the NAV. If the determination to release the NAV is made in the determination, the normal NAV is released even in addition to the above. The transmission prohibition state setting unit 210 outputs the transmission prohibition state information related to the NAV setting or NAV release to the transmission control unit 207.

[0132] [Action examples]

[0133] Fig.10 1 is a sequence diagram showing an example of the operation of the wireless network 100" when trigger frame transmission and reception are performed in the fourth embodiment. Fig.10 In the example, it is assumed that terminal C pre-sets a conventional NAV.

[0134] like Fig.10 As shown, first, the access point A transmits a trigger frame requesting the terminal B and the terminal E (if there are more terminals in the OBSS, the terminal may be included in them) to transmit data (ST401).

[0135] When receiving the trigger frame from the access point A, the terminal C extracts information related to the MU multiplexing number (ST402). The information related to the MU multiplexing number is included in the trigger frame, for example.

[0136] Terminal C determines whether to release the normal NAV based on the information on the MU multiplexing number extracted in ST402 (ST403). The details of the normal NAV determination method in ST403 will be described later.

[0137] exist Fig.10 In FIG. 4 , a case where it is determined in ST403 that the normal NAV is not to be released is illustrated. In this case, the terminal C continues the normal NAV and maintains the transmission prohibition state.

[0138] Next, terminal B and terminal E transmit data to access point A (ST404 and ST405). At this time, terminal C does not transmit data to access point D because normal NAV is set in terminal C.

[0139] [NAV release determination method]

[0140] The following explains Fig.10 The details of the method of determining whether to release the normal NAV in ST403 are shown in FIG. 1. That is, when the MU multiplexing number notified by the trigger frame is higher than a predetermined threshold, the terminal C does not release the normal NAV.

[0141] Thus, in the fourth embodiment, whether to release the normal NAV is determined based on the MU multiplexing number, and the normal NAV is not released when the MU multiplexing number is higher than a predetermined threshold. Thus, a decrease in the communication performance of the wireless network 100" caused by data retransmission can be prevented, and the SR effect can be maintained. Furthermore, when the MU multiplexing number is below a predetermined threshold, terminal C can maintain the SR effect by performing the NAV control as before. Therefore, inappropriate release of the normal NAV can be prevented, and the communication performance of the wireless network can be improved.

[0142] <Fifth embodiment>

[0143] Hereinafter, a fifth embodiment will be described. Fig.11 1 is a diagram illustrating the positional relationship between access points and terminals constituting a wireless network 100"' according to the fifth embodiment. Fig.11 As shown, in the wireless network 100'', the distance from terminal B to access point A is almost equal to the distance from terminal C to access point A, or is within a predetermined difference.

[0144] In such a case, the RSSI of the signal transmitted from terminal B to access point A is close to the RSSI of the signal transmitted from terminal C to access point A. This is because the strength of the signal transmitted from terminal B (desired signal) and the signal transmitted from terminal C (interference signal) are almost the same at access point A, so the reception quality at access point A may be reduced. In the fifth embodiment, a wireless network 100'' that can perform communication appropriately without reducing the communication quality even in such a situation is described.

[0145] [Description of structure]

[0146] Fig.12 This is a block diagram showing the structure of a terminal 200''' according to the fifth embodiment. Fig.12 The terminal 200"' shown in the example corresponds to Fig.11 Terminal C is shown. Furthermore, Fig.11 The structure of the access points A and D and the terminal B shown can also be the same as Fig.12 The terminal 200'' shown has the same structure.

[0147] Fig.12As shown, the terminal 200'' has a transmitting and receiving antenna 201, a wireless transmitting and receiving unit 202, a transmitting signal generating unit 203, a receiving signal demodulating and decoding unit 204, an RSSI measuring unit 205, a BSS category determining unit 206, a transmitting control unit 207, a transmitting buffer 208, a MAC frame generating unit 209, a transmitting prohibited state setting unit 210, and a trigger information analyzing unit 213. In addition, the BSS category determining unit 206, the transmitting control unit 207, the transmitting buffer 208, the MAC frame generating unit 209, the transmitting prohibited state setting unit 210, and the trigger information analyzing unit 213 constitute an access control unit 212'' (MAC). That is, the terminal 200'' in the fifth embodiment is different from the first embodiment in that it does not have a terminal information setting unit 211 but has a trigger information analyzing unit 213. Figure 2 The configuration of the terminal 200 in the first embodiment shown is different. Also, the operation of the transmission prohibition state setting unit 210 is slightly different from that in the first embodiment.

[0148] The trigger information analyzing unit 213 extracts the target RSSI and AP Tx power included in the trigger frame input from the received signal demodulating and decoding unit 204 , and outputs the extracted information to the transmission disabled state setting unit 210 .

[0149] The transmission prohibition state setting unit 210 sets NAV based on the MAC frame input from the received signal demodulation and decoding unit 204, the BSS category information input from the BSS category determination unit 206, and the target RSSI and AP Tx power input from the trigger information analysis unit 213. In addition, when the set NAV period expires or a CF-End frame instructing NAV release is received, the transmission prohibition state setting unit 210 releases the NAV.

[0150] Furthermore, when setting the NAV, the transmission prohibition state setting unit 210 distinguishes the states of the intra-BSS NAV and the normal NAV, and performs the above-mentioned NAV setting and NAV release for each NAV. Specifically, for example, when receiving a MAC frame of the intra-BSS, the transmission prohibition state setting unit 210 performs the setting of the intra-BSS, and when receiving a MAC frame of the OBSS, the normal NAV is set.

[0151] However, the transmission prohibition state setting unit 210 uses the NAV release determination method described later to determine whether to release the NAV. If the determination to release the NAV is made in the determination, the normal NAV is released even in addition to the above. The transmission prohibition state setting unit 210 outputs the transmission prohibition state information related to the NAV setting or NAV release to the transmission control unit 207.

[0152] [Action examples]

[0153] Fig.13 1 is a sequence diagram showing an example of the operation of the wireless network 100'' when trigger frame transmission and reception are performed in the fifth embodiment. Fig.13 In the example, it is assumed that terminal C has preset a conventional NAV.

[0154] like Fig.13 As shown, first, access point A sends a trigger frame to terminal B (ST501). Terminal C performs a trigger frame reception process from access point A (ST502). The trigger frame reception process includes extraction of target RSSI and AP Tx power and measurement of RSSI. Terminal C estimates the RSSI that can be measured by access point A when terminal C transmits data based on the RSSI of the trigger frame and the AP Tx power extracted from the trigger frame (ST503). Then, terminal C determines whether the RSSI estimated in ST503 is higher than the value obtained by adding the target RSSI to the prescribed allowable interference amount, and based on the determination result, determines whether to release the normal NAV (ST504). The details of the determination method of the normal NAV in ST504 will be described later.

[0155] exist Fig.13 In FIG. 5 , a case where it is determined in ST503 that the normal NAV is not to be released is illustrated. In this case, terminal C continues the normal NAV and maintains the transmission prohibition state.

[0156] Next, terminal B transmits data to access point A (ST505). At this time, normal NAV is set in terminal C, so terminal C does not transmit data to access point D.

[0157] [NAV release determination method]

[0158] The following explains Fig.13 The details of the method of determining whether to release the normal NAV in ST504 are shown.

[0159] As described above, if a trigger frame from the OBSS is received, the terminal C estimates the RSSI that can be measured by the access point A of the OBSS when the terminal C transmits data based on the RSSI of the trigger frame and the AP Tx power extracted from the trigger frame. Based on this, the terminal C determines whether the estimated RSSI is higher than the value obtained by adding the target RSSI to the prescribed allowable interference amount. In the case where the estimated RSSI is higher than the value obtained by adding the target RSSI to the prescribed allowable interference amount, the terminal C does not release the normal NAV. Furthermore, the prescribed allowable interference amount is a preset margin.

[0160] Thus, in the fifth embodiment, the strength (target RSSI) of the transmission signal (expected signal) from terminal B in access point A is compared with the strength (estimated RSSI) of the transmission signal (interference signal) from terminal C, and when the estimated RSSI is higher than the value obtained by adding the target RSSI to the prescribed allowable interference amount, terminal C does not release the normal NAV. Thus, the degradation of the communication performance in the wireless network 100'' can be reduced. Therefore, the inappropriate release of the normal NAV can be prevented, and the communication performance of the wireless network can be improved.

[0161] <Sixth embodiment>

[0162] Hereinafter, a third embodiment will be described. Fig.14 1 is a diagram illustrating the positional relationship between access points and terminals constituting a wireless network 100"" according to the sixth embodiment. Fig.14 As shown, in the sixth embodiment, there are access point A, terminal B, terminal C, access point D, terminal E, and access point F. In addition, access point A and terminal B belong to BSS1 (OBSS), terminal C and access point D belong to BSS2 (intra-BSS), and terminal E and access point F belong to BSS3 (OBSS).

[0163] In this way, when there are multiple OBSSs, in 11ax, terminal C does not distinguish and manage the NAVs of multiple OBSSs, so sometimes releasing the NAV of one OBSS causes relatively large interference to other OBSSs. In the sixth embodiment, a wireless network 100" is described in which communication can be properly performed without reducing the communication quality even in such a situation.

[0164] [Description of structure]

[0165] Fig.15 This is a block diagram showing an example of the structure of a terminal 200"" according to the sixth embodiment. Fig.15 The terminal 200"" shown in the example corresponds to Fig.14 Terminal C is shown. Furthermore, Fig.14 The structure of the access points A, D and F, terminals B and E shown can also be the same as Fig.15 The terminal 200"" shown has the same structure.

[0166] like Fig.15As shown, the terminal 200"" has a transmitting and receiving antenna 201, a wireless transmitting and receiving unit 202, a transmitting signal generating unit 203, a receiving signal demodulating and decoding unit 204, an RSSI measuring unit 205, a BSS category determining unit 206, a transmitting control unit 207, a transmitting buffer 208, a MAC frame generating unit 209, a transmitting prohibition state setting unit 210, and a target BSS information storage unit 214. In addition, the BSS category determining unit 206, the transmitting control unit 207, the transmitting buffer 208, the MAC frame generating unit 209, the transmitting prohibition state setting unit 210, and the target BSS information storage unit 214 constitute an access control unit 212"" (MAC).

[0167] The transmission prohibition state setting unit 210 performs NAV setting based on the RSSI information input from the RSSI measurement unit 205, the MAC frame input from the received signal demodulation and decoding unit 204, the BSS category information input from the BSS category determination unit 206, and the target BSS information input from the target BSS information storage unit 214. The details of the target BSS information will be described later. In addition, when the set NAV period expires or a CF-End frame indicating NAV release is received, the transmission prohibition state setting unit 210 releases the NAV.

[0168] Furthermore, when setting the NAV, the transmission prohibition state setting unit 210 distinguishes the states of the intra-BSS NAV and the normal NAV, and performs the above-mentioned NAV setting and NAV release for each NAV. Specifically, for example, when receiving a MAC frame of the intra-BSS, the transmission prohibition state setting unit 210 performs the setting of the intra-BSS, and when receiving a MAC frame of the OBSS, the normal NAV is set.

[0169] However, the transmission prohibition state setting unit 210 uses the NAV release determination method described later to determine whether to release the NAV. If the determination to release the NAV is made in the determination, the normal NAV is released even in addition to the above. The transmission prohibition state setting unit 210 outputs the transmission prohibition state information related to the NAV setting or NAV release to the transmission control unit 207.

[0170] Furthermore, when the target BSS information needs to be updated, transmission prohibition state setting section 210 generates new target BSS information and outputs it to target BSS information storage section 214 .

[0171] The target BSS information storage unit 214 stores the target BSS information. If new target BSS information is input from the transmission prohibition state setting unit 210, the target BSS information storage unit 214 updates the stored target BSS information with the new target BSS information. In addition, the target BSS information storage unit 214 outputs the stored target BSS information to the transmission prohibition state setting unit 210 as needed.

[0172] [Action examples]

[0173] Fig.16 This is a sequence diagram showing an example of the operation of the wireless network 100"" when sending and receiving RTS / CTS frames in the sixth embodiment.

[0174] like Fig.16 As shown, first, access point F sends an RTS frame to terminal E (ST601). Terminal C performs RTS frame reception processing from access point F (ST602). RTS frame reception processing includes extracting the BSS color from the RTS frame and measuring the RSSI of the RTS frame. Terminal C sets a normal NAV based on the RTS frame (ST603).

[0175] If the normal NAV is set, terminal C generates target BSS information (ST604). Here, the target BSS information is information indicating the OBSS for which the NAV is set. That is, the target BSS information generated in ST604 is information indicating the target BSS. Fig.14 The target BSS information includes the BSS color of the target BSS and the RSSI of the RTS frame.

[0176] Next, terminal E transmits a CTS frame, which is a response signal of the RTS frame, to access point F (ST605). Terminal C performs a CTS frame reception process from terminal E (ST606). The CTS frame reception process includes extracting the BSS color from the CTS frame and measuring the RSSI of the CTS frame.

[0177] Then, terminal C compares the RSSI stored in ST604 with the RSSI of the CTS frame received in ST606, and updates the target BSS information (ST607) when the RSSI of the CTS frame is higher. Here, assuming that the current RSSI (RSSI from terminal E) is higher than the stored RSSI (RSSI from access point F), terminal C updates the target BSS information. Furthermore, in ST607, terminal C only updates the RSSI included in the target BSS information, and does not update the BSS color.

[0178] Terminal C determines whether to release the normal NAV (ST608). The details of the method of determining the normal NAV in ST608 will be described later.

[0179] exist Fig.16 In FIG. 5 , a case where it is determined in ST608 that the normal NAV is not to be released is illustrated. In this case, terminal C continues the normal NAV and maintains the transmission prohibition state.

[0180] Next, access point F transmits data to terminal E (ST609). At this time, since normal NAV is set in terminal C, terminal C does not transmit data to access point D.

[0181] Next, it is assumed that terminal B transmits an RTS frame to access point A (ST610). Terminal C performs RTS frame reception processing from terminal B (ST611). RTS frame reception processing includes extraction of the BSS color from the RTS frame and RSSI measurement of the RTS frame.

[0182] Terminal C determines whether to release the normal NAV (ST612). The details of the method of determining the normal NAV in ST612 will be described later.

[0183] exist Fig.16 In the example, it is shown that the normal NAV is not released in ST612. In this case, terminal C continues the normal NAV and maintains the transmission prohibition state. In the case where the normal NAV is not released in ST612, terminal C compares the stored RSSI with the current RSSI, and updates the target BSS information (ST613) when the current RSSI is higher. Here, assuming that the stored RSSI (RSSI from terminal E) is higher than the current RSSI (RSSI from terminal B), terminal C does not update the target BSS information.

[0184] Next, access point A transmits a CTS frame, which is a response signal of the RTS frame, to terminal B (ST614). Terminal C performs a CTS frame reception process from access point A (ST615). The CTS frame reception process includes extracting the BSS color from the CTS frame and measuring the RSSI of the CTS frame.

[0185] Terminal C determines whether to release the normal NAV (ST616). The details of the method of determining the normal NAV in ST616 will be described later.

[0186] exist Fig.16In the example, it is shown that the normal NAV is not released in ST616. In this case, terminal C continues the normal NAV and maintains the transmission prohibition state. In the case where the normal NAV is not released in ST616, terminal C compares the stored RSSI with the current RSSI, and updates the target BSS information (ST617) when the current RSSI is higher. Here, assuming that the stored RSSI (RSSI from terminal E) is higher than the current RSSI (RSSI from terminal B), terminal C does not update the target BSS information.

[0187] Next, terminal B transmits data to access point A (ST618). At this time, since normal NAV is set in terminal C, terminal C does not transmit data to access point D.

[0188] [NAV release determination method]

[0189] The following explains Fig.16 Details of the method of determining whether to release the normal NAV in ST608, ST612, and ST616 are shown.

[0190] As mentioned above, when the normal NAV is set ( Fig.16 In ST603 of the present invention, terminal C stores the target BSS information that sets the BSS as the target BSS. Then, when determining whether to release the normal NAV (ST608, ST612, and ST616), the normal NAV is released based on the signal received from the target BSS, but the normal NAV is not released based on the signal received from other BSSs.

[0191] Then, in the case of regular NAV update by reception of RTS / CTS frames, etc., when the RSSI of the received signal is higher than the RSSI stored as the target BSS information, the terminal C updates the target BSS information using the BSS color and RSSI of the received signal. However, the release of the regular NAV due to the expiration of the NAV period can be implemented regardless of the target BSS.

[0192] Thus, in the sixth embodiment, the normal NAV is released based on the signal received from the target BSS, but the normal NAV is not released based on the signal received from other BSSs. Therefore, even when there are multiple OBSSs, it is possible to avoid a situation where the release of the NAV of one OBSS causes relatively large interference to other OBSSs. Therefore, it is possible to prevent inappropriate normal NAV release and improve the communication performance of the wireless network.

[0193] The above, while referring to the attached Figure 1While various embodiments are described, it goes without saying that the present invention is not limited to such examples. As long as one is skilled in the art, various variations or modifications can be envisioned within the scope described in the claims, and it is recognized that they certainly belong to the technical scope of the present invention. In addition, the various constituent elements in the above-mentioned embodiments can also be arbitrarily combined within the scope of the purpose of the invention.

[0194] In the above-mentioned first to sixth embodiments, terminal C releases NAV when receiving a CF-End frame. However, for example, when there are multiple OBSSs, the RSSI of the CF-End frame is measured, and the measured RSSI is compared with the RSSI of the stored target BSS information. Terminal C may also release the regular NAV only when the RSSI of the CF-End frame is high. With such a structure, inappropriate regular NAV release can be prevented, and the communication performance of the wireless network can be improved.

[0195] The method of releasing the transmission prohibited state in the above-mentioned embodiment is not limited to NAV release. For example, the same method can be applied to the case where the NAV is not released but the transmission permitted state is temporarily achieved (the time in the transmission permitted state is managed, and even if the time has passed, if the original NAV period is valid, it returns to the transmission prohibited state).

[0196] Furthermore, in the above-described embodiment, instead of releasing the transmission prohibition state, the predetermined interference behavior can be reduced by reducing the transmission power.

[0197] In the above embodiment, when the transmission prohibition state cannot be released, there is a case where ACK for data reception is not returned. In this case, the operation of sending ACK after NAV release may also be adopted.

[0198] In the above-mentioned respective embodiments, the present invention has been described by taking the case where the hardware configuration is used as an example, but the present invention can also be realized by software in cooperation with hardware.

[0199] In addition, each functional block used in the description of the above-mentioned embodiments is usually implemented as an integrated circuit, i.e., LSI. These integrated circuits can be integrated into a single chip individually, or a part or all of them can be integrated into a single chip. Although it is set as LSI here, it is sometimes also called IC, system LSI, super LSI (SuperLSI), and ultra LSI (Ultra LSI) depending on the degree of integration.

[0200] In addition, the integrated circuit method is not limited to LSI, and can also be implemented by a dedicated circuit or a general-purpose processor. It is also possible to use an FPGA (Field Programmable Gate Array) that can be programmed after LSI manufacturing, or a reconfigurable processor (Reconfigurable Processor) that can reconfigure the connection and setting of the circuit unit inside the LSI.

[0201] Furthermore, if there is an integrated circuit technology that can replace LSI as semiconductor technology advances or other technologies derived therefrom, it is of course possible to use this technology to integrate functional blocks. There is also the possibility of applying biotechnology, etc.

[0202] <Summary of the present invention>

[0203] The wireless station of the present invention is a wireless station in a wireless network having multiple wireless stations, and includes: a receiving unit that receives a trigger signal sent from a first wireless station belonging to an interference cell to a second wireless station belonging to the interference cell; and a transmission prohibition period control unit that, after setting a transmission prohibition period for other wireless stations belonging to the communication cell to which this station belongs, when the receiving unit receives the trigger signal, determines whether to release the transmission prohibition period based on the reception strength of the trigger signal.

[0204] In the wireless station of the present invention, the wireless station is a wireless station compliant with IEEE 802.11ax.

[0205] In the radio station of the present invention, the communication cell to which the own station belongs is an intra-BSS (Basic Service Set), and the interference cell is an OBSS (Overlapping Basic Service Set) or an inter-BSS.

[0206] In the radio station of the present invention, the transmission prohibition period control unit determines whether to release the transmission prohibition period based on a threshold value set according to the reception strength measurement accuracy of the own station and the reception strength of the trigger signal.

[0207] In the wireless station of the present invention, the transmission prohibition period control unit sets the threshold value based on terminal classes (STA classes) specified in IEEE 802.11ax.

[0208] In the wireless station of the present invention, when a response signal to the trigger signal is received from the second wireless station, the transmission prohibition period control unit determines whether to release the transmission prohibition period based on a threshold set according to the reception strength measurement accuracy of the station, the reception strength of the trigger signal and the reception strength of the response signal.

[0209] In the radio station of the present invention, the transmission prohibition period control unit releases the transmission prohibition period when the reception strength of the trigger signal is within a predetermined range set based on the reception strength measurement accuracy of the own station.

[0210] In the radio station of the present invention, the transmission prohibition period control unit determines the type of the trigger signal, and does not release the transmission prohibition period if the trigger signal is a trigger signal requesting responses from a plurality of radio stations in the interfering cell.

[0211] In the wireless station of the present invention, when the trigger signal is a trigger signal requesting responses from multiple wireless stations in the interfering cell, the transmission prohibition period control unit extracts information related to the number of wireless stations requested to respond by the trigger signal from the trigger signal, and determines whether to release the transmission prohibition period based on the extracted information.

[0212] In the wireless station of the present invention, the transmission prohibition period control unit compares the strength of the response signal from the second wireless station to the first wireless station extracted from the trigger signal with the estimated reception strength in the first wireless station of the signal sent from the own station to the first wireless station, which is estimated in advance, and does not release the transmission prohibition period if the difference is smaller than a prescribed value.

[0213] In the wireless station of the present invention, when the transmission prohibition period is set by using a trigger signal from any wireless station belonging to the interfering cell as a trigger, after storing the identifier of the interfering cell to which the wireless station that sent the trigger signal as a trigger for setting the transmission prohibition period belongs and the reception strength of the trigger signal as a trigger for setting the transmission prohibition period, and when a trigger signal from the interfering cell is newly received, if the reception strength of the newly received trigger signal is higher than the reception strength of the stored trigger signal, the transmission prohibition period control unit releases the transmission prohibition period.

[0214] The communication method of the present invention is a communication method in a wireless network having multiple terminals or access points, i.e., wireless stations, and includes the following steps: after one wireless station among the multiple wireless stations sets a transmission prohibition period for other wireless stations belonging to a communication cell to which the wireless station belongs, when a trigger signal sent to a second wireless station belonging to an interference cell to which the wireless station does not belong is received from a first wireless station belonging to an interference cell to which the wireless station does not belong, the first wireless station determines whether to release the transmission prohibition period based on the reception strength of the trigger signal.

[0215] In the communication method of the present invention, the wireless station is a wireless station compliant with IEEE 802.11ax.

[0216] In the communication method of the present invention, the communication cell to which the own station belongs is an intra-BSS (Basic Service Set), and the interference cell is an OBSS (Overlapping Basic Service Set) or an inter-BSS.

[0217] In the communication method of the present invention, the first wireless station determines whether to release the transmission prohibition period based on a threshold value set according to the reception strength measurement accuracy of the own station and the reception strength of the trigger signal.

[0218] In the communication method of the present invention, the first wireless station sets the threshold value based on terminal classes (STA classes) specified in IEEE 802.11ax.

[0219] In the communication method of the present invention, when a response signal to the trigger signal is received from the second wireless station, the first wireless station determines whether to release the transmission prohibition period based on a threshold set according to the reception strength measurement accuracy of the own station, the reception strength of the trigger signal and the reception strength of the response signal.

[0220] In the communication method of the present invention, when the reception strength of the trigger signal is within a predetermined range set based on the reception strength measurement accuracy of the own station, the first wireless station releases the transmission prohibition period.

[0221] In the communication method of the present invention, the first radio station determines the type of the trigger signal, and does not release the transmission prohibition period if the trigger signal is a trigger signal requesting responses from a plurality of radio stations in the interfering cell.

[0222] In the communication method of the present invention, when the trigger signal is a trigger signal requesting responses from multiple wireless stations in the interfering cell, the first wireless station extracts information related to the number of wireless stations requested to respond by the trigger signal from the trigger signal, and determines whether to release the transmission prohibition period based on the extracted information.

[0223] In the communication method of the present invention, the first wireless station compares the strength of the response signal from the second wireless station to the first wireless station extracted from the trigger signal with the estimated reception strength in the first wireless station of the signal sent from the own station to the first wireless station, which is estimated in advance, and does not release the transmission prohibition period if the difference is smaller than a prescribed value.

[0224] In the communication method of the present invention, when the transmission prohibition period is set by using a trigger signal from any wireless station belonging to the interference cell as a trigger, after storing the identifier of the interference cell to which the wireless station that sent the trigger signal as a trigger for setting the transmission prohibition period belongs and the reception strength of the trigger signal as a trigger for setting the transmission prohibition period, and when a trigger signal from the interference cell is newly received, if the reception strength of the newly received trigger signal is higher than the reception strength of the stored trigger signal, the first wireless station releases the transmission prohibition period.

[0225] Industrial Applicability

[0226] The present invention is suitable for a wireless station that performs appropriate wireless communication in an environment where interference between wireless stations occurs.

[0227] Description of symbols

[0228] 100, 100', 100", 100"', 100"" Wireless network

[0229] 200, 200', 200", 200"', 200"" Terminal

[0230] 201 Transmitting and receiving antenna

[0231] 202 Wireless transceiver unit

[0232] 203 Transmitting signal generating unit

[0233] 204 Received signal demodulation and decoding unit

[0234] 205RSSI measurement unit

[0235] 206BSS Classification Unit

[0236] 207 Sending control unit

[0237] 208 Send Buffer

[0238] 209MAC frame generation unit

[0239] 210 Sending prohibition status setting unit

[0240] 211 Terminal information setting unit

[0241] 212, 212', 212", 212"', 212"" Access control unit

[0242] 213 Trigger Information Analysis Unit

[0243] 214 Target BSS information storage unit

Claims

1. An integrated circuit for a first wireless station, the first wireless station belonging to a basic service set (BSS), The integrated circuit comprises: A control circuit is provided, wherein the control circuit performs the following control: receiving a trigger frame transmitted from an access point (AP) belonging to an overlapping BSS (OBSS), the trigger frame requesting an uplink multi-user signal from a plurality of wireless stations belonging to the OBSS, When the uplink multi-user signal is transmitted, the signal is transmitted to a second wireless station belonging to the BSS in a spatial multiplexing operation, Wherein the spatial multiplexing operation is limited based on a rank of the first wireless station, the rank being indicative of a received signal strength indicator (RSSI) measurement accuracy.

2. The integrated circuit according to claim 1, wherein: The first wireless station includes circuitry that determines whether the first wireless station is to perform the spatial multiplexing operation based on a rank of the first wireless station.

3. The integrated circuit according to claim 1, wherein: The rank of the first wireless station indicates transmission power accuracy.

4. The integrated circuit according to claim 1, wherein: The first wireless station includes circuitry that decodes a received trigger frame and extracts a plurality of parameters encoded in the trigger frame.

5. The integrated circuit according to claim 4, wherein: The circuit determines whether the first wireless station is to perform the spatial multiplexing operation based on the plurality of parameters.

6. The integrated circuit according to claim 5, wherein: One of the plurality of parameters is a target RSSI, wherein the target RSSI indicates a target received power value of the uplink multi-user signal measured at the access point. The control circuit controls the first wireless station to determine whether to perform the spatial multiplexing operation based on the target RSSI.

7. The integrated circuit according to claim 5, wherein: One of the multiple parameters is AP transmit power, and the AP transmit power indicates a transmit power of the trigger frame. The control circuit controls the first wireless station to determine whether to perform the spatial multiplexing operation based on the AP transmission power.

8. The integrated circuit according to claim 5, wherein: One of the plurality of parameters is a tolerable interference level, The control circuit controls whether the first wireless station performs the spatial multiplexing operation based on the allowable interference level.

9. The integrated circuit according to claim 5, wherein: The control circuit controls adjustment of transmission power of a signal based on the plurality of parameters.

10. The integrated circuit of claim 5, wherein: The control circuit controls setting of a period during which the spatial multiplexing operation is permitted.

11. The integrated circuit of claim 6, wherein: The control circuit controls the first wireless station to perform the determination of the spatial multiplexing operation based on a rank of the first wireless station.

12. An integrated circuit for a first wireless station, the first wireless station belonging to a basic service set (BSS), The integrated circuit comprises: A control circuit is provided, wherein the control circuit performs the following control: receiving a signal transmitted from another wireless station belonging to an overlapping BSS (OBSS), When the wireless communication of the OBSS is in operation, transmitting a transmission signal to a second wireless station belonging to the BSS in a spatial multiplexing operation, The spatial multiplexing operation is limited based on the signal and a rank of the first wireless station, the rank indicating a received signal strength indicator (RSSI) measurement accuracy.

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