JP5723318B2 - Wireless communication system, access point device, and wireless communication method - Google Patents

Description

  The present invention relates to a wireless communication system, an access point device, and a wireless communication method.

  There is an IEEE 802.11a standard as a high-speed wireless access system using the 5 GHz band. In this system, an orthogonal frequency division multiplexing (OFDM) modulation scheme, which is a technique for stabilizing characteristics in a multipath fading environment, is used, and a maximum throughput of 54 Mbps is realized. However, the throughput here is the throughput on the physical layer, and actually the transmission efficiency in the MAC (Medium Access Control) layer is about 50 to 70%, so the upper limit of the actual throughput is , About 30 Mbps.

  Furthermore, in IEEE 802.11n, MIMO (Multiple input multiple output) technology that can realize spatial multiplexing using the same time and the same frequency channel using multiple antennas, Technology that uses two 20 MHz frequency channels that were used simultaneously for 40 MHz frequency channel, frame aggregation that bundles multiple frames for transmission, and efficiency by reducing control signal overhead using block ACK signals Aiming to realize high-speed communication by technology such as realization, it is possible to realize a maximum transmission rate of 600 Mbps on the physical layer.

  In addition, IEEE 802.11ac, which is a standard that is currently being developed, uses communication technologies that simultaneously use four 20 MHz frequency channels and use them as 80 MHz frequency channels, and the same frequency channel at the same time. It aims to realize wireless communication at a speed higher than that of IEEE802.11n by MU-MIMO (Multi-User MIMO) technology for performing communication.

  In addition, the demand for wireless communication is rapidly increasing, and the installation of wireless LAN APs (Access Points) in places such as homes, offices, and stations is increasing. However, in an environment where communication cells (consisting of one AP and a plurality of stations) are close to each other, there is a problem that signals of adjacent communication cells interfere with each other and good wireless communication cannot be performed ( In general, in a wireless communication system such as a mobile phone or a wireless LAN, a communication cell composed of one wireless base station or an access point and a plurality of stations is regarded as a minimum unit of the wireless network).

  Furthermore, in the future environment such as an apartment house, it is expected that an AP will be installed in each home, and a plurality of APs will be installed in close proximity. With respect to these problems, radio communication is performed by avoiding interference between communication cells by assigning different frequency channels and different times to the respective communication cells.

  In the case of frequency channels, when there are IEEE802.11a / n / ac radio devices, they operate using any of the frequency channels of 20 MHz, 40 MHz, and 80 MHz, respectively. Further, in terms of time, transmission is performed using CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance), thereby avoiding interference by performing communication at different times (Non-Patent Document 1).

Masahiro Morikura, Shuji Kubota, “Revised Third Edition 802.11 High-Speed Wireless LAN Textbook”, Impress R & D, March 27, 2008

  However, when the number of adjacent communication cells increases, the radio resources (frequency channel and time) allocated to each communication cell are limited, so the radio resources allocated to one communication cell decrease. As a result, the average throughput of each communication cell in which the allocation of radio resources is reduced decreases. For example, when there are a plurality of adjacent communication cells, the average throughput when the adjacent communication cells do not exist is reduced to (1 / (number of adjacent communication cells)).

  Furthermore, as standardization progresses in the order of IEEE802.11a, IEEE802.11n, and IEEE802.11ac, the frequency bandwidth used for communication becomes wider and can be allocated while avoiding duplication of frequency bands between adjacent cells. Fewer frequency channels. As a result, there is a higher possibility that the proximity communication cells that perform communication using the same frequency channel increase.

  Moreover, since the wireless LAN is a wireless communication system established by autonomous distributed control of each communication cell, it is difficult to allocate an optimal frequency channel and optimal time for each communication cell, and the capability provided Inability to demonstrate was also a problem. In order to solve these problems, studies have been made to optimize time and frequency channel allocation in cooperation between communication cells. However, in a wireless LAN, since communication means between communication cells is not defined, it is difficult to introduce it practically.

  Similarly, a technique for optimizing the transmission power of a transmitter in cooperation between communication cells has been studied, but it is still difficult to determine the optimal transmission power for each communication cell in autonomous distributed control. Moreover, suppressing the transmission power to suppress the interference power also decreases the transmission power of its own communication, and a significant increase in throughput is not expected.

  Similarly, a technique for suppressing interference power by optimizing the directivity of radio waves using a plurality of antennas in cooperation between a plurality of cells has been studied. This technique can suppress interference power without lowering transmission power, and is expected to increase the throughput of the entire system. Here, the more the direction in which the directivity null is directed, the more interference power is suppressed. However, the number of directions in which the null can be directed depends on the degree of freedom of the antenna. However, there is no method for determining the number of degrees of freedom of antennas used for interference suppression or a control method in autonomous distributed control.

  The present invention has been made in view of such circumstances, and its object is to reduce the interference power between communication cells in a situation where a plurality of communication cells are close to each other, and the throughput of each communication cell. It is an object to provide a wireless communication system, an access point device, and a wireless communication method that can improve the performance.

  In order to solve the above-described problem, the present invention provides a station in each communication cell in which the access point devices in each of the adjacent first communication cell and second communication cell use the same frequency channel at the same time. A wireless communication system that communicates with a device, wherein an access point device obtains a maximum number of eigenvalues in which a sum of eigenvalues of a propagation channel between station devices in adjacent communication cells does not exceed a predetermined allowable interference amount, A degree-of-freedom calculation unit that calculates the maximum number of eigenvalues as an antenna degree of freedom used for interference suppression, and a transmission weight for interference suppression are calculated based on the number of antenna degrees of freedom calculated by the degree-of-freedom calculation unit, and the transmission A transmission signal generator that generates a transmission signal using weights, and a stasis in the first communication cell and the second communication cell. And an updating unit that updates the predetermined allowable interference amount so that the predetermined allowable interference amount is maximized based on the sum of the throughputs acquired from the network device, and the station device calculates the throughput based on the received signal. A throughput calculation unit that generates a throughput information signal including the throughput calculated by the throughput calculation unit, and a radio unit that transmits the throughput information signal generated by the throughput information signal generation unit to the access point device. It is characterized by providing.

  Further, according to the present invention, when the sum of the throughputs acquired from the station devices in the first communication cell and the second communication cell by the update unit is smaller than the previous sum of the throughputs, the allowable interference amount is set to a predetermined amount. If the sum of the acquired throughputs is smaller than the sum of the previously acquired throughputs, the allowable interference amount is increased by a predetermined amount.

  Further, the present invention is characterized in that the access point device further includes a radio unit that notifies the access point device of the other communication cell of the throughput acquired from the station device of its own communication cell.

  Further, the present invention is characterized in that the station device notifies the throughput information signal generated by the throughput information signal generation unit to the access point device of its own communication cell and the access point device of the other communication cell.

  In addition, the present invention is an access point device that communicates with a station device in its own communication cell using the same frequency channel at the same time as an adjacent communication cell, and between the station devices in the adjacent communication cell. Calculated by a degree-of-freedom calculation unit and a degree-of-freedom calculation unit that calculates the maximum number of eigenvalues whose sum of eigenvalues of propagation channels does not exceed a predetermined allowable interference amount, and calculates the maximum number of eigenvalues as an antenna degree of freedom used for interference suppression A transmission signal generator for calculating a transmission weight for interference suppression based on the determined number of degrees of freedom of the antenna and generating a transmission signal using the transmission weight, and a station apparatus in an adjacent communication cell and its own communication cell The predetermined allowable interference amount is updated so that the predetermined allowable interference amount is maximized based on the sum of the throughputs obtained from Characterized in that it comprises a Shinbu Prefecture.

  Further, the present invention reduces the allowable interference amount by a predetermined amount when the sum of the throughputs acquired from the station apparatus in the adjacent communication cell and its own communication cell is smaller than the previous sum of the throughputs acquired. When the sum of the acquired throughputs is larger than the sum of the previously acquired throughputs, the allowable interference amount is increased by a predetermined amount.

  Further, the present invention is characterized in that the access point device further includes a radio unit that notifies the access point device of the other communication cell of the throughput acquired from the station device of its own communication cell.

  The present invention also provides wireless communication in which access point devices in adjacent first communication cells and second communication cells communicate with station devices in respective communication cells using the same frequency channel at the same time. A method for obtaining a maximum number of eigenvalues in which the sum of eigenvalues of a propagation channel between adjacent communication cells and a station apparatus does not exceed a predetermined allowable interference amount, and using the maximum eigenvalue number for interference suppression Calculating as a frequency, calculating a transmission weight for interference suppression based on the calculated antenna degree of freedom, generating a transmission signal using the transmission weight, a first communication cell, and a second Based on the sum of the throughput obtained from the station devices in the communication cell, the predetermined allowable interference amount is maximized. , Characterized in that it comprises the step of updating the predetermined allowable interference quantity.

  According to the present invention, interference power between communication cells can be reduced in a situation where a plurality of communication cells are close to each other, and the throughput of each communication cell can be improved.

1 is a block diagram illustrating an example configuration of a wireless communication system according to an embodiment of the present invention. It is a schematic block diagram which shows the structure of the access point 100 and the station apparatus 200 by this 1st Embodiment. It is a flowchart for demonstrating the operation | movement of the transmission process by this 1st Embodiment. It is a flowchart for demonstrating the operation | movement of the transmission process by this 2nd Embodiment.

  A feature of the present invention is that, in a wireless communication system in which communication cells performing wireless packet communication by autonomous distributed control are adjacent, an allowable interference amount is set at an access point of each communication cell, and interference suppression is performed so as not to exceed the allowable interference amount. Set the number of antenna degrees of freedom used for. By transmitting according to the number of degrees of freedom of the antenna used for interference suppression by the access point of each communication cell, the interference power can be suppressed and the throughput of the entire system can be improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration example of a wireless communication system according to an embodiment of the present invention. As shown in FIG. 1, the wireless communication system performs wireless packet communication with two access points (AP) 110 and 120, a station (STA) device 111 that performs wireless packet communication with the access point 110, and the access point 120. The station apparatus 121 is configured. The station device 111 belongs to the communication cell 131 formed by the access point 110, and communicates with an external network (not shown) via the access point 110. The station device 121 belongs to the communication cell 132 formed by the access point 120 and communicates with an external network via the access point 120.

A. In the wireless communication system according to the first embodiment, the access points 110 and 120 and the station apparatuses 111 and 121 wirelessly use a CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) method. Perform packet communication. Further, the wireless packet communication in the two communication cells 131 and 132 is performed using the same frequency channel. In wireless packet communication, transmitted and received wireless packets include an identifier indicating a transmission station and a destination station. Here, the transmitting station is a device that generates and transmits a wireless packet, and the destination station is a device that is a destination of the wireless packet.

  In the wireless communication system illustrated in FIG. 1, there is an area where the communication cell 131 and the communication cell 132 overlap. In this area, the communication cell 131 and the communication cell 132 share the communication band of the frequency channel used for wireless communication.

  In the wireless communication system, the access points 110 and 120 are, for example, access points in a wireless LAN, and the station devices 111 and 121 are computers and portable information electronic devices. The external network is a network other than the local network formed by the access points 110 and 120, such as the Internet.

  The access point 110 and the access point 120 have the same configuration. Hereinafter, the access point 110 and / or the access point 120 will be referred to as the access point 100. The station apparatuses 111 and 121 have the same configuration, and are hereinafter referred to as the station apparatus 200 when any one or all of the station apparatuses 111 and 121 are shown.

  FIG. 2 is a schematic block diagram showing configurations of the access point 100 and the station apparatus 200 according to the first embodiment. As shown in FIG. 2, the access point 100 includes antennas 101-1 to 101-N, a radio unit 102, an allowable interference amount setting unit 103, a degree-of-freedom calculation unit 104, a transmission signal generation unit 105, a throughput comparison unit 106, an update Unit 107, information storage unit 108, and network interface 109.

  Radio section 102 detects a radio packet from received signals received via a plurality of antennas 101-1 to 101 -N, and outputs the detected radio packet to throughput comparison section 106 and network interface 109. In addition, the radio unit 102 transmits the radio packet input from the transmission signal generation unit 105 via the antennas 101-1 to 101 -N.

  In the allowable interference amount setting unit 103, an initial value of the allowable interference amount is set. The initial value of the allowable interference amount is a value common to the access points 110 and 120. The set allowable interference amount is output to the degree-of-freedom calculation unit 104.

  The degree-of-freedom calculation unit 104 determines the number of antenna degrees of freedom based on the allowable interference amount stored in the allowable interference amount setting unit 103 or the information storage unit 108. Hereinafter, an example of calculating the number of antenna degrees of freedom will be described. In general, the amount of interference given from the access point 100 to the station device 200 of a communication cell in the vicinity can be expressed by the sum of the eigenvalues of the propagation channels between these devices. Think based. The access point 100 of each communication cell calculates a plurality of eigenvalues from the propagation channel with the station device 200 and adds them in order from the smallest eigenvalue. At the same time, the added value of the eigenvalues and the allowable interference amount are compared to determine the maximum number of eigenvalues that does not exceed the allowable interference amount. This is the number of antenna degrees of freedom used for interference suppression.

Specifically, the number of antennas of the access points 110 and 120 is N, and the number of antennas of the station apparatuses 111 and 121 is M. However, N is M or more. The communication method assumes a MIMO-OFDM downlink. The propagation channel between the access point 110 and station 111 and _{H 11,} the propagation channel between the access point 110 and station 121 and _{H 12.} That is, H ₁₁ and H ₁₂ are expressed as an M × N matrix based on the number of antennas N of the access point 110 and the number of antennas M of the station apparatuses 111 and 121. Similarly, the propagation channel between the access point 120 and station 121 and _{H 22,} the propagation channel between the access point 120 and station 111 and _{H 21.}

Further, let P be the allowable interference amount, and let S ₁ and S ₂ be the number of antennas used for interference suppression at the access points 110 and 120. As shown in Equation (1), S ₁ and S ₂ are antenna degrees of freedom K ₁ and K _{2 that} are not used for interference suppression of the access points 110 and 120 calculated so as not to exceed the allowable interference amount P. It can be represented by the number M of receiving antennas.

λ _{12, i} represents the eigenvalue of H ₁₂ ^H H ₁₂ , and λ _{21, i} represents the eigen value of H ₂₁ ^H H ₂₁ . With the above calculation, the antenna degrees of freedom S ₁ and S ₂ necessary for making the interference amount smaller than the allowable interference amount are calculated.

The transmission signal generation unit 105 generates a transmission signal based on the antenna degrees of freedom S ₁ and S ₂ by the degree of freedom calculation unit 104. An example for generating a transmission signal will be described below.

In Equation (2), x ′ ₁ is a transmission signal of the access point 110 calculated based on the antenna degree of freedom S ₁ , and x ′ ₂ is a value of the access point 120 calculated based on the antenna degree of freedom S ₂ . It is a transmission signal.

Here, W ₁ is a transmission weight for suppressing interference of the access point 110, and x ₁ is data transmitted from the access point 110 to the station apparatus 111. Similarly, W ₂ is a transmission weight for suppressing interference of the access point 120, and x ₂ is data transmitted from the access point 120 to the station apparatus 121.

Next, the transmission weights W ₁ and W ₂ will be described. In order to calculate the transmission weights W ₁ and W ₂ , first, singular value decomposition is performed on H ₁₂ and H ₂₁ as shown in Equation (3).

Here, U ₁₂ and U ₂₁ indicate left singular matrices, and (V ₁₂ ^(s) V ₁₂ ⁽ⁿ⁾ ) and (V ₂₁ ^(s) V ₂₁ ⁽ⁿ⁾ ) are right singular matrices. , Σ ₁₂ , and Σ ₂₁ indicate diagonalization matrices having diagonal square roots of eigenvalues of H ₁₂ ^H H ₁₂ and H ₂₁ ^H H ₂₁ . Further, V ₁₂ ^(s) and V ₂₁ ^(s) indicate transmission weights corresponding to the signal space, and V ₁₂ ⁽ⁿ⁾ and V ₂₁ ⁽ⁿ⁾ indicate transmission weights indicating the null space. . Transmission weights W ₁ and W ₂ using the antenna degrees of freedom S ₁ and S ₂ used for interference suppression are expressed by Equation (4).

  The transmission weight is calculated by the above method, and the transmission signal is generated by the equation (2).

The throughput comparison unit 106 compares the sum of the throughputs C ₁ and C ₂ notified from the station apparatus 200 described later with the size of the threshold value C ₀ stored in the information storage unit 108 and compares it with the threshold value C _0. Information about whether C ₁ + C ₂ is large or small and C ₁ + C ₂ are output to the updating unit 107. The throughputs C ₁ and C ₂ are the throughputs of the station apparatuses 111 and 121, respectively. Further, the throughput comparison unit 106 exchanges throughput information with each other by notifying the neighboring access point of the throughput notified from the station apparatus 200 as necessary.

Updating unit 107, based on the information input from the throughput comparing unit 106, when compared to the threshold value _{C 0} is _C 1 + _{C 2} large, updated allowable interference quantity P, and及閾value _{C 0} according to Equation (5) And output to the information storage unit 108.

Here, ΔP is a value that increases the allowable interference amount P. When C ₁ + C ₂ is smaller than the threshold value C ₀ , the allowable interference amount P and the threshold value C ₀ are updated according to the equation (6). The allowable interference amount P and the threshold value C ₀ are stored in the information storage unit 108.

The information storage unit 108 stores the allowable interference amount P and the threshold value C ₀ supplied from the update unit 107. Further, the allowable interference amount P is output to the degree-of-freedom calculation unit 104, and the threshold value C ₀ is output to the throughput comparison unit 106.

  The network interface 109 converts a packet addressed to the station apparatus 200 belonging to the same communication cell, out of packets received from an external network, into a radio packet and outputs the radio packet to the transmission signal generation unit 105. Also, the wireless packet input from the wireless unit 102 is converted into a packet used in an external network and transmitted to the external network.

  Next, the configuration of the station apparatus 200 will be described. As shown in FIG. 2, the station apparatus 200 includes a plurality of antennas 201-1 to 201-N, a radio unit 202, a throughput calculation unit 203, a throughput information signal generation unit 204, and an information storage unit 205.

  Radio section 202 detects a radio packet from the received signals received via antennas 201-1 to 201-N, and outputs the detected radio packet to throughput calculation section 203. In addition, the radio unit 202 transmits the radio packet input from the throughput information signal generation unit 204 via the antennas 201-1 to 201-N.

  The throughput calculation unit 203 calculates the throughput from the wireless packet input from the wireless unit 202. The throughput calculation method includes a method of calculating from the error rate of the signal in the data part, a method of calculating the throughput from the propagation channel, and a method of calculating the throughput by signal power to interference power plus noise power ratio (SINR). You may use the method. Further, the throughput calculation unit 203 outputs the calculated throughput to the information storage unit 205 and the throughput information signal generation unit 204.

  The throughput information signal generation unit 204 converts the throughput supplied from the throughput calculation unit 203 into a transmission signal of a wireless packet as throughput information, and outputs it to the wireless unit 202.

  FIG. 3 is a flowchart for explaining the operation of the transmission processing according to the first embodiment. In FIG. 3, the flowchart on the left side is a flowchart on the access point 110 and station apparatus 111 side, and the flowchart on the right side is a flowchart on the access point 120 and station apparatus 121 side.

Each access point 110, 120 performs allowable interference power P, and the initialization of the threshold _{C 0} (step Sa10, Sb10). Here, the initialization means, for example, setting an allowable interference power P = −100 [dB] and a threshold value C ₀ = 0 [bps] that are input in advance as initial values. Each of the access points 110 and 120 calculates the number of degrees of freedom S ₁ or S ₂ for suppressing the interference using the allowable interference power P (steps Sa11 and Sb11). Each of the access points 110 and 120 transmits to the station devices 111 and 121 of its own communication cell using the number of degrees of freedom S ₁ or S ₂ (steps Sa12 and Sb12).

The station apparatuses 111 and 121 calculate the throughput C ₁ or C ₂ from the signals transmitted from the access points 110 and 120, respectively, and use the calculated throughput information for the access points 110 and 120 using radio packets. Notification is made (steps Sa13 and Sb13). The access points 110 and 120 receive the throughput C ₁ or C ₂ from the station devices 111 and 121 of their communication cells, and notify the other access points 110 and 120 of the throughput C ₁ or C _2. The throughputs C ₁ and C ₂ are exchanged with each other (steps Sa14 and Sb14).

The access point 110 determines each compares the threshold value _{C 0} and _C 1 + _{C 2,} thresholds _{C 0} is whether a _{C 1} + _{C 2} or more (step Sa15, Sb15). If the threshold value C ₀ is equal to or greater than C ₁ + C ₂ (YES in step Sa15, YES in Sb15), the allowable interference power P (= P + ΔP) and the threshold value C ₀ (= C ₁ + C ₂ ) are updated. Is performed (steps Sa16 and Sb16). On the other hand, when the threshold value C ₀ is not equal to or greater than C ₁ + C ₂ (NO in step Sa15, NO in Sb15), the allowable interference power P (= P−ΔP) and the threshold value C ₀ (= C ₁ + C ₂ ) Updating is performed (steps Sa17 and Sb17).

  The allowable interference power P updated in the above steps Sa16 and Sb16 or steps Sa17 and Sb17 is input again to steps Sa11 and Sb11.

  According to the first embodiment described above, the access points 110 and 120 share the allowable interference amount with respect to the interference amount given to the station devices 111 and 121 of the adjacent cells, and the antenna is within the allowable interference amount range. By selecting the degree of freedom, it is possible to control the interference amounts in the station apparatuses 111 and 121 to be equal. Further, by controlling the allowable interference amount so that the throughput of all the station apparatuses 111 and 121 is maximized under the limitation, it is possible to maximize the total system throughput while ensuring fairness of the interference amount. it can.

B. Second Embodiment Next, a second embodiment of the present invention will be described.
The second embodiment is characterized in that it is simplified by eliminating the exchange of the throughputs C ₁ and C ₂ between the access points 110 and 120 in steps Sa14 and Sb14 in FIG.

FIG. 4 is a flowchart for explaining the operation of the transmission process according to the second embodiment. In FIG. 4, the flowchart on the left side is a flowchart on the access point 110 and station apparatus 111 side, and the flowchart on the right side is a flowchart on the access point 120 and station apparatus 121 side. Each of the access points 110 and 120 initializes the allowable interference power P and the threshold value C ₀ (steps Sa20 and Sb20). Here, the initialization is, for example, allowable interference power P = −100 [dB] and threshold value C ₀ = 0 [bps]. Next, each of the access points 110 and 120 calculates the number of antenna degrees of freedom S ₁ or S ₂ for suppressing the interference using the allowable interference power P (steps Sa21 and Sb21).

Next, the access points 110 and 120 transmit to the station devices 111 and 121 of their own communication cells using the antenna degrees of freedom S ₁ or S ₂ (steps Sa22 and Sb22). The station apparatuses 111 and 121 calculate the throughput C ₁ or C ₂ from the signals transmitted from the access points 110 and 120, respectively, and the calculated throughput C ₁ or C ₂ is sent to both access points 110 and 120, respectively. Notification is performed using a wireless packet (steps Sa23 and Sb23).

The access point 110 determines each compares the threshold value _{C 0} and _C 1 + _{C 2,} thresholds _{C 0} is whether a _{C 1} + _{C 2} or more (step SA25, SB25). When the threshold value C ₀ is equal to or greater than C ₁ + C ₂ (YES in step Sa25, YES in Sb25), the allowable interference power P (= P + ΔP) and the threshold value C ₀ (= C ₁ + C ₂ ) are updated. Is performed (steps Sa26 and Sb26). On the other hand, when the threshold value C ₀ is not equal to or greater than C ₁ + C ₂ (NO in step Sa25, NO in Sb25), the allowable interference power P (= P−ΔP) and the threshold value C ₀ (= C ₁ + C ₂ ) Updating is performed (steps Sa27 and Sb27).

  The allowable interference power P updated in the above steps Sa26 and Sb26 or steps Sa27 and Sb27 is input again to steps Sa21 and Sb21.

According to the second embodiment described above, the station apparatuses 111 and 121 notify the respective throughputs C ₁ and C ₂ to both access points 110 and 120. Each station device can select the degree of freedom of the antenna within the range of the allowable interference amount while sharing the allowable interference amount with respect to the interference amount that the access points 110 and 120 give to the station devices 111 and 121 of adjacent cells. It is possible to control so that the interference amounts at 111 and 121 are equal. Further, by controlling the allowable interference amount so that the throughput of all the station apparatuses 111 and 121 is maximized under the limitation, it is possible to maximize the total system throughput while ensuring fairness of the interference amount. it can.

100, 110, 120 Access point (AP)
200, 111, 121 stations (STA)
101-1 to 101-N, 201-1 to 201-N Antennas 102 and 202 Radio unit 103 Allowable interference amount setting unit 104 Degree of freedom calculation unit 105 Transmission signal generation unit 106 Throughput comparison unit 107 Update unit 108 and 205 Information storage unit 109: Network interface 131, 132 Communication cell 203 Throughput calculation unit 204 Throughput information signal generation unit

Claims (8)

A wireless communication system in which access point devices in adjacent first communication cells and second communication cells communicate with station devices in the respective communication cells using the same frequency channel at the same time,
The access point device is
The maximum number of eigenvalues in which the sum of eigenvalues of the propagation channel between the station cells in the adjacent communication cell does not exceed a predetermined allowable interference amount is calculated, and the maximum eigenvalue number is calculated as the number of antenna degrees of freedom used for interference suppression. A degree of freedom calculation unit,
Based on the number of degrees of freedom of the antenna calculated by the degree-of-freedom calculating unit, a transmission weight for calculating interference is calculated, and a transmission signal generating unit that generates a transmission signal using the transmission weight;
An update for updating the predetermined allowable interference amount so that the predetermined allowable interference amount is maximized based on a sum of throughputs acquired from the station devices in the first communication cell and the second communication cell. The department and
The station device is
A throughput calculator that calculates the throughput based on the received signal;
A throughput information signal generating unit that generates a throughput information signal including the throughput calculated by the throughput calculating unit;
A wireless communication system comprising: a wireless unit that transmits the throughput information signal generated by the throughput information signal generation unit to the access point device. The update unit
When the sum of the throughputs acquired from the station device in the first communication cell and the second communication cell is smaller than the sum of the previously acquired throughputs, the allowable interference amount is reduced by a predetermined amount and the acquired The wireless communication system according to claim 1, wherein when the sum of throughputs is larger than the sum of throughputs acquired previously, the allowable interference amount is increased by a predetermined amount. The access point device is
The wireless communication system according to claim 1, further comprising a wireless unit that notifies the access point device of the other communication cell of the throughput acquired from the station device of its own communication cell. The station device is
The throughput information signal generated by the throughput information signal generation unit is notified to the access point device of its own communication cell and the access point device of the other communication cell. Wireless communication system. An access point device that communicates with a station device in its own communication cell using the same frequency channel at the same time as an adjacent communication cell,
The maximum number of eigenvalues in which the sum of eigenvalues of the propagation channel between the station cells in the adjacent communication cell does not exceed a predetermined allowable interference amount is calculated, and the maximum eigenvalue number is calculated as the number of antenna degrees of freedom used for interference suppression. A degree of freedom calculation unit,
Based on the number of degrees of freedom of the antenna calculated by the degree-of-freedom calculating unit, a transmission weight for calculating interference is calculated, and a transmission signal generating unit that generates a transmission signal using the transmission weight;
An updating unit that updates the predetermined allowable interference amount so that the predetermined allowable interference amount is maximized based on a sum of throughputs acquired from the station device in the adjacent communication cell and the own communication cell; An access point device comprising: The update unit
When the sum of the throughputs acquired from the station device in the adjacent communication cell and its own communication cell is smaller than the sum of the previously acquired throughput, the allowable interference amount is reduced by a predetermined amount, and the acquired throughput The access point device according to claim 5, wherein when the sum is larger than the sum of the throughputs acquired last time, the allowable interference amount is increased by a predetermined amount. The access point device according to claim 5 or 6, further comprising a wireless unit that notifies the access point device of the other communication cell of the throughput acquired from the station device of its own communication cell. A wireless communication method in which access point devices in adjacent first communication cells and second communication cells communicate with station devices in respective communication cells using the same frequency channel at the same time,
The maximum number of eigenvalues in which the sum of eigenvalues of the propagation channel between the station cells in the adjacent communication cell does not exceed a predetermined allowable interference amount is calculated, and the maximum eigenvalue number is calculated as the number of antenna degrees of freedom used for interference suppression. And steps to
Calculating a transmission weight for interference suppression based on the calculated number of antenna degrees of freedom, and generating a transmission signal using the transmission weight; and
Updating the predetermined allowable interference amount based on the sum of the throughputs acquired from the station devices in the first communication cell and the second communication cell so that the predetermined allowable interference amount is maximized; A wireless communication method comprising:

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