JP2010109644A - Wireless relay device and wireless relay method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless relay device capable of normally continuing data relay even when a large difference is generated between communication quality in a first communication part and communication quality in a second communication part while improving the efficiency for use of an antenna. <P>SOLUTION: The wireless relay device 100 includes: an antenna allocation part 141 allocating partial antennas within antennas Ant<SB>1</SB>-Ant<SB>N</SB>to a donor-side communication part 110, and allocating remaining antennas to a remote-side communication part 120; and a decision part 142 determining whether a difference between communication quality in wireless communication between the donor-side communication part 110 and a wireless base station BS and communication quality in wireless communication between the remote-side communication part 120 and a wireless terminal MS exceeds a threshold. When the difference is determined to exceed the threshold by the decision part 142, the antenna allocation part 141 changes the allocation of the antennas Ant<SB>1</SB>-Ant<SB>N</SB>to the donor-side communication part 110 and the remote-side communication part 120. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless relay device and a wireless relay method for relaying data transmitted and received between a first wireless communication device and a second wireless communication device.

  Conventionally, a wireless relay device that relays data transmitted and received between a first wireless communication device (for example, a wireless base station) and a second wireless communication device (for example, a wireless terminal) has been widely used. The wireless relay device includes a first communication unit that performs wireless communication with the first wireless communication device, and a second communication unit that performs wireless communication with the second wireless communication device.

In such a wireless relay device, a method for improving communication quality by comparing the reception level of each antenna, selecting an antenna with a good reception level, and performing wireless communication has been proposed (see Patent Document 1). ). Specifically, the wireless relay device described in Patent Document 1 compares the reception levels of N antennas provided in the wireless relay device, and among the N antennas, A (N Reception is performed using the antenna of> A). At the time of transmission, one antenna having the highest reception level among the A antennas is used.
Japanese Patent Laid-Open No. 11-168422 (paragraph [0019], FIG. 6)

  However, in the wireless relay device described in Patent Document 1, the maximum number of antennas simultaneously used for wireless communication among N antennas is A, and (NA) antennas are used for wireless communication. Therefore, there is a problem that the antenna usage efficiency is poor.

  In addition, there is often a difference between the communication quality (for example, throughput) in the first communication unit and the communication quality in the second communication unit. In the wireless relay device described in Patent Document 1, since the balance between the communication quality in the first communication unit and the communication quality in the second communication unit is not taken into account, an overflow of a buffer that holds data in the wireless relay device occurs. However, there is a problem that it is difficult to continue data relay normally.

  Therefore, the present invention provides a radio relay apparatus capable of normally continuing data relay even when a large difference occurs between the communication quality in the first communication unit and the communication quality in the second communication unit, while improving the antenna usage efficiency. An object is to provide a wireless relay method.

In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is that a plurality of antennas (antennas Ant _{1 to} Ant _N ) arranged at intervals and a first wireless communication apparatus (for example, a wireless base station BS) perform wireless communication. A first communication unit (donor-side communication unit 110) and a second communication unit (remote-side communication unit 120) that performs wireless communication with a second wireless communication device (for example, a wireless terminal MS), the first wireless communication A wireless relay device (wireless relay device 100) that relays data transmitted and received between a device and the second wireless communication device, wherein the first communication unit performs wireless communication and the second communication An antenna allocation unit that allocates a part of the plurality of antennas to the first communication unit and allocates the remaining antennas to the second communication unit when the time period in which the unit performs wireless communication overlaps Antenna split The difference between the communication quality in wireless communication between the contact unit 141), the first communication unit and the first wireless communication device, and the communication quality in wireless communication between the second communication unit and the second wireless communication device is A determination unit (determination unit 142) that determines whether or not a threshold value has been exceeded, wherein the first communication unit performs wireless communication with the first wireless communication device via the partial antenna, Two communication units execute wireless communication with the second wireless communication device via the remaining antennas, and the antenna allocation unit determines that the difference exceeds the threshold when the determination unit determines that the difference exceeds the threshold value. The gist is to reduce the difference by changing assignment of the plurality of antennas to one communication unit and the second communication unit.

  According to such a radio relay device, the antenna allocation unit allocates some of the plurality of antennas to the first communication unit, and allocates the remaining antennas of the plurality of antennas to the second communication unit. When each of the first communication unit and the second communication unit performs wireless communication in the same time zone, many of the plurality of antennas are simultaneously used for wireless communication, and the use efficiency of the antenna can be improved. .

  The antenna allocating unit reduces the difference by changing the allocation of the plurality of antennas when the difference between the communication quality in the first communication unit and the communication quality in the second communication unit exceeds a threshold value. . Therefore, even if there is a large difference between the communication quality in the first communication unit and the communication quality in the second communication unit, data relay can be continued normally.

A second feature of the present invention is that a plurality of antennas (antennas Ant _{1 to} Ant _N ) arranged at intervals and a first communication that performs wireless communication with a first wireless communication device (for example, a wireless base station BS). Unit (donor side communication unit 110), and a second communication unit (remote side communication unit 120) that performs wireless communication with a second wireless communication device (for example, a wireless terminal MS), and the first wireless communication device A wireless relay device (wireless relay device 100) that relays data transmitted to and received from the second wireless communication device, wherein a time zone during which the first communication unit performs wireless communication and the second communication unit When a time zone for performing wireless communication overlaps, an antenna allocation unit (antenna allocation) that allocates a part of the plurality of antennas to the first communication unit and allocates the remaining antennas to the second communication unit. Part 141) and a determination unit (determination unit 142) that determines whether or not the amount of data held in the buffer (buffer unit 114a, buffer unit 124a) that holds the data until the data relay is completed exceeds a threshold value. The first communication unit performs wireless communication with the first wireless communication device via the partial antenna, and the second communication unit transmits the second wireless communication device via the remaining antenna. The antenna allocation unit allocates the plurality of antennas to the first communication unit and the second communication unit when the determination unit determines that the data retention amount exceeds the threshold value. The gist is to reduce the data holding amount by changing the value.

  According to such a wireless relay device, as in the first feature of the present invention, many of the plurality of antennas are simultaneously used for wireless communication, and the use efficiency of the antennas can be increased. Further, the antenna allocation unit reduces the data retention amount by changing the allocation of the plurality of antennas when the data retention amount in the buffer exceeds the threshold value. Therefore, the buffer can be prevented from overflowing, and data relay can be continued normally.

  A third feature of the present invention relates to the first or second feature of the present invention, wherein the first wireless communication device and the second wireless communication device transmit and receive the data according to a time division duplex method. The antenna allocating unit is configured to perform data transmission from the first wireless communication apparatus to the second wireless communication apparatus in a first time period in which data transmission is performed, and to transmit data from the second wireless communication apparatus to the first wireless communication apparatus. The gist is to change the assignment of the plurality of antennas to the first communication unit and the second communication unit in a non-signal period (TTG, RTG) provided between the second time slot to be executed.

  A fourth feature of the present invention relates to any one of the first to third features of the present invention, wherein the antenna assigning unit communicates from among the plurality of antennas when changing the assignment of the plurality of antennas. When a deteriorated antenna whose quality has deteriorated is detected and the deteriorated antenna is included in the partial antenna, the deteriorated antenna included in the partial antenna is replaced with one of the remaining antennas, and the remaining antenna When the degraded antenna is included in the antenna, the degraded antenna included in the remaining antennas is replaced with one of the partial antennas.

  A fifth feature of the present invention relates to any one of the first to third features of the present invention, wherein the antenna allocating unit changes communication quality in the first communication unit when changing the allocation of the plurality of antennas. Or when the communication quality of the second communication unit has deteriorated, and when it is determined that the communication quality of the first communication unit has deteriorated, at least one of the remaining antennas is connected to the first communication unit. The gist is to assign at least one of the antennas to the second communication unit when it is determined that communication quality is deteriorated in the second communication unit.

  A sixth feature of the present invention relates to any one of the first to fifth features of the present invention, wherein the second communication unit starts wireless communication with the second wireless communication device. Before the wireless communication device starts wireless communication with the first wireless communication device, and the antenna allocating unit starts the wireless communication with the first wireless communication device when the first communication unit starts wireless communication with the first wireless communication device. The communication quality with one wireless communication device is measured for each of the plurality of antennas, and the upper predetermined number of antennas with the high measured communication quality, or the antennas with the measured communication quality exceeding the predetermined value are the part The gist is that the antenna is assigned to the first communication unit.

  A seventh feature of the present invention relates to any one of the first to sixth features of the present invention, wherein the first communication unit transmits a signal sequence using the same frequency band via the partial antenna. A plurality of multi-input / multi-output type wireless communication for simultaneous transmission or reception is executed with the first wireless communication device, and the second communication unit transmits a plurality of signal sequences using the same frequency band via the remaining antennas. The gist of the present invention is to perform multi-input multi-output wireless communication simultaneously with transmission or reception with the second wireless communication device.

  An eighth feature of the present invention relates to any one of the first to seventh features of the present invention, wherein the first communication unit performs a time period for performing wireless communication with the first wireless communication device, and the second communication. The antenna assigning unit assigns the same antenna among the plurality of antennas to the first communication unit and the second communication unit when the unit does not overlap the time zone for performing wireless communication with the second wireless communication device The gist is to assign.

  A ninth feature of the present invention is that a plurality of antennas arranged at intervals, a first communication unit that performs wireless communication with the first wireless communication device, and a first communication unit that performs wireless communication with the second wireless communication device. A wireless relay method used in a wireless relay device that relays data transmitted and received between the first wireless communication device and the second wireless communication device, the first communication portion When the time zone in which wireless communication is performed and the time zone in which the second communication unit performs wireless communication overlap, a part of the plurality of antennas is assigned to the first communication unit, and the remaining Assigning an antenna to the second communication unit, communication quality in wireless communication between the first communication unit and the first wireless communication device, and wireless communication between the second communication unit and the second wireless communication device Difference from communication quality is threshold Determining whether the difference exceeds the threshold in the determining step and changing the allocation of the plurality of antennas to the first communication unit and the second communication unit. The first communication unit performs wireless communication with the first wireless communication device via the partial antenna, and the second communication unit transmits the remaining antenna to the remaining antenna. The gist of the present invention is to perform wireless communication with the second wireless communication device via the network.

  A tenth feature of the present invention is that a plurality of antennas arranged at intervals, a first communication unit that performs wireless communication with the first wireless communication device, and a first communication unit that performs wireless communication with the second wireless communication device. A wireless relay method used in a wireless relay device that relays data transmitted and received between the first wireless communication device and the second wireless communication device, the first communication portion When the time zone in which wireless communication is performed and the time zone in which the second communication unit performs wireless communication overlap, a part of the plurality of antennas is assigned to the first communication unit, and the remaining A step of assigning an antenna to the second communication unit, a step of determining whether or not a data holding amount in a buffer holding the data exceeds a threshold until the data relay is completed, and a step of determining. Reducing the data retention amount by changing allocation of the plurality of antennas to the first communication unit and the second communication unit when it is determined that the data retention amount exceeds the threshold value. The first communication unit performs wireless communication with the first wireless communication device via the partial antenna, and the second communication unit communicates with the second wireless communication device via the remaining antenna. The gist is to execute wireless communication.

  According to the present invention, there is provided a radio relay apparatus capable of normally continuing data relay even when a large difference occurs between the communication quality in the first communication unit and the communication quality in the second communication unit while improving the antenna usage efficiency. A wireless relay method can be provided.

  Next, a first embodiment, a second embodiment, and other embodiments of the present invention will be described with reference to the drawings. In the description of the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

[First Embodiment]
In the first embodiment, (1) a schematic configuration of a wireless communication system, (2) a configuration of a wireless relay device, (3) an operation of the wireless relay device, and (4) actions and effects will be described.

(1) Schematic Configuration of Radio Communication System FIG. 1 is an overall schematic configuration diagram of a radio communication system 10 according to the first embodiment.

  As illustrated in FIG. 1, the radio communication system 10 includes a radio base station BS (first radio communication device), a radio terminal MS (second radio communication device), and a radio relay device 100.

  The radio relay device 100 relays data transmitted and received by the radio base station BS and the radio terminal MS. Thereby, even if the radio terminal MS is located outside the range of the cell which is a communication area formed by the radio base station BS or is located at the end (self-fringing) of the cell, the radio terminal MS passes through the radio relay device 100. Data can be transmitted and received with the radio base station BS.

  Each of the radio base station BS, the radio terminal MS, and the radio relay apparatus 100 has a plurality of antennas, and can transmit and receive data using the plurality of antennas. That is, the radio communication system 10 has introduced a multi-input multi-output (MIMO) radio communication (hereinafter, MIMO communication) technique.

  In the MIMO communication technique, the transmission side converts data to be transmitted into a plurality of streams (signal series), and transmits the plurality of streams simultaneously through a plurality of antennas using the same frequency band. The receiving side receives a plurality of streams in an interference state via a plurality of antennas, and then separates them into each stream. With such a MIMO communication technique, parallel data transmission / reception is possible, and throughput, which is an effective data transfer rate, can be improved. In the MIMO communication technique, the throughput increases as the number of antennas used (or the number of streams) increases.

  In the first embodiment, the wireless communication system 10 has a configuration based on WiMAX (IEEE802.16). For example, the radio communication system 10 employs an orthogonal frequency division multiple access (OFDMA) scheme and a time division duplex (TDD) scheme.

  The OFDMA scheme realizes multiple connections using a number of subcarriers orthogonal to each other. The TDD scheme realizes bidirectional communication by executing uplink UL communication and downlink DL communication in a time division within one communication frame.

(2) Configuration of Radio Relay Device FIG. 2 is a functional block diagram showing the configuration of the radio relay device 100.

As illustrated in FIG. 2, the wireless relay device 100 includes a donor-side communication unit 110, a remote-side communication unit 120 (second communication unit), antennas Ant _{1 to} Ant _N , an antenna connection unit 130, and a connection control unit 140. .

  The donor-side communication unit 110 constitutes a first communication unit that performs radio communication with the radio base station BS (first radio communication device). The remote communication unit 120 configures a second communication unit that performs wireless communication with the wireless terminal MS (second wireless communication device).

  The donor-side communication unit 110 has a communication function equivalent to that of a radio terminal, and the remote-side communication unit 120 has a communication function equivalent to that of a radio base station. The donor-side communication unit 110 and the remote-side communication unit 120 are connected by wire using Ethernet (registered trademark) or the like, and can communicate with each other.

The antennas Ant _{1 to} Ant _N are arranged at intervals, and are connected to the donor-side communication unit 110 and the remote-side communication unit 120 via the antenna connection unit 130. The antenna connection unit 130 includes a plurality of switches, and connects each of the antennas Ant _{1 to} Ant _N to at least one of the donor-side communication unit 110 and the remote-side communication unit 120 under the control of the connection control unit 140. The connection control unit 140 monitors the communication state in each of the donor side communication unit 110 and the remote side communication unit 120 and controls the antenna connection unit 130.

The connection control unit 140 includes an antenna allocation unit 141 and a determination unit 142. The antenna allocating unit 141 is configured such that when the time zone in which the donor-side communication unit 110 executes radio communication with the radio base station BS and the time zone in which the remote-side communication unit 120 executes radio communication with the radio terminal MS overlap, Among Ant _{1 to} Ant _N , some antennas are assigned to the donor-side communication unit 110 and the remaining antennas are assigned to the remote-side communication unit 120. Here, the antenna assigning unit 141 can assign all of the remaining antennas to the remote communication unit 120, but not all of the remaining antennas need to be assigned to the remote communication unit 120.

  The antenna connection unit 130 connects a part of the antennas allocated by the antenna allocation unit 141 to the donor-side communication unit 110 and connects the remaining antennas allocated by the antenna allocation unit 141 to the remote-side communication unit 120.

  The donor-side communication unit 110 can perform MIMO communication with the radio base station BS via some antennas connected by the antenna connection unit 130. The remote communication unit 120 can perform MIMO communication with the radio base station BS via the remaining antennas connected by the antenna connection unit 130.

The determination unit 142 determines whether or not the difference between the communication quality in the wireless communication between the donor-side communication unit 110 and the wireless base station BS and the communication quality in the wireless communication between the remote-side communication unit 120 and the wireless terminal MS exceeds a threshold value. Determine. In the first embodiment, throughput is used as the communication quality to be determined by the determination unit 142. However, the determination unit 142 may determine reception field strength (RSSI), carrier-to-interference noise ratio (CINR), header error rate, or the like instead of the throughput. When the determination unit 142 determines that the difference in throughput exceeds the threshold, the antenna allocation unit 141 changes the allocation of the antennas Ant ₁ to Ant _{N to} the donor-side communication unit 110 and the remote-side communication unit 120.

Donor-side communication unit 110 includes a RF unit ₁₁₁ 1 - 111 _K, the signal processing unit 112, the control unit 113, a storage unit 114 and the I / F section 115.

Each of the RF units 111 _{1 to} 111 _K transmits and receives a radio frequency (RF) signal to and from the radio base station BS using the OFDMA method. Specifically, each of the RF units 111 _{1 to} 111 _K includes an up converter that converts the transmission stream from the signal processing unit 112 to a transmission RF signal, a power amplifier that amplifies the transmission RF signal, and an antenna connection unit. A low-noise amplifier that amplifies the received RF signal from 130, a down converter that converts the frequency of the received RF signal, and the like.

At the time of transmission, the signal processing unit 112 converts the transmission data from the control unit 113 into a plurality of transmission streams, and distributes the transmission streams to the RF units 111 _{1 to} 111 _K. At the time of reception, the signal processing unit 112 separates the received streams from the RF units 111 _{1 to} 111 _K and combines the separated received streams to obtain received data.

  The control unit 113 includes, for example, a CPU and controls various functions provided in the donor-side communication unit 110. The control unit 113 transfers the received data from the signal processing unit 112 to the remote side communication unit 120. The control unit 113 inputs the transmission data transferred from the remote side communication unit 120 to the signal processing unit 112.

  The storage unit 114 includes, for example, a memory, and stores various types of information used for control in the donor-side communication unit 110. The storage unit 114 includes a buffer unit 114a. The buffer unit 114a holds, for example, transmission waiting data in the uplink UL until transmission to the radio base station BS is completed. The I / F unit 115 is connected to the remote communication unit 120.

The remote communication unit 120 includes RF units 121 _{1 to} 121 _L , a signal processing unit 122, a control unit 123, a storage unit 124, and an I / F unit 125. For example, the number L of the RF units 121 _{1 to} 121 _L of the remote communication unit 120 is larger than the number K of the RF units 111 _{1 to} 111 _K of the donor communication unit 110.

Each of the RF units 121 _{1 to} 121 _L transmits and receives an RF signal to and from the radio terminal MS using the OFDMA scheme. Specifically, each of the RF units 121 _{1 to} 121 _L includes an up-converter that converts the transmission stream from the signal processing unit 122 into a transmission RF signal, a power amplifier that amplifies the transmission RF signal, and an antenna connection unit. A low-noise amplifier that amplifies the received RF signal from 130, a down converter that converts the frequency of the received RF signal, and the like.

At the time of transmission, the signal processing unit 122 converts transmission data from the control unit 123 into a plurality of transmission streams, and distributes the transmission streams to the RF units 121 _{1 to} 121 _L. At the time of reception, the signal processing unit 122 separates the received streams from the RF units 121 _{1 to} 121 _L and combines the separated received streams to obtain received data.

  The control unit 123 includes, for example, a CPU and controls various functions provided in the remote side communication unit 120. The control unit 123 transfers the reception data from the signal processing unit 122 to the donor side communication unit 110. The control unit 123 inputs the transmission data transferred from the donor side communication unit 110 to the signal processing unit 122.

  The storage unit 124 is configured by a memory, for example, and stores various types of information used for control in the remote side communication unit 120. The storage unit 124 includes a buffer unit 124a. The buffer unit 124a holds, for example, transmission waiting data in the downlink DL until transmission to the radio terminal MS is completed. The I / F unit 125 is connected to the donor-side communication unit 110.

Number N of antennas _Ant 1 _{~Ant N,} the number of RF unit ₁₁₁ 1 - 111 _K K (or the number K of input and output ports ₁₁₆ 1 -116 _K) and the number of RF unit ₁₂₁ 1 _{~121 L L} (or , The number of the input / output ports 126 _{1 to} 126 _L is less than the sum L). That is,
N <K + L (1)
The relationship holds.

Moreover, when further reducing the number N of antennas _Ant 1 _{~Ant N,} the value of N may be equal to the greater one of K or L. in this case,
N = MAX (K, L) (2)
The relationship holds. However, than the cost savings by reducing the number N of antennas Ant ₁ ~Ant _N, when the improvement of the communication performance is given priority may increase the value of N.

(3) Operation of Radio Relay Device Next, the operation of the radio relay device 100 will be described. Specifically, (3.1) operation flow and (3.2) antenna change timing will be described.

(3.1) Operation Flow FIG. 3 is a flowchart showing an operation flow of the wireless relay device 100 according to the first embodiment.

  First, when the power of the wireless relay device 100 is turned on, network entry processing of the wireless relay device 100 for the wireless base station BS is started.

In step S101, the antenna allocation unit 141 allocates an antenna to the donor-side communication unit 110 from the antennas Ant _{1 to} Ant _N. The antenna allocation unit 141 performs antenna allocation to the donor-side communication unit 110 before antenna allocation to the remote-side communication unit 120. This is because the wireless terminal MS connected to the wireless relay device 100 is not connected to the remote communication unit 120 when the power is turned on, and unless the donor communication unit 110 is connected to the wireless base station BS. This is because cannot communicate with the radio base station BS.

Here, when the number N of antennas _Ant 1 _{~Ant N} is larger than the number K of the RF unit ₁₁₁ 1 - 111 _K of the donor-side communication unit 110, an antenna allocation unit 141, the donor from the antenna _Ant 1 _{~Ant N} An antenna connected to the side communication unit 110 can be selected. In this case, the antenna allocation unit 141 measures the communication quality (for example, RSSI, CINR, or header error rate) with the radio base station BS for each of the antennas Ant ₁ to Ant _N , and the higher predetermined communication quality is high. A number of antennas or antennas whose measured throughput exceeds a predetermined value are assigned to the donor-side communication unit 110. The antenna assigned to the donor side communication unit 110 is connected to the donor side communication unit 110 by the antenna connection unit 130.

  In step S102, the donor-side communication unit 110 executes a network entry to the radio base station BS via the antenna assigned by the antenna assignment unit 141. Thereby, wireless communication between the donor-side communication unit 110 and the wireless base station BS is started.

  However, when the donor communication unit 110 fails in network entry to the radio base station BS in step S102, the antenna allocation unit 141 may reassign the antenna in the same manner as in step S101.

  In step S103, the remote communication unit 120 waits for a network entry from the wireless terminal MS. At that time, the antenna assigning unit 141 assigns at least one antenna to the remote communication unit 120 for network entry from the wireless terminal MS. When there is a network entry request from the wireless terminal MS, network entry processing of the wireless terminal MS for the wireless relay device 100 is started in step S104.

  In step S105, the antenna allocation unit 141 determines whether the antenna use timing of the donor-side communication unit 110 and the antenna use timing of the remote-side communication unit 120 are the same. If they are the same, the process proceeds to step S106, and if they are different, the process proceeds to step S107.

  When the radio base station BS and the radio terminal MS communicate according to the TDD scheme, the antenna use timing of the donor-side communication unit 110 and the antenna use timing of the remote-side communication unit 120 usually overlap. That is, the remote communication unit 120 transmits data to the radio terminal MS at the same time that the donor communication unit 110 receives data from the radio base station BS. The donor-side communication unit 110 transmits data to the radio base station BS at the same time when the remote-side communication unit 120 receives data from the radio terminal MS. However, when operating the transmission / reception timings of the remote communication unit 120 and the donor communication unit 110, the antenna use timing of the donor communication unit 110 is different from the antenna use timing of the remote communication unit 120. Can be made.

In step S <b> 106, the antenna allocation unit 141 allocates an unallocated antenna among the antennas Ant _{1 to} Ant _N to the remote communication unit 120.

On the other hand, in step S107, the antenna assigning unit 141 selects an antenna to be assigned to the remote communication unit 120 from the antennas Ant _{1 to} Ant _N. In step S <b> 107, the antenna assigning unit 141 can assign the antenna assigned to the donor-side communication unit 110 to the remote-side communication unit 120.

  When antennas are assigned to the donor-side communication unit 110 and the remote-side communication unit 120, the radio relay device 100 relays data transmitted and received by the radio base station BS and the radio terminal MS. Here, when there is a difference between the throughput in the donor-side communication unit 110 and the throughput in the remote-side communication unit 120, data buffering occurs in at least one of the donor-side communication unit 110 and the remote-side communication unit 120. If the data holding amount in the buffer unit 114a or the buffer unit 124a exceeds the holdable amount, data loss (that is, overflow) occurs.

  Therefore, in the first embodiment, the determination unit 142 measures and compares the throughput in the donor-side communication unit 110 and the throughput in the remote-side communication unit 120, and the throughput in the donor-side communication unit 110 and the remote-side communication unit 120 It is determined whether or not the difference from the throughput exceeds a threshold value (step S108). If the difference exceeds the threshold, the process proceeds to step S109. If the difference does not exceed the threshold, the process returns to step S108.

In step S109, the difference in throughput is reduced by changing the assignment of the antennas Ant ₁ to Ant _{N to} the donor-side communication unit 110 and the remote-side communication unit 120. As the allocation change process, for example, there is the following method A) or B).

A) The antenna assigning unit 141 detects a deteriorated antenna whose communication quality (in this case, RSSI, CINR, header error rate, feedback from a communication partner, etc.) is deteriorated from the antennas Ant _{1 to} Ant _N. Specifically, the antenna allocation unit 141 measures the communication quality with the radio base station BS for each of the antennas allocated to the donor-side communication unit 110, and each of the antennas allocated to the remote-side communication unit 120. The communication quality with the wireless terminal MS is measured, and an antenna whose communication quality is a predetermined value or less is defined as a degraded antenna.

  If the antenna allocation unit 141 determines that the antenna allocated to the donor-side communication unit 110 includes a degraded antenna, the antenna allocation unit 141 replaces the degraded antenna with one of the antennas allocated to the remote-side communication unit 120. Further, when the antenna allocated to the remote communication unit 120 includes a degraded antenna, the antenna allocation unit 141 replaces the degraded antenna with any of the antennas allocated to the donor communication unit 110.

  B) The antenna allocating unit 141 determines whether communication quality (here, throughput, RSSI, CINR, header error rate, etc.) in the donor-side communication unit 110 has deteriorated or deterioration in the remote-side communication unit 120 has occurred. Specifically, the antenna allocating unit 141 compares the communication quality in each of the donor-side communication unit 110 and the remote-side communication unit 120 with a threshold value, and determines that quality degradation has occurred on the side below the threshold value.

  If it is determined that the communication quality in the donor-side communication unit 110 has deteriorated, the antenna allocating unit 141 allocates at least one of the antennas allocated to the remote-side communication unit 120 to the donor-side communication unit 110, thereby providing donor-side communication. The number of antennas of the unit 110 is increased. At that time, the number of antennas of the remote communication unit 120 may be reduced.

  On the other hand, if it is determined that the communication quality in the remote communication unit 120 has deteriorated, the antenna allocation unit 141 allocates at least one of the antennas allocated to the donor communication unit 110 to the remote communication unit 120, thereby The number of antennas of the side communication unit 120 is increased. At that time, the number of antennas of the donor-side communication unit 110 may be reduced.

  Through the processing of A) or B), the difference in throughput is eliminated. However, when the difference in throughput does not decrease so much due to the antenna change, or conversely increases, the antenna allocating unit 141 determines that the antenna change is not appropriate, and returns to the state before the change, or reassigns. You may perform the process of changing.

  Note that the process of step S105 is not limited to the case where it is executed at the time of network entry of the wireless terminal MS as in this operation flow, and may be executed during the subsequent wireless communication. For example, when the donor side communication unit 110 and the remote side communication unit 120 perform wireless communication at the same time and the donor side communication unit 110 suspends the wireless communication, the antenna allocation unit 141 includes the donor side communication unit 110. Can be assigned to the remote communication unit 120 during the interruption period.

(3.2) Antenna Change Timing Next, the antenna assignment change timing by the antenna assignment unit 141 will be described with reference to FIG. FIG. 4 is a diagram showing a communication frame configuration in WiMAX.

  As shown in FIG. 4, a DL subframe (first time zone) in which DL communication is executed and a UL subframe (second time zone) in which UL communication is executed are provided in a time-sharing manner within one communication frame. It has been.

  The head portion of the DL subframe is an area where various control data is arranged, and thereafter a burst area where a data burst is arranged. The control data includes a preamble which is a known symbol used for establishing and maintaining synchronization, a MAP indicating a data burst arrangement state, and the like.

  A no-signal section (TTG; Transmit Transition Gap, RTG; Receive Transition Gap) is provided between the DL subframe and the UL subframe. TTG functions as a guard time when switching from DL to UL, and RTG functions as a guard time when switching from UL to DL.

  The antenna allocation unit 141 changes the antenna allocation in the no-signal section (TTG, RTG). However, depending on the burst arrangement situation in each of the DL subframe and the UL subframe, the antenna allocation unit 141 may change the antenna allocation in the DL subframe or the UL subframe.

  For example, when the DL bursts # 3 to # 6 shown in FIG. 4 are not used, the state is the same as the no-signal period in the period of the OFDM symbol numbers “k + 11” to “k + 15”. You can change the antenna assignment. In addition, when the antenna switching time of the antenna connection unit 130 due to the change of the antenna assignment is small enough to be regarded as 0, the antenna assignment may be changed during the burst.

  Further, a no-signal section may be intentionally generated using idle processing and scanning processing in WiMAX. The idle process is a process for temporarily interrupting communication. Scanning is a process that can interrupt communication of a communication partner in order to search for a new connection destination.

(4) Operation and Effect As described above, the antenna allocating unit 141 according to the first embodiment is used when the donor-side communication unit 110 and the remote-side communication unit 120 each perform wireless communication in the same time zone. , Some of the antennas Ant _{1 to} Ant _N are allocated to the donor-side communication unit 110, and the remaining antennas of the antennas Ant _{1 to} Ant _N are allocated to the remote-side communication unit 120. As a result, many of the antennas Ant _{1 to} Ant _N are simultaneously used for wireless communication, and the use efficiency of the antenna can be improved.

Further, when the difference between the throughput in the donor-side communication unit 110 and the throughput in the remote-side communication unit 120 exceeds the threshold, the antenna allocation unit 141 changes the allocation of the antennas Ant _{1 to} Ant _N by changing the allocation of the antennas Ant _{1 to} Ant _N Decrease the difference. Therefore, even if there is a large difference between the throughput in the donor-side communication unit 110 and the throughput in the remote-side communication unit 120, data relay can be continued normally.

According to the first embodiment, the antenna allocation unit 141 changes the allocation of the antennas Ant ₁ to Ant _{N to} the donor-side communication unit 110 and the remote-side communication unit 120 in TTG or RTG that is a no-signal section. Therefore, it is possible to prevent an instantaneous interruption of communication due to a change in assignment of the antennas Ant _{1 to} Ant _N.

According to the first embodiment, the antenna allocation unit 141 changes the allocation of the antennas Ant _{1 to} Ant _N by the method of A) or B). In the method A), even when the difference in throughput increases due to deterioration in communication quality in any of the antennas Ant _{1 to} Ant _N , the difference in throughput is reduced by replacing the antenna that causes the quality deterioration. can do. In the method B), it is possible to reduce the difference in throughput by increasing the number of antennas whose throughput is degraded in the donor-side communication unit 110 or the remote-side communication unit 120.

According to the first embodiment, the donor-side communication unit 110 communicates with the radio base station BS before the remote-side communication unit 120 starts radio communication (specifically, network entry) with the radio terminal MS. Start wireless communication. The antenna allocating unit 141 measures the communication quality with the radio base station BS for each of the antennas Ant ₁ to Ant _N when the donor-side communication unit 110 starts radio communication with the radio base station BS. The upper predetermined number of antennas having high communication quality or the antennas whose measured communication quality exceeds a predetermined value are allocated to the donor-side communication unit 110.

  Thereby, the network entry to the radio base station BS can be more reliably executed, and the radio terminal MS connected to the radio relay apparatus 100 can start communication with the radio base station BS at an early stage.

  According to the first embodiment, the donor-side communication unit 110 performs MIMO communication with the radio base station BS, and the remote-side communication unit 120 executes MIMO communication with the radio terminal MS. The data relay speed can be increased, and as a result, the radio base station BS and the radio terminal MS can also realize high-speed communication.

According to the first embodiment, when the time zone in which the donor-side communication unit 110 executes radio communication with the radio base station BS and the time zone in which the remote-side communication unit 120 executes radio communication with the radio terminal MS are different, The antenna assigning unit 141 can assign the same antenna among the antennas Ant _{1 to} Ant _N to the donor-side communication unit 110 and the remote-side communication unit 120. Therefore, the number of antennas Ant ₁ to Ant _N can be reduced as shown in the equation (2). However, the antenna assignment unit 141 does not necessarily have to assign the same antenna to the donor-side communication unit 110 and the remote-side communication unit 120, and can assign different antennas to the donor-side communication unit 110 and the remote-side communication unit 120. .

[Second Embodiment]
In the following second embodiment, differences from the first embodiment will be described. In the first embodiment described above, the determination unit 142 measures and compares the throughput in the donor-side communication unit 110 and the throughput in the remote-side communication unit 120. In the second embodiment, the determination unit 142 measures and compares the data holding amounts in the buffer unit 114a and the buffer unit 124a. The determination unit 142 may use the determination process described in the first embodiment together in the second embodiment.

  As described above, the buffer unit 114a holds, for example, transmission waiting data in the uplink UL until transmission to the radio base station BS is completed. The buffer unit 124a holds, for example, transmission waiting data in the downlink DL until transmission to the radio terminal MS is completed.

  As shown in FIG. 5A, when the data amount IN stored in the buffer unit 114a and the buffer unit 124a is smaller than the read data amount OUT, data is hardly accumulated in the transmission buffer.

  On the other hand, as shown in FIG. 5B, when the data amount IN is larger than the data amount OUT, the data holding amount in the buffer increases. Therefore, the determination unit 142 according to the second embodiment determines whether or not the data retention amount in the buffer unit 114a and the buffer unit 124a exceeds the threshold value TH, and when the data retention amount exceeds the threshold value TH, the antenna allocation unit 141 changes the antenna assignment.

  FIG. 6 is a flowchart showing an operation flow of the wireless relay device 100 according to the second embodiment.

The processes in steps S201 to S207 are executed in the same manner as in the first embodiment. In step S208, the determination unit 142 determines whether the data holding amount in the buffer unit 114a and the buffer unit 124a exceeds the threshold value TH. In step S209, the data holding amount is decreased by changing the assignment of the antennas Ant ₁ to Ant _{N to} the donor-side communication unit 110 and the remote-side communication unit 120. As the assignment changing process, the above method A) or B) can be used. However, when the data retention amount does not decrease so much due to the antenna change, or conversely increases, the antenna allocating unit 141 determines that the antenna change is not appropriate, and returns to the state before the change or reassigns. You may perform the process of changing.

[Other Embodiments]
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

In the embodiment described above, the RF units 111 _{1 to} 111 _K are provided in the donor-side communication unit 110 and the RF units 121 _{1 to} 121 _L are provided in the remote-side communication unit 120. As shown in FIG. The RF units 111 _{1 to} 111 _K and the RF units 121 _{1 to} 121 _L may be provided on the antenna connection unit 130 side.

  In the above-described embodiment, it has been described that the wireless relay device 100 is used in WiMAX. However, the wireless relay device 100 is applicable not only to WiMAX but also to other wireless communication systems such as next-generation PHS.

  In the above-described embodiment, an example in which the radio relay apparatus 100 executes MIMO communication, which is one of the multi-antenna communication techniques, has been described. However, the present invention is not limited to MIMO communication, and other multi-antenna communication techniques may be applied to the radio relay apparatus 100. For example, multi-antenna communication techniques such as space-time coding (STC) and maximum ratio combining (MRC) can be applied to the radio relay apparatus 100.

  In the above-described embodiment, the radio relay apparatus 100 performs data relay between the radio base station BS and the radio terminal MS. However, when two wireless terminals MS communicate with each other, the wireless relay device 100 may relay data transmitted and received between these wireless terminals MS. Alternatively, when a plurality of radio relay apparatuses 100 perform data relay between the radio base station BS and the radio terminal MS, the radio relay apparatus 100 relays data transmitted and received between the other radio relay apparatuses 100. May be.

  Thus, it should be understood that the present invention includes various embodiments and the like not described herein. Therefore, the present invention is limited only by the invention specifying matters in the scope of claims reasonable from this disclosure.

1 is an overall schematic configuration diagram of a radio communication system according to a first embodiment. It is a functional block diagram which shows the structure of the radio relay apparatus which concerns on 1st Embodiment. It is a flowchart which shows the operation | movement flow of the radio relay apparatus which concerns on 1st Embodiment. The timing of the antenna allocation change by the antenna allocation unit according to the first embodiment will be described. It is a conceptual diagram for demonstrating operation | movement of the radio relay apparatus which concerns on 2nd Embodiment. It is a flowchart which shows the operation | movement flow of the radio relay apparatus which concerns on 2nd Embodiment. It is a functional block diagram which shows the structure of the radio relay apparatus which concerns on other embodiment.

Explanation of symbols

BS ... Radio base station, MS ... Radio terminal, 10 ... Radio communication system, 100 ... Radio relay device, 110 ... Donor side communication unit, 112 ... Signal processing unit, 113 ... Control unit, 114 ... Storage unit, 114a ... Buffer unit 115 ... I / F unit, 120 ... remote side communication unit, 122 ... signal processing unit, 123 ... control unit, 124 ... storage unit, 124a ... buffer unit, 125 ... I / F unit, 130 ... antenna connection unit, 140 ... connection control unit, 141 ... antenna allocation unit, 142 ... determination unit, 111 _{1 to} 111 _K ... RF unit, 116 _{1 to} 116 _K ... input / output port, 121 _{1 to} 121 _L ... RF unit, 126 _{1 to} 126 _L ... I / O port

Claims (10)

A plurality of antennas arranged at intervals, a first communication unit that performs wireless communication with the first wireless communication device, and a second communication unit that performs wireless communication with the second wireless communication device, A wireless relay device that relays data transmitted and received between a first wireless communication device and the second wireless communication device,
When the time zone in which the first communication unit performs wireless communication and the time zone in which the second communication unit performs wireless communication overlap, a part of the plurality of antennas is set to the first communication unit. An antenna allocating unit that allocates the remaining antennas to the second communication unit;
Whether or not the difference between the communication quality in wireless communication between the first communication unit and the first wireless communication device and the communication quality in wireless communication between the second communication unit and the second wireless communication device exceeds a threshold value And a determination unit for determining
The first communication unit performs wireless communication with the first wireless communication device via the partial antenna,
The second communication unit performs wireless communication with the second wireless communication device via the remaining antennas,
The antenna allocation unit reduces the difference by changing allocation of the plurality of antennas to the first communication unit and the second communication unit when the determination unit determines that the difference exceeds the threshold value. Wireless relay device to make. A plurality of antennas arranged at intervals, a first communication unit that performs wireless communication with the first wireless communication device, and a second communication unit that performs wireless communication with the second wireless communication device, A wireless relay device that relays data transmitted and received between a first wireless communication device and the second wireless communication device,
When the time zone in which the first communication unit performs wireless communication and the time zone in which the second communication unit performs wireless communication overlap, a part of the plurality of antennas is set to the first communication unit. An antenna allocating unit that allocates the remaining antennas to the second communication unit;
A determination unit that determines whether or not a data holding amount in a buffer that holds the data until the data relay is completed exceeds a threshold;
The first communication unit performs wireless communication with the first wireless communication device via the partial antenna,
The second communication unit performs wireless communication with the second wireless communication device via the remaining antennas,
The antenna allocating unit changes the allocation of the plurality of antennas to the first communication unit and the second communication unit when the determination unit determines that the data retention amount exceeds the threshold value. A wireless relay device that reduces the amount held.   When the first wireless communication device and the second wireless communication device transmit and receive the data according to a time division duplex method, the antenna allocation unit transmits data from the first wireless communication device to the second wireless communication device. In the non-signal period provided between the first time zone in which the data transmission is executed and the second time zone in which data transmission from the second wireless communication device to the first wireless communication device is executed. The wireless relay device according to claim 1 or 2, wherein assignment of the plurality of antennas to the communication unit and the second communication unit is changed. When the antenna allocation unit changes the allocation of the plurality of antennas,
Detecting a deteriorated antenna whose communication quality has deteriorated from the plurality of antennas;
When the degraded antenna is included in the partial antenna, the degraded antenna included in the partial antenna is replaced with any of the remaining antennas,
The radio relay device according to any one of claims 1 to 3, wherein when the remaining antenna includes the degraded antenna, the degraded antenna included in the remaining antenna is replaced with one of the partial antennas. . When the antenna allocation unit changes the allocation of the plurality of antennas,
Determining whether communication quality degradation in the first communication unit or communication quality degradation in the second communication unit has occurred;
If it is determined that communication quality degradation has occurred in the first communication unit, assign at least one of the remaining antennas to the first communication unit;
The wireless relay device according to any one of claims 1 to 3, wherein when it is determined that communication quality has deteriorated in the second communication unit, at least one of the partial antennas is assigned to the second communication unit. . The first communication unit starts wireless communication with the first wireless communication device before the second communication unit starts wireless communication with the second wireless communication device,
The antenna allocation unit measures the communication quality with the first wireless communication device for each of the plurality of antennas when the first communication unit starts wireless communication with the first wireless communication device. The high-order predetermined number of antennas with high measured communication quality or the antennas with the measured communication quality exceeding a predetermined value are assigned to the first communication unit as the partial antennas. The wireless relay device described in 1. The first communication unit performs, with the first wireless communication device, multi-input multiple-output wireless communication that simultaneously transmits or receives a plurality of signal sequences using the same frequency band via the partial antennas,
The said 2nd communication part performs the multi-input multiple-output type radio | wireless communication with the said 2nd radio | wireless communication apparatus which transmits or receives two or more signal sequences which use the same frequency band simultaneously via the said remaining antenna. The wireless relay device according to any one of 1 to 6.   When the time period in which the first communication unit performs wireless communication and the time period in which the second communication unit performs wireless communication do not overlap, the antenna allocating unit assigns the same antenna to the first antenna among the plurality of antennas. The radio relay device according to claim 1, which is assigned to one communication unit and the second communication unit. A plurality of spaced antennas;
A first communication unit that performs wireless communication with the first wireless communication device;
A second communication unit that performs wireless communication with the second wireless communication device;
A wireless relay method used in a wireless relay device that relays data transmitted and received between the first wireless communication device and the second wireless communication device,
When the time zone in which the first communication unit performs wireless communication and the time zone in which the second communication unit performs wireless communication overlap, a part of the plurality of antennas is set to the first communication unit. And assigning the remaining antennas to the second communication unit;
Whether or not the difference between the communication quality in wireless communication between the first communication unit and the first wireless communication device and the communication quality in wireless communication between the second communication unit and the second wireless communication device exceeds a threshold value Determining
A step of reducing the difference by changing an assignment of the plurality of antennas to the first communication unit and the second communication unit when it is determined in the determining step that the difference exceeds the threshold value. ,
The first communication unit performs wireless communication with the first wireless communication device via the partial antenna,
The wireless communication method in which the second communication unit performs wireless communication with the second wireless communication device via the remaining antenna. A plurality of spaced antennas;
A first communication unit that performs wireless communication with the first wireless communication device;
A second communication unit that performs wireless communication with the second wireless communication device;
A wireless relay method used in a wireless relay device that relays data transmitted and received between the first wireless communication device and the second wireless communication device,
When the time zone in which the first communication unit performs wireless communication and the time zone in which the second communication unit performs wireless communication overlap, a part of the plurality of antennas is set to the first communication unit. And assigning the remaining antennas to the second communication unit;
Determining whether the data retention amount in the buffer that retains the data until the relay of the data is completed exceeds a threshold;
When it is determined in the determining step that the data retention amount exceeds the threshold value, the data retention amount is decreased by changing assignment of the plurality of antennas to the first communication unit and the second communication unit. With steps,
The first communication unit performs wireless communication with the first wireless communication device via the partial antenna,
The wireless communication method in which the second communication unit performs wireless communication with the second wireless communication device via the remaining antenna.

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