Communication method and integrated circuit

Abstract

The communication method of the present invention receives a trigger frame containing separate information, wherein the separate information includes a target receiving power value related to a target value of receiving power when an access point receives an uplink response frame, i.e., a UL response frame; estimates a path loss by using the transmission power of the trigger frame notified by the trigger frame and the measured receiving power of the trigger frame, and sets the transmission power of the UL response frame based on the target receiving power value and the path loss; and transmits the UL response frame immediately after receiving the trigger frame.

Description

[0001] This application is a divisional application of the invention patent application with the application date of November 28, 2016, application number 201680073851.6, and invention name “Communication device and communication method”. Technical Field

[0002] The present invention relates to a communication method and an integrated circuit for performing uplink transmission power control. Background Art

[0003] In Task Group ax of the IEEE (the Institute of Electrical and Electronics Engineers) 802.11Working Group, the technical specifications of IEEE 802.11ax (hereinafter referred to as 11ax) are being planned and formulated as the successor standard of 802.11ac. In 11ax, it is expected that a multi-user transmission method (hereinafter referred to as MU transmission) based on OFDMA (Orthogonal Frequency-Division Multiple Access) and MU-MIMO (MultiUser-Multi Input Multi Output) will be introduced in the uplink (UL).

[0004] During the UL MU transmission process, the access point (sometimes also referred to as a base station) sends a control signal as a trigger of an uplink signal to multiple terminals (sometimes also referred to as STA (Station)) accommodated therein. The terminal that sends the uplink signal sends a UL response signal (sometimes also referred to as a UL response frame) to the access point based on the control signal. During the UL MU transmission process, there are two methods: a method in which the access point individually specifies the terminal to allocate frequency resources (hereinafter referred to as Resource unit (RU)), and a method in which the terminal selects the RU based on random access (RA: Random Access). TF (Trigger frame) is a control signal in which the access point individually specifies the terminal to indicate resources, and TF-R (Triggerframe-Random) is a control signal in which the access point indicates at least one resource for random access.

[0005] In addition, the TF-R includes allocation information for a terminal that secures resources by random access (hereinafter, random access allocation information) and allocation information for a terminal that allocates resources by individually specifying a terminal (hereinafter, individual allocation information). The terminal that sends a UL response signal by random access decodes the RU information for random access from the TF-R, randomly selects one RU from a plurality of random access RUs, and uses the selected RU to send a UL response signal (for example, refer to non-patent document 1).

[0006] Prior art literature

[0007] Non-patent literature

[0008] Non-patent document 1: IEEE 802.11-15 / 0132r12 “Specification Framework for TGax”

[0009] Non-patent document 2: IEEE 802.11-14 / 1446r0 "Analysis of frequency and power requirements for UL-OFDMA"

[0010] Non-patent document 3: IEEE Std 802.11h-2003

[0011] Non-patent document 4: 3GPP TS 36.331

[0012] Non-patent document 5: IEEE Std 802.11-2012 Summary of the invention

[0013] However, in the above-mentioned MU transmission, in the random access indicated by the random access control signal (TF-R), it is difficult for the access point side to determine which terminal has secured resources from the random access. Therefore, the access point cannot appropriately set the transmission power of the terminal that transmits the UL response signal in the random access. Therefore, there is a problem that the difference in received power between terminals in the access point increases, and the received signal in the access point is not included in the dynamic range of the A / D conversion, or there is a problem that the SINR (Signal to Interference plus Noise Ratio) decreases due to interference between terminals.

[0014] Therefore, one embodiment of the present invention provides a communication method and a communication device that can improve the problems of inter-carrier interference and the dynamic range of A / D conversion by effectively performing transmission power control in the UL response signal sent by the MU during random access, thereby reducing the reception power difference between terminals in the access point.

[0015] A communication device of one embodiment of the present invention adopts a structure including: a target reception power setting unit, which sets at least one target reception power value as UL transmission power control information for controlling the uplink transmission power of each of a plurality of terminals, wherein the target reception power value is a target value of the reception power when uplink signals are received from the plurality of terminals; a signal generating unit, which generates a random access control signal including the at least one target reception power value; and a sending unit, which sends the random access control signal.

[0016] A communication method in another aspect of the present invention receives a trigger frame including separate information, wherein the separate information includes a target receiving power value related to a target value of receiving power when an access point receives an uplink response frame, i.e., a UL response frame; estimates a path loss by using the transmission power of the trigger frame notified by the trigger frame and the measured receiving power of the trigger frame, and sets the transmission power of the UL response frame based on the target receiving power value and the path loss; and sends the UL response frame immediately after receiving the trigger frame.

[0017] An integrated circuit of another embodiment of the present invention controls the following processing: a process of receiving a trigger frame containing separate information, wherein the separate information includes a target receiving power value related to a target value of receiving power when an access point receives an uplink response frame, i.e., a UL response frame; a process of estimating a path loss by using the transmission power of the trigger frame notified by the trigger frame and the measured receiving power of the trigger frame, and setting the transmission power of the UL response frame based on the target receiving power value and the path loss; and a process of sending the UL response frame immediately after receiving the trigger frame.

[0018] Furthermore, these general or specific methods can be implemented through systems, devices, methods, integrated circuits, computer programs or recording media, or through any combination of systems, devices, methods, integrated circuits, computer programs and recording media.

[0019] According to one method of the present invention, in the UL response signal sent by the MU in random access, the difference in reception power between terminals in the access point can be reduced, the interference between terminals (MU interference) in MU transmission can be reduced, and the reception signal can be contained within the dynamic range of A / D conversion.

[0020] It will be clear from the description and drawings that more advantages and effects of one embodiment of the present invention can be provided by several embodiments and the features described in the description and drawings, respectively, without providing all the features in order to obtain one or more of the same features. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is a flowchart showing the operations of the access point and the terminal according to the first embodiment.

[0022] Figure 2 This is a block diagram showing a main configuration of an access point according to the first embodiment.

[0023] Figure 3 This is a block diagram showing a main structure of a terminal according to the first embodiment.

[0024] Figure 4 This is a block diagram showing the structure of an access point according to the first embodiment.

[0025] Figure 5 A block diagram showing the structure of a terminal according to the first embodiment.

[0026] Figure 6 A diagram showing an example of a random access control signal in the transmission power control information and area setting method 1 according to the first embodiment.

[0027] Fig. 7A A diagram showing an example of a target reception power determination method in the target reception power setting method 1 (individual allocation) in the transmission power control information and area setting method 1 according to the first embodiment.

[0028] Figure 7B A diagram showing an example of a target reception power determination method in target reception power setting method 2 (individual allocation) in method 1 for setting transmission power control information and a region according to Embodiment 1.

[0029] Figure 7C A diagram showing an example of a target reception power determination method of target reception power setting method 3 (individual allocation) in method 1 for setting transmission power control information and a region according to Embodiment 1.

[0030] Fig. 8A A diagram showing an example of an allowable power difference based on A / D conversion performance in the transmission power control information and the area setting method 1 according to the first embodiment.

[0031] Figure 8B A diagram showing an example of the allowable power difference based on the number of multiplexed terminals in the transmission power control information and the area setting method 1 according to the first embodiment.

[0032] Fig. 9A A diagram showing an example of a method for determining a target reception power in the target reception power setting method 1 (random access allocation) in the transmission power control information and area setting method 1 according to the first embodiment.

[0033] Fig. 9BA diagram showing an example of a target reception power determination method in the target reception power setting method 2 (random access allocation) in the transmission power control information and area setting method 1 according to the first embodiment.

[0034] Fig. 9C A diagram showing an example of the purpose of target reception power setting method 4 (random access allocation) in transmission power control information and area setting method 1 according to Embodiment 1 and target reception power.

[0035] Fig.10 A diagram showing an example of a random access control signal in the transmission power control information and area setting method 2 according to the first embodiment.

[0036] Fig.11A A diagram showing an example of a target reception power determination method of the target reception power setting method 1 ′ (individual allocation) in the transmission power control information and area setting method 2 according to the first embodiment.

[0037] Fig. 11B A diagram showing an example of a target reception power determination method of the target reception power setting method 2' (individual allocation) in the transmission power control information and area setting method 2 according to the first embodiment.

[0038] Fig. 11C A diagram showing an example of a target reception power determination method of the target reception power setting method 3 ′ (individual allocation) in the transmission power control information and area setting method 2 according to the first embodiment.

[0039] Fig.12 A diagram showing an example of a target reception power value for each response signal type in the transmission power control information and region setting method 3 according to the first embodiment.

[0040] Fig.13 A diagram showing an example of a target reception power value for each allocation method in the transmission power control information and area setting method 4 according to the first embodiment.

[0041] Fig.14 A diagram showing an example of a random access control signal in the transmission power control information and area setting method 5 according to the first embodiment.

[0042] Fig.15 A diagram showing an example of a pattern of a target reception power offset in the transmission power control information and area setting method 5 according to the first embodiment.

[0043] Fig.16 A diagram showing an example of a random access control signal in the transmission power control information and area setting method 6 according to the first embodiment.

[0044] Fig.17 A diagram showing an example of a random access control signal in the transmission power control information and area setting method 7 according to the first embodiment.

[0045] Fig.18 A flowchart showing path loss feedback timing 1 according to the first embodiment.

[0046] Fig.19 A flowchart showing path loss feedback timing 2 according to the first embodiment.

[0047] Fig. 20 A flowchart showing path loss feedback timing 3 according to the first embodiment.

[0048] Fig.21 A flowchart showing path loss feedback timing 4 according to the first embodiment.

[0049] Fig. 22 A block diagram showing the structure of a terminal according to the second embodiment.

[0050] Fig.23 A diagram showing an example of determination method 6 of the second embodiment for determining whether or not transmission is stopped for each response signal type.

[0051] Fig.24 This is a block diagram showing a main structure of an access point according to the third embodiment.

[0052] Fig.25 A diagram showing an example of a UL MU transmission procedure in control method 1 according to Embodiment 3.

[0053] Fig.26A A diagram showing an example of permissible conditions in the permissible condition setting method 1 according to the fourth embodiment.

[0054] Fig.26B A diagram showing an example of permissible conditions in the permissible condition setting method 2 according to the fourth embodiment.

[0055] Fig.26C A diagram showing an example of permissible conditions in the permissible condition setting method 3 according to the fourth embodiment.

[0056] Fig.27A A diagram showing an example of the range of the allowable power value in the setting method 1 of the range of the allowable power value according to the fourth embodiment.

[0057] Fig.27B A diagram showing an example of the range of the allowable power value in the setting method 2 of the range of the allowable power value according to the fourth embodiment.

[0058] Fig.27CA diagram showing an example of the range of the allowable power value in the setting method 3 of the range of the allowable power value according to the fourth embodiment.

[0059] Fig.27D A diagram showing an example of the range of allowable power values ​​in method 4 for setting the range of allowable power values ​​according to the fourth embodiment.

[0060] Description of symbols

[0061] 100,400 access points

[0062] 200, 300 Terminal

[0063] 101 Scheduling Unit

[0064] 102 Target receiving power setting unit

[0065] 103 Transmit power control information setting unit

[0066] 104RA control signal generation unit

[0067] 105, 210 Transmitting signal generating unit

[0068] 106, 202 Wireless transceiver unit

[0069] 107,201 Antenna

[0070] 108, 203 Received signal demodulation unit

[0071] 109 Feedback information decoding unit

[0072] 110 Response signal decoding unit

[0073] 204 RA control signal decoding unit

[0074] 205 Transmit power calculation unit

[0075] 206 Power control information storage unit

[0076] 207 Path Loss Estimation Unit

[0077] 208 feedback information generating unit

[0078] 209 Response signal generating unit

[0079] 301, 401 Send control unit DETAILED DESCRIPTION

[0080] (Foundation underlying the present invention)

[0081] In each of TF and TF-R, there is a common information field (Common information field) (sometimes also referred to as a common field (Common field). Hereinafter, it is referred to as a "common area") for notifying common control information to each terminal to which resources for MU transmission are allocated, and a user information field (User information field) (sometimes also referred to as a STA-specific field or a RU-specific field. Hereinafter, it is referred to as a "terminal-specific area") for notifying control information individually to each terminal or each RU. The common area includes the trigger type for notifying the category of the TF, etc. In addition, the terminal-specific area includes information for identifying the terminal (for example, AID (Association ID)), MCS (Modulation and Coding Scheme; modulation and coding method), etc. (for example, refer to non-patent document 1).

[0082] In addition, multiple TFs and TF-Rs can be continuously transmitted in a TXOP (Transmission opportunity) (sometimes also referred to as multiple trigger frames in a TXOP). In the cascade area (sometimes also referred to as the cascaded field) in the TF and TF-R, the presence or absence of continuous transmission of TF and TF-R can be explicitly indicated (for example, refer to non-patent document 1).

[0083] In UL MU transmission, the necessity of transmission power control of each terminal is being discussed due to inter-carrier interference caused by reception power differences between terminals in an access point and the dynamic range of AD conversion (for example, see Non-Patent Document 2).

[0084] However, regarding uplink transmission power control, according to 802.11h, although the formats such as TPC report / request are determined, no specific control method is mentioned. The TPC report is included in the beacon, probe response or action frame. In the TPC report, the transmission power (EIRP: Equivalent Isotopic Radiation Power) and link margin are notified. The link margin is control information used to notify excess quality. The terminal that receives the link margin can reduce the transmission power by an amount equivalent to the link margin (for example, refer to non-patent document 3).

[0085] As described above, the link margin in the transmission power control of 802.11h only notifies the excess quality, and therefore does not perform control to increase the transmission power. Therefore, the transmission power control of 802.11h cannot be applied as transmission power control for solving the above-mentioned problem in UL MU transmission.

[0086] In addition, in the random access of LTE (Long Term Evolution), RRC (Radio Resource Control) signaling is used to notify the common target received power value and power ramping of the cell, and the terminal controls the transmission power to increase the corresponding power ramping for each retransmission from the initial target received power. The target received power can be changed to semi-static at a minimum interval of 640ms (for example, refer to non-patent document 4).

[0087] In this way, in the LTE transmission power control method, since the cycle of changing the target reception power value is long, it is impossible to change the target reception power value according to the combination of terminals to which resources are allocated in each scheduling. That is, in UL MU transmission, even if the LTE transmission power control is applied, the target reception power value of the terminal located at the cell edge (hereinafter referred to as the cell edge terminal) can be fixed, but the target reception power value cannot be dynamically controlled to match the quality of each terminal near the access point and the terminal at the cell edge far from the access point. Therefore, it is impossible to obtain the gain for performing optimal adaptive modulation on each terminal based on the scheduling gain, that is, the reception quality of each terminal in the access point.

[0088] Therefore, in one embodiment of the present invention, the purpose is to efficiently perform transmission power control in UL MU transmission. Specifically, the purpose is to introduce efficient transmission power control for the UL response signal transmitted by MU through random access to the resources indicated by the random access control signal, reduce the reception power difference between terminals in the access point, and improve the problems of inter-carrier interference and dynamic range of A / D conversion. In addition, the purpose is to dynamically change the target reception power value in each scheduling according to the reception quality of the terminals allocated by random access and individually allocated, so that the optimal adaptive modulation for each terminal can be applied instantaneously, thereby improving the system throughput.

[0089] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. In each embodiment, the same components are denoted by the same reference numerals, and their description will be omitted if it is redundant.

[0090] (Implementation Method 1)

[0091] [Overview of Communication System]

[0092] The communication system of this embodiment includes an access point (communication device) 100 and a terminal 200. The access point 100 is an access point compatible with 11ax, and the terminal 200 is a terminal compatible with 11ax.

[0093] Figure 1 The following shows the processing flow in the communication system according to the present embodiment.

[0094] exist Figure 1 In the process, the access point 100 generates a beacon signal (step (hereinafter, referred to as “ST”) 101).

[0095] The beacon signal includes the transmission power of the access point 100. Specifically, the equivalent isotropic radiated power (EIRP) of the access point 100 is set in the transmission power. Generally, the broadcast EIRP is determined based on the antenna gain in the maximum radiation direction of the directional antenna. Therefore, when the terminal 200 performs the path loss estimation and transmission power setting described later based on the equivalent isotropic radiated power, a difference may occur between the actual reception power and the target reception power in the access point. In order to solve this problem, the total radiated power (TRP) of the access point 100 may be used as the broadcast transmission power. By using the total radiated power, when beamforming is applied, the difference in reception power caused by the difference in the position of the terminal 200 and the beam direction can be reduced. In addition, the transmission power may be broadcast to the terminal 200 using a management frame such as a probe response or an association response, or may be included in a random access control signal to notify the terminal 200.

[0096] The generated beacon signal is wirelessly notified from access point 100 to terminal 200 (ST102).

[0097] The access point 100 performs scheduling (frequency allocation, MCS selection) of downlink data (DL Data) / UL response signals (ST103). The access point 100 may perform scheduling using channel quality information (CSI (Channel state information)) fed back from the terminal 200, or the like.

[0098] The access point 100 sets the target reception power value of each terminal to which resources are allocated based on the scheduling result (ST104). The method of setting the target reception power value will be described later.

[0099] The access point 100 generates a control signal (TF-R) for random access (RA) (ST105).

[0100] The random access control signal includes at least one random access allocation information, and may also arbitrarily include separate allocation information. In the separate allocation information, in order to explicitly indicate the allocation of RUs, a unique ID (STA_ID) that distinguishes the terminals 200 is used. That is, each terminal 200 determines the RU to which the local ID is allocated as an RU that can be used in the transmission of the UL response signal. On the other hand, in the random access allocation information, in order to explicitly indicate the allocation of RUs for random access, a random access ID is used. As a random access ID, an ID that is not allocated in order to distinguish a specific terminal 200 is used. For example, as a STA_ID, a unique ID assigned when associating with the network to which the access point 100 belongs (BSS: Basic Service Set, multiple terminals 200 under the access point 100), that is, an association ID (AID), may also be used. As a random access ID, a spare value that is not usually used in the AID may also be used.

[0101] In this embodiment, the access point 100 includes the target reception power value in the random access control signal. The access point 100 notifies the target reception power value using the random access control signal, and can dynamically change the target reception power value in each scheduling according to the reception quality of the terminal assigned by random access or individually assigned. In this way, the optimal adaptive modulation can be applied instantaneously to each terminal 200, thereby improving the system throughput.

[0102] The target received power value is a power value (target value) that is a target received power when the access point 100 receives the UL response signal of each terminal 200. Each terminal 200 controls the transmission power so that the received power of the access point 100 is within a predetermined allowable power difference (±X [dB]) of the target received power value. The allowable power difference is notified to the terminal 200 from the access point 100 by a management frame such as a beacon, a probe response, or an association response. By controlling the allowable power difference by a management frame, a value suitable for each BSS (Basic Service Set, a plurality of terminals under the access point) can be set. In addition, the allowable power difference can also be notified by a random access control signal. By controlling the allowable power difference for each transmission of the random access control signal, although the overhead increases, appropriate control can be performed to follow the changes in an environment where the status of the terminal 200 greatly changes. Here, the range in which the upper limit value and the lower limit value are defined according to the allowable power difference of the target received power value may be renamed as the allowable power range.

[0103] In addition, the target received power value may not be the absolute value of the received power, but may be expressed as an offset value offset from a certain reference such as the minimum received quality. In addition, the size of the permissible power difference of the target received power value and the number of notification bits may be changed by random access allocation and individual allocation. In the case of random access, the received power increases significantly when a conflict occurs, which becomes a major factor in the occurrence of the power difference. Therefore, for example, in the case of random access allocation, by setting the permissible power difference small, the upper limit value of the received power when a conflict occurs can be suppressed.

[0104] The generated random access control signal is wirelessly notified from access point 100 to terminal 200 (ST106).

[0105] The terminal 200 determines the available RU from the RUs indicated in the random access control signal notified (broadcasted) by the access point 100 based on the terminal information of the terminal 200 (ST107). Specifically, when the terminal 200 has control information including the STA_ID of the terminal in the terminal-independent area of ​​the random access control signal, the terminal 200 determines that it is a separate allocation. On the other hand, when the terminal 200 does not have the STA_ID of the terminal in the terminal-independent area but has control information including the random access ID, and the signal transmitted by random access is maintained, the terminal 200 determines that it is a random access allocation and selects the RU according to a predetermined procedure.

[0106] When the RU can be secured, the terminal 200 estimates the path loss from the transmission power and antenna gain notified by the beacon signal (ST108). The path loss estimation is expressed by, for example, equation (1).

[0107] pathLoss=ApTxPower+ApTxAntGain-StaRxPower…(1)

[0108] In formula (1), pathLoss is the estimated path loss [dBm], ApTxPower is the transmission power (TRP) [dBm] of the access point 100 notified from a beacon, etc., StaRxPower is the received power in the antenna element of the preamble and data in the terminal 200 [dBm], and ApTxAntGain is the antenna gain [dB] of the access point 100.

[0109] The antenna gain includes the beamforming gain. ApTxAntGain can be notified from the access point 100 to the terminal 200 using a management frame such as a beacon, a probe response, or an association response, or it can be calculated from the number of transmitting antennas of the access point 100 in the terminal 200. Preferably, the access point 100 notifies ApTxPower and ApTxAntGain in the same frame, and the terminal 200 measures the received power of the frame. In addition, when measuring the received power of the random access control signal, the terminal 200 can also calculate the power of the subcarrier included in the RU that sends the UL response signal, and convert it into the power of the full band as needed. In this way, errors caused by interference and frequency selectivity can be reduced. In addition, the beamforming gain changes due to the frame and part (Preamble (Legacy) or HE (High Efficiency)), data) where the received power is measured, so the beamforming gain is also changed according to the measurement object. Specifically, there may be no beamforming gain in the case of a broadcast frame such as a beacon and a control signal for random access, a non-HT duplicate PPDU that is backward compatible with the legacy method, and a legacy preamble of a single address frame, and there may be a beamforming gain after the HE preamble of a single address frame. By taking the beamforming gain into account, the estimation accuracy of the path loss is improved when measuring the part after the HE preamble. The received power uses the received power of the signal received immediately before, or uses the average received power.

[0110] Furthermore, when the terminal 200 estimates the path loss from a signal to which beamforming is not applied (for example, a control signal for random access), the ApTxAntGain in equation (1) may be regarded as a beamforming gain and ignored, and the following equation (2) may be used. In addition, even when the terminal 200 estimates the path loss from a signal to which beamforming is effective, when the transmission power ApTxPower is EIRP, the beamforming gain is included in ApTxPower, so the following equation (2) may be used.

[0111] pathLoss=ApTxPower-StaRxPower…(2)

[0112] The terminal 200 generates a UL response signal (for example, data, a transmission buffer status report, or a DL Data request signal) to be transmitted by the MU in the random access (ST109).

[0113] Terminal 200 sets the transmission power of the UL response signal using the estimated path loss and the target reception power value included in the random access control signal (ST110). Furthermore, the path loss is applied to the path loss estimated from the downlink signal (the signal from access point 100 to terminal 200). That is, from the reversibility of the uplink and downlink propagation paths, the path loss of the downlink signal is applied as the path loss for calculating the transmission power of the UL response signal (the signal from terminal 200 to access point 100). The transmission power of the UL response signal is calculated, for example, according to equation (3). Furthermore, when the transmission power exceeds the maximum transmission power allowed by terminal 200, or when it is lower than the minimum transmission power, terminal 200 transmits the UL response signal at the maximum transmission power or the minimum transmission power.

[0114] StaTxPower=α·pathLoss+P target +StaTxAntGain+10log 10 (RUsize)+C…(3)

[0115] In equation (3), StaTxPower is the transmission power [dBm] set by the terminal 200, pathLoss is the path loss [dBm] estimated according to equation (1) or equation (2), α is the correction coefficient multiplied by the path loss, and P target is the target received power value [dBm] notified by the random access control signal, StaTxAntGain is the antenna gain [dB] of the terminal 200, and RUsize is the size of the allocated RU. In addition, C is an environment-dependent correction constant, which is set according to the surrounding OBSS (Overlapping BSS) conditions, etc. target is the received power in the antenna element.

[0116] The correction coefficient α of the path loss may be broadcasted from the access point 100 to the terminal 200 using a management frame such as a beacon, a probe response, or an association response, or may be included in a random access control signal and notified to the terminal 200. By controlling the correction coefficient α using a management frame, a value suitable for each BSS can be set. Furthermore, by controlling the correction coefficient α for each transmission of a random access control signal, although the overhead increases, appropriate control can be performed to follow the changes in an environment where the terminal status greatly changes.

[0117] For example, in an OBSS environment where BSSs are densely configured, the correction coefficient α of the path loss is set in consideration of the interference to the BSS. For example, when there are many BSSs configured in the vicinity, the correction coefficient α of the path loss is set to a smaller value (e.g., 0.8), and the interference to the BSSs configured in the vicinity is reduced by suppressing the transmission power of the cell edge terminal. On the other hand, when there are few BSSs configured in the vicinity, the correction coefficient α of the path loss is set to a larger value (e.g., 1.0), and the throughput of the cell edge terminal is improved by increasing the transmission power of the cell edge terminal.

[0118] Terminal 200 transmits a UL response signal to access point 100 at the set transmission power (ST111).

[0119] The above describes the processing flow in the communication system according to the present embodiment.

[0120] Figure 2 FIG. 1 is a block diagram showing the main structure of the access point 100 according to the present embodiment. Figure 2 In the access point 100 shown in the figure, the transmission power control information setting unit 103 sets the transmission power control information of each resource based on the target reception power value obtained from the target reception power setting unit 102 and the resource allocation information (individual allocation, random access allocation, etc.) obtained from the scheduling unit 101. The RA control signal generating unit 104 generates a random access control signal (TF-R) including allocation information indicating at least one transmission frequency resource. The random access control signal includes the target reception power value calculated by the transmission power control information setting unit 103. The wireless transmission and reception unit 106 transmits the random access control signal.

[0121] Figure 3 This is a block diagram of the main structure of the terminal 200 of this embodiment. The wireless transmission and reception unit 202 receives a random access control signal (TF-R) including allocation information indicating at least one transmission frequency resource. Here, one of a plurality of random access IDs is allocated to each of the at least one transmission frequency resource. The RA control signal decoding unit 204 acquires the target reception power value included in the random access control signal. The path loss estimation unit 207 estimates the path loss based on the transmission power notified from the access point 100 and the reception power of the received signal. The transmission power calculation unit 205 sets the transmission power of the response signal using the target reception power value and the path loss.

[0122] [Structure of Access Point 100]

[0123] Figure 4 is a block diagram showing the structure of the access point 100 according to the present embodiment. Figure 4In the example, the access point 100 includes a scheduling unit 101, a target reception power setting unit 102, a transmission power control information setting unit 103, an RA control signal generating unit 104, a transmission signal generating unit 105, a wireless transmission and reception unit 106, an antenna 107, a reception signal demodulating unit 108, a feedback information decoding unit 109, and a response signal decoding unit 110. The scheduling unit 101, the target reception power setting unit 102, the transmission power control information setting unit 103, and the RA control signal generating unit 104 constitute an access control (MAC: Media Access Control) unit, and the transmission signal generating unit 105, the reception signal demodulating unit 108, the feedback information decoding unit 109, and the response signal decoding unit 110 constitute a baseband (BB: Base Band) processing unit.

[0124] The scheduling unit 101 determines the RU allocation and MCS of each terminal 200 based on the CSI, buffer status report, etc. fed back from each terminal 200. These terminals 200 are terminals 200 to which the access point 100 specifies the allocation of resources, so they are individually allocated terminals. On the other hand, when it is necessary to allocate resources to the terminal 200 for random access, the scheduling unit 101 secures the RU for random access.

[0125] The target received power setting unit 102 sets the target received power value of each RU according to the RU allocation status of the scheduling unit 101. The target received power setting unit 102 sets at least one target received power value as UL transmission power control information for controlling the uplink transmission power of each of the plurality of terminals 200. Details of the method for setting the target received power value in the target received power setting unit 102 will be described later.

[0126] The transmission power control information setting unit 103 generates transmission power control information for each RU based on the target reception power value determined by the target reception power setting unit 102 and the resource allocation information indicating the scheduling result determined by the scheduling unit 101. The details of the control information set by the transmission power control information setting unit 103 will be described later. In addition, the scheduling unit 101 may also perform rescheduling operations such as reselection of MCS based on the transmission power control information calculated by the transmission power control calculation unit 103.

[0127] The RA control signal generating unit 104 generates a random access control signal for requesting the terminal 200 to send a UL response signal. The random access control signal includes a trigger type (common area) notifying the type of the control signal, terminal identification information (terminal individual area), MCS (terminal individual area), etc. In the terminal identification information, a unique ID (STA_ID) for distinguishing the terminal 200 is set in the case of individual allocation, and a random access ID is set in the case of random access allocation. In addition, the random access control signal includes the transmission power control information set by the transmission power control information setting unit 103. In addition, the random access control signal includes at least one target reception power value. The details of the set transmission power control information and the area (common area or terminal individual area) will be described later.

[0128] The transmission signal generating section 105 performs encoding and modulation processing on the random access control signal input from the RA control signal generating section 104. In addition, the transmission signal generating section 105 performs encoding and modulation processing on the information indicating the transmission power of the access point 100 and the information indicating the transmission antenna gain of the access point 100. Then, the transmission signal generating section 105 adds a control signal (also called a preamble) such as a pilot signal for frequency synchronization and timing synchronization at the receiving side (terminal 200) and a channel estimation signal to the modulated signal, generates a radio frame (transmission signal), and outputs it to the radio transmission and reception section 106.

[0129] Wireless transmission and reception section 106 performs predetermined wireless transmission processing such as D / A conversion and up-conversion to a carrier frequency on the signal input from transmission signal generation section 105 , and transmits the signal after the wireless transmission processing via antenna 107 .

[0130] When receiving a UL response signal (a response signal to a random access control signal transmitted by the access point 100 ) and feedback information from the terminal 200 , the access point 100 operates as follows.

[0131] The wireless signal received by antenna 107 is input to wireless transmission and reception section 106. Wireless transmission and reception section 106 performs predetermined wireless reception processing such as down-converting the carrier frequency on the wireless signal, and outputs the signal after the wireless reception processing to reception signal demodulation section 108.

[0132] Received signal demodulation section 108 extracts received wireless frames by performing autocorrelation processing or the like on the signal input from wireless transmission / reception section 106 , and outputs the extracted frames to feedback information decoding section 109 and response signal decoding section 110 .

[0133] The feedback information decoding section 109 demodulates and decodes CSI, path loss, and the like fed back from the terminal 200 in the radio frame input from the reception signal demodulation section 108 , and outputs the demodulated information to the scheduling section 101 .

[0134] The response signal decoding unit 110 demodulates and decodes the UL response signal included in any RU indicated by the random access control signal in the radio frame input from the received signal demodulation unit 108. The response signal decoding unit 110 outputs the reception result to the scheduling unit 101. The scheduling unit 101 performs retransmission control and the like based on the reception result.

[0135] [Structure of Terminal 200]

[0136] Figure 5 is a block diagram showing the structure of the terminal 200 according to this embodiment. Figure 5 In the present invention, the terminal 200 has an antenna 201, a wireless transmission and reception unit 202, a reception signal demodulation unit 203, an RA control signal decoding unit 204, a transmission power calculation unit 205, a power control information storage unit 206, a path loss estimation unit 207, a feedback information generation unit 208, a response signal generation unit 209, and a transmission signal generation unit 210. In addition, the transmission power calculation unit 205, the power control information storage unit 206, the path loss estimation unit 207, the feedback information generation unit 208, and the response signal generation unit 209 constitute an access control unit (MAC), and the reception signal demodulation unit 203, the RA control signal decoding unit 204, and the transmission signal generation unit 210 constitute a baseband (BB: Base Band) processing unit.

[0137] The wireless transmission and reception unit 202 receives the data from the access point 100 ( Figure 4 ), performs predetermined wireless reception processing such as down-conversion and A / D conversion on the received signal, outputs the signal after the wireless reception processing to the reception signal demodulation unit 203, and outputs information indicating the reception power to the power control information storage unit 206. In addition, 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 signal input from the transmission signal generation unit 210 described later, and transmits the signal after the wireless transmission processing through the antenna 201.

[0138] The reception signal demodulation unit 203 extracts the received wireless frame by performing autocorrelation processing on the signal input from the wireless transmission and reception unit 202, and outputs it to the RA control signal decoding unit 204. In addition, the reception signal demodulation unit 203 outputs information indicating the transmission power and transmission antenna gain of the access point 100 included in the extracted wireless frame to the power control information storage unit 206.

[0139] The RA control signal decoding unit 204 demodulates and decodes the random access control signal contained in the transmission RU of the random access control signal in the wireless frame input from the received signal demodulation unit 203, outputs the transmission power control information to the transmission power calculation unit 205, and outputs the information required for the transmission signal generation such as MCS to the transmission signal generation unit 210.

[0140] Power control information storage section 206 stores information indicating reception power input from wireless transmission / reception section 202 and information indicating transmission power and transmission antenna gain of access point 100 input from reception signal demodulation section 203 .

[0141] The path loss estimation unit 207 calculates the path loss using the equation (1) or the equation (2) based on the transmission power of the access point 100 input from the power control information storage unit 206 (further the transmission antenna gain in the equation (1)) and the measured reception power, and outputs it to the transmission power calculation unit 205 and the feedback information generation unit 208.

[0142] Transmit power calculation section 205 calculates the transmit power of the UL response signal using, for example, equation (3) based on the target reception power value included in the transmit power control information input from RA control signal decoding section 204 and the path loss input from path loss estimation section 207 .

[0143] Feedback information generating section 208 generates feedback information including estimated channel quality information (CSI, RSSI) and path loss input from path loss estimating section 207 as necessary, and outputs it to transmission signal generating section 210. The timing of feeding back path loss will be described later.

[0144] Response signal generating section 209 generates a UL response signal including the terminal ID of terminal 200 and transmission information (data, transmission buffer status notification, DL Data request, etc.) of terminal 200 , and outputs the signal to transmission signal generating section 210 .

[0145] The transmission signal generating section 210 encodes and modulates the UL response signal input from the response signal generating section 209 or the feedback information input from the feedback information generating section 208, using information such as the MCS input from the RA control signal decoding section 204. The transmission signal generating section 210 then adds a control signal (preamble) such as a pilot signal for frequency synchronization and timing synchronization and a channel estimation signal for the receiving side (access point 100) to the modulated signal, generates a radio frame (transmission signal), and outputs the signal to the radio transmission and reception section 202.

[0146] [Transmission power control information and area setting method]

[0147] Next, the area in which the transmission power control information and the random access control signal for the access point 100 are set will be described in detail.

[0148] Hereinafter, the transmission power control information and the setting methods 1 to 7 of the regions will be described respectively.

[0149] <Setting method 1>

[0150] In setting method 1, the access point 100 (RA control signal generating section 104) arranges the target received power value in the terminal-specific field of the random access control signal. Figure 6 An example of setting method 1 and control signal for random access is shown. Figure 6 The trigger type in indicates the type of the trigger frame (Trigger frame), so for example, the trigger type is set to a control signal for random access.

[0151] After receiving the random access control signal, the terminal 200 obtains the target reception power value configured in the terminal individual area in which the STA_ID or random access ID of the terminal 200 (the terminal itself) is set in the terminal identification ID. Then, the terminal 200 calculates the transmission power of the response signal from the path loss calculated by the path loss estimation unit 207 and the above-obtained target reception power value, for example, by equation (3), and performs transmission power control on the response signal.

[0152] [Method for setting the target received power value]

[0153] Next, a method for setting the target received power value in the access point 100 when the setting method 1 is applied will be described. The target received power value is the received power value in the antenna element. Therefore, when the target received power value is determined from the received power including the receive antenna gain, after the target received power value is determined, the access point 100 needs to correct it to the value excluding the receive antenna gain and notify the terminal 200.

[0154] Below, use Figure 7A to Figure 7C Methods 1 to 3 for setting the target received power value in individual allocation will be described respectively.

[0155] <Target reception power setting method 1 (individual allocation)>

[0156] The target reception power setting unit 102 determines the target reception power value based on the difference in the minimum required reception power of each MCS between resources, from the terminal information indicating the resources allocated by individual allocation determined by the scheduling unit 101 and the MCS of each terminal 200. The minimum required reception power (minimum sensitivity) of each MCS is defined in the 802.11 specification (for example, in the case of 11n, refer to non-patent document 5).

[0157] Fig. 7A An example of a method for determining target received power in target received power setting method 1 (individual allocation) in setting method 1 is shown. Fig. 7A In FIG. 1 , resources (RU=1, 2, 3) are allocated to three terminals (ID=1, 2, 3), respectively. Also, the MCS of each terminal is #2, #3, and #5, respectively.

[0158] The target reception power setting unit 102 sets the offset so that the maximum and minimum difference between the reception powers obtained by adding each offset (offset1 to offset3) to the minimum required reception power of each MCS falls within the allowable power difference. Fig. 7A In the example, the target receiving power setting unit 102 sets each offset so that the difference between the minimum required receiving power of MCS#5 having the largest minimum required receiving power among MCS#2, #3, and #5 plus the receiving power of offset3 and the minimum required receiving power of MCS#2 having the smallest minimum required receiving power plus the receiving power of offset1 is within the allowable power difference.

[0159] In this way, the access point 100 sets the target reception power value for each terminal 200 to which each resource is allocated based on the minimum required reception power of each MCS, thereby setting the minimum necessary transmission power, thereby reducing power consumption of the terminal 200 and interference with other access points 100.

[0160] Furthermore, Fig. 8A As shown, the allowable power difference may also be changed according to the A / D conversion performance of the access point 100. By changing the allowable power difference according to the A / D conversion performance of the access point 100, the reception performance of the terminal 200 is not degraded due to the reception power difference, and the target reception power value can be flexibly set, thereby improving the scheduling gain.

[0161] also, Figure 8BAs shown, the allowable power difference can also be changed according to the number of multiplexed terminals of OFDMA / MU-MIMO. When the number of multiplexed terminals is small, the possibility of a smaller reception power difference between terminals is higher than when the number of multiplexed terminals is large. Therefore, by changing the allowable power difference according to the number of multiplexed terminals, the target reception power value can be flexibly set, and the scheduling gain is improved.

[0162] <Target reception power setting method 2 (individual allocation)>

[0163] Target received power setting section 102 determines a target received power value based on the difference in received power of signals previously received by terminal 200 , from terminal information indicating that resources are allocated by individual allocation, determined by scheduling section 101 .

[0164] Figure 7B An example of a method for determining the target received power in the target received power setting method 2 (individual allocation) in the setting method 1 is shown. Figure 7B , the target reception power setting unit 102 assumes that the scheduling unit 101 has allocated resources to three terminals (ID=1, 2, 3), and sets an offset (offset1~3) based on the reception power difference of the signal previously received from the terminal so that the power difference is within the allowable power difference.

[0165] In this way, the access point 100 can suppress the fluctuation of the target reception power value of each terminal 200 by setting the target reception power value based on the reception power of the signal received previously.

[0166] Furthermore, similarly to the target reception power setting method 1 (individual allocation), Fig. 8A , Figure 8B As shown, the allowable power difference may also be changed according to the A / D conversion performance and the number of multiplexed terminals of OFDMA / MU-MIMO.

[0167] <Target reception power setting method 3 (individual allocation)>

[0168] The target receiving power setting unit 102 uses the terminal information determined by the scheduling unit 101, which indicates the terminal to which resources are allocated through individual allocation, calculates the estimated receiving power from the maximum transmission power and path loss of the terminal, and determines the target receiving power value based on the difference in estimated power between the terminals allocated to each resource.

[0169] Figure 7C An example of a method for determining the target received power in the target received power setting method 3 (individual allocation) in the setting method 1 is shown. Figure 7CIn the example, the target reception power setting unit 102 assumes that the scheduling unit 101 allocates resources to three terminals (ID=1, 2, 3), and sets offsets (offset1 to 3) so that the estimated reception power difference between the terminals 200 is within the allowable power difference. Figure 7C This is an example in which the maximum transmission power of each terminal 200 is equal. For example, target reception power setting section 102 uses the value included in the association request signal as the maximum transmission power of terminal 200 .

[0170] In this way, the access point 100 sets the target reception power value according to the maximum transmission power and path loss of each terminal 200, thereby preventing the setting of a target reception power value that requires a transmission power exceeding the maximum transmission power that can be set by the terminal 200.

[0171] Furthermore, similarly to the target reception power setting method 1 (individual allocation), Fig. 8A , Figure 8B As shown, the allowable power difference may also be changed according to the A / D conversion performance or the multiplexing number of OFDMA / MU-MIMO.

[0172] Next, use Figures 9A to 9C Methods 1 to 4 for setting the target received power value during random access assignment will be described respectively.

[0173] <Target reception power setting method 1 (random access allocation)>

[0174] The target received power setting unit 102 sets the average value of the target received power values ​​of the terminals to which resources are allocated by individual allocation as the target received power value of the random access allocation RU.

[0175] Fig. 9A An example of a target received power determination method of target received power setting method 1 (random access allocation) in setting method 1 is shown. Terminals with ID=1 and 2 are terminals to which resources are allocated by individual allocation, and ID=0 is a resource for random access. In addition, for example, it is assumed that the target received power value of the resource with ID=1 and 2 is determined by one of the target received power setting methods 1 to 3 (individual allocation). In this case, the target received power setting unit 102 calculates the target received power of the resource for random access (ID=0) from the average value of the target received power values ​​of the resources with ID=1 and 2.

[0176] In this way, access point 100 sets the average of the target reception power values ​​of the terminals to which resources are allocated by individual allocation as the target reception power of the random access allocation RU, thereby reducing the difference in reception power between the random access allocation terminals and the individual allocation terminals.

[0177] <Target reception power setting method 2 (random access allocation)>

[0178] The target received power setting unit 102 sets the lowest value of the target received power values ​​of the terminals to which resources are allocated by individual allocation as the target received power value of the random access allocation RU.

[0179] Fig. 9B An example of a method for determining the target received power of the target received power setting method 2 (random access allocation) in the setting method 1 is shown. The terminals 200 with ID=1 and 2 are terminals to which resources are allocated by individual allocation, and ID=0 is a resource for random access. In addition, it is assumed that the target received power value of the resource with ID=1 and 2 is determined by one of the target received power setting methods 1 to 3 (individual allocation). The target received power setting unit 102 selects the minimum value ( Fig. 9B The target received power value of the resource used for random access (ID=0) is calculated based on the target received power value of the resource with ID=2.

[0180] In this way, the access point 100 sets the lowest value of the target received power values ​​of the terminals to which resources are allocated by individual allocation as the target received power value of the random access allocation RU, thereby preventing the difference in received power between the random access allocation terminal and other terminals from increasing even if the random access received power increases. This is because the reason for the increase in random access received power is that the access point 100 may simultaneously receive signals from a plurality of terminals 200 due to collision.

[0181] <Target reception power setting method 3 (random access allocation)>

[0182] Target reception power setting section 102 sets the average reception power of previously received signals of all or part of the terminals connected to access point 100 as a target reception power value.

[0183] The terminal 200 that actually transmits the response signal in random access allocation cannot be determined. Therefore, the average reception power of previously received signals from all or part of the terminals connected to the access point 100 is set as the target reception power value, and the transmission power required to meet the target reception power value in random access allocation is easily accommodated within the range between the minimum transmission power and the maximum transmission power of each terminal 200.

[0184] <Target reception power setting method 4 (random access allocation)>

[0185] The target reception power setting unit 102 sets a fixed value of target reception power according to a purpose.

[0186] Fig. 9C An example of the purpose and target received power value of target received power setting method 4 (random access allocation) in setting method 1 is shown. For example, the target received power setting unit 102 sets the target received power value lower (e.g., -75 dBm) for the purpose of preferentially receiving signals from cell edge terminals so that the required target received power is satisfied even at cell edge terminals. On the other hand, the target received power setting unit 102 sets the required target received power value higher (e.g., -65 dBm) for the purpose of preferentially receiving signals from terminals near access points.

[0187] In this way, the access point 100 can prioritize reception of cell edge terminals or terminals near the access point by setting the target reception power value of the random access allocation terminal according to the purpose.

[0188] The above describes the method for setting the target received power value in setting method 1.

[0189] Thus, in setting method 1, the access point 100 notifies the terminal 200 of the target reception power value in the terminal individual area of ​​the random access control signal. In addition, the terminal 200 performs transmission power control of the response signal based on the estimated path loss and the notified target reception power value. In this way, the reception power difference in the access point 100 between the terminals 200 to which resources are allocated by the random access control signal can be reduced, and the problems of inter-carrier interference and dynamic range of A / D conversion can be improved. In addition, by setting the target reception power value for each terminal 200 in the individual area of ​​the terminal 200, the access point 100 can set the transmission power in accordance with the channel quality of each terminal 200.

[0190] <Setting method 2>

[0191] In setting method 2, the access point 100 (RA control signal generating section 104) places the target reception power value in the common region of the random access control signal. Fig.10 This figure shows an example of a control signal for random access in setting method 2. Fig.10 The trigger type in is a type indicating the type of the trigger frame (Trigger frame), for example, the trigger type is set to a control signal for random access.

[0192] After receiving the random access control signal, the terminal 200 obtains the target reception power value configured in the terminal common area. Then, the terminal 200 calculates the transmission power of the response signal from the path loss calculated by the path loss estimation unit 207 and the above-obtained target reception power value, for example, using equation (3), and performs transmission power control on the response signal.

[0193] Furthermore, in the case of this setting example, since the target received power value of each terminal 200 is the same, the received quality of each terminal 200 is substantially the same. The access point 100 can uniquely determine the MCS of each terminal 200 based on the common target received power value. Therefore, it is also possible to set a configuration in which information such as MCS is not transmitted in the terminal-specific area but is transmitted in the common area. By transmitting the MCS in the common area, the overhead of the random access control signal can be reduced.

[0194] [Method for setting the target received power value]

[0195] Next, a method for setting the target reception power value in the access point 100 when the setting method 2 is applied will be described.

[0196] Below, use Figures 11A to 11C Methods 1' to 3' for setting the target received power in individual allocation will be described respectively.

[0197] <Target reception power setting method 1' (individual allocation)>

[0198] Target reception power setting section 102 determines a target reception power value based on the highest MCS minimum required reception power from the terminal information indicating the terminal to which resources are allocated by individual allocation and the MCS of each terminal determined by scheduling section 101 .

[0199] Fig.11A An example of a method for determining the target received power in the target received power setting method 1' (individual allocation) in the setting method 2 is shown. Fig.11A In FIG. 1 , resources (RU=1, 2, 3) are allocated to three terminals (ID=1, 2, 3), respectively. Also, the MCS of each terminal 200 is #2, #3, and #5, respectively.

[0200] Target reception power setting section 102 sets a target reception power value common to each terminal 200 by adding a certain offset to the minimum required reception power of MCS#5 of terminal ID=3, which is the highest MCS among MCS#2, #3, and #5 of each terminal 200.

[0201] In this way, the access point 100 sets a common target reception power value for all the terminals 200 based on the highest MCS among the MCSs set for the terminals 200 , thereby increasing the possibility of receiving the response signals of all the terminals without error.

[0202] <Target reception power setting method 2' (individual allocation)>

[0203] Target received power setting section 102 determines a target received power value based on an average value of received powers of signals previously received by terminal 200 , from terminal information indicating that resources are allocated by individual allocation, determined by scheduling section 101 .

[0204] Fig. 11B An example of a method for determining target received power in target received power setting method 2' (individual allocation) in setting method 2 is shown. Fig. 11B , target reception power setting section 102 assumes that scheduling section 101 has allocated resources to three terminals 200 (ID=1, 2, 3), and sets the average value of reception powers of signals previously received from the terminals 200 as a common target reception power value for each terminal 200.

[0205] In this way, by setting the average value of the reception powers of signals previously received from the terminal 200 as the target reception power value, the access point 100 can easily keep the transmission power required to meet the target reception power value within the range between the minimum transmission power and the maximum transmission power of each terminal 200 .

[0206] <Target reception power setting method 3' (individual allocation)>

[0207] The target receiving power setting unit 102 uses the terminal information determined by the scheduling unit 101, which indicates that resources are allocated through individual allocation, to calculate the estimated receiving power from the maximum transmission power and path loss of the terminal 200, and determines the estimated receiving power of the terminal 200 with the lowest estimated receiving power as the common target receiving power value in each terminal 200.

[0208] Fig. 11C An example of a method for determining the target received power in the target received power setting method 3' (individual allocation) in the setting method 2 is shown. Fig. 11C , the target reception power setting unit 102 assumes that the scheduling unit 101 has allocated resources to three terminals 200 (ID=1, 2, 3), and sets the estimated reception power of the terminal 200 with the lowest estimated reception power among the terminals 200, i.e., terminal ID=3, as the common target reception power value among the terminals 200.

[0209] In this way, the access point 100 estimates the target reception power based on the maximum transmission power and path loss of each terminal 200, and sets the target reception power of the terminal 200 having the lowest target reception power as the target reception power value common to the terminals 200, thereby being able to set the target reception power low, thereby reducing power consumption of the terminal 200 and interference with other access points 100. In addition, it is possible to prevent the setting of a target reception power value that requires a transmission power exceeding the maximum transmission power that can be set by the terminal 200.

[0210] Next, a method of setting a target reception power value during random access allocation will be described below.

[0211] <Target reception power setting method (random access allocation)>

[0212] The target received power setting unit 102 may use the same setting method as the target received power setting methods 1' to 3' (individual allocation) in the above-mentioned setting method 2, and may set the target received power value commonly set for each terminal 200 to which resources are allocated by individual allocation as the target received power value of the RU for random access allocation. Furthermore, the target received power setting unit 102 may use the same setting method as the target received power setting method 3 (random access allocation) and the target received power setting method 4 (random access allocation) in the setting method 1, and may set the target received power value.

[0213] The above describes the method for setting the target received power value in setting method 2.

[0214] Thus, in setting method 2, the access point 100 is configured to Fig.10 By configuring the target reception power value in the common area of ​​the random access control signal, the time length of the terminal's individual area can be shortened, and the overhead of the random access control signal can be reduced. The access point 100 cannot determine which terminal 200 among the random access allocation terminals 200 sends a response signal, and cannot set the optimal value of the target reception power value for each terminal 200. Therefore, when the proportion of random access allocation terminals 200 is large, even if the target reception power value is configured in the common area, performance degradation is small.

[0215] <Setting method 3>

[0216] In setting method 3, the access point 100 (RA control signal generating section 104) configures the target reception power value in the common region of the random access control signal in the same manner as in setting method 2. However, the target reception power value is set to a different value for each type of response signal (information) transmitted in random access.

[0217] As the type of the response signal, for example, data, control information, management information, etc. can be listed. Fig.12 This is an example of setting the target received power value for each response signal type in method 3. When the importance of the response signal is high, the target received power value is set high, and when the importance of the response signal is low, the target received power value is set low. Fig.12 In FIG. 1 , there is an example in which the priority is expressed in the order of control information, data, and management information.

[0218] Furthermore, a higher target received power value means, for example, adding an offset of ZdB to the target received power value calculated by setting method 2. Similarly, a lower target received power value means, for example, adding an offset of YdB to the target received power value calculated by setting method 2 (where Y <Z)。

[0219] Furthermore, for example, a response signal with a high degree of importance is a signal whose value is frequently updated, and a response signal with a low degree of importance is a signal whose value is not frequently updated.

[0220] In addition, the categories of response signals may not be divided into data, control information, and management information, but management information may be further subdivided to notify the target reception power value of each probe response (Probe Response) and association response (Association Response).

[0221] After receiving the random access control signal, the terminal 200 obtains a plurality of target reception power values ​​configured in the terminal common area, and switches the target reception power value to be used according to the type of the signal transmitted as the response signal. Then, the terminal 200 calculates the transmission power of the response signal from the path loss calculated by the path loss estimation unit 207 and the above-selected target reception power value, for example, using equation (3), and performs transmission power control on the response signal.

[0222] Thus, in setting method 3, the access point 100 is Fig.10 The target received power value is arranged in the common region of the random access control signal, and the target received power value is set to a different value for each type of the response signal. Thus, in the random access, even if the response signals collide, the access point 100 has a high probability of correctly receiving the response signal for which the target received power value is set high, and the probability of successfully receiving the signal with high importance can be improved.

[0223] <Setting method 4>

[0224] In setting method 4, access point 100 arranges the target reception power value in the common region of the random access control signal in the same manner as in setting method 2. However, the target reception power value is notified separately for each of the individual allocation and the random access allocation.

[0225] Fig.13This shows an example of setting the target reception power value for each allocation method in method 4. When the allocation method is individual allocation, no collision of response signals occurs, or the maximum transmission power and the minimum transmission power of the terminal 200 to which the access point 100 allocates resources can be estimated in advance. Therefore, it is considered that the difference between the reception power of the response signal actually received by the access point 100 and the target reception power value is small. Therefore, when the allocation method is individual allocation, the access point 100 sets the target reception power value higher.

[0226] On the other hand, when the allocation method is random access allocation, there is a possibility that a collision of response signals may occur. Due to the collision, the difference between the received power of the response signal and the target received power value increases. In other words, it is considered that the received power of the response signal is likely to exceed the target received power value. Therefore, when the allocation method is random access allocation, the access point 100 sets the target received power value to a lower value.

[0227] After receiving the random access control signal, the terminal 200 obtains a plurality of target receiving power values ​​configured in the terminal common area. The terminal 200 determines whether the resources used in sending the response signal are resources allocated through random access allocation from the terminal identification ID of the terminal separate area. That is, if the terminal identification ID is the ID of the local terminal, the terminal 200 determines that it is allocated separately, and if it is an ID for random access, it determines that it is allocated by random access. The terminal 200 switches the target receiving power value used in sending the response signal according to whether the allocation method is a separate allocation or a random access allocation. Then, the terminal 200 calculates the transmission power of the response signal from the path loss calculated by the path loss estimation unit 207 and the target receiving power value selected above, for example, using formula (3), and performs transmission power control on the response signal.

[0228] Thus, in setting method 4, the access point 100 is Fig.10 The target received power value is arranged in the common area of ​​the random access control signal, and the target received power value is set to a different value for each allocation method (individual allocation, random access allocation). Thus, for example, in the case of random access allocation, the received power increases when a collision occurs. Therefore, the access point 100 sets the target received power value in random access allocation that takes into account the increase in received power due to the collision, thereby preventing the degradation of the A / D conversion performance and the increase in interference to other terminals when a collision occurs.

[0229] <Setting method 5>

[0230] In setting method 5, access point 100 configures the target reception power value in the common area of ​​the random access control signal. Furthermore, access point 100 configures an offset value (target reception power offset) from the target reception power value set in the common area in the terminal-independent area.

[0231] Fig.14 An example of setting method 5 for the random access control signal is shown. Fig.14 The trigger type in is a type indicating the type of the trigger frame (Trigger frame), for example, the trigger type is set to a control signal for random access.

[0232] After receiving the random access control signal, the terminal 200 obtains the target received power value configured in the terminal common area. Furthermore, the terminal 200 obtains the target received power offset configured in the terminal individual area where the STA_ID or random access ID of the terminal 200 (the terminal) is set as the terminal identification ID, and adds the target received power offset to the target received power value obtained from the common area. Then, the terminal 200 calculates the transmission power of the response signal from the path loss calculated by the path loss estimation unit 207 and the target received power value after adding the above-mentioned target received power offset, for example, using formula (3), and performs transmission power control for the response signal.

[0233] [Method for setting the target received power value]

[0234] Next, a method for setting the target reception power value in the access point 100 when the setting method 5 is applied will be described.

[0235] Fig.15 This is an example of a pattern for setting the target received power offset of method 5. Fig.15 Indicates the offset value when the target received power offset is shown with 2 bits. Furthermore, if the target received power offset value is a value smaller than the number of bits of the target received power value, it may be any number of bits.

[0236] The target received power value when setting method 5 is applied is calculated in the same procedure as setting method 1. However, in setting method 1, the target received power value set individually for the terminal 200 is set in the terminal-individual region of the random access control signal. In setting method 5, the access point 100 calculates the average value of the target received power values ​​obtained for each terminal 200, for example, and sets the average value in the common region of the random access control signal. Furthermore, the access point 100 measures the difference between the target received power value of each terminal 200 and the average value, and uses Fig.15 The table quantifies the difference from the averaged target received power value to generate a target received power offset, which is set in the terminal's individual area.

[0237] Thus, in setting method 5, the access point 100 is Fig.14 In the common region of the random access control signal, the target received power value is configured, and in the terminal individual region, the offset value from the target received power value set in the common region is configured. In this way, the number of bits of the target received power offset is less than the number of bits of the target received power value, so when the number of allocated terminals is large, the total time length of the common region and the terminal individual region can be shortened, and the overhead of the random access control signal can be reduced.

[0238] <Setting method 6>

[0239] In setting method 6, the access point 100 sets different transmission power control information for the individually assigned terminal and the random access assigned terminal in the terminal individual area of ​​the random access control signal. As an example, the access point 100 configures the transmission power value for transmitting uplink signals in the terminal individual area for the individually assigned terminal, and configures the target reception power value in the terminal individual area for the random access assigned terminal.

[0240] Fig.16 An example of setting method 6 for the random access control signal is shown. Fig.16 The trigger type in is a type indicating the type of the trigger frame (Trigger frame), for example, the trigger type is set to a control signal for random access.

[0241] The access point 100 configures the transmission power value in the area where the control signal for individual allocation of the terminal individual area is set, that is, the area where the unique ID (STA_ID) for distinguishing the terminal 200 is set. On the other hand, the access point 100 configures the target reception power value in the area where the control signal for random access allocation of the terminal individual area is set, that is, the area where the random access ID (RA_ID) is set.

[0242] After receiving the random access control signal, the terminal 200 obtains the transmission power value configured in the corresponding terminal independent area when there is a terminal independent area in which the STA_ID of the terminal 200 is set as the terminal identification ID, and performs transmission power control on the response signal based on the obtained transmission power. On the other hand, when there is a terminal independent area in which the random access ID is set as the terminal identification ID, the terminal 200 obtains the target reception power value configured in the corresponding terminal independent area, calculates the transmission power of the response signal from the path loss calculated by the path loss estimation unit 207 and the above-obtained target reception power value, for example, using equation (3), and performs transmission power control on the response signal.

[0243] [Method for setting the target received power value]

[0244] Next, a method for setting the target reception power value in the access point 100 when the setting method 6 is applied will be described. As in the setting method 1, the access point 100 obtains the target reception power value for each terminal 200.

[0245] In the case of setting method 6, the access point 100 needs to set the transmission power for the individually assigned terminal, so the transmission power of the terminal 200 is calculated using equation (3), for example. Then, the access point 100 sets the calculated transmission power value in the terminal individual area of ​​the random access control signal for the individually assigned terminal. In addition, the format (number of bits) of the target reception power value and the transmission power value may be the same.

[0246] Thus, when the transmission antenna gain is not notified to the terminal 200 and the influence of the transmission antenna gain is large, the transmission power control can be performed more accurately by calculating the transmission power for the individually assigned terminal by the access point 100. In addition, by notifying the individually assigned terminal of the transmission power, the path loss calculation process and the transmission power calculation process can be omitted on the terminal 200 side, so that the power consumption of the terminal 200 can be reduced. In addition, when the format (number of bits) of the transmission power value and the target reception power value is the same, the position where the terminal identification ID is set is not changed from the past, so the complexity of the process of determining the position of the terminal identification ID does not increase.

[0247] <Setting method 7>

[0248] In setting method 7, access point 100 configures a target reception power value for a random access assigned terminal in a common region of a random access control signal, and configures a target reception power value for an individual assigned terminal in an individual terminal region of a random access control signal.

[0249] Fig.17 An example of setting method 7 for the random access control signal is shown. Fig.17 The trigger type in is a type indicating the type of the trigger frame (Trigger frame), so for example, the trigger type is set to a random access control signal. The access point 100 configures the target reception power value in the terminal-specific area where the unique ID (STA_ID) for distinguishing the terminal 200 is set, and does not configure the target reception power value in the terminal-specific area where the random access ID (RA_ID) is set. In addition, the access point 100 configures the target reception power value for random access allocation terminals in the common area.

[0250] After receiving the random access control signal, the terminal 200 obtains the target reception power value configured in the corresponding terminal separate area when there is a terminal separate area in which the STA_ID of the terminal 200 is set as the terminal identification ID, and performs transmission power control of the response signal based on the obtained target reception power value. On the other hand, when the STA_ID of the terminal 200 is not set as the terminal identification ID, the terminal 200 obtains the target reception power value configured in the common area, calculates the transmission power of the response signal from the path loss calculated by the path loss estimation unit 207 and the above-obtained target reception power value, for example, using equation (3), and performs transmission power control on the response signal.

[0251] Thus, in setting method 7, if Fig.17 As shown in FIG. 1 , the access point 100 configures the target received power value in the common area of ​​the random access control signal for the random access allocation terminal, and configures the target received power value in the terminal-specific area of ​​the random access control signal for the individual allocation terminal. In this way, when there are many random access allocation terminals, the total time length of the common area and the terminal-specific area can be shortened, and the overhead of the random access control signal can be reduced. In addition, the access point 100 cannot determine which terminal 200 among the random access allocation terminals sends a response signal, and cannot set the optimal value of the target received power value for each terminal 200. Therefore, when the proportion of the random access allocation terminals 200 is large, even if the target received power value is configured in the common area, performance degradation is small.

[0252] In the above, the transmission power control information and the setting methods 1 to 7 in the present embodiment have been described.

[0253] [Path loss feedback timing]

[0254] Next, in the present embodiment, description will be given of the timing at which the terminal 200 feeds back the path loss to the access point 100 when the access point 100 uses the path loss when calculating the target received power value.

[0255] Hereinafter, timings 1 to 4 at which the terminal 200 feeds back the path loss will be described respectively.

[0256] <Timing 1>

[0257] At timing 1 , the terminal 200 transmits a path loss notification signal to the access point 100 as a response to a request signal (path loss request signal) from the access point 100 . Fig.18 An example of the processing flow of the path loss feedback at timing 1 is shown.

[0258] exist Fig.18In the present invention, the access point 100 generates a beacon signal (ST201). The beacon signal includes the transmission power of the access point 100.

[0259] The generated beacon signal is wirelessly notified from the access point 100 to the terminal 200 (ST202).

[0260] Next, the access point 100 periodically generates a path loss request signal (ST203). For example, the path loss request signal is generated as an action frame. The action frame is a frame for setting a measurement request (Measurement Request), a TPC request (TPC Request), etc. (for example, refer to Non-Patent Document 3).

[0261] The generated path loss request signal is wirelessly notified from access point 100 to terminal 200 (ST204).

[0262] When receiving the path loss request signal, terminal 200 estimates the path loss from the transmission power and antenna gain notified by the beacon signal (ST205). For example, the path loss estimation is expressed by equation (1) or equation (2).

[0263] Next, the terminal 200 generates a path loss notification signal (ST206). For example, the path loss notification signal is generated as an action frame.

[0264] The generated path loss notification signal is wirelessly notified from the terminal 200 to the access point 100 (ST207).

[0265] Thus, the terminal 200 transmits the path loss as a response to the path loss request signal to the access point 100 at timing 1. Thus, the terminal 200 can notify the access point 100 of the path loss at the timing when the path loss is required.

[0266] <Timing 2>

[0267] In timing 2, terminal 200 regularly estimates the path loss, and transmits a path loss notification signal to access point 100 when the path loss change amount from the timing of the last path loss notification reaches a certain reference or when a certain time has passed from the timing of the last path loss notification. Fig.19 An example of the processing flow of the path loss feedback at timing 2 is shown.

[0268] exist Fig.19 In the process, the access point 100 generates a beacon signal (ST211). The beacon signal includes the transmission power of the access point 100.

[0269] The generated beacon signal is wirelessly notified from the access point 100 to the terminal 200 (ST212).

[0270] Terminal 200 periodically estimates path loss from the transmission power notified by the beacon signal and the antenna gain (ST213). For example, the path loss estimation is expressed by equation (1) or equation (2). The signal used in the path loss estimation may also be a signal received just before the path loss estimation.

[0271] Terminal 200 determines whether a change in the estimated path loss from the timing when the previous path loss was notified has reached a certain reference, or whether a certain time has passed from the timing when the previous path loss was notified.

[0272] When the determination condition is satisfied, the terminal 200 generates a path loss notification signal (ST215). For example, the path loss notification signal is generated as an action frame.

[0273] The generated path loss notification signal is wirelessly notified from terminal 200 to access point 100 (ST216).

[0274] Thus, in timing 2, terminal 200 notifies access point 100 of the path loss only at the timing when the path loss changes. In this way, it is possible to reduce the overhead of control information.

[0275] <Timer 3>

[0276] At timing 3, the terminal 200 determines the access point 100 to which it is to connect, and when transmitting the association request signal, causes the path loss estimated by the terminal 200 to be included in the association request signal. Fig. 20 An example of the processing flow of the path loss feedback at timing 3 is shown.

[0277] exist Fig. 20 In the process, the access point 100 generates a beacon signal (ST221). The beacon signal includes the transmission power of the access point 100.

[0278] The generated beacon signal is wirelessly notified from the access point 100 to the terminal 200 (ST222).

[0279] The terminal 200 selects an access point 100 to connect to based on reception quality and the like (ST223).

[0280] Terminal 200 estimates the path loss from the transmission power and antenna gain notified by the beacon signal (ST224). For example, the path loss estimation is expressed by equation (1) or equation (2).

[0281] The terminal 200 generates an association request signal (ST225). The association request signal is a signal for notifying the access point 100 of the connection destination of the information of the terminal 200 (for example, refer to Non-Patent Document 5). The terminal 200 also includes the estimated path loss in the association request signal.

[0282] The generated association request signal is wirelessly notified from terminal 200 to access point 100 (ST226).

[0283] In this way, by including the path loss in the association request signal at timing 3, the overhead of the control information can be reduced compared to the case where the path loss is transmitted alone.

[0284] <Timing 4>

[0285] At timing 4, when the terminal 200 transmits the buffer status report (Buffer status report), the path loss estimated by the terminal 200 is included in the buffer status report (Buffer status report) as a response to the random access control signal. Fig.21 An example of the processing flow of the path loss feedback at timing 4 is shown.

[0286] exist Fig.21 In the process, the access point 100 generates a beacon signal (ST231). The beacon signal includes the transmission power of the access point 100.

[0287] The generated beacon signal is wirelessly notified from the access point 100 to the terminal 200 (ST232).

[0288] In order to check the buffer status of the terminal 200, the access point 100 generates a random access control signal for requesting a buffer status report (bufferstatus report) (ST233).

[0289] The generated random access control signal is wirelessly notified from access point 100 to terminal 200 (ST234).

[0290] Terminal 200 estimates the path loss from the transmission power and antenna gain notified by the beacon signal (ST235). For example, the path loss estimation is expressed by equation (1) or equation (2).

[0291] Terminal 200 generates a buffer status report (Buffer status report) for notifying the buffer status of the terminal 200 (ST236). Terminal 200 also includes the estimated path loss in the buffer status report (Buffer status report).

[0292] The generated buffer status report is wirelessly notified from the access point 100 to the terminal 200 (ST237).

[0293] Thus, in timing 4, the buffer status report and the path loss are sent simultaneously by the terminal 200, and the control information overhead can be reduced compared with the case where the path loss is sent alone. In addition, the buffer status report and the path loss are used for random access scheduling and transmission power control, and since the timing used is the same, it is efficient to feed back them simultaneously.

[0294] The path loss feedback timings 1 to 4 have been described above.

[0295] Thus, in this embodiment, the access point 100 notifies the terminal 200 of the target reception power value using a random access control signal, and the terminal 200 calculates the transmission power from the estimated path loss and the notified target reception power value, etc., and performs transmission power control. As a result, when the access point 100 receives a signal multiplexed by a plurality of terminals 200 through UL MU-MIMO or OFDMA, the reception power difference between the terminals 200 can be reduced. Therefore, MU interference can be reduced, and the received signal can be contained within the dynamic range of A / D conversion. As described above, according to this embodiment, by efficiently performing transmission power control in the UL response signal sent by the MU in random access, the reception power difference between the terminals 200 is reduced, and the problems of inter-carrier interference and the dynamic range of A / D conversion can be improved.

[0296] Furthermore, in this embodiment, by notifying the target reception power value with a random access control signal, the target reception power value can be dynamically changed in each scheduling according to the reception quality of the random access allocation terminal or the individual allocation terminal, and the optimal adaptive modulation can be instantly applied to each terminal 200. Thus, in this embodiment, the system throughput can be improved.

[0297] (Implementation Method 2)

[0298] As mentioned above, the access point notifies the terminal of the target receiving power value using a random access control signal, performs transmit power control on the terminal side, and when the access point receives a signal that multiplexes signals from multiple terminals in UL MU-MIMO or OFDMA mode, the receiving power difference between the terminals in the access point can be reduced.

[0299] However, the transmit power control capability of terminals compatible with 11ax is low. For example, among the terminals compatible with 11ax, there may be terminals that can only change the transmit power by a few levels, or terminals that do not have the transmit power control function depending on the situation. Therefore, in each terminal, although the transmit power is calculated from the notified target receive power value, etc., due to the limitations of the maximum transmit power, minimum transmit power, and transmit power variable range of the terminal, it is possible that the response signal cannot be sent with the transmit power that satisfies the target receive power value on the access point side.

[0300] Therefore, in this embodiment, a method of controlling the transmission of a terminal is described when it is difficult to meet the target reception power value due to the limitation of the maximum transmission power, the minimum transmission power, and the transmission power variable range of the terminal. In this way, the reception power difference between terminals in the access point can be reduced.

[0301] Fig. 22 is a block diagram showing the structure of the terminal 300 according to this embodiment. Fig. 22 Zhongyu Figure 5 The difference is that the information output from the transmission power calculation unit 205 and the information output from the RA control signal demodulation unit 204 are input to the transmission control unit 301, and the output of the transmission control unit 301 is input to the wireless transmission and reception unit 202. In addition, the structure of the access point 100 is different from that of the first embodiment ( Figure 4 )same.

[0302] This embodiment is different from Embodiment 1 in that transmission control section 301 controls wireless transmission and reception section 202 based on the calculated transmission power value to cancel signal transmission (details will be described later).

[0303] Transmit power calculation section 205 calculates transmit power using equation (3) based on the target reception power value input from RA control signal decoding section 204 and the path loss value input from path loss estimation section 207 .

[0304] The transmission control unit 301 determines whether the transmission of the signal is stopped from the viewpoint of whether the transmission power within the allowable power difference that satisfies the target reception power value can be set based on the transmission power value input from the transmission power calculation unit 205, the information (target reception power value, etc.) input from the RA control signal decoding unit 204, and the maximum transmission power, minimum transmission power, and transmission power variable range of the terminal 300, and outputs information indicating whether the transmission is stopped to the wireless transmission and reception unit 202. The method for determining whether the transmission is stopped will be described later.

[0305] The wireless transmission and reception unit 202 does not transmit the corresponding signal when there is a transmission stop instruction from the transmission control unit 301. On the other hand, when there is no transmission stop instruction from the transmission control unit 301, 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 signal input from the transmission signal generating unit 210, and transmits the signal after the wireless transmission processing through the antenna 201.

[0306] Hereinafter, methods 1 to 6 of determining whether or not transmission is stopped will be described respectively.

[0307] <Judgment method 1>

[0308] In determination method 1, transmission control section 301 does not issue a transmission stop instruction at any transmission power.

[0309] Thus, in determination method 1, the transmission control unit 301 does not issue a transmission stop instruction. Therefore, when there are many terminals 300 that cannot set the transmission power within the allowable power difference that satisfies the target reception power value due to the transmission power limitation, the power difference of the received signal in the access point 100 may be greater than the specified value. However, when the number of terminals is small, the possibility that the reception power difference is within the specified range increases. Therefore, by not issuing a transmission stop instruction by the transmission control unit 301, resources can be used effectively. In addition, when the A / D conversion performance of the access point 100 is high, there is no problem of the dynamic range of the A / D conversion caused by the transmission power difference.

[0310] <Judgment method 2>

[0311] In determination method 2, the transmission control unit 301 instructs to stop transmission when the transmission power calculated by the transmission power calculation unit 205 cannot be set to a transmission power within the allowable power difference that satisfies the target receiving power value due to limitations on the maximum transmission power, minimum transmission power, and variable transmission power range of the terminal 300.

[0312] In this way, the transmission control unit 301 always stops transmission when it is impossible to set the transmission power within the allowable power difference that satisfies the target reception power value of the terminal 300. In this way, it is possible to prevent the reception power difference between the terminals 300 from increasing and failing to meet the target reception power value. In addition, by stopping transmission of a signal that does not meet the target reception power value and may fail to be received, the collision rate of random access allocation can be reduced.

[0313] <Judgment method 3>

[0314] In determination method 3, the transmission control unit 301 does not issue a transmission stop instruction at any transmission power in the case of individual allocation. On the other hand, the transmission control unit 301 instructs transmission stop in the case of random access allocation when the transmission power within the allowable power difference that satisfies the target reception power value cannot be set due to the limitations of the maximum transmission power, the minimum transmission power, and the transmission power variable range of the terminal 300.

[0315] In this way, in the random access allocation in which the terminal 300 cannot determine which terminal 300 actually transmits the response signal in the access point 100, that is, in a state where the transmission power control capability such as the maximum transmission power and the minimum transmission power of the terminal 300 is unknown, the terminal 300 is instructed to stop transmission according to the transmission power only for the terminal 300 for which the target reception power value may be set in the access point 100. In this way, it is possible to prevent the reception power difference between the terminals 300 from increasing and failing to meet the target reception power value. On the other hand, in the individual allocation, the access point 100 can set the target reception power value in consideration of the transmission power control capability such as the maximum transmission power and the minimum transmission power of the terminal 300 to which the resource is allocated. Therefore, the target reception power value is less likely to change greatly due to the transmission power restriction, so that the individual allocation terminal always transmits the response signal regardless of the transmission power, and resource utilization efficiency can be improved.

[0316] <Judgment method 4>

[0317] In determination method 4, when the transmission power cannot be set within the allowable power difference to satisfy the target reception power value due to the maximum transmission power, minimum transmission power, and transmission power variable range of terminal 300, whether transmission should be stopped or not is signaled from access point 100 to terminal 300. Terminal 300 specifies whether transmission should be stopped or not based on the signaling (0: not to transmit, 1: to transmit).

[0318] Thus, terminal 300 switches whether to stop transmission when transmission power cannot be set within the allowable power difference that satisfies the target reception power value based on signaling from access point 100 , thereby changing transmission control according to the A / D conversion performance of access point 100 .

[0319] <Judgment method 5>

[0320] In determination method 5, the transmission control unit 301 does not issue a transmission stop instruction at any transmission power even in the case of individual allocation, but in the case of random access allocation, instructs to stop transmission when the transmission power within the allowable power difference that satisfies the target reception power value cannot be set due to the limitation of the maximum transmission power, the minimum transmission power, and the transmission power variable range of the terminal 300, based on the BSS LOAD notified by the beacon. That is, the transmission control unit 301 does not issue a transmission stop when the BSS LOAD is low, but issues a transmission stop when the BSS LOAD is high. BSSLOAD is information on the number of terminals connected to the BSS and the degree of congestion corresponding to the traffic situation, which is notified by the access point 100 to the terminal 300 by the beacon (for example, refer to non-patent document 5).

[0321] In this way, terminal 300 switches whether to stop sending during random access allocation according to BSS LOAD. For signals that do not meet the target receiving power value and may fail to be received, when the possibility of conflict in random access is high (i.e., when BSS LOAD is high), the possibility of conflict in random access can be reduced by stopping sending.

[0322] <Judgment method 6>

[0323] In determination method 6, transmission control section 301 does not issue a transmission stop instruction at any transmission power in the case of individual allocation, and switches the presence or absence of transmission stop according to each type of response signal in the case of random access allocation.

[0324] As the type of the response signal, for example, data, control information, management information, etc. can be listed. Fig.23 An example of determining whether or not to stop transmission based on the type of response signal according to method 6 is shown. In the case of a response signal type with a high degree of importance, the transmission control unit 301 does not issue a transmission stop instruction at any transmission power. On the other hand, in the case of a response signal type with a low degree of importance, the transmission control unit 301 instructs to stop transmission when the transmission power within the allowable power difference that satisfies the target reception power value cannot be set due to the limitations of the maximum transmission power, the minimum transmission power, and the transmission power variable range of the terminal 300.

[0325] In this way, the terminal 300 can prevent the failure to send a signal with a higher importance during random access by switching the presence or absence of transmission stop during random access allocation according to the type of the response signal. Furthermore, the operation of the transmission stop instruction is not limited to completely stopping the transmission. For example, by suppressing the transmission probability of random access, an operation of lowering the priority can also be performed.

[0326] Determination methods 1 to 6 for determining whether or not transmission is stopped in the transmission control unit 301 have been described above.

[0327] Furthermore, the switching of the above-mentioned determination method may be broadcasted from the access point 100 to the terminal 300 using a management frame such as a beacon, a probe response, or an association response, or may be included in a random access control signal and notified to the terminal 300. By controlling with a management frame, a suitable value for each BSS can be set. Furthermore, by controlling each time a random access control signal is sent, although the overhead increases, appropriate control that follows the change can be performed even in an environment where the status of the terminal 300 greatly changes.

[0328] Thus, in this embodiment, when the terminal 300 cannot transmit the UL response signal at a transmission power that satisfies the target reception power notified by the access point 100 due to the transmission power control capability (performance) of the terminal 300, such as the maximum transmission power, the minimum transmission power, and the transmission power variable range of the terminal 300, the transmission control unit 301 stops the transmission processing of the terminal 300 according to the situation. As a result, regardless of the performance of the terminal 300, that is, the maximum transmission power, the minimum transmission power, and the transmission power variable range of the terminal 300, the reception power difference between the terminals 300 in the access point 100 can be reduced. Therefore, according to this embodiment, MU interference can be reduced, the reception signal can be contained within the dynamic range of the A / D conversion, and the system throughput can be improved.

[0329] (Implementation 3)

[0330] As described above, by stopping the transmission of response signals that cannot meet the target reception power according to the situation, the reception power difference between the terminals in the access point can be reduced regardless of the performance of the terminal. However, by stopping the transmission, the number of terminals whose transmission opportunities of response signals are greatly reduced may increase depending on the setting of the target reception power value.

[0331] Therefore, in this embodiment, a method is described for preventing a significant reduction in the opportunity for a specific terminal such as a terminal with low transmission power control capability to transmit a response signal by changing the target reception power value each time a random access control signal is continuously transmitted.

[0332] Fig.24 : is a block diagram showing the structure of the access point 400 according to the present embodiment. Fig.24 Zhongyu Figure 4The difference is that the resource allocation information determined by the scheduling unit 101 and the target reception power value calculated by the target reception power setting unit 102 are input to the transmission control unit 401, and the transmission control unit 401 outputs information indicating control to the scheduling unit 101 and the target reception power setting unit 102. In addition, the structure of the terminal 300 is different from that of the embodiment 2 ( Fig. 22 )same.

[0333] In this embodiment, when transmitting a random access control signal continuously, transmission control section 401 controls the operation of scheduling section 101 and target reception power setting section 102 for each number of consecutive transmissions, which is different from Embodiment 1 (details will be described later).

[0334] Transmission control section 401 receives inputs of resource allocation information determined by scheduling section 101 and target reception power value calculated by target reception power setting section 102. Transmission control section 401 stores the input resource allocation information (including MCS) and target reception power value for each transmission of a random access control signal.

[0335] When transmitting a continuous random access control signal, the transmission control unit 401 controls the target received power value included in the random access control signal. Specifically, when the random access control signal is continuously transmitted, the transmission control unit 401 controls the scheduling unit 101 and the target received power setting unit 102 based on the target received power value and resource allocation information previously notified to the terminal 300 by the random access control signal, so that different target received power values ​​and resource allocation information are set for each number of transmissions of continuous transmission. In addition, the control method in the transmission control unit 401 will be described later.

[0336] The scheduling unit 101 determines resource allocation based on the content instructed by the transmission control unit 401, and outputs the resource allocation information to the transmission power control information setting unit 103 and the RA control signal generating unit 104. The target reception power setting unit 102 determines the target reception power value based on the content instructed by the transmission control unit 401, and outputs the target reception power value to the transmission power control information setting unit 103.

[0337] Fig.25 An example of a UL MU transmission procedure when the random access control signal (TF-R) is continuously transmitted according to the third embodiment is shown.

[0338] exist Fig.25In the ULMU transmission process within the TXOP interval in the access point 400 (AP) that has obtained the transmission right through CSMA / CA, TF-R#1 is the random access control signal for the first transmission, and TF-R#2 is the random access control signal for the second transmission. Fig.25 In the UL MU, UL MU is a UL response signal, and ACK (or M-BA (Multi-STA Block ACK)) is information indicating successful reception of the UL response signal. Fig.25 In , P1 and P2 are the target receiving power values ​​for each transmission number.

[0339] Furthermore, continuous transmission means that the random access control signal is continuously transmitted within the TXOP. After the access point 400 obtains the transmission right through CSMA / CA, it counts the number of transmissions. In addition, the access point 400 uses one of the target reception power setting methods (random access allocation) of the first embodiment to set the target reception power value applicable to the random access control signal (TF-R#1) transmitted for the first time.

[0340] Hereinafter, control methods 1 to 3 of the transmission control unit 401 will be described respectively.

[0341] <Control method 1>

[0342] In control method 1, when the transmission control unit 401 continuously transmits the random access control signal, it controls to reduce the target received power value of the random access allocation terminal each time it transmits. In addition, the transmission control unit 401 reduces the MCS level of the response signal (i.e., changes it to an MCS with a lower transmission speed) as the target received power is reduced each time the random access control signal is transmitted. The MCS level can also be uniquely set according to the target received power value.

[0343] For example, the transmission control unit 401 applies the target reception power setting method 1 (random access allocation) to the calculation of the target reception power value P1 notified by the random access control signal transmitted first. Then, the transmission control unit 401 reduces the target reception power value P2 notified by the random access control signal transmitted second by 10 dB from the target reception power P1 notified first (P2 = P1-10 [dB]). Preferably, the difference between the different target reception powers is determined based on the value of the allowable power difference. For example, the allowable power difference may be set to ±5 dB, and the change amount of the target reception power value may be set to 10 dB.

[0344] In this way, the transmission control unit 401 lowers the target reception power value and the MCS level each time the random access control signal is continuously transmitted. That is, the access point 400 (transmission control unit 401) performs a UL MU-MIMO / OFDMA transmission process of a random access control signal specifying a target reception power value P2 (<P1) immediately after the UL MU-MIMO / OFDMA transmission process of the random access control signal specifying the target reception power value P1.

[0345] Therefore, in the first random access control signal, since the target receiving power value is high, even if the terminal 300 cannot send a response signal due to the maximum transmission power limitation, it can send a response signal when the target receiving power value with reduced receiving power notified by the second random access control signal is below the maximum transmission power of the terminal 300.

[0346] That is, it is possible to prevent a significant reduction in the transmission opportunities of response signals of specific terminals 300 such as cell edge terminals 300. In addition, by changing the target reception power value based on the value of the allowable power difference, it is possible to provide transmission opportunities even for terminals without a transmission power control function.

[0347] Furthermore, the control method 1 can also be applied to control in which access by the terminal 300 at the cell edge is suppressed by the first random access control signal, and access by the terminal 300 near the access point is suppressed by the second random access control signal.

[0348] <Control method 2>

[0349] In control method 2, when the transmission control unit 401 continuously transmits the random access control signal, the permissible power difference is increased each time it is transmitted. For example, the transmission control unit 401 sets the target reception power value according to the target reception power setting method 1 (random access allocation). In addition, the transmission control unit 401 accommodates the terminal 300 that averages power with a smaller permissible power difference when transmitting the first random access control signal. Next, the transmission control unit 401 can accommodate the terminal 300 that cannot send a response signal due to the first random access control signal by increasing the permissible power difference when transmitting the second random access control signal.

[0350] Thus, when the random access control signal is continuously transmitted, the transmission control unit 401 increases the permissible power difference each time the random access control signal is transmitted. Thus, the permissible power difference of the target reception power value increases each time the random access control signal is transmitted, so even if the terminal 300 cannot transmit a response signal due to the limitation of the maximum transmission power, the minimum transmission power, and the transmission power variable range in the previous transmission, it can transmit a response signal in the subsequent transmission. That is, the response signal from the terminal 300 having a large difference between the target reception power value specified by the access point 400 and the transmission power that the terminal 300 can transmit can be easily transmitted each time the random access control signal is continuously transmitted.

[0351] <Control method 3>

[0352] In control method 3, similarly to control method 1, the transmission control unit 401 lowers the target reception power value and MCS for each transmission during the continuous transmission of the random access control signal. Furthermore, the transmission control unit 401 increases the PPDU length of the UL MU transmission for each transmission.

[0353] In this way, in the continuous transmission of the random access control signal, by reducing the target reception power value and the MCS level for each transmission and increasing the PPDU length, in addition to the same effect as control method 1, the amount of information that can be transmitted by the first UL response signal and the second UL response signal can be made the same. That is, the inequality between the terminal 300 transmitting with the first UL response signal and the terminal 300 transmitting with the second UL response signal can be eliminated.

[0354] In addition, as described below, the control of lowering the target received power value in stages is also effective in improving the utilization efficiency of time resources and delay characteristics. Specifically, when the target received power value is small, the terminal 300 with a margin in the link budget (i.e., the terminal 300 with a power margin for the path loss) may reduce the transmission power to transmit. In this case, using a low-speed MCS compared to the maximum transmittable speed requires a longer transmission time for the same amount of data. In contrast, in the present embodiment, by first setting a large target received power value, the possibility of a terminal 300 capable of high-speed transmission sending a response signal with a high-speed MCS and a shorter PPDU without reducing the speed increases. As a result, the utilization efficiency of time resources can be improved and the transmission delay can be shortened.

[0355] In the above, control methods 1 to 3 of the transmission control unit 401 have been described.

[0356] Furthermore, continuous transmission is not limited to transmission within the TXOP interval for which the transmission right is obtained in advance, and in the cascaded area (also referred to as the Cascaded field) included in the random access control signal, the interval in which the random access control signal is continuously transmitted (the interval in which the flag of the cascaded area is "1") can also be used as the interval for continuous transmission. In addition, the transmission control unit 401 can perform transmission control in the same manner even when the continuous transmission is three or more times.

[0357] Thus, in this embodiment, when the random access control signal is continuously transmitted, the transmission control unit 401 performs an action of reducing the target reception power value and the MCS level for each continuous transmission. Thus, it is possible to prevent the transmission opportunity of the response signal of a specific terminal 300, such as a terminal 300 with a low transmission power control capability, from being greatly reduced.

[0358] (Implementation 4)

[0359] In 11ax, two types of terminal classes (also called STA Classes) with different required accuracy for setting the transmission power or RSSI measurement accuracy are supported. Class A terminals are high-function terminals, and the setting accuracy of the transmission power (absolute value) is required to be within ±3dB. In other words, Class A terminals allow a maximum setting error of 3dB for the transmission power indicated by the access point. On the other hand, Class B terminals are low-function terminals, and the setting accuracy of the transmission power (absolute value) is required to be within ±9dB. In other words, Class B terminals allow a maximum setting error of 9dB for the transmission power indicated by the access point.

[0360] As described above, from the perspective of whether the transmission power of the terminal can be set to satisfy the condition within the allowable power difference from the target received power value, it is determined whether the transmission of the signal is stopped, and the transmission of the response signal is stopped. In this way, MU interference can be reduced and the received signal can be contained within the dynamic range of A / D conversion. In addition, the system throughput can be improved. In this embodiment, from the perspective of whether the transmission power of the terminal can be set to a transmission power that satisfies the allowable condition based on the target received power set by the access point, it is determined whether the transmission of the signal is prohibited.

[0361] Therefore, in this embodiment, when it is difficult to satisfy the permissible conditions due to the limitations on the maximum transmission power, minimum transmission power, and transmission power variable range of the terminal, the reception power difference between the terminals in the access point can be reduced by prohibiting the terminal from transmitting.

[0362] The structure of the terminal 300 is similar to that of the second embodiment ( Fig. 22 ). In addition, the structure of the access point 100 is the same as that of the first embodiment ( Figure 4 )same.

[0363] Transmission power calculation section 205 calculates a transmission power value using equation (3) based on the target reception power value input from RA control signal decoding section 204 and the path loss value input from path loss estimation section 207 .

[0364] The transmission control unit 301 determines whether the transmission power that satisfies the permissible condition can be set based on the transmission power value input from the transmission power calculation unit 205, the information (target reception power value, etc.) input from the RA control signal decoding unit 204, and the maximum transmission power, minimum transmission power, and transmission power variable range of the terminal 300. Then, if the transmission power value that satisfies the permissible condition cannot be set, the transmission control unit 301 generates information indicating that transmission is prohibited. In this way, the transmission control unit 301 determines whether the transmission power value that satisfies the permissible condition can be set, and if it cannot be set, the information indicating that transmission is prohibited is output to the wireless transmission and reception unit 202. In addition, the details of the method for setting the permissible condition will be described later.

[0365] When information indicating prohibition of transmission is input from the transmission control unit 301, the wireless transmission and reception unit 202 does not transmit the signal input from the transmission signal generating unit 210. On the other hand, when information indicating suspension of transmission is not input from the transmission control unit 301, 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 signal input from the transmission signal generating unit 210, and transmits the signal after the wireless transmission processing through the antenna 201.

[0366] Below, use Figures 26A to 26C Methods 1 to 3 of setting the permissible conditions are described respectively.

[0367] <Method 1 for setting the permissible conditions>

[0368] Fig.26AThis is an example of a method for setting a permissible condition in the method for setting a permissible condition 1. In the method for setting a permissible condition 1, when the terminal cannot send a response signal by using the transmission power value calculated by the formula (3), the terminal side estimates the received power value in the access point when the response signal is sent with the transmission power value that can actually be sent. Then, even when the terminal sets the transmission power value to the maximum transmission power value, if the estimated received power value in the access point is lower than the lower limit value of the permissible power range set with the target received power value as a reference, the terminal is prohibited from sending. In addition, even when the terminal sets the transmission power value to the minimum transmission power value, if the estimated received power value in the access point still exceeds the upper limit value of the permissible power range, the terminal is prohibited from sending. In addition, if the step of the transmission power value that can be set by the terminal is too coarse and the transmission power value cannot be set so that the estimated received power value in the access point is within the permissible power range from the target received power value, the terminal is prohibited from sending. In other words, when the estimated received power value at the access point is between the lower limit and the upper limit of the permissible power range and there is no transmit power value that the terminal can set, the terminal is prohibited from transmitting. The method of setting the permissible power range will be described later.

[0369] In this way, when the estimated received power value in the access point is between the upper limit and the lower limit of the permissible power range due to the limitations of the maximum transmit power, the minimum transmit power, and the transmit power variable range of the terminal, and there is no transmit power value that the terminal can set, transmission is prohibited. This can prevent the receive power difference in the access point from increasing and reduce MU interference.

[0370] <How to set the permission condition 2>

[0371] Fig.26BThis is an example of a method for setting a permissible condition in method 2 for setting a permissible condition. In method 2 for setting a permissible condition, when the terminal cannot send a response signal at the transmission power value calculated using equation (3) due to the limitation of the maximum transmission power, the minimum transmission power, and the transmission power variable range of the terminal, the terminal side estimates the reception power value in the access point when the response signal is sent at the transmission power value that can actually be transmitted. Moreover, even when the terminal sets the transmission power value to the minimum transmission power value, when the reception power estimation value in the access point exceeds the upper limit value of the permissible power range set with the target reception power value as a reference, the terminal is prohibited from sending. In addition, when the interval of the transmission power value that can be set by the terminal is too coarse and the reception power estimation value in the access point cannot be set to a transmission power value below the upper limit value of the permissible power range, the terminal is prohibited from sending. In other words, when the reception power estimation value in the access point is below the upper limit value of the permissible power range and there is no transmission power value that can be set by the terminal, the terminal is prohibited from sending.

[0372] In this way, by limiting the maximum transmission power, minimum transmission power, and transmission power variable range of the terminal, transmission is prohibited only when the estimated reception power value in the access point is below the upper limit of the allowable power range and there is no transmission power value that can be set by the terminal, so that the transmission of a response signal that has a large influence on the interference generated by other terminals can be prohibited. That is, by prohibiting the transmission of a response signal having a reception power estimation value that exceeds the target reception power value in the access point to a certain extent, MU interference can be reduced. In addition, by allowing transmission below the allowable power lower limit, a decrease in the transmission opportunity of the terminal can be prevented.

[0373] <Method 3 for setting the permissible condition>

[0374] Fig.26C This is an example of a method for setting a permissible condition in method 3 for setting a permissible condition. In method 3 for setting a permissible condition, when the terminal cannot send a response signal using the transmission power value calculated by equation (3), the terminal side estimates the received power value in the access point when the response signal is sent with the transmission power value that can actually be sent. Then, even if the terminal sets the transmission power value to the minimum transmission power value, when the estimated received power value in the access point exceeds the target received power value, the terminal is prohibited from sending. In addition, when the interval of the transmission power value that can be set by the terminal is too coarse and the estimated received power value in the access point cannot be set to a transmission power value below the target received power value, the terminal is prohibited from sending. In other words, the terminal is prohibited from sending only when the estimated received power value in the access point exceeds the target received power value notified by the access point.

[0375] In this way, transmission is prohibited only when the estimated received power value in the access point exceeds the target received power value notified by the access point due to the limitation of the maximum transmission power, minimum transmission power, and transmission power variable range of the terminal. In this way, the transmission of the response signal can be restricted under conditions stricter than those in the setting method 2 of the permissible condition, and the MU interference can be further reduced. In addition, by allowing transmission below the target received power value, the reduction of the transmission opportunity of the terminal can be further prevented.

[0376] In the above, the setting methods 1 to 3 of the permission conditions in the present embodiment have been described.

[0377] Below, use Figures 27A to 27D Of the methods 1 to 3 for setting the permissible condition, methods 1 to 4 for setting the range of the permissible power value will be described respectively.

[0378] <Method 1 for setting the range of permissible power values>

[0379] Fig.27A An example of a method for setting a range of allowable power values ​​in method 1 for setting a range of allowable power values ​​is shown. In method 1 for setting a range of allowable power values, the range of allowable power values ​​is changed according to the performance of the terminal (e.g., class A, class B). For example, the width of the range of allowable power values ​​is increased for class A terminals, and the width of the range of allowable power values ​​is reduced for class B terminals compared to class A terminals. This is because the setting accuracy of the transmission power of class A terminals is higher than that of class B terminals.

[0380] In this way, in a terminal with low terminal performance, the power difference between the actual received power value and the target received power value in the access point is likely to increase due to the received power estimation accuracy. Therefore, by changing the width of the range of the allowable power value according to the performance of the terminal, it is easy to prohibit the transmission of the terminal with low performance and reduce MU interference.

[0381] <Method 2 for setting the range of permissible power values>

[0382] Fig.27B An example of a method for setting a range of allowable power values ​​in method 2 for setting a range of allowable power values ​​is shown. In method 2 for setting a range of allowable power values, the range of allowable power values ​​is changed according to random access allocation and individual allocation. For example, the range of allowable power values ​​is increased in individual allocation, and decreased in random access allocation.

[0383] In random access allocation, it is difficult for the access point side to determine which terminal has secured resources from random access, so the scheduler cannot allocate resources taking into account the received power difference. Therefore, random access allocation is more likely to increase interference from adjacent RUs due to the received power difference than individual allocation. Therefore, there is a tendency for interference due to the received power difference to occur easily. Therefore, according to this setting method 2, MU interference can be reduced by easily prohibiting the transmission of the terminal for random access allocation.

[0384] <Method 3 for setting the range of permissible power values>

[0385] Fig.27C An example of a method for setting a range of allowable power values ​​in method 3 for setting a range of allowable power values ​​is shown. In method 3 for setting a range of allowable power values, the range of allowable power values ​​is changed according to the number of terminals connected to an access point and information about traffic volume (BSS LOAD). For example, when the BSS LOAD is low, that is, when the number of terminals connected to an access point is small, the range of allowable power values ​​is increased. In addition, when the BSS LOAD is high, that is, when the number of terminals connected to an access point is large, the range of allowable power values ​​is reduced. Furthermore, the BSS LOAD is notified by a beacon.

[0386] When BSS LOAD is high, it is considered that the resource utilization rate is high, so the possibility of adjacent RU being used and the possibility of signal collision in random access are high. Therefore, according to this setting method 3, MU interference can be reduced by easily prohibiting the transmission of the terminal when BSS LOAD is high.

[0387] <Method 4 for setting the range of permissible power values>

[0388] Fig.27D An example of a method for setting a range of allowable power values ​​in method 4 for setting a range of allowable power values ​​is shown. In method 4 for setting a range of allowable power values, the width of the range of allowable power values ​​is changed based on the portion where the estimated received power value at the access point estimated from the transmission power value calculated using equation (3) exceeds the target received power value and the portion where the estimated received power value is below the target received power value. For example, the width of the range of allowable power values ​​is reduced in the portion where the received power value exceeds the target received power value, and the width of the range of allowable power values ​​is increased in the portion where the received power value is below the target received power value.

[0389] When the target received power value is exceeded, there is a tendency for the interference effect on other terminals to increase. Therefore, according to the present setting method 4, MU interference can be reduced by easily prohibiting the transmission of a terminal that can only transmit a response signal with a transmission power value exceeding the transmission target received power value.

[0390] In the above, methods 1 to 4 of setting the range of the allowable power value in the present embodiment have been described.

[0391] Furthermore, the range of the allowable power value may be a power difference from the target received power value, or may be a range defined by the upper and lower limits of the range of the allowable power value. In addition, in the above-mentioned method 2 for setting the allowable condition, only the upper limit of the allowable power value may be set.

[0392] Note that the range of the allowable power value may use a predetermined value or a value notified by the access point.

[0393] Furthermore, the methods for setting the ranges of the allowable power values ​​may be used in combination.

[0394] Furthermore, the method of setting the permission condition and the method of setting the range of the allowable power value may be changed dynamically according to the signaling from the access point.

[0395] Thus, in this embodiment, when the terminal 300 cannot transmit the UL response signal at the transmission power that satisfies the permissible condition based on the target reception power value notified by the access point 100 due to the transmission power control capability (performance) of the terminal 300 such as the maximum transmission power, minimum transmission power, and transmission power variable range of the terminal 300, the transmission control unit 301 prohibits the transmission process of the terminal 300. As a result, regardless of the performance of the terminal 300, that is, the maximum transmission power, minimum transmission power, and transmission power variable range of the terminal 300, the reception power difference between the terminals 300 in the access point 100 can be reduced. Therefore, according to this embodiment, MU interference can be reduced and the system throughput can be improved.

[0396] In the above, each embodiment of the present invention has been described.

[0397] [Other embodiments]

[0398] (1) In the above-mentioned embodiments, the target reception power value is always transmitted in the random access control signal. However, it is also possible to not perform transmission power control, that is, not transmit the target reception power value, depending on the A / D conversion performance of the access point. It is also possible to switch whether to transmit the target reception power value according to the trigger type.

[0399] (2) In the above-mentioned embodiment, a case where one aspect of the present invention is configured by hardware is described by way of example. However, the present invention can be implemented by software in cooperation with hardware.

[0400] In addition, in the above-mentioned embodiments, the case of using the random access control signal including the random access allocation is described, but the present invention is not limited to this, and the case of only including the individual allocation is also applicable. In particular, it is useful when the access point cannot properly evaluate the path loss and the transmission power control capability of the terminal due to the state and position change of the terminal.

[0401] In addition, in the communication method of the present invention, the transmission power (TRP) of the access point notified by a beacon, TF, TF-R, etc. can also be set to the power in the antenna connector that does not include the influence of the antenna directivity, or when multiple antennas are included, it can be set to the sum of the powers in multiple antenna connectors, that is, the composite power.

[0402] In addition, each functional block used in the description of the above-mentioned embodiment is usually implemented as an integrated circuit, i.e., LSI. The integrated circuit controls each functional block used in the description of the above-mentioned embodiment, and may also include input terminals and output terminals. These integrated circuits may be integrated into a single chip individually, or may include a part or all of each functional block integrated into a single chip. Here, although it is set as LSI, it is sometimes also referred to as IC, system LSI, super LSI (Super LSI), and ultra LSI (Ultra LSI) depending on the degree of integration.

[0403] 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.

[0404] Furthermore, if integrated circuit technology that can replace LSI emerges with the advancement of semiconductor technology 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.

[0405] The communication device of the present invention adopts such a structure, including: a target receiving power setting unit, which sets at least one target receiving power value as UL transmission power control information for controlling the uplink transmission power of each of multiple terminals, and the target receiving power value is a target value of the receiving power when receiving uplink signals from multiple terminals; a signal generating unit, which generates a random access control signal including at least one target receiving power value; and a sending unit, which sends the random access control signal.

[0406] In the communication device of the present invention, the random access control signal has: a common area for notifying control information common to multiple terminals; and a terminal-independent area for notifying each of the multiple terminals of independent control information, and the signal generating unit configures the target receiving power value in the terminal-independent area of ​​the random access control signal.

[0407] In the communication device of the present invention, the random access control signal has: a common area for notifying common control information among multiple terminals; and a terminal-independent area for notifying each of the multiple terminals of independent control information, and the signal generating unit configures the target receiving power value in the common area of ​​the random access control signal.

[0408] In the communication device of the present invention, the target reception power value is set to a different value for each type of information transmitted in random access.

[0409] In the communication apparatus of the present invention, the target reception power value is notified for each individual allocation and random access allocation.

[0410] In the communication device of the present invention, the signal generating unit arranges the target reception power value in the common area of ​​the random access control signal, and arranges the offset value offset from the target reception power value in the terminal-specific area of ​​the random access control signal.

[0411] In the communication device of the present invention, the signal generating unit arranges the target reception power value in the terminal individual area for the random access allocation terminal, and arranges the transmission power value for transmitting an uplink signal in the terminal individual area for the individual allocation terminal.

[0412] In the communication device of the present invention, the signal generating unit arranges the target reception power value in the common area for the random access allocation terminal and arranges the target reception power value in the terminal individual area for the individual allocation terminal.

[0413] The communication device of the present invention further includes: a transmission control unit that controls a target reception power value included in the random access control signal when the random access control signal is continuous.

[0414] In the communication device of the present invention, the target receiving power setting unit sets a first target receiving power value and a second target receiving power value, and the sending control unit performs a UL MU-MIMO / OFDMA sending process of a random access control signal specifying a second target receiving power value immediately after the UL MU-MIMO / OFDMA sending process of a random access control signal specifying the first target receiving power value.

[0415] In the communication device of the present invention, the transmission control unit sets the second target reception power value to a value smaller than the first target reception power value.

[0416] The communication method of the present invention includes: setting at least one target receiving power value as UL transmission power control information for controlling the uplink transmission power of each of multiple terminals, the target receiving power value is a target value of the receiving power when uplink signals are received from multiple terminals, generating a random access control signal including at least one target receiving power value, and sending the random access control signal.

[0417] In the communication method of the present invention, the random access control signal has: a common area for notifying common control information among multiple terminals; and a terminal-independent area for notifying each of the multiple terminals of independent control information, and the target receiving power value is configured in the terminal-independent area of ​​the random access control signal.

[0418] In the communication method of the present invention, the random access control signal has: a common area for notifying control information common to multiple terminals; and a terminal-independent area for notifying each of the multiple terminals of independent control information, and the target receiving power value is configured in the common area of ​​the random access control signal.

[0419] In the communication method of the present invention, the target reception power value is set to a different value for each type of information transmitted in random access.

[0420] In the communication method of the present invention, a target reception power value is notified for each individual allocation and random access allocation.

[0421] In the communication method of the present invention, the target reception power value is arranged in the common area of ​​the random access control signal, and the offset value offset from the target reception power value is arranged in the terminal-specific area of ​​the random access control signal.

[0422] In the communication method of the present invention, the target reception power value for the random access assigned terminal is arranged in the terminal individual region, and the transmission power value for transmitting the uplink signal for the individual assigned terminal is arranged in the terminal individual region.

[0423] In the communication method of the present invention, the target reception power value for the random access allocation terminal is arranged in the common area, and the target reception power value for the individual allocation terminal is arranged in the terminal individual area.

[0424] In the communication method of the present invention, when continuous random access control signals are transmitted, a target reception power value included in the random access control signals is controlled.

[0425] In the communication method of the present invention, a first target receiving power value and a second target receiving power value are set, and immediately after the UL MU-MIMO / OFDMA transmission process of the random access control signal specifying the first target receiving power value, a UL MU-MIMO / OFDMA transmission process of the random access control signal specifying the second target receiving power value is performed.

[0426] In the communication method of the present invention, the second target received power value is set to a value smaller than the first target received power value.

[0427] One aspect of the present invention is useful as a method for improving problems of inter-carrier interference and dynamic range of AD conversion by reducing the difference in received power between terminals in UL MU-MIMO / OFDMA.

Claims

1. Communication method, receiving a trigger frame including separate information, the separate information including a target reception power value related to a target value of reception power when the access point receives an uplink response frame, i.e., a UL response frame; estimating a path loss by using the transmission power of the trigger frame notified by the trigger frame and the measured reception power of the trigger frame, and setting the transmission power of the UL response frame based on the target reception power value and the path loss; and sending the UL response frame immediately after receiving the trigger frame, The trigger frame includes: a common area containing common information for a plurality of terminals receiving the trigger frame and a separate area containing the separate information for each of the plurality of terminals, The separate information includes the modulation and coding scheme, i.e., MCS. The separate area includes a plurality of separate information for each of the plurality of terminals. The first individual information included in the plurality of individual information includes a terminal identification ID for identifying a terminal corresponding to the first individual information, The trigger frame is a control signal for random access. The UL response frame is a random access response, The first individual information includes resource unit allocation information for random access. A random access ID is set in the terminal identification ID.

2. Integrated circuits that control the following processes: A process of receiving a trigger frame including separate information including a target received power value related to a target value of received power when the access point receives an uplink response frame, i.e., a UL response frame; A process of estimating a path loss by using the transmission power of the trigger frame notified by the trigger frame and the measured reception power of the trigger frame, and setting the transmission power of the UL response frame based on the target reception power value and the path loss; and the process of sending the UL response frame immediately after receiving the trigger frame, The trigger frame includes: a common area containing common information for a plurality of terminals receiving the trigger frame and a separate area containing the separate information for each of the plurality of terminals, The separate information includes the modulation and coding scheme, i.e., MCS. The separate area includes a plurality of separate information for each of the plurality of terminals. The first individual information included in the plurality of individual information includes a terminal identification ID for identifying a terminal corresponding to the first individual information, The trigger frame is a control signal for random access. The UL response frame is a random access response, The first individual information includes resource unit allocation information for random access. A random access ID is set in the terminal identification ID.

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