Wireless base station apparatus and method of controlling number of space multiplexed transmissions

The present invention relates to a base station device of a wireless communication system that performs spatial multiplex communication.

In recent years, smart antenna technology using an array antenna has been put into practical use in base stations and access points (hereinafter collectively referred to as wireless communication devices) of wireless communication systems such as mobile phones and wireless LANs. The operating principle of the smart antenna technology is described in, for example, Non-Patent Document 1. For example, Patent Document 1 discloses a wireless communication device in which a plurality of terminals share the same time and frequency and perform spatial multiplex communication by smart antenna technology.

In addition, the demand for data communication in wireless communication systems is increasing, and as a packet transmission method for IMT-2000, cdma2000 1xEV-DO (EVolution Data Only) is used for the purpose of increasing the peak transmission speed and throughput of downlinks. ) Has been standardized (for example, Non-Patent Document 2). In this high-speed packet communication system, scheduling is performed in order to efficiently utilize the limited frequency and time.

Scheduling in single-carrier communication (1xEV-DO also applies to this) is a technology that determines how to allocate time resources for downlink communication to which terminal, and the order in which data waiting to be transmitted in the transmission buffer is transmitted. To control. Currently, typical scheduling methods are (1) Maximum CIR method, (2) Round Robin method, and (3) Proportional method. There are three types of Fairness method. In the method (1), transmission opportunities are given priority to terminals with better wireless link quality. This is a scheduling method in which the service gap between terminals increases because communication opportunities with terminals near the wireless communication device increase and communication opportunities with terminals far away decrease. In method (2), communication opportunities are evenly allocated to all terminals. On the other hand, the throughput of the wireless communication device decreases as the communication opportunity with the distant terminal increases. Method (3) uses (instantaneous wireless communication quality) / (average wireless communication quality) as the evaluation value, and the terminal with the higher evaluation value is given priority for transmission opportunities, so the communication opportunities are even and (2) This method is more efficient as a whole. However, the issue is how to correctly estimate the instantaneous wireless communication quality for each terminal.

Spatio-temporal scheduling can be provided by combining the above scheduling technology with spatial multiplexing communication using smart antenna technology. Spatio-temporal scheduling in single-carrier communication is a technique for determining how to allocate time and space resources in downlink communication to which terminal, and controls the transmission order and space of data waiting to be transmitted in a transmission buffer. At this time, the throughput of the wireless communication device improves as the number of simultaneous transmissions by spatial multiplexing increases.

<patcit num="1"><text>Japanese Patent No. 3167682</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 10-145286</text></patcit><nplcit num="1"><text>B. Widrow, et al .: Adaptive Antenna Systems, Proc. IEEE, vol. 55, No. 12, pp. 2143-2159, Dec. 1967</text></nplcit><nplcit num="2"><text>3GPP2 C.S0024-A "cdma2000 High Rate Packet Data Air Interface Specification" (pages 13-42 to 13-78, 2004/3/31)</text></nplcit><nplcit num="3"><text>ROSchmidt, "Multiple Emitter Location and Signal Parameter Estimation", IEEE Trans. AP-34, 1986</text></nplcit><nplcit num="4"><text>3GPP2 C.S0024-A "cdma2000 High Rate Packet Data Air Interface Specification" (pages 13-7 to 13-41, 2004/3/31)</text></nplcit>

<p> The present invention solves the problem of downlink packet communication by the wireless communication device in the wireless communication system in which the wireless communication device equipped with the smart antenna technology constitutes a network.</p><p> In the spatiotemporal packet scheduling method using the smart antenna technology, the efficiency of the entire wireless communication system improves as the number of simultaneous transmissions by spatial multiplexing for each wireless communication device increases. On the other hand, as the number of terminals communicating with the wireless communication device increases, the communication opportunity per terminal decreases. This will be described with reference to FIG.</p><p> FIG. 1 shows an overview of the wireless communication system. The gateway 1 is a node that connects to another communication system, and is connected to, for example, a general telephone network or an IP network. The wireless communication network 2 is a network to which the wireless communication device (base station device) 4 is connected, and is composed of a router and a cable. The geographic area 5 is an area capable of communicating with a wireless communication device. The directional beam 7 is a directional beam for communicating with the terminal 6, and when a plurality of beams are output simultaneously at the same time, spatial multiplex communication is realized.</p><p> In the example of FIG. 1, the number of terminals communicating with the wireless communication device 4-1 is 4, and the number of terminals communicating with the wireless communication device 4-2 is 2. Since the number of beams for spatial multiplexing communication is set to 2 for both wireless communication devices, the terminal that communicates with the wireless communication device 4-2 has a communication opportunity with a simple calculation compared to the terminal that communicates with the wireless communication device 4-1. Double. As a result, there is a problem that a disparity in communication opportunities between terminals occurs depending on the wireless communication device of the communication partner. This problem is further accompanied by the problem that the wireless communication device that gives the terminal a large number of communication opportunities causes excessive interference in the peripheral area due to excessive spatial multiplexing communication.</p>

<p> The solution is to control the number of terminals that simultaneously transmit in spatial multiplexing (the number of spatial multiplex transmissions) according to the number of terminals that communicate with the wireless communication device. The aim of the control is to equalize the communication opportunities of the terminals connected to each of the plurality of wireless communication devices, that is, (the number of connected terminals) / (the number of spatial multiplex transmissions). To achieve this, as shown in Fig. 2, the number of connected terminals and the number of spatial multiplex transmissions are collected from multiple wireless communication devices, and the ratio of (number of connected terminals) / (number of spatial multiplex transmissions) is set for each wireless communication device. A spatial multiplex transmission number control device that adjusts the number of spatial multiplex transmissions of each wireless communication device so that this is equal among a plurality of wireless communication devices, and the multiplex number control device that determines the number of connected terminals and the number of spatial multiplex transmissions. The solution is to prepare multiple wireless communication devices to transmit to. In Fig. 2, the number of terminals is 4 in the area (cell) 5-1, the number of spatial multiplex transmissions (the number of directional beams used at the same timing) in the wireless communication device 4-1 is 2, and the number of terminals is in the area 5-2. 2. The number of spatial multiplex transmissions in the wireless communication device 4-1 is 1.</p>

<p> According to the present invention, the communication opportunity gap between terminals generated between wireless communication devices and the terminal throughput gap between wireless communication devices are reduced. As a result, it is possible to provide a wireless communication system in which the service disparity between terminals is small. Further, according to the present invention, the number of spatial multiplex transmissions of the wireless communication device that provides an excessive service as compared with other wireless communication devices is reduced, so that the interference of the wireless communication device with the peripheral region can be reduced. , The communication quality of the terminal communicating with the wireless communication device whose peripheral area is a communicable geographic area is improved.</p>

FIG. 3 shows an example of the configuration of the present invention. The spatial multiplex transmission number control device 3 is connected to a plurality of wireless communication devices 4 via a network, collects representative values of traffic (for example, the number of terminals and throughput, details will be described later) from each wireless communication device 4, and represents a plurality of traffic. It plays a role of evaluating the value, determining the number of spatial multiplex transmissions of each wireless communication device 4, and notifying each wireless communication device 4 of the spatial multiplex transmission number.

The wireless communication device 4 transmits a downlink signal with the directional beam 7 to the terminal 6 existing in the geographic area 5. The directional beam 7 is multiple-output by the number of spatial multiplex transmissions instructed by the spatial multiplex transmission number control device 3, thereby performing spatial multiplex transmission to a plurality of terminals. In order for the spatial multiplex transmission number control device 3 to indicate the spatial multiplex number, the wireless communication device 4 observes the downlink signal, obtains the traffic representative value of the wireless communication device, and transmits the traffic representative value to the spatial multiplex transmission number control device 3.

In this embodiment, it is assumed that the spatial multiplex transmission number control device 3 and the wireless communication device 4 are installed at geographically separated positions. However, even if the spatial multiplex transmission number control device 3 is installed in one wireless communication device 4 as shown in FIG. 4, the effect of the present invention does not change.

FIG. 5 shows an example of a spatial multiplex transmission number control device that controls the multiplex number of wireless communication devices by referring to the traffic representative values of a plurality of wireless communication devices.

The traffic information collecting unit 101 receives the number of spatial multiplex transmissions transmitted from the plurality of wireless communication devices, the traffic representative value, and the identification number of the wireless communication device of the source, and records them in the traffic recording unit 102. When the recording is completed, the traffic information collection unit 101 notifies the traffic evaluation unit 103 of the completion of recording.

The traffic evaluation unit 103 is driven by receiving a recording completion notification from the traffic information collection unit 101. After driving, the traffic evaluation unit 103 reads out the number of spatial multiplex transmissions and the traffic representative value of a specific wireless communication device from the traffic recording unit 102, and sets the number of spatial multiplex transmissions (X) for each wireless communication device as shown in FIG. Plot the points corresponding to the traffic representative value (Y). After that, the traffic evaluation unit 103 finds a first-order approximate straight line (Y = AX + B) that minimizes the sum of the squared errors with all the plotted points. When the first-order approximate straight line is obtained, the traffic evaluation unit 103 notifies the multiple number determination unit 104 of the parameters (A, B) of the obtained first-order approximate straight line and the completion of the approximation of the straight line. By the way, the condition of the specific wireless communication device that reads the spatial multiplex transmission number and the traffic representative value from the traffic recording unit 102 is the wireless communication device that the multiplex control device collects the traffic representative value. The traffic evaluation unit 103 refers to the flag for each wireless communication device recorded in the list holding unit 106, and determines whether or not the condition is satisfied.

The multiple number determination unit 104 is driven by receiving an approximation completion notification from the traffic evaluation unit 103. After driving, the multiplex determination unit 104 reads the spatial multiplex transmission number and the traffic representative value of the specific wireless communication device from the traffic recording unit 102, and sets the first-order approximate straight line notified from the traffic evaluation unit 103 and the read value. Make a comparison. The comparison method will be described later. As a result of the comparison, the multiplex determination unit 104 determines the spatial multiplex transmission number of the specific wireless communication device, and overwrites the traffic recording unit 102 with the spatial multiplex transmission number. When the overwriting is completed, the multiplex determination unit 104 notifies the multiplex notification unit 105 that the number of spatial multiplex transmissions recorded in the traffic recording unit 102 has been updated. By the way, the condition of the specific wireless communication device that reads the spatial multiplex transmission number and the traffic representative value from the traffic recording unit 102 is the wireless communication device in which the multiplex number control device controls the multiplex number. The multiple number determination unit 104 determines whether or not the condition is satisfied by referring to the flag for each wireless communication device recorded in the list holding unit 106.

The multiple number notification unit 105 is driven by receiving an update completion notification from the multiple number determination unit 104. After driving, the multiplex notification unit 105 reads out the spatial multiplex transmission number of the specific wireless communication device from the traffic recording unit 102, and notifies the specific wireless communication device of each spatial multiplex transmission number. By the way, the condition of the specific wireless communication device for reading the spatial multiplex transmission number from the traffic recording unit 102 is the wireless communication device in which the multiplex number control device controls the multiplex number. The multiple number notification unit 105 refers to the flag for each wireless communication device recorded in the list holding unit 106, and determines whether or not the condition is satisfied.

In the above spatial multiplex transmission number control device, the traffic recording unit 102 and the list holding unit 106 are memories, the traffic evaluation unit 103 and the multiplex number determination unit 104 are arithmetic units such as a CPU and DSP, and are multiplexed with the traffic information collection unit 101. The number notification unit 105 can be realized by an arithmetic unit for transmission / reception control and a network adapter.

FIG. 7 is a message sequence diagram when the wireless communication device reports the traffic representative value to the spatial multiplex transmission number control device. First, the wireless communication device carries the number of spatial multiplex transmissions, the traffic representative value, and the identification number of its own wireless communication device in a traffic information message (Traffic Information, T-Info) and transmits it to the spatial multiplex transmission number control device. The message is received by the traffic information collecting unit 101, and is checked for errors by, for example, a parity check. If there is no error, the traffic information collection unit 101 transmits an ACK (T-Info Acknowledgement, T-ACK) to the source wireless communication device as in the example of the wireless communication device 1, and the received traffic representative value, etc. Information is recorded in the traffic recording unit 102. If there is an error, as in the example of wireless communication device 2, the traffic information collection unit 101 applies NAK (T-Info No ACK,) to the source wireless communication device. Sends T-NAK) and prompts to resend the traffic information message (T-Info). Retransmission is repeated until T-ACK is transmitted by the traffic information collecting unit 101. After the T-ACK is transmitted, the traffic information collecting unit 101 records information such as the received traffic representative value in the traffic recording unit 102.

FIG. 8 shows the operation flow of the traffic information collecting unit 101. First, when the spatial multiplex transmission number control device is activated (S101-1), the traffic information collection unit 101 waits for a T-Info message from the wireless communication device (S101-2). When the T-Info message is received, the traffic information collection unit 101 detects an error in the received message (S101-3). When it is determined that there is an error (S101-4), the traffic information collection unit 101 sends a T-NAK to the source wireless communication device and prompts the T-Info to be retransmitted (S101-5). If there is no error, the traffic information collection unit 101 transmits a T-ACK to the source wireless communication device (S101-6), and the information in the T-Info message (the number of spatial multiplex transmissions of the wireless communication device, the traffic representative). The value and the identification number of the wireless communication device) are taken out (S101-7) and recorded in the traffic recording unit 102 (S101-8). After the recording is completed, the traffic information collection unit 101 triggers the traffic evaluation unit 103 to mean that the recording is completed (S101-9).

FIG. 9 is an example of information recording in the traffic recording unit 102. FIG. 9A shows an example of recording when the traffic representative value is the number of terminals for each wireless communication device. When the traffic information collecting unit 101 receives the T-Info message and transmits the T-ACK, the number of spatial multiplex transmissions of the wireless communication device, the traffic representative value, and the wireless communication device of the T-info message transmission source Record in the traffic recording unit 102 so that the identification numbers are paired. Here, the traffic representative value is the number of terminals communicating with each wireless communication device. The information recorded here is selectively referred to by the traffic evaluation unit 103, the multiple number determination unit 104, and the multiple number notification unit 105 for each identification number of the wireless communication device. Further, the multiplex determination unit 104 overwrites the newly determined spatial multiplex transmission number.

FIG. 9 (b) is a recording example when the traffic representative value is the total throughput [Mbps] for each wireless communication device. The usage of recording in the spatial multiplex transmission number controller is the same as in FIG. 9 (a). The traffic representative value indicates how much communication resource is required for each wireless communication device. If the number of terminals is set as shown in Fig. 9 (a), it will be easier to obtain the traffic representative value, and if the total throughput is set as shown in Fig. 9 (b), the actual traffic volume will be reflected more accurately. ..

FIG. 10 shows the operation flow of the traffic evaluation unit 103. First, when the spatial multiplex transmission number control device is activated (S103-1), the traffic evaluation unit 103 waits for a trigger from the traffic information collection unit 101 (S103-2). Upon receiving the trigger, the traffic evaluation unit 103 reads the number of spatial multiplex transmissions and the traffic representative value of the specific wireless communication device from the traffic recording unit 102 and copies them to the calculation buffer (S103-3).

The method of copying to the calculation buffer will be described with reference to FIG. FIG. 11 (a) is a recording example of the traffic recording unit 102, which is the same as FIG. 9 (a). FIG. 11B shows the flag state for each wireless communication device recorded in the list holding unit 106. The spatial multiplex transmission number control device acquires information such as a traffic representative value from a wireless communication device having an information collection flag of 1, and determines the multiplex number of the wireless communication device having a multiplex number determination flag of 1. In step S103-3 of FIG. 10, the traffic evaluation unit 103 copies the information of the wireless communication device of the information collection flag 1 from FIG. 11A to the calculation buffer. As a result, it is possible to evaluate the traffic representative value for all the wireless communication devices collected by the spatial multiplex transmission number control device. Figure 11 (c) shows the result copied to the calculation buffer. The traffic evaluation unit 103 counts the number of wireless communication devices for each number of spatial multiplex transmissions, and records all the traffic representative values for each number of spatial multiplex transmissions.

When step S103-3 in FIG. 10 is completed, the traffic evaluation unit 103 calculates A and B of the first-order approximate straight line equation 1 from the recording of the calculation buffer (S103-4). A is the proportional coefficient between the number of spatial multiplex transmissions and the traffic representative value, B is the offset value, X is the number of spatial multiplex transmissions, and Y is the traffic representative value. Specifically, A and B that minimize the squared error of Equation 2 are calculated. x is a counter for the number of spatial multiplex transmissions, n is a counter for the number of wireless communication devices, M is the maximum value of the number of spatial multiplex transmissions, and N (x) is the number of wireless communication devices for the number of spatial multiplex transmissions x. N (x) corresponds to the numerical value in the second row from the top in FIG. 11 (c), and n corresponds to the nth row of the traffic representative value in FIG. 11 (c). y (x, n) is a traffic representative value, and corresponds to the column of the number of spatial multiplex transmissions x in FIG. 11 (c) and the nth stage value of the traffic representative value.

<maths num="1"><img file="JP2007150416A_D0001.tif" /></maths>

<maths num="2"><img file="JP2007150416A_D0002.tif" /></maths>

When the calculation of the first-order approximate straight line (S103-4) is completed, the traffic evaluation unit 103 notifies the multiple number determination unit 104 that the calculation is completed and the parameters (A, B) of the approximate straight line (S103-5).

FIG. 12 shows the operation flow of the multiple number determination unit 104.

First, when the spatial multiplex transmission number control device is activated (S104-1), the multiplex determination unit 104 waits for a trigger from the traffic evaluation unit 103 (S104-2). Upon receiving the trigger, the multiplex determination unit 104 reads the spatial multiplex transmission number and the traffic representative value of the specific wireless communication device from the traffic recording unit 102 and copies them to the calculation buffer (S104-3).

The method of copying to the calculation buffer will be described with reference to FIG. Since FIGS. 13 (a) and 13 (b) are the same as those of FIGS. 11 (a) and 11 (b), the description thereof is omitted here. As a result of being copied to the calculation buffer, FIG. 13 (c) is obtained by extracting the stage of the wireless communication device of the multiple number determination flag 1 of FIG. 13 (b) from FIG. 13 (a) (S104-3). ..

The multiplex determination unit 104 evaluates whether the traffic representative value is too large or too small with respect to the spatial multiplex transmission number for each wireless communication device extracted here, and recalculates the spatial multiplex transmission number (S104). -Four). There are two ways to recalculate.

The first method, as shown in FIG. 14, is to directly specify the number of spatial multiplex transmissions (X) with the smallest error by comparing the traffic representative value of the wireless communication device with the first-order approximate straight line. The other is, as shown in FIG. 15, when the traffic representative value of the wireless communication device is greater than or equal to the threshold value (d) with respect to the first-order approximate straight line in the number of spatial multiplex transmissions of the wireless communication device. This is a method of increasing or decreasing the number of spatial multiplex transmissions of the wireless communication device by 1.

When the recalculation is completed, the multiplex determination unit 104 overwrites the spatial multiplex communication number for each wireless communication device with the traffic recording unit 102 (S104-5), and notifies that the update of the spatial multiplex transmission number is completed. Notify 105 (S104-6).

FIG. 16 is a message sequence diagram when the spatial multiplex transmission number control device notifies the wireless communication device of the spatial multiplex transmission number.

First, the multiplex notification unit 105 of the spatial multiplex transmission number control device transmits the spatial multiplex transmission number on the multiplex notification message (Multiplex Information, M-Info) to the wireless communication device. The message is received by the wireless communication device, and is checked for errors by, for example, a parity check. If there is no error, the wireless communication device transmits an ACK (M-Info ACK, M-ACK) to the source spatial multiplex transmission number control device as in the example of the wireless communication device 1. If there is an error, the wireless communication device transmits NAK (M-Info NAK, M-NAK) to the source spatial multiplex transmission number control device as in the example of the wireless communication device 2. The multiples notification unit 105 repeats retransmission until M-ACK is received from the wireless communication device.

FIG. 17 shows the operation flow of the multiple number notification unit 105. First, when the spatial multiplex transmission number control device is activated (S105-1), the multiplex notification unit 105 waits for a trigger from the multiplex determination unit 104 (S105-2), or responds to an M-Info message from the wireless communication device. Waiting for a response (S105-3). When the multiplex notification unit 105 receives a trigger from the multiplex determination unit 104, the multiplex notification unit 105 notifies a specific terminal of the number of spatial multiplex transmissions. The notification target is the wireless communication device of the multiple number determination flag 1 with reference to the record of the list holding unit 106 (for example, FIG. 13B), and the number of each spatial multiplex transmission recorded in the traffic recording unit 102. Notify by posting in M-Info message (S105-4). Upon receiving the response to the M-Info message from the wireless communication device, the multiple number notification unit 105 determines whether the message is M-NAK (S105-5). If it is M-NAK, the multiply perfect number notification unit 105 resends the M-Info message to the wireless communication device (S105-6).

FIG. 18 shows another example of the configuration of the spatial multiplex transmission number control device. This configuration is an example of the above configuration with the addition of a request transmission unit 107 and a timer 108.

The request transmission unit 107 is driven by receiving a trigger from the timer 108. After driving, the request transmission unit 107 transmits a message requesting a specific wireless communication device to transmit each traffic representative value to the spatial multiplexing control device. At the time of message transmission, the request transmission unit 107 transmits a Request message promised in advance to the wireless communication device. By the way, the condition of the specific wireless communication device to which the request message is transmitted is the wireless communication device in which the multiple number control device controls the multiple number. The request transmission unit 107 refers to the flag for each wireless communication device recorded in the list holding unit 106, and determines whether or not the condition is satisfied.

FIG. 19 is a message sequence diagram when the spatial multiplex transmission number control device requests the wireless communication device to report the traffic representative value. First, the request transmission unit 107 of the spatial multiplex transmission number control device transmits a request message (Request) for requesting the wireless communication device to report the traffic representative value. The message is received by the wireless communication device, and is checked for errors by, for example, a parity check. If there is no error, the wireless communication device transmits an ACK (Request ACK, R-ACK) to the source spatial multiplex transmission number control device as in the example of the wireless communication device 1. If there is an error, the wireless communication device transmits NAK (Request NAK, R-NAK) to the source spatial multiplex transmission number control device as in the example of the wireless communication device 2. The request transmission unit 107 repeats retransmission until R-ACK is received from the wireless communication device.

FIG. 20 shows an operation flow of the request transmission unit 107. First, when the spatial multiplex transmission number control device is activated (S107-1), the request transmitter 107 waits for a trigger from the timer 108 (S107-2) or waits for a response to a Request message from the wireless communication device (S107-3). ). Upon receiving the trigger from the timer 108, the request transmission unit 107 transmits a request message to the specific wireless communication device. The transmission target transmits a Request message to the wireless communication device of the information collection flag 1 with reference to the record of the list holding unit 106 (for example, FIG. 13B) (S107-4). Upon receiving the response to the Request message from the wireless communication device, the request transmission unit 107 determines whether the message is R-NAK (S107-5). If it is R-NAK, the request transmitter 107 retransmits the Request message to the wireless communication device (S107-6).

FIG. 21 shows an example of the configuration of the wireless communication device. The spatial multiplex setting unit 201 receives a multiplex notification message (M-Info) from the spatial multiplex transmission number control device and notifies the terminal selection unit 205 of the spatial multiplex transmission number of the wireless communication device. Further, the spatial multiplex setting unit 201 transmits a response message to M-Info to the spatial multiplex transmission number control device of the transmission source.

In response to the trigger from the timer 214, the terminal selection unit 205 selects the terminals that are wirelessly communicating with the wireless communication device by the number of multiple terminals specified by the spatial multiplex setting unit 201. At this time, the terminals are selected so that there is one terminal for each directional beam. The identification number of the selected terminal is notified to the downlink signal processing unit 206 and the weight recording unit 208. When selecting a terminal, since the terminal selection unit 205 selects from the terminal that has at least the downlink data to be transmitted (the remaining amount of data is not 0 bits), the downlink data buffer of the data recording unit 204 is referred to. For example, terminal selection is performed by selecting a plurality of terminals by the Round Robin method among terminals whose remaining amount of data is not 0.

The downlink signal processing unit 206 reads the downlink data bit sequence of the terminal from the downlink data buffer of the data recording unit 204 based on the identification number of the selected terminal notified from the terminal selection unit 205. The read bit sequence is subjected to baseband signal processing according to the protocol of the physical layer with the terminal (for example, Non-Patent Document 2). The baseband signal processed signal is written to the input signal buffer of the weighting unit 209 together with the terminal identification number.

The weight recording unit 208 records the array weight for the downlink signal for each terminal created by the array weight creation unit 210. Upon receiving the notification of the terminal identification number from the terminal selection unit 205, the weight recording unit 208 notifies the weighting unit 209 of the array weight for each notified terminal identification number.

The weighting unit 209 distributes the signal after baseband processing written in the buffer from the downlink signal processing unit 206 by the number of antenna elements, integrates the array weights notified from the weight recording unit 208 for each element, and integrates each element. After the array weighting of, the baseband signal is obtained. When integrating the weights, it is necessary to match the input baseband signal with the terminal identification number of the array weights.

The array weight creation unit 210 obtains the array weight used by each terminal in downlink communication based on the uplink signal from the terminal, and records it in the weight recording unit 208 together with the terminal identification number. Multiple terminals may use the same array weight. For example, in a method in which a base station has M types of fixed beam patterns and uses different beams for each range of M / 360 degrees, the array weighting unit 210 uses an uplink signal from a terminal by the MUSIC algorithm (Non-Patent Document 3). Estimate the arrival direction of, determine which M / 360 degree range the direction falls into, select one of the fixed beam patterns, and associate the array weight that generates the fixed beam with the terminal identification number. Record in the weight recording unit 208.

The frequency conversion unit 211 converts the downlink baseband signal from the baseband to the carrier band, and the uplink carrier band signal from the carrier band to the baseband. The duplexer DUP212 discriminates between upstream and downstream signals.

The uplink signal processing unit 207 performs baseband signal processing on the uplink signal converted into the baseband band according to the protocol of the physical layer with the terminal (for example, Non-Patent Document 4), extracts a bit sequence, and extracts the bit sequence of the data recording unit 204. Record in the uplink signal buffer together with the terminal identification number. Further, the uplink signal processing unit 207 inputs signals from a plurality of antenna elements, and diversifies each of them as a space diversity branch.

In the data recording unit 204, the bit sequence (voice or data) of each terminal wirelessly communicating with the wireless communication device is stored in a buffer for both the downlink bit sequence and the uplink bit sequence. The downlink bit sequence is transmitted from another wireless communication device or the gateway of the wireless communication system to the wireless communication device. The uplink bit sequence is transmitted from the wireless communication device to another wireless communication device or gateway.

The traffic measurement unit 203 receives a trigger from the timer 214, obtains a traffic representative value of the wireless communication device by referring to the downlink data buffer of the data recording unit 204, and notifies the own station information transmission unit 202. How to obtain the traffic representative value will be described later.

The own station information transmission unit 202 notifies a specific multiple transmission number control device of the traffic representative value notified from the traffic measurement unit 203. The notification destination of the information is recorded in the report destination list holding unit 215.

FIG. 22 shows an example of the downlink data buffer of the data recording unit 204 observed by the traffic measuring unit 203. The information to be recorded in the buffer is the identification number of the terminal to be transmitted, the number of untransmitted bits, and the bit sequence itself. When the identification number of the terminal is specified by the downlink signal processing unit 206, a part or all of the bit sequence of the identification number is read, the read bit sequence is deleted from the buffer, and the number of bits read. Is also subtracted. The number of bits to be read follows the protocol of the physical layer with the terminal (for example, Non-Patent Document 2). Unless the protocol has a fixed number of read bits, the downlink signal processing unit 206 also needs to specify the number of bits to be read. When a bit sequence is received from another wireless communication device or a gateway of the wireless communication system, the number of bits and the bit sequence are added according to the format shown in FIG. The number of bits of the terminal 00000003 in FIG. 22 is 0. This indicates that the connection with the wireless communication device has been established, but there is no downlink data at this point.

FIG. 23 shows an example of the operation flow of the traffic measurement unit 203. In this flow, the traffic measurement unit 203 counts the number of terminals that have had a moment when the number of bits is not 0 even once in the downlink data buffer of the data recording unit 204 within a fixed observation time, and temporarily stores the corresponding terminal.

First, when the wireless communication device is activated (S203-1), the observation time is reset (S203-2). When the observation time is reset, the traffic measurement unit 203 refers to the downlink data buffer (Fig. 22) of the data recording unit 204, counts the number of terminals whose number of bits is not 0, and sets a wait time in S203-6. Check the number of bits of each terminal in the downlink data buffer at regular intervals. When the number of bits changes in at least one terminal, it is checked whether or not there is an uncounted terminal in which the number of bits is not 0 by comparing it with the temporary storage (S203-4). If there is an uncounted terminal, the number of terminals whose bit number is not 0 is added, and the corresponding terminal is added to the temporary storage. The traffic measurement unit 203 repeats S203-4 to S203-6 until the observation time ends (S203-7), and when it ends, determines the number of terminals whose bit number is not 0 at that time as the traffic representative value (S203-8). , Notify the own station information transmission unit 202 (S203-9). Further, when the notification is completed, the temporary memory is cleared.

FIG. 24 shows another example of the operation flow of the traffic measurement unit 203. In this flow, the traffic measurement unit 203 measures the total number of communication bits from the downlink data buffer of the data recording unit 204, that is, the throughput of the wireless communication device within a fixed observation time.

First, when the wireless communication device is activated (S203-1), the observation time is reset (S203-2). When the observation time is reset, the total number of communication bits communicated by the wireless communication device is also cleared (S203-10). Check the number of bits of each terminal in the downlink data buffer at regular intervals with a wait time of S203-6. When the number of bits changes in at least one terminal (S203-11), the total number of reduced bits of all terminals whose number of bits has decreased is added to the total number of communication bits (S203-12). The traffic measurement unit 203 repeats S203-11 to S203-6 until the observation time ends (S203-7), and when the observation time ends, the traffic representative is the throughput of the wireless communication device obtained by dividing the total number of communication bits at that time by the observation time. Determine the value (S203-13) and notify the own station information transmission unit 202 (S203-9).

FIG. 25 shows yet another example of the operation flow of the traffic measurement unit 203. In this flow, the traffic measurement unit 203 measures the total number of communication bits for each terminal from the downlink data buffer of the data recording unit 204 within a fixed observation time, that is, the throughput for each terminal device.

First, when the wireless communication device is activated (S203-1), the observation time is reset (S203-2). When the observation time is reset, the number of communication bits for each terminal communicated by the wireless communication device is also cleared (S203-14). Check the number of bits of each terminal in the downlink data buffer at regular intervals with a wait time of S203-6. When the number of bits changes in at least one terminal (S203-11), the reduced number of bits of each terminal in which the number of bits has decreased is added to the number of communication bits for each terminal (S203-15). The traffic measurement unit 203 repeats S203-11 to S203-6 until the observation time ends (S203-7), and when the observation time ends, the throughput for each terminal divided by the number of communication bits for each terminal at that time is in descending order. The terminal throughput N% value viewed from the top of the throughput is determined as the traffic representative value (S203-13), and notified to the own station information transmission unit 202 (S203-9).

The own station information transmission unit 202 transmits the traffic representative value to the multiple transmission number control device in a T-Info message according to the sequence of FIG. 7, and retransmits it when receiving T-NAK from the multiple transmission number control device.

FIG. 26 shows the operation flow of the own station information transmission unit 202. First, when the wireless communication device is activated (S202-1), the own station information transmission unit 202 waits for a trigger from the traffic measurement unit 203 (S202-2), or responds to a T-Info message from the multiple transmission number control device. Wait (S202-3). When the own station information transmission unit 202 receives a trigger from the traffic measurement unit 203, the own station information transmission unit 202 notifies the specific multiplex transmission number control device of the traffic representative value (S202-4). The notification target is the total multiple transmission number control device recorded in the report destination list holding unit 215. When the own station information transmission unit 202 receives a response to the T-Info message from the multiple transmission number control device, it determines whether the message is T-NAK (S202-5). In the case of T-NAK, the own station information transmission unit 202 retransmits the T-Info message to the multiple transmission number control device (S202-6).

The spatial multiples setting unit 201 receives the M-Info message transmitted from the multiplex transmission number control device according to the sequence of FIG. 16, and checks whether or not there is an error by, for example, a parity check. If there is no error, as in the example of the wireless communication device 1, the spatial multiplex setting unit 201 transmits M-ACK to the multiplex transmission number control device of the source, and the spatial multiplex transmission included in the received M-Info. Notify the terminal selection unit 205 of the number. If there is an error, as in the example of the wireless communication device 2, the spatial multiples setting unit 201 transmits M-NAK to the multiple transmission number control device of the source and prompts the retransmission of the M-Info message.

FIG. 27 shows the operation flow of the spatial multiples setting unit 201. First, when the wireless communication device is activated (S201-1), the spatial multiplex setting unit 201 waits for an M-Info message from the multiplex transmission number control device (S201-2). When the M-Info message is received, the spatial multiples setting unit 201 detects an error in the received message (S201-3). When it is determined that there is an error (S201-4), the spatial multiples setting unit 201 sends M-NAK to the source multiples transmission number control device and prompts the retransmission of M-Info (S201-5). .. If there is no error, the spatial multiples setting unit 201 transmits M-ACK to the source multiples transmission number control device (S201-6), and extracts the information (spatial multiplex transmissions) in the M-Info message (spatial multiplex transmissions). S201-7), notify the terminal selection unit 205 (S201-8).

FIG. 28 shows another example of the configuration of the wireless communication device. In this configuration, the request detection unit 216 is added instead of the report destination list holding unit 215 to the above configuration example.

The request detection unit 216 triggers the own station information transmission unit 202 when it receives a message (Request) requesting the transmission of the traffic representative value from the spatial multiplex transmission number control device. In this configuration, the own station information transmission unit 202 receives a trigger from the request detection unit 216 and starts a T-Info transmission operation. In the above configuration example, the same operation was started by receiving a trigger from the traffic measurement unit 203. That is, the source of the trigger is different. Further, the transmission destination of T-Info is the spatial multiplex transmission number control device of the transmission source of the request message (Request) in this configuration. In the above configuration example, the destination of T-Info is determined by referring to the report destination list holding unit 215, so this point is also different.

The request detection unit 216 receives the Request message transmitted from the multiple transmission number control device according to the sequence of FIG. 19, and checks whether there is an error by, for example, a parity check. If there is no error, as in the example of the wireless communication device 1, the request detection unit 216 transmits R-ACK to the multiple transmission number control device of the transmission source, and the request is received by the own station information transmission unit 202 itself. (Trigger) and the identification number of the multiple transmission number control device of the request source are notified. If there is an error, the request detection unit 216 transmits R-NAK to the multiple transmission number control device of the transmission source, as in the example of the wireless communication device 2.

FIG. 29 shows the operation flow of the request detection unit 216. First, when the wireless communication device is activated (S216-1), the request detection unit 216 waits for a Request message from the multiple transmission number control device (S216-2). When the Request message is received, the request detection unit 216 detects an error in the received message (S216-3). When it is determined that there is an error (S216-4), the request detection unit 216 sends an R-NAK to the source multiple transmission number control device and prompts the request to be retransmitted (S216-5). If there is no error, the request detection unit 216 sends an R-ACK to the source multiple transmission number control device (S216-6), and the request itself (trigger) and the request source multiple transmission number control Notify the identification number of the device to the local information transmission unit 202 (S216-7).

The operation flow of the own station information transmission unit 202 basically follows FIG. 26. However, in this configuration example, since the own station information transmission unit 202 is driven by a trigger from the request detection unit 216, S202-2 is changed to receive the trigger from 216. Further, the specific multiple transmission number control device in S202-4 refers to the multiple transmission number control device that is the source of the Request message received by the request detection unit 216.

FIG. 30 shows another example of the configuration of the present invention. Here, the spatial multiplex transmission number control device 3 and the wireless communication device 4 are regarded as an integrated device, and each device operates ad hoc.

The spatial multiplex transmission number control device 3 is connected to a plurality of wireless communication devices 4 via a network, collects traffic representative values from each wireless communication device 4, evaluates a plurality of traffic representative values, and evaluates the space of each wireless communication device 4. It is responsible for determining the number of multiplex transmissions and notifying a single wireless communication device 4 of the number of spatial multiplexes. The wireless communication device 4 transmits a downlink signal with the directional beam 7 to the terminal 6 existing in the geographic area 5. The directional beam 7 is multiple-output by the number of spatial multiplex transmissions instructed by the spatial multiplex transmission number control device 3, thereby performing spatial multiplex transmission to a plurality of terminals. In order for the spatial multiplex transmission number control device 3 to indicate the spatial multiplex number, the wireless communication device 4 observes the downlink signal, obtains the traffic representative value of the wireless communication device, and transmits the traffic representative value to the spatial multiplex transmission number control device 3.

The difference from the configuration shown in FIGS. 3 to 4 is whether the notification destination of the number of spatial multiplex transmissions is multiple or singular.

The notification destination of the number of spatial multiplex transmissions is recorded in the list holding unit 106 in the spatial multiplex transmission number control device, for example, as shown in FIG. 13 (b). Here, if the multiple number determination flag is 1 for a plurality of wireless communication devices, the first embodiment is implemented, and if it is 1 for a single wireless communication device, the second embodiment is implemented. Except for this difference, the same spatial multiplex transmission number control device and wireless communication device of the first embodiment shown in FIGS. 5 to 20 can be used.

FIG. 31 shows yet another example of the configuration of the present invention. Here, the wireless communication device 4 is divided into a network side device 8 and a front end side device 9, and the network side device 8 is geographically concentrated in an ROF (Patent Document 2) configuration. The network side device 8 and the front end side device 9 are connected by an optical fiber 11. By arranging the spatial multiplex transmission number control device 3 together with the network side device 8, information exchange between the spatial multiplex transmission number control device and the wireless communication device becomes easy.

The spatial multiplex transmission number control device 3 is connected to a plurality of wireless communication devices 4 by 10 in the centralized control device, collects traffic representative values from each wireless communication device 4, evaluates a plurality of traffic representative values, and performs each wireless communication. It is responsible for determining the number of spatial multiplex transmissions of the device 4 and notifying each wireless communication device 4 of the number of spatial multiplex transmissions. The wireless communication device 4 transmits a downlink signal with the directional beam 7 to the terminal 6 existing in the geographic area 5. The directional beam 7 is multiple-output by the number of spatial multiplex transmissions instructed by the spatial multiplex transmission number control device 3, thereby performing spatial multiplex transmission to a plurality of terminals. In order for the spatial multiplex transmission number control device 3 to indicate the spatial multiplex number, the wireless communication device 4 observes the downlink signal, obtains the traffic representative value of the wireless communication device, and transmits the traffic representative value to the spatial multiplex transmission number control device 3.

Compared with the examples shown in FIGS. 3 and 4, the spatial multiplex transmission number control device 3 has the same spatial multiplex transmission number because the information exchange partner only changes from the entire wireless communication device 4 to the network side device 8. Control device can be used. The interface of the wireless communication device 4 with the spatial multiplex transmission number control device 3 does not change, and the internal configuration of the wireless communication device 4 changes.

FIG. 32 shows an example in which the ROF-configured wireless communication device is used in the present invention.

In this configuration, the configuration example shown in FIG. 21 is divided into a network side device 8 and a front end side device 9, and the network side device 8 has an electric / optical converter E / O (221) and an optical / electric converter O / E. (222), an electric / optical converter E / O (224) and an optical / electric converter O / E (223) are also added to the front-end side device 9. These electric / optical converters and optical / electric converters are prepared for the number of antenna elements 213 of the front-end side device 9. The electric / optical converter E / O (221) of the network side device 8, the optical / electric converter O / E (223) of the front-end side device 9, and the optical / electric converter O / E (optical / electric converter O / E) of the network side device 8. 222) and the electric / optical converter E / O (224) of the front-end side device 9 are connected by an optical fiber. In this embodiment, as compared with the configuration example shown in FIG. 21, the communication means between the frequency conversion unit 211, the array weight creation unit 210, and the uplink signal processing unit 207 is changed from electric to light, and each part is changed. The behavior of is the same. Therefore, this ROF-configured wireless communication device operates in the same manner as the wireless communication device of the configuration example shown in FIG.

The wireless communication device and the spatial multiplex transmission number control device of the present invention control the spatial multiplex transmission number of each wireless communication device in consideration of the traffic situation of the plurality of wireless communication devices to be spatially multiplexed. It can be applied to all wireless communication systems in which a plurality of wireless communication devices that perform spatial multiplex communication are constructing a network, but it is suitable for a cellular system in which the traffic situation tends to be biased depending on the geographical area. Further, if the wireless communication device has an ROF configuration, the realization of the present invention becomes easy.

<figref num="1">Diagram showing wireless communication system</figref><figref num="2">The figure which showed the wireless communication system in the state where the effect of this invention was obtained.</figref><figref num="3">First Example of System Configuration According to the Present Invention</figref><figref num="4">Modification of First Example of System Configuration According to the Present Invention</figref><figref num="5">First configuration example of spatial multiplex transmission number control device</figref><figref num="6">First-order approximation of the relationship between the traffic representative value and the number of spatial multiplex transmissions</figref><figref num="7">Sequence when the wireless communication device sends the traffic representative value</figref><figref num="8">Operation flow of traffic information collection unit</figref><figref num="9">Example of recording format for traffic information recording unit</figref><figref num="10">Operation flow of traffic evaluation unit</figref><figref num="11">Recording example of the calculation buffer of the traffic evaluation unit</figref><figref num="12">Operation flow of the multiple number determination unit</figref><figref num="13">Recording example of the calculation buffer of the multiple number determination unit</figref><figref num="14">Method for determining the number of multiple transmissions that fits the number of multiple transmissions of the wireless communication device to an approximate straight line</figref><figref num="15">Method for determining the number of multiple transmissions that gently adjusts the number of multiple transmissions of the wireless communication device</figref><figref num="16">Sequence when the spatial multiplex transmission number controller sends the spatial multiplex transmission number</figref><figref num="17">Operation flow of multiple notification unit</figref><figref num="18">Second configuration example of spatial multiplex transmission number control device</figref><figref num="19">Sequence in which the spatial multiplex transmission number controller requests the traffic representative value from the wireless communication device</figref><figref num="20">Operation flow of request transmitter</figref><figref num="21">First configuration example of wireless communication device</figref><figref num="22">Recording format of the downlink data buffer of the data recording section</figref><figref num="23">First Example of Operation Flow of Traffic Measurement Unit</figref><figref num="24">Second Example of Operation Flow of Traffic Measurement Unit</figref><figref num="25">Third Example of Operation Flow of Traffic Measurement Unit</figref><figref num="26">Operation flow of own station information transmission unit</figref><figref num="27">Operation flow of spatial multiples setting unit</figref><figref num="28">Second configuration example of wireless communication device</figref><figref num="29">Operation flow of request detector</figref><figref num="30">Second Example of System Configuration According to the Present Invention</figref><figref num="31">Third Example of System Configuration According to the Present Invention</figref><figref num="32">First configuration example of ROF configuration wireless communication device according to the present invention</figref>

Code description

1 ... Gateway of wireless communication system, 2 ... Wireless communication network, 3 ... Spatial multiplex transmission number controller, 4 ... Wireless communication device, 5 ... Geographical area capable of communicating with wireless communication device , 6 ... Terminal device, 7 ... Directional beam, 8 ... Network side device in wireless communication device with ROF configuration, Front-end device in wireless communication device with 9 ... ROF configuration, 10 ... Centralized control device, 11 ... Optical fiber, 101 ... Traffic information collection unit, 102 ... Traffic information recording unit, 103 ... traffic evaluation unit, 104 ... multiple number determination unit, 105 ... multiple number notification unit, 106 ... list holding unit, 107 ... request transmission unit, 108 ... multiple transmission number controller Timer, 201 ... Spatial multiples setting unit, 202 ... Own station information transmission unit, 203 ... Traffic measurement unit, 204 ... Data recording unit, 205 ... Terminal selection unit, 206 .. Down signal transmitter, 207 ... Up signal transmitter, 208 ... Weight recording section, 209 ... Weight section, 210 ... Array weight creation section, 211 ... Frequency conversion section, 212 .. .Duplexer DUP, 213 ... Antenna element, 214 ... Wireless communication device timer, 215 ... Report destination list holder, 216 ... Request detector, 221 ... Electric / optical converter, 222 ... optical / electric converter, 223 ... optical / electric converter, 224 ... electric / optical converter.