JP2010130191A - Wireless communication device and wireless communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication device reducing the consumption of wireless communication resources and a giving interference amount while improving throughput in wireless communication, when a modulation system is determined on the basis of wireless quality of each of a plurality of communication channels. <P>SOLUTION: A wireless base station 1A includes: a throughput calculation part 122 for calculating the throughput T(n) in the case of executing the wireless communication using all of the plurality of communication channels and the throughput T(n/2) in the case of executing the wireless communication using some communication channels in the descending order of the wireless quality from the plurality of communication channels; and a wireless communication part 110 for stopping the use of the remaining communication channels excluding the some communication channels from the plurality of communication channels when the throughput T(n/2) exceeds the throughput T(n). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus and a wireless communication method used in a wireless communication system employing adaptive modulation and a multicarrier wireless communication system.

  Conventionally, adaptive modulation is known as one of techniques for improving the throughput in wireless communication. In such adaptive modulation, the radio communication device can transmit more bits per symbol as the radio quality (for example, signal-to-noise interference power ratio (SINR)) in radio communication with the radio communication partner is better. A modulation scheme with high modulation efficiency is used.

  As one of techniques for effectively utilizing limited radio communication resources, multi-carrier radio communication schemes such as orthogonal frequency division multiple access (OFDMA) are known. In the multi-carrier wireless communication system, a wireless communication apparatus can perform wireless communication with a wireless communication partner using a plurality of communication channels (so-called sub-channels) configured using at least one subcarrier. (For example, refer to Patent Document 1).

In a wireless communication system that uses both adaptive modulation and a multicarrier wireless communication system, a plurality of communication channels are allocated based on the wireless quality of each of the plurality of communication channels used for wireless communication between the wireless communication device and the wireless communication partner. A method for determining a modulation scheme to be used has been studied. In such a method, for example, a modulation scheme with higher modulation efficiency is used for wireless communication as the average value of the wireless quality of each of the plurality of communication channels is larger.
Japanese Patent Laid-Open No. 2003-169036

  However, the method for determining the modulation scheme based on the radio quality of each of the plurality of communication channels has the following problems.

  Specifically, if a communication channel with degraded radio quality is included in a plurality of communication channels, a modulation scheme with high modulation efficiency cannot be used due to the influence of the communication channel with degraded radio quality, There was a problem that throughput could not be improved.

  In addition, when such a communication channel with deteriorated wireless quality is used for wireless communication, not only is a wireless communication resource consumed wastefully compared with a case where only a communication channel with good wireless quality is used, but also peripheral wireless There has been a problem that the amount of interference (hereinafter referred to as the amount of interference) given to the wireless communication performed by the communication apparatus becomes large.

  Therefore, the present invention provides a radio that can reduce the amount of radio communication resources consumed and the amount of interference while improving the throughput in radio communication when the modulation scheme is determined based on the radio quality of each of a plurality of communication channels. An object is to provide a communication device and a wireless communication 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, in a wireless communication system (wireless communication system 10) employing adaptive modulation and a multicarrier wireless communication system, a plurality of communication channels are used to communicate with a wireless communication partner (for example, wireless terminal 2A). A wireless communication apparatus (wireless base station 1A) having a wireless communication unit (wireless communication unit 110) that performs wireless communication, wherein the plurality of communication channels and the first modulation based on the wireless quality of each of the plurality of communication channels A throughput calculation unit (throughput calculation unit 122) for calculating a first throughput value (throughput T (n)) indicating a throughput when performing wireless communication using a method, and among the plurality of communication channels, A communication channel selection unit (communication channel selection unit 121) that selects some communication channels in the order of higher radio quality, The throughput calculator is configured to provide a second throughput value (throughput) indicating a throughput when performing the wireless communication using the some communication channels and the second modulation scheme based on the radio quality of each of the some communication channels. T (n / 2)) is calculated, and when the second throughput value exceeds the first throughput value, the wireless communication unit removes the part of the communication channels from the plurality of communication channels. The gist is to stop using the channel and to perform wireless communication using the part of the communication channels and the second modulation scheme.

  According to such a wireless communication device, when the second throughput value exceeds the first throughput value, the wireless communication resource is stopped by stopping the use of the remaining communication channels except for some communication channels with high wireless quality. Consumption and interference can be reduced.

  Further, when the second throughput value exceeds the first throughput value, wireless communication is performed by performing wireless communication using some communication channels and the second modulation scheme having higher modulation efficiency than the first modulation scheme. Throughput can be improved.

  Therefore, according to the wireless communication apparatus according to the first feature, it is possible to provide a wireless communication apparatus that can reduce the consumption of radio communication resources and the amount of interference while improving the throughput in wireless communication.

  A second feature of the present invention relates to the first feature of the present invention, wherein the first modulation scheme is a modulation scheme corresponding to an average value of the radio qualities of each of the plurality of communication channels. The modulation method is a modulation method corresponding to the average value of the radio quality of each of the some communication channels, and the throughput calculation unit is configured to determine the number of communication channels of the plurality of communication channels and 1 in the first modulation method. The result of multiplying the first modulation efficiency, which is the number of bits that can be transmitted per symbol, is calculated as the first throughput value, and the number of communication channels of the part of communication channels and per symbol in the second modulation scheme. In summary, the second throughput value is calculated by multiplying the second modulation efficiency, which is the number of bits that can be transmitted, by the second modulation efficiency.

  A third feature of the present invention relates to the first or second feature of the present invention, and when the second throughput value exceeds the first throughput value, the communication channel selection unit is configured to select the plurality of communication channels. The communication channel selects a smaller number of communication channels than the some communication channels in descending order of the radio quality, and the throughput calculation unit is based on the radio quality of each of the small number of communication channels and the small number of communication channels. When a third throughput value (throughput T (n / 4)) indicating a throughput when performing wireless communication using the third modulation method is calculated, and the third throughput value exceeds the second throughput value, The wireless communication unit stops using the remaining communication channels obtained by removing the small number of communication channels from the plurality of communication channels, and the small number of communication channels. And summarized in that executes wireless communication using a third modulation scheme with.

  A fourth feature of the present invention relates to the third feature of the present invention, wherein the third modulation scheme is a modulation scheme corresponding to an average value of the radio quality of each of the small number of communication channels, and the throughput calculation The unit calculates a result of multiplying the number of communication channels of the small number of communication channels by a third modulation efficiency that is the number of bits that can be transmitted per symbol in the third modulation scheme, as the third throughput value. Is the gist.

  A fifth feature of the present invention relates to any one of the first to third features of the present invention, and when the second throughput value is lower than the first throughput value, the communication channel selector The communication channel selects a larger number of communication channels than the some communication channels in descending order of the radio quality, and the throughput calculation unit is configured to select the plurality of communication channels and the radio of each of the many communication channels. A fourth throughput value (throughput T (3n / 4)) indicating a throughput when performing wireless communication using the fourth modulation method based on quality is calculated, and the fourth throughput value is set to the first throughput value. If so, the wireless communication unit stops using the remaining communication channels excluding the multiple communication channels from the multiple communication channels, and the multiple communication And summarized in that executes wireless communication using said a Yaneru fourth modulation scheme.

  A sixth feature of the present invention relates to the fifth feature of the present invention, wherein the fourth modulation method is a modulation method corresponding to an average value of the radio quality of each of the plurality of communication channels, and the throughput calculation A unit that calculates a result of multiplying the number of communication channels of the plurality of communication channels by a fourth modulation efficiency that is the number of bits that can be transmitted per symbol in the fourth modulation scheme, as the fourth throughput value; Is the gist.

  A seventh feature of the present invention relates to any one of the first to sixth features of the present invention, and is summarized in that the multicarrier wireless communication system is an orthogonal frequency division multiple access system.

  An eighth feature of the present invention is a wireless communication method for performing wireless communication with a wireless communication partner using a plurality of communication channels in a wireless communication system employing adaptive modulation and a multicarrier wireless communication system, Calculating a first throughput value indicating a throughput in the case of performing wireless communication using the communication channel and the first modulation scheme based on the wireless quality of each of the plurality of communication channels (steps S101 and S102); Selecting a part of the communication channels from the plurality of communication channels in descending order of the radio quality (step S103), the radio quality of each of the some communication channels and each of the some communication channels; Calculating a second throughput value indicating the throughput when performing wireless communication using the second modulation scheme based on And when the second throughput value exceeds the first throughput value, the use of the remaining communication channels excluding the part of the communication channels from the plurality of communication channels is stopped. And a step of performing wireless communication using the some communication channels and the second modulation scheme (steps S109 and S110).

  According to the present invention, when a modulation scheme is determined based on radio quality of each of a plurality of communication channels, radio that can reduce radio communication resource consumption and interference amount while improving radio communication throughput. A communication device and a wireless communication method can be provided.

  Next, an embodiment of the present invention will be described with reference to the drawings. Specifically, (1) overall schematic configuration of radio communication system, (2) configuration of radio base station, (3) schematic operation of radio base station, (4) detailed operation of radio base station, (5) action / Effects, (6) Other embodiments will be described. In the description of the drawings in the following embodiments, the same or similar parts are denoted by the same or similar reference numerals.

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

  In the present embodiment, it is assumed that the wireless communication system 10 has a configuration based on the next generation PHS (Personal Handyphone System). The radio communication system 10 employs an OFDMA system and a time division multiple access (TDMA) system as a multiplexing system, and employs a time division duplex (TDD) system as a duplex system.

  In the example of FIG. 1, the radio communication system 10 includes a radio base station 1A, a radio base station 1B, a radio terminal 2A, a radio terminal 2B, and a radio terminal 2C.

  The radio base station 1A assigns a communication channel to the radio terminal 2A in response to an assignment request from the radio terminal 2A located in the cell 3A of the own station, and executes radio communication with the radio terminal 2A using the assigned communication channel. . Similarly, the radio base station 1A allocates a communication channel to the radio terminal 2C, and executes radio communication with the radio terminal 2C using the assigned communication channel. The radio base station 1B allocates a communication channel to the radio terminal 2B located in the cell 3B of the own station, and executes radio communication with the radio terminal 2B using the allocated communication channel.

  The radio base station 1A can assign a plurality of communication channels to the radio terminal 2A and the radio terminal 2C, respectively, and dynamically change the assigned communication channel. The radio base station 1B can allocate a plurality of communication channels to the radio terminal 2B and dynamically change the assigned communication channels.

  In the radio communication system 10, the entire frequency band in the radio communication system 10 is frequency-divided into a subchannels according to the OFDMA scheme, and b times each of uplink and downlink in one frame period of the radio communication system 10 according to the TDMA scheme. Time is divided into slots. As a result, a × b communication channels are configured in each uplink and downlink. Each communication channel configured in this way is called a physical resource unit (PRU) in the next generation PHS.

  The radio communication system 10 employs adaptive modulation. In adaptive modulation, a modulation scheme is defined by a combination of the modulation level and the coding rate. Such a modulation scheme is also called a modulation class or an MCS level. In the wireless communication system 10 adopting adaptive modulation, a plurality of modulation methods are determined in advance, and any one of these modulation methods is used for wireless communication.

  In adaptive modulation, the modulation efficiency, which is the number of bits that can be transmitted per symbol, differs for each modulation scheme. As an example, the modulation efficiency in the modulation scheme combining the modulation multi-level number “256QAM” and the coding rate “7/8” is 7. The modulation efficiency in the modulation scheme combining the modulation multi-level number “16QAM” and the coding rate “1/2” is 2. The modulation efficiency in the modulation scheme combining the modulation multi-level number “BPSK” and the coding rate “1/2” is 0.5. The higher the modulation efficiency, the higher the communication speed but the lower the error tolerance. The lower the modulation efficiency, the higher the error tolerance but the lower the communication speed.

  The radio base station 1A acquires the radio quality of each of the plurality of communication channels assigned to the radio terminal 2A, and obtains an average value of these radio qualities (hereinafter, quality average value) and a threshold provided for each modulation scheme. By comparing, a modulation scheme to be applied to the plurality of communication channels is selected. In the present embodiment, SINR is used as the radio quality. Similarly, the radio base station 1A uses a modulation scheme corresponding to an average quality value (for example, average SINR) of a plurality of communication channels assigned to the radio terminal 2C for radio communication with the radio terminal 2C. The radio base station 1B uses a modulation scheme corresponding to the quality average value of a plurality of communication channels assigned to the radio terminal 2B for radio communication with the radio terminal 2B.

  Further, the wireless communication system 10 employs an autonomous distributed cell configuration. Specifically, the radio base station 1A receives a radio signal transmitted by the radio base station 1B, thereby determining a communication channel to which the radio base station 1B is assigned, and communication in which the radio base station 1B is not assigned. Channels are assigned to the wireless terminal 2A and the wireless terminal 2C. Similarly, the radio base station 1B receives a radio signal transmitted from the radio base station 1A, thereby determining a communication channel that is assigned by the radio base station 1A, and selects a communication channel that is not assigned by the radio base station 1A. Assigned to the wireless terminal 2B. Such processing is called carrier sense in the next generation PHS, and interference between the radio base station 1A and the radio base station 1B can be independently avoided.

  In the following description of the embodiment, mainly wireless communication between the wireless base station 1A and the wireless terminal 2A will be described. In this embodiment, the radio base station 1A constitutes a radio communication device that performs radio communication with the radio terminal 2A (radio communication partner) using a plurality of communication channels.

(2) Configuration of Radio Base Station FIG. 2 is a block diagram showing the configuration of the radio base station 1A according to the embodiment of the radio communication apparatus of the present invention.

  As illustrated in FIG. 2, the radio base station 1A includes an antenna unit 101, a radio communication unit 110, a control unit 120, a wired communication unit 130, and a storage unit 140.

  The wireless communication unit 110 transmits and receives wireless signals to and from the wireless terminal 2A via the antenna unit 101. The antenna unit 101 may be an adaptive array antenna configured using a plurality of antennas. The control unit 120 is constituted by a CPU, for example, and controls various functions provided in the radio base station 1A. The storage unit 140 is configured by a memory, for example, and stores various types of information used for control and the like in the radio base station 1A. The wired communication unit 130 functions as an interface with a wired communication network.

  Specifically, the wireless communication unit 110 includes a wireless signal transmission unit 111, a wireless signal reception unit 112, a signal processing unit 113, and a wireless quality acquisition unit 114.

  The signal processing unit 113 encodes data to be transmitted to the wireless terminal 2A according to a modulation scheme selected based on adaptive modulation, and modulates the encoded data. The signal processing unit 113 performs serial / parallel conversion and inverse fast Fourier transform (IFFT) on the modulated data. The OFDM signal generated in this way is input to the radio signal transmission unit 111. The radio signal transmission unit 111 includes a power amplifier, an up converter, and the like, converts the input OFDM signal into a radio signal, and transmits the radio signal to the radio terminal 2A.

  The radio signal receiving unit 112 includes a low noise amplifier, a down converter, and the like, converts the radio signal received from the radio terminal 2A into an OFDM signal, and inputs the OFDM signal to the signal processing unit 113. The signal processing unit 113 performs fast Fourier transform (FFT) and parallel / serial conversion on the OFDM signal, and then performs demodulation and decoding according to the modulation scheme selected based on adaptive modulation.

  The radio quality acquisition unit 114 acquires the radio quality of each of the n communication channels assigned to the radio terminal 2A (n ≧ 2). For example, the radio quality acquisition unit 114 may measure the radio quality for each of the n communication channels based on the radio signal received from the radio terminal 2A. Alternatively, the radio quality acquisition unit 114 may acquire the radio quality of each of the n communication channels based on feedback from the radio terminal 2A.

  The control unit 120 includes a communication channel selection unit 121, a throughput calculation unit 122, a throughput comparison unit 123, a communication channel management unit 124, and a modulation scheme selection unit 125.

  The communication channel selection unit 121 selects some communication channels in descending order of the radio quality acquired by the radio quality acquisition unit 114 from the n communication channels assigned to the radio terminal 2A. The communication channel selection unit 121 selects, for example, the upper half (n / 2) communication channels with high radio quality from n communication channels. Here, n / 2 means that n is divided by 2 to be the smallest integer equal to or greater than that value.

  Throughput calculation unit 122 is based on the wireless quality acquired by wireless quality acquisition unit 114, and throughput when wireless communication using all n communication channels allocated to wireless terminal 2A is performed with wireless terminal 2A. T (n) and a throughput T (n / 2) when performing wireless communication using the n / 2 communication channels selected by the communication channel selection unit 121 with the wireless terminal 2A are calculated.

  As described above, if a communication channel with degraded radio quality is included in n communication channels, a modulation scheme with high modulation efficiency cannot be used due to the influence of the communication channel with degraded radio quality. The throughput cannot be improved. On the other hand, a modulation scheme with high modulation efficiency can be used for n / 2 communication channels selected in descending order of radio quality, and throughput can be improved. Therefore, the throughput T (n / 2) when only n / 2 communication channels selected in order of higher radio quality are used than the throughput T (n) when all n communication channels are used. Can be expensive.

  The throughput comparison unit 123 compares the throughput T (n) and the throughput T (n / 2) calculated by the throughput calculation unit 122.

  The communication channel management unit 124 has a function of assigning a communication channel to the wireless terminal 2A, a function of managing the assigned communication channel, and a function of releasing the assigned communication channel. Specifically, the communication channel management unit 124 stores the communication channel allocation information in the storage unit 140 and updates the allocation information as necessary.

  The communication channel management unit 124 changes the communication channel assignment for the wireless terminal 2 </ b> A according to the comparison result in the throughput comparison unit 123. Specifically, when the throughput T (n / 2) exceeds the throughput T (n), the communication channel management unit 124 selects n communication channels assigned to the wireless terminal 2A in descending order of radio quality. Release the remaining communication channels except for the n / 2 communication channels.

  In the following, n / 2 communication channels selected in descending order of radio quality are referred to as upper n / 2 communication channels, and the remaining communication channels excluding the upper n / 2 communication channels are referred to as lower n / Called 2 communication channels.

  The modulation scheme selection unit 125 selects a modulation scheme corresponding to the quality average value of each communication channel assigned to the wireless terminal 2A. Specifically, the threshold value and the modulation efficiency for each modulation method are stored in the storage unit 140, and the modulation method selection unit 125 selects the modulation method by comparing the quality average value with the threshold value.

  When the lower n / 2 communication channels are released by the communication channel management unit 124, the wireless communication unit 110 stops using the lower n / 2 communication channels and uses the upper n / 2 communication channels. Wireless communication with the wireless terminal 2A.

  In addition, when the lower n / 2 communication channels are released by the communication channel management unit 124, the modulation scheme selection unit 125 selects a modulation scheme corresponding to the quality average value of the upper n / 2 communication channels. The wireless communication unit 110 performs wireless communication with the wireless terminal 2A using a modulation scheme corresponding to the quality average value of the upper n / 2 communication channels.

(3) Schematic Operation of Radio Base Station FIG. 3 is a diagram for explaining the schematic operation of the radio base station 1A.

  As shown in FIG. 3A, the communication channel management unit 124 is assumed to allocate eight communication channels U1 to U8 to the wireless terminal 2A in response to an allocation request from the wireless terminal 2A, for example. Here, it is assumed that the radio quality of the four communication channels U5 to U8 among the eight communication channels U1 to U8 is deteriorated, and the radio quality of the communication channels U1 and U2 is outstanding and good.

  The throughput calculation unit 122 performs throughput T (8) in the case where wireless communication using all of the eight communication channels U1 to U8 assigned to the wireless terminal 2A is performed with the wireless terminal 2A, and the upper four communications. A throughput T (4) when wireless communication using channels U1 to U4 is executed with the wireless terminal 2A is calculated. The throughput comparison unit 123 compares the throughput T (8) and the throughput T (4) calculated by the throughput calculation unit 122. In this operation example, it is assumed that the throughput T (4) exceeds the throughput T (8).

  As shown in FIG. 3B, the communication channel management unit 124 releases the lower four communication channels U5 to U8 among the eight communication channels U1 to U8 assigned to the wireless terminal 2A. As a result, the wireless communication unit 110 stops using the lower four communication channels U5 to U8 and performs wireless communication using the upper four communication channels U1 to U4 with the wireless terminal 2A. In addition, the wireless communication unit 110 performs wireless communication with the wireless terminal 2A using a modulation scheme corresponding to the quality average values of the upper four communication channels U1 to U4.

  When the throughput T (4) exceeds the throughput T (8), processing for further reducing the number of communication channels may be performed. That is, the throughput calculation unit 122 uses the throughput T (4) when wireless communication using the upper four communication channels U1 to U4 is performed with the wireless terminal 2A, and the upper two communication channels U1 and U2. A throughput T (2) in the case of executing wireless communication with the wireless terminal 2A is calculated. The throughput comparison unit 123 compares the throughput T (4) and the throughput T (2) calculated by the throughput calculation unit 122. In this operation example, it is assumed that the throughput T (2) exceeds the throughput T (4).

  In this case, the communication channel management unit 124 releases the lower six communication channels U3 to U8 among the eight communication channels U1 to U8 assigned to the wireless terminal 2A. Then, the wireless communication unit 110 stops using the lower six communication channels U3 to U8, and performs wireless communication using the upper two communication channels U1 and U2 with the wireless terminal 2A. In addition, the wireless communication unit 110 performs wireless communication with the wireless terminal 2A using a modulation scheme corresponding to the quality average value of the upper two communication channels U1 and U2.

(4) Detailed Operation of Radio Base Station FIG. 4 is a flowchart showing detailed operation of the radio base station 1A.

  In step S101, the throughput calculator 122 calculates an average quality value of n communication channels in order to calculate the throughput T (n). In step S102, the throughput calculation unit 122 calculates a multiplication result of the modulation efficiency (n) corresponding to the average quality value of n communication channels and n as the throughput T (n).

  In steps S103 and S104, the throughput calculator 122 calculates an average quality value of the upper n / 2 communication channels in order to calculate the throughput T (n / 2). In step S104, the throughput calculation unit 122 sets the multiplication result of the modulation efficiency (n / 2) corresponding to the average quality value of the upper n / 2 communication channels and n / 2 as the throughput T (n / 2). calculate.

  In step S105, the throughput comparison unit 123 compares the throughput T (n) and the throughput T (n / 2) calculated by the throughput calculation unit 122. If the throughput T (n / 2) exceeds the throughput T (n), the process proceeds to step S106. If the throughput T (n / 2) is lower than the throughput T (n), the process proceeds to step S111.

  In step S106, the throughput calculator 122 calculates the average quality value of the upper n / 4 communication channels in order to calculate the throughput T (n / 4). In step S107, the throughput calculator 122 sets the multiplication result of the modulation efficiency (n / 4) corresponding to the average quality value of the upper n / 4 communication channels and n / 4 as the throughput T (n / 4). calculate.

  In step S108, the throughput comparison unit 123 compares the throughput T (n / 2) and the throughput T (n / 4) calculated by the throughput calculation unit 122. If the throughput T (n / 2) exceeds the throughput T (n / 4), the process proceeds to step S109.

  When the throughput T (n / 2) is lower than the throughput T (n / 4), the same processing as steps S106 to S108 is repeated. For example, the throughput T (n / 8) when performing wireless communication using the upper n / 8 communication channels is calculated, and the comparison between the throughput T (n / 4) and the throughput T (n / 8) is performed. Done.

  In step S109, the communication channel management unit 124 releases the lower n / 2 communication channels among the n communication channels allocated to the wireless terminal 2A. As a result, the wireless communication unit 110 stops using the lower n / 2 communication channels and performs wireless communication using the upper n / 2 communication channels with the wireless terminal 2A. In step S110, the modulation scheme selection unit 125 selects the modulation scheme (n / 2) of the modulation efficiency (n / 2). Note that the process of step S110 may be executed before the process of step S109 or simultaneously with the process of step S109.

  On the other hand, in step S111, the throughput calculator 122 calculates the average quality value of the upper 3n / 4 communication channels in order to calculate the throughput T (3n / 4). In step S112, the throughput calculation unit 122 sets the multiplication result of the modulation efficiency (3n / 4) corresponding to the average quality value of the upper 3n / 4 communication channels and 3n / 4 as the throughput T (3n / 4). calculate.

  In step S113, the throughput comparison unit 123 compares the throughput T (n) calculated by the throughput calculation unit 122 and the throughput T (3n / 4). If the throughput T (n) exceeds the throughput T (3n / 4), the process proceeds to step S116. On the other hand, when the throughput T (n) is lower than the throughput T (3n / 4), the process proceeds to step S114.

  In step S114, the communication channel management unit 124 releases the lower n / 4 communication channels among the n communication channels allocated to the wireless terminal 2A. As a result, the wireless communication unit 110 stops using the lower n / 4 communication channels and executes wireless communication using the upper 3n / 4 communication channels with the wireless terminal 2A. In step S115, the modulation scheme selection unit 125 selects the modulation scheme (3n / 4) of the modulation efficiency (3n / 4). Note that the process of step S115 may be executed before the process of step S114 or simultaneously with the process of step S114.

  In step S116, the communication channel cannot be reduced, and the modulation scheme selection unit 125 selects the modulation scheme (n) with the modulation efficiency (n) as in the conventional case.

(5) Operation / Effect As described above, when the throughput T (n / 2) exceeds the throughput T (n), the radio base station 1A performs communication with the lower n / 2 in the radio communication with the radio terminal 2A. By stopping the use of the channel and using the modulation scheme (n / 2) with the modulation efficiency (n / 2), it is possible to improve the throughput and reduce the consumption of radio communication resources and the amount of interference.

  In particular, in the autonomous distributed wireless communication system 10, the wireless base station 1 </ b> A can stop using the lower n / 2 communication channels, thereby increasing the number of communication channels that can be allocated by the wireless base station 1 </ b> B. . Alternatively, the radio base station 1A may assign the lower n / 2 communication channels whose use has been stopped to the radio terminal 2C as necessary.

  In the present embodiment, the radio base station 1A calculates the multiplication result of the modulation efficiency (n) and n as the throughput T (n), and calculates the multiplication result of the modulation efficiency (n / 2) and n as the throughput T (n / 2). For this reason, a pseudo throughput can be obtained by calculation without actually measuring the throughput. For this reason, the throughput T (n) and the throughput T (n / 2) can be obtained without interrupting normal wireless communication.

  In the present embodiment, when the throughput T (n / 4) exceeds the throughput T (n / 2), the radio base station 1A stops using the lower 3n / 4 communication channel and modulates the modulation efficiency (n / 4). The modulation method (n / 4) is used. Thereby, it is possible to further reduce the amount of radio communication resource consumption and the amount of interference while improving the throughput.

  At that time, the radio base station 1A calculates the multiplication result of the modulation efficiency (n / 4) and n / 4 as the throughput T (n / 4). For this reason, the throughput T (n / 4) can be obtained without interrupting normal wireless communication.

  In the present embodiment, when the throughput T (3n / 4) exceeds the throughput T (n), the radio base station 1A stops using the communication channel of the lower n / 4 and modulates the modulation efficiency (3n / 4). The method (3n / 4) is used. Thereby, it is possible to reduce the amount of radio communication resource consumption and the amount of interference while improving the throughput.

  At that time, the radio base station 1A calculates the multiplication result of the modulation efficiency (3n / 4) and 3n / 4 as the throughput T (3n / 4). For this reason, the throughput T (3n / 4) can be obtained without interrupting normal wireless communication.

(6) Other Embodiments As described above, the present invention has been described according to the embodiment. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the above-described embodiment, an example in which the operation flow in FIG. 4 is executed in the radio base station 1A has been described. However, the present invention is not limited to this, and the operation flow in FIG. Further, in the operation flow of FIG. 4, in steps S103 and S104, the throughput (n / 2) when the upper n / 2 communication channels are used is calculated. However, the throughput is not limited to the upper n / 2. The throughput in the case of using the upper fixed number (for example, the upper two) or the upper n / 4 communication channels may be calculated.

  In the above-described embodiments, SINR is used as a measure of radio quality. However, the present invention is not limited to SINR, and the signal to noise power ratio (SNR), the signal to interference power ratio (SIR), or the received signal strength (RSSI). Etc. may be used.

  In the above-described embodiment, the radio communication system 10 has a configuration based on the next generation PHS. However, the present invention can be applied not only to the next generation PHS but also to other radio communication systems employing adaptive modulation and OFDMA. It is. In addition to OFDMA, other multicarrier communication schemes may be applied.

  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 wireless communication system including a wireless base station according to an embodiment of a wireless communication apparatus of the present invention. It is a block diagram which shows the structure of the radio base station which concerns on embodiment of the radio | wireless communication apparatus of this invention. It is a figure for demonstrating schematic operation | movement of the radio base station which concerns on embodiment of the radio | wireless communication apparatus of this invention. It is a flowchart which shows detailed operation | movement of the radio base station which concerns on embodiment of the radio | wireless communication apparatus of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1A, 1B ... Wireless base station, 2A, 2B, 2C ... Wireless terminal, 3A, 3B ... Cell, 10 ... Wireless communication system, 101 ... Antenna part, 110 ... Wireless communication part, 111 ... Wireless signal transmission part, 112 ... Wireless Signal receiving unit 113 ... Signal processing unit 114 ... Radio quality acquisition unit 120 ... Control unit 121 ... Communication channel selection unit 122 ... Throughput calculation unit 123 ... Throughput comparison unit 124 ... Communication channel management unit 125 ... Modulation method selection unit, 130 ... wired communication unit, 140 ... storage unit

Claims (8)

In a wireless communication system employing adaptive modulation and a multi-carrier wireless communication system, a wireless communication device having a wireless communication unit that performs wireless communication with a wireless communication partner using a plurality of communication channels,
A throughput calculator that calculates a first throughput value indicating a throughput when performing wireless communication using the plurality of communication channels and a first modulation scheme based on the radio quality of each of the plurality of communication channels;
A communication channel selection unit that selects a part of the communication channels from the plurality of communication channels in descending order of the radio quality;
The throughput calculation unit calculates a second throughput value indicating a throughput when performing wireless communication using the some communication channels and a second modulation scheme based on the radio quality of each of the some communication channels. Calculate
When the second throughput value is greater than the first throughput value, the wireless communication unit stops using the remaining communication channels excluding the some communication channels from the plurality of communication channels, and A wireless communication apparatus that performs wireless communication using a communication channel and the second modulation method. The first modulation scheme is a modulation scheme corresponding to an average value of the radio quality of each of the plurality of communication channels;
The second modulation scheme is a modulation scheme corresponding to an average value of the radio quality of each of the some communication channels,
The throughput calculator is
The result of multiplying the number of communication channels of the plurality of communication channels by the first modulation efficiency, which is the number of bits that can be transmitted per symbol in the first modulation scheme, is calculated as the first throughput value,
2. The result obtained by multiplying the number of communication channels of the part of communication channels by a second modulation efficiency that is the number of bits that can be transmitted per symbol in the second modulation scheme is calculated as the second throughput value. A wireless communication device according to 1. When the second throughput value is higher than the first throughput value, the communication channel selection unit selects a smaller number of communication channels than the some communication channels in the descending order of the radio quality from the plurality of communication channels. Selected,
The throughput calculation unit calculates a third throughput value indicating a throughput when performing wireless communication using the small number of communication channels and a third modulation scheme based on the wireless quality of each of the small number of communication channels. ,
When the third throughput value exceeds the second throughput value, the wireless communication unit stops using the remaining communication channels except for the small number of communication channels from the plurality of communication channels, and the small number of communication channels. The wireless communication apparatus according to claim 1 or 2, wherein wireless communication using the third modulation scheme is performed. The third modulation scheme is a modulation scheme corresponding to an average value of the radio quality of each of the small number of communication channels,
The throughput calculating unit multiplies the number of communication channels of the small number of communication channels by a third modulation efficiency that is the number of bits that can be transmitted per symbol in the third modulation scheme, as the third throughput value. The wireless communication apparatus according to claim 3, wherein the wireless communication apparatus calculates the wireless communication apparatus. When the second throughput value is lower than the first throughput value, the communication channel selection unit selects a plurality of communication channels from the plurality of communication channels in order of higher radio quality than the some communication channels. Selected,
The throughput calculation unit calculates a fourth throughput value indicating a throughput when performing wireless communication using the multiple communication channels and a fourth modulation scheme based on the wireless quality of each of the multiple communication channels. ,
When the fourth throughput value exceeds the first throughput value, the wireless communication unit stops using the remaining communication channels except for the multiple communication channels from the multiple communication channels, and the multiple communication channels The wireless communication device according to any one of claims 1 to 3, wherein wireless communication is performed using the fourth modulation method. The fourth modulation scheme is a modulation scheme corresponding to an average value of the radio quality of each of the multiple communication channels,
The throughput calculation unit multiplies the number of communication channels of the plurality of communication channels by a fourth modulation efficiency that is the number of bits that can be transmitted per symbol in the fourth modulation scheme as the fourth throughput value. 6. The wireless communication device according to claim 5, wherein the wireless communication device calculates the wireless communication device.   The wireless communication apparatus according to claim 1, wherein the multicarrier wireless communication system is an orthogonal frequency division multiple access system. In a wireless communication system adopting adaptive modulation and a multicarrier wireless communication system, a wireless communication method for performing wireless communication with a wireless communication partner using a plurality of communication channels,
Calculating a first throughput value indicating a throughput when performing wireless communication using the plurality of communication channels and a first modulation scheme based on an average value of radio quality of each of the plurality of communication channels;
Selecting some communication channels from the plurality of communication channels in descending order of the radio quality;
Calculating a second throughput value indicating a throughput when performing the wireless communication using the partial communication channel and the second modulation scheme based on the average value of the wireless quality of each of the partial communication channels. When,
When the second throughput value exceeds the first throughput value, the use of the remaining communication channels excluding the some communication channels from the plurality of communication channels is stopped, and the some communication channels and the first And a step of executing wireless communication using a two-modulation method.

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