JP2007150906A - Base station, wireless communication terminal, and wireless communication system - Google Patents

Base station, wireless communication terminal, and wireless communication system Download PDF

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JP2007150906A
JP2007150906A JP2005344677A JP2005344677A JP2007150906A JP 2007150906 A JP2007150906 A JP 2007150906A JP 2005344677 A JP2005344677 A JP 2005344677A JP 2005344677 A JP2005344677 A JP 2005344677A JP 2007150906 A JP2007150906 A JP 2007150906A
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Hiroyuki Shoji
裕之 庄司
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Kyocera Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To raise throughput by effectively preventing degradation of an error rate characteristic even under a communication environment with phasing generated therein in a wireless communication system with an adaptive modulation system adopted thereto. <P>SOLUTION: A base station comprises a calculating part for calculating change between training signals included in a transmission signal; a line quality acquiring part for acquiring line quality information from the transmission signal; a line quality information correcting part for correcting the line quality information, based on the calculation result of the calculating part; and a modulation system determining part for determining the modulation system at the side of a wireless communication terminal, based on the line quality information corrected by the line quality information correcting part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、基地局、無線通信端末及び無線通信システムに関する。   The present invention relates to a base station, a wireless communication terminal, and a wireless communication system.

近年の無線通信システムにおいては、データ通信の高速化・大容量化への要求に対する解決手段の一つとして、複数の変調方式を用意し、回線品質に応じて変調方式を切換える適応変調方式が用いられている。複数の変調方式としてはビットレートの異なるものが用いられ、例えばビットレートの低いものから順に、BPSK（Binary Phase Shift keying）、QPSK（Quadrature Phase Shift keying）、16QAM(16 Quadrature Amplitude Modulation）、64QAM(64Quadrature Amplitude Modulation)等の変調方式が用いられている。  In recent wireless communication systems, as one of the solutions to the demand for higher speed and larger capacity of data communication, an adaptive modulation method is used in which multiple modulation methods are prepared and the modulation method is switched according to the line quality. It has been. A plurality of modulation schemes having different bit rates are used. For example, BPSK (Binary Phase Shift keying), QPSK (Quadrature Phase Shift keying), 16QAM (16 Quadrature Amplitude Modulation), 64QAM ( A modulation scheme such as 64 Quadrature Amplitude Modulation is used.

このような適応変調方式では、基地局と無線通信端末との間の回線品質情報であるSNR（信号対雑音比：Signal to Noise Ratio）やCNR（搬送波対雑音比：Carrier to Noise Ratio）等を基に、ダウンリンク（下り方向）及びアップリンク（上り方向）の変調方式を適宜変更している。より具体的には、回線品質が良好な場合はビットレートの高い変調方式に切換えてデータ伝送速度を速くし、回線品質が悪い場合はビットレートの低い変調方式に切換えてデータ伝送速度を遅くすることにより、データ伝送速度の最適化を図ると共に、通信に最低限要求される誤り率（フレーム誤り率やビット誤り率等）を確保可能な変調方式を決定している。
例えば、特開２００３−３４７９８０号公報には、上記のような回線品質情報を基に、基地局側の送信ダイバーシチの切替タイミングを制御して回線品質の劣化を低減する技術が開示されている。
特開２００３−３４７９８０号公報 In such an adaptive modulation system, SNR (Signal to Noise Ratio), CNR (Carrier to Noise Ratio), etc., which are channel quality information between a base station and a wireless communication terminal, are used. Based on this, the downlink (downlink) and uplink (uplink) modulation schemes are appropriately changed. More specifically, when the line quality is good, the data transmission rate is increased by switching to a modulation method with a higher bit rate, and when the line quality is poor, the data transmission rate is decreased by switching to a modulation method with a lower bit rate. As a result, the data transmission rate is optimized, and a modulation scheme capable of ensuring an error rate (frame error rate, bit error rate, etc.) required for communication at the minimum is determined.
For example, Japanese Patent Application Laid-Open No. 2003-347980 discloses a technique for reducing deterioration in channel quality by controlling transmission diversity switching timing on the base station side based on the channel quality information as described above.
JP 2003-347980 A

ところで、このような適応変調方式において、ユーザが高速で移動している等、通信環境の変動が激しい場合、フェージングの影響によりSNR等の回線品質情報が変動してしまい、通信環境に応じた最適な変調方式を選択することができず、その結果、誤り率特性の劣化が生じてスループットが低下するという問題があった。  By the way, in such an adaptive modulation system, when the communication environment is severely changed such as when the user is moving at high speed, the line quality information such as SNR fluctuates due to the fading, and the optimum according to the communication environment. As a result, there is a problem that the error rate characteristic is deteriorated and the throughput is lowered.

本発明は、上述した事情に鑑みてなされたものであり、適応変調方式が採用された無線通信システムにおいて、フェージングが発生する通信環境下であっても、誤り率特性の劣化を効果的に防止してスループットの向上を実現することを目的とする。  The present invention has been made in view of the above-described circumstances, and in a wireless communication system employing an adaptive modulation scheme, it is possible to effectively prevent deterioration of error rate characteristics even in a communication environment in which fading occurs. Thus, it is an object to improve the throughput.

上記目的を達成するために、本発明では、基地局に係る第１の解決手段として、送信信号に含まれるトレーニング信号間の変化を算出する算出部と、前記送信信号から回線品質情報を取得する回線品質取得部と、前記算出部の算出結果に基づいて前記回線品質情報を補正する回線品質情報補正部と、当該回線品質情報補正部にて補正された回線品質情報に基づいて無線通信端末側の変調方式を決定する変調方式決定部とを具備する、という手段を採用する。  In order to achieve the above object, in the present invention, as a first solving means related to a base station, a calculation unit that calculates a change between training signals included in a transmission signal, and channel quality information is acquired from the transmission signal A channel quality acquisition unit; a channel quality information correction unit that corrects the channel quality information based on a calculation result of the calculation unit; and a wireless communication terminal side based on the channel quality information corrected by the channel quality information correction unit And a modulation method determining unit that determines the modulation method.

また、本発明では、基地局に係る第２の解決手段として、上記第１の解決手段において、前記回線品質情報補正部は、前記トレーニング信号間の位相回転量に基づく補正値を前記回線品質情報に乗算することで当該回線品質情報を補正することを特徴とする。  Also, in the present invention, as a second solving means relating to a base station, in the first solving means, the line quality information correction unit sets a correction value based on a phase rotation amount between the training signals to the line quality information. The channel quality information is corrected by multiplying by.

また、本発明では、基地局に係る第３の解決手段として、上記第２の解決手段において、前記回線品質情報補正部は、位相回転量に応じた前記補正値をテーブルとして予め記憶しており、当該テーブルから前記補正値を読み出して前記回線品質情報に乗算することで当該回線品質情報を補正することを特徴とする。   Further, in the present invention, as the third solving means relating to the base station, in the second solving means, the line quality information correction unit stores the correction value according to the phase rotation amount as a table in advance. The channel quality information is corrected by reading the correction value from the table and multiplying the channel quality information.

また、本発明では、基地局に係る第４の解決手段として、上記第１の解決手段において、前記算出部は、前記トレーニング信号間のベクトル変化量を算出し、前記送信信号のシンボル座標における隣接するシンボル間の距離を算出し、前記回線品質取得部は、前記シンボル間の距離の２乗を前記ベクトル変化量の２乗で除算した値を補正値として算出する
ことを特徴とする。 Further, in the present invention, as a fourth solving means related to the base station, in the first solving means, the calculation unit calculates a vector change amount between the training signals, and is adjacent to a symbol coordinate of the transmission signal. The distance between symbols to be calculated is calculated, and the channel quality acquisition unit calculates a value obtained by dividing the square of the distance between the symbols by the square of the vector change amount as a correction value.

また、本発明では、基地局に係る第５の解決手段として、上記第１〜４のいずれかの解決手段において、前記回線品質情報は、信号または搬送波と雑音との比、もしくは信号または搬送波と干渉波を含む雑音との比であることを特徴とする。  Further, in the present invention, as a fifth solving means relating to the base station, in any one of the first to fourth solving means, the channel quality information is a ratio of a signal or carrier wave to noise, or a signal or carrier wave. It is characterized by a ratio to noise including interference waves.

一方、本発明では、無線通信端末に係る第１の解決手段として、受信信号に含まれるトレーニング信号間の変化を算出する算出部と、前記受信信号から回線品質情報を取得する回線品質取得部と、前記算出部の算出結果に基づいて前記回線品質情報を補正する回線品質情報補正部と、当該回線品質情報補正部にて補正された回線品質情報に基づいて基地局側の変調方式を決定する変調方式決定部とを具備する、という手段を採用する。  On the other hand, in the present invention, as a first solving means related to the radio communication terminal, a calculation unit that calculates a change between training signals included in a received signal, a channel quality acquisition unit that acquires channel quality information from the received signal, A channel quality information correction unit that corrects the channel quality information based on a calculation result of the calculation unit, and a base station side modulation scheme is determined based on the channel quality information corrected by the channel quality information correction unit A means of including a modulation method determination unit is employed.

また、本発明では、無線通信端末に係る第２の解決手段として、上記第１の解決手段において、前記回線品質情報補正部は、前記トレーニング信号間の位相回転量に基づく補正値を回線品質情報に乗算することで前記回線品質情報を補正することを特徴とする。  Also, in the present invention, as a second solving means relating to a radio communication terminal, in the first solving means, the line quality information correction unit sets a correction value based on a phase rotation amount between the training signals to the line quality information. The channel quality information is corrected by multiplying by.

また、本発明では、無線通信端末に係る第３の解決手段として、上記第２の解決手段において、前記回線品質情報補正部は、位相回転量に応じた前記補正値をテーブルとして予め記憶しており、当該テーブルから補正値を読み出して前記回線品質情報に乗算することで当該回線品質情報を補正することを特徴とする。  Also, in the present invention, as a third solving means relating to a radio communication terminal, in the second solving means, the line quality information correction unit stores the correction value according to the phase rotation amount in advance as a table. The channel quality information is corrected by reading the correction value from the table and multiplying the channel quality information.

また、本発明では、無線通信端末に係る第４の解決手段として、上記第１の解決手段において、前記算出部は、前記トレーニング信号間のベクトル変化量を算出し、前記受信信号のシンボル座標における隣接するシンボル間の距離を算出し、前記回線品質取得部は、前記シンボル間の距離の２乗を前記ベクトル変化量の２乗で除算した値を補正値として算出することを特徴とする。  Further, in the present invention, as a fourth solving means relating to the radio communication terminal, in the first solving means, the calculation unit calculates a vector change amount between the training signals, and uses the symbol coordinates of the received signal. The distance between adjacent symbols is calculated, and the channel quality obtaining unit calculates a value obtained by dividing the square of the distance between the symbols by the square of the vector change amount as a correction value.

また、本発明では、無線通信端末に係る第５の解決手段として、上記第１〜４のいずれかの解決手段において、前記回線品質情報は、信号または搬送波と雑音との比、もしくは信号または搬送波と干渉波を含む雑音との比であることを特徴とする。  Also, in the present invention, as a fifth solving means relating to a radio communication terminal, in any one of the first to fourth solving means, the channel quality information is a signal or a ratio of carrier wave to noise, or a signal or carrier wave. And the noise including the interference wave.

さらに、本発明では、無線通信システムに係る第１の解決手段として、上記基地局に関する解決手段１〜５のいずれかを有する基地局と、無線通信端末に関する解決手段１〜５のいずれかを有する無線通信端末とを具備し、互いに決定した変調方式にて通信を行うことを特徴とする。  Furthermore, in the present invention, as a first solving means relating to the radio communication system, a base station having any one of the solving means 1 to 5 relating to the base station and any of the solving means 1 to 5 relating to the radio communication terminal are provided. It comprises a wireless communication terminal and performs communication using a mutually determined modulation scheme.

また、本発明では、無線通信システムに係る第２の解決手段として、上記第１の解決手段において、前記基地局に、無線通信端末側で補正された回線品質情報に基づいて基地局側の変調方式を決定する変調方式決定部を備えることを特徴とする。  Further, in the present invention, as a second solving means related to the wireless communication system, in the first solving means, the base station side modulates the base station side based on the channel quality information corrected on the wireless communication terminal side. A modulation scheme determining unit that determines a scheme is provided.

また、本発明では、無線通信システムに係る第３の解決手段として、上記第１または２の解決手段において、前記無線通信端末に、基地局側で補正された回線品質情報に基づいて無線通信端末側の変調方式を決定する変調方式決定部を備えることを特徴とする。  Further, in the present invention, as a third solving means relating to the wireless communication system, in the first or second solving means, the wireless communication terminal is connected to the wireless communication terminal based on the line quality information corrected on the base station side. And a modulation scheme determining unit that determines a modulation scheme on the side.

本発明によれば、適応変調方式が採用された無線通信システムにおいて、フェージングが発生する通信環境下であっても、誤り率特性の劣化を効果的に防止してスループットの向上を実現することが可能である。  According to the present invention, in a wireless communication system employing an adaptive modulation scheme, even in a communication environment where fading occurs, it is possible to effectively prevent deterioration of error rate characteristics and improve throughput. Is possible.

以下、図面を参照して、本発明の一実施形態について説明する。図１及び２は、本発明の実施形態に係る適応変調方式を採用した無線通信システムを構成する基地局Ｂ及び無線通信端末Ｔの構成ブロック図である。なお、基地局Ｂとして、アダプティブアレーアンテナシステムを採用した送受信機能を有するものを例示して説明する。   Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 and 2 are configuration block diagrams of a base station B and a radio communication terminal T that constitute a radio communication system employing an adaptive modulation scheme according to an embodiment of the present invention. The base station B will be described as an example having a transmission / reception function employing an adaptive array antenna system.

図１に示すように、基地局Ｂは、Ｎ個のアンテナ素子１を備えるＲＦ送受信部２、信号処理部３、前半トレーニング相関算出部４、後半トレーニング相関算出部５、復調部６、復号化部７、上りSNR算出部８、上りSNR補正値算出部９、端末側変調方式決定部１０、下りSNR補正値算出部１１、基地局側変調方式決定部１２、符号化部１３及び変調部１４から構成されている。  As shown in FIG. 1, the base station B includes an RF transceiver unit 2 including N antenna elements 1, a signal processing unit 3, a first half training correlation calculation unit 4, a second half training correlation calculation unit 5, a demodulation unit 6, and a decoding unit. Unit 7, uplink SNR calculation unit 8, uplink SNR correction value calculation unit 9, terminal side modulation scheme determination unit 10, downlink SNR correction value calculation unit 11, base station side modulation scheme determination unit 12, encoding unit 13, and modulation unit 14 It is composed of

アンテナ素子１は、無線通信端末Ｔとの間でＲＦ信号の送受信を行う。ＲＦ送受信部２は、アンテナ素子１からのＮ個の受信信号を増幅してベースバンド信号へ変換後、デジタル信号に変換し、受信信号ｘ1〜ｘNとして信号処理部３に出力する。 The antenna element 1 transmits and receives an RF signal to and from the wireless communication terminal T. The RF transmission / reception unit 2 amplifies N received signals from the antenna element 1 and converts them to baseband signals, converts them into digital signals, and outputs the received signals x 1 to x N to the signal processing unit 3.

信号処理部３は、ＭＭＳＥ（Minimum Mean Square Error：最小２乗誤差法）ベースなどの適応アルゴリズム、例えばＬＭＳ（Least Mean Square）アルゴリズムを用いて適応信号処理を行うものであり、受信ウエイト算出部３a及び信号合成部３bを備えている。受信ウエイト算出部３aは、上記ＲＦ送受信部２から入力される受信信号ｘ1〜ｘNに基づいてアレーアンテナの最適な指向性パターンを形成するためのウエイト定数ｗ1〜ｗNを算出し信号合成部３bに出力する。信号合成部３bは、上記ＲＦ送受信部２から入力される受信信号ｘ1〜ｘNにそれぞれ対応したウエイト定数ｗ1〜ｗNを乗じて重み付けした後、これら受信信号を合成して出力信号ｙとして前半トレーニング相関算出部４、後半トレーニング相関算出部５及び復調部６に出力する。 The signal processing unit 3 performs adaptive signal processing using an adaptive algorithm such as an MMSE (Minimum Mean Square Error) base, such as an LMS (Least Mean Square) algorithm, and a reception weight calculation unit 3a. And a signal synthesizer 3b. Reception weight calculating section 3a, the signal to calculate the weight constant w 1 to w N to form an optimal directivity pattern of the array antenna based on the received signal x 1 ~x N inputted from the RF transmitting and receiving unit 2 Output to the combining unit 3b. Signal combining unit 3b, after weighting by multiplying the weight constant w 1 to w N corresponding respectively to the received signal x 1 ~x N inputted from the RF transmitting and receiving unit 2, an output signal by combining these reception signals y Are output to the first half training correlation calculation unit 4, the second half training correlation calculation unit 5, and the demodulation unit 6.

また、この信号処理部３は、送信時において、変調部１４から入力される変調後の送信データを送信する最適なアンテナ素子１を決定し、上記変調後の送信データをＲＦ送受信部２に出力する。ＲＦ送受信部２は、変調後の送信データをＲＦ信号に変換し、信号処理部３にて決定されたアンテナ素子１から上記ＲＦ信号を無線通信端末Ｔに送信する。  In addition, the signal processing unit 3 determines an optimal antenna element 1 that transmits the transmission data after modulation input from the modulation unit 14 during transmission, and outputs the transmission data after modulation to the RF transmission / reception unit 2. To do. The RF transmitting / receiving unit 2 converts the modulated transmission data into an RF signal, and transmits the RF signal from the antenna element 1 determined by the signal processing unit 3 to the wireless communication terminal T.

前半トレーニング相関算出部４は、上記出力信号ｙに含まれる前半トレーニング信号を基に第１の相関値を算出し、上りSNR補正値算出部９に出力する。後半トレーニング相関算出部５は、上記出力信号ｙに含まれる後半トレーニング信号を基に第２の相関値を算出し、上りSNR補正値算出部９に出力する。なお、これら前半トレーニング相関算出部４及び後半トレーニング相関算出部５における相関値算出処理についての詳細は後述する。   The first-half training correlation calculation unit 4 calculates a first correlation value based on the first-half training signal included in the output signal y and outputs the first correlation value to the uplink SNR correction value calculation unit 9. The latter half training correlation calculation unit 5 calculates the second correlation value based on the latter half training signal included in the output signal y and outputs the second correlation value to the uplink SNR correction value calculation unit 9. Details of the correlation value calculation processing in the first half training correlation calculation unit 4 and the second half training correlation calculation unit 5 will be described later.

復調部６は、上記出力信号ｙを復調し、復調信号を復号化部７及び上りSNR算出部８に出力する。復号化部７は、上記復調信号を復号化して受信データを生成し、当該受信データを下りSNR補正値算出部１１に出力すると共に受信データの信号処理を行うデータ処理部（図示せず）に出力する。上りSNR算出部８は、上記復調信号を基に、上りSNR値を算出し（つまりアップリンクにおける回線品質情報を取得する）、上りSNR補正値算出部９に出力する。なお、このSNRは、干渉IをノイズとみなすことによりSINR(Signal to Interference and Noise Ratio)と同等に取り扱うことができる。   The demodulator 6 demodulates the output signal y and outputs the demodulated signal to the decoder 7 and the uplink SNR calculator 8. The decoding unit 7 decodes the demodulated signal to generate reception data, outputs the reception data to the downlink SNR correction value calculation unit 11, and performs a signal processing on the reception data to a data processing unit (not shown). Output. The uplink SNR calculation unit 8 calculates an uplink SNR value (that is, acquires uplink channel quality information) based on the demodulated signal, and outputs the uplink SNR value to the uplink SNR correction value calculation unit 9. This SNR can be handled in the same way as SINR (Signal to Interference and Noise Ratio) by regarding the interference I as noise.

上りSNR補正値算出部９は、上記第１の相関値及び第２の相関値に基づいて上りSNR値を補正して上りSNR補正値を生成し、端末側変調方式決定部１０に出力する。この上りSNR補正値算出部９における補正処理についての詳細は後述する。端末側変調方式決定部１０は、上記上りSNR補正値に基づいて無線通信端末Ｔ側、つまりアップリンク側の変調方式を決定し、当該変調方式を示す端末変調方式情報を送信データに多重化する。   The uplink SNR correction value calculation unit 9 corrects the uplink SNR value based on the first correlation value and the second correlation value, generates an uplink SNR correction value, and outputs the uplink SNR correction value to the terminal side modulation scheme determination unit 10. Details of the correction processing in the uplink SNR correction value calculation unit 9 will be described later. The terminal-side modulation scheme determination unit 10 determines a modulation scheme on the radio communication terminal T side, that is, the uplink side based on the uplink SNR correction value, and multiplexes terminal modulation scheme information indicating the modulation scheme with transmission data. .

下りSNR補正値算出部１１は、受信データに含まれる無線通信端末Ｔ側のSNR値（つまり下りSNR値）、第１の相関値及び第２の相関値を示す情報に基づいて下りSNR値を補正して下りSNR補正値を生成し、基地局側変調方式決定部１２に出力する。基地局側変調方式決定部１２は、上記下りSNR補正値に基づいて基地局Ｂ側、つまりダウンリンク側の変調方式を決定し、当該変調方式を示す基地局変調方式情報を変調部１４に出力する。   The downlink SNR correction value calculation unit 11 calculates the downlink SNR value based on information indicating the SNR value on the radio communication terminal T side (that is, the downlink SNR value), the first correlation value, and the second correlation value included in the received data. Correction is performed to generate a downlink SNR correction value, which is output to the base station side modulation scheme determination unit 12. Based on the downlink SNR correction value, the base station side modulation scheme determination unit 12 determines a modulation scheme on the base station B side, that is, the downlink side, and outputs base station modulation scheme information indicating the modulation scheme to the modulation unit 14 To do.

符号化部１３は、送信データ（端末変調方式情報を含む）を符号化して変調部１４に出力する。変調部１４は、上記基地局変調方式情報が示す変調方式にて符号化後の送信データを変調して信号処理部３に出力する。   The encoding unit 13 encodes transmission data (including terminal modulation scheme information) and outputs the encoded transmission data to the modulation unit 14. The modulation unit 14 modulates the encoded transmission data by the modulation method indicated by the base station modulation method information and outputs the modulated transmission data to the signal processing unit 3.

一方、図２に示すように、無線通信端末Ｔは、アンテナ２０、ＲＦ送受信部２１、前半トレーニング相関算出部２２、後半トレーニング相関算出部２３、復調部２４、下りSNR算出部２５、復号化部２６、符号化部２７及び変調部２８から構成されている。  On the other hand, as shown in FIG. 2, the radio communication terminal T includes an antenna 20, an RF transmission / reception unit 21, a first half training correlation calculation unit 22, a second half training correlation calculation unit 23, a demodulation unit 24, a downlink SNR calculation unit 25, and a decoding unit. 26, an encoding unit 27, and a modulation unit 28.

アンテナ２０は、基地局Ｂとの間でＲＦ信号の送受信を行う。ＲＦ送受信部２１は、アンテナ２０によって受信したＲＦ信号を増幅し、ベースバンド信号に変換した後、デジタル信号に変換し、受信信号として前半トレーニング相関算出部２２、後半トレーニング相関算出部２３及び復調部２４に出力する。また、このＲＦ送受信部２１は、変調部２８から入力される変調後の送信データをＲＦ信号に変換し、当該ＲＦ信号をアンテナ２０を介して基地局Ｂに送信する。  The antenna 20 transmits and receives RF signals to and from the base station B. The RF transmitter / receiver 21 amplifies the RF signal received by the antenna 20, converts it to a baseband signal, converts it to a digital signal, and receives the first-half training correlation calculator 22, the second-half training correlation calculator 23, and the demodulator as received signals. 24. In addition, the RF transmission / reception unit 21 converts the modulated transmission data input from the modulation unit 28 into an RF signal, and transmits the RF signal to the base station B via the antenna 20.

前半トレーニング相関算出部２２は、上記受信信号に含まれる前半トレーニング信号を基に第１の相関値を算出し、当該第１の相関値を示す情報を送信データに多重化する。後半トレーニング相関算出部２３は、上記受信信号に含まれる後半トレーニング信号を基に第２の相関値を算出し、当該第２の相関値を示す情報を送信データに多重化する。  The first-half training correlation calculation unit 22 calculates a first correlation value based on the first-half training signal included in the received signal, and multiplexes information indicating the first correlation value with transmission data. The latter-half training correlation calculation unit 23 calculates a second correlation value based on the latter-half training signal included in the received signal, and multiplexes information indicating the second correlation value with transmission data.

復調部２４は、上記受信信号を復調し、復調信号を下りSNR算出部２５及び復号化部２６に出力する。下りSNR算出部２５は、上記復調信号を基に、下りSNR値を算出し（つまりダウンリンクにおける回線品質情報を取得する）、当該下りSNR値を示す情報を送信データに多重化する。復号化部７は、上記復調信号を復号化して受信データ（端末変調方式情報を含む）を生成し、当該受信データを変調部２８に出力すると共に受信データの信号処理を行うデータ処理部（図示せず）に出力する。   The demodulator 24 demodulates the received signal and outputs the demodulated signal to the downlink SNR calculator 25 and the decoder 26. The downlink SNR calculation unit 25 calculates a downlink SNR value (that is, acquires channel quality information in the downlink) based on the demodulated signal, and multiplexes information indicating the downlink SNR value with transmission data. The decoding unit 7 decodes the demodulated signal to generate reception data (including terminal modulation scheme information), outputs the reception data to the modulation unit 28, and performs signal processing on the reception data (see FIG. (Not shown).

符号化部２７は、送信データ（ダウンリンク側の第１の相関値、第２の相関値及び下りSNR値を示す情報を含む）を符号化して変調部２８に出力する。変調部２８は、受信データに含まれる端末変調方式情報が示す変調方式にて符号化後の送信データを変調してＲＦ送受信部２１に出力する。   The encoding unit 27 encodes transmission data (including information indicating the first correlation value, the second correlation value, and the downlink SNR value on the downlink side) and outputs the encoded data to the modulation unit 28. The modulation unit 28 modulates the encoded transmission data using the modulation scheme indicated by the terminal modulation scheme information included in the reception data, and outputs the modulated transmission data to the RF transmission / reception unit 21.

次に、このように基地局Ｂ及び無線通信端末Ｔによって構成される本無線通信システムの動作について説明する。  Next, the operation of the wireless communication system constituted by the base station B and the wireless communication terminal T will be described.

〔無線通信端末Ｔ側の変調方式を決定する場合〕
まず、無線通信端末Ｔ側、つまりアップリンク側の変調方式を決定する場合の動作について、図３のフローチャートを用いて説明する。 [When determining the modulation method on the wireless communication terminal T side]
First, the operation in the case of determining the modulation method on the radio communication terminal T side, that is, the uplink side will be described with reference to the flowchart of FIG.

まず、基地局Ｂ（具体的にはアンテナ素子１）は、無線通信端末Ｔから送信されるバースト信号（アップリンクバースト信号）を受信する（ステップＳ１）。アンテナ素子１にて受信されたアップリンクバースト信号は、ＲＦ送受信部２において増幅され、ベースバンド信号へ変換後デジタル信号に変換され、受信信号ｘ1〜ｘNとして信号処理部３に出力される。 First, the base station B (specifically, the antenna element 1) receives a burst signal (uplink burst signal) transmitted from the radio communication terminal T (step S1). The uplink burst signal received by the antenna element 1 is amplified by the RF transmission / reception unit 2, converted into a baseband signal, converted into a digital signal, and output to the signal processing unit 3 as reception signals x 1 to x N. .

信号処理部３の信号合成部３bは、上記受信信号ｘ1〜ｘNにそれぞれに対応したウエイト定数ｗ1〜ｗNを乗じて重み付けした後、これら受信信号を合成して出力信号ｙとして前半トレーニング相関算出部４、後半トレーニング相関算出部５及び復調部６に出力する。 Signal combining unit 3b of the signal processing unit 3, after weighting by multiplying the weight constant w 1 to w N corresponding to each of the received signals x 1 ~x N, the first half as the output signal y by synthesizing these reception signals The result is output to the training correlation calculation unit 4, the latter half training correlation calculation unit 5, and the demodulation unit 6.

前半トレーニング相関算出部４は、上記出力信号ｙに含まれる前半トレーニング信号を基に第１の相関値を算出し、上りSNR補正値算出部９に出力する（ステップＳ２）。図４は、出力信号ｙの構成を示したものである。この図に示すように、出力信号ｙには、インフォメーションシンボルを挟むように前半トレーニング信号ｔ１と後半トレーニング信号ｔ２とが含まれている。前半トレーニング相関算出部４は、この内、前半トレーニング信号ｔ１を使用して第１の相関値を算出する。なお、上記前半トレーニング信号ｔ１及び後半トレーニング信号ｔ２として使用する信号は、それぞれ既知の信号であれば別の信号（シンボル値）であっても良い。   The first-half training correlation calculation unit 4 calculates a first correlation value based on the first-half training signal included in the output signal y, and outputs the first correlation value to the uplink SNR correction value calculation unit 9 (step S2). FIG. 4 shows the configuration of the output signal y. As shown in this figure, the output signal y includes a first half training signal t1 and a second half training signal t2 so as to sandwich an information symbol. Among these, the first-half training correlation calculation unit 4 calculates the first correlation value using the first-half training signal t1. The signals used as the first training signal t1 and the second training signal t2 may be different signals (symbol values) as long as they are known signals.

具体的には、第１の相関値とは、前半トレーニング信号ｔ１を既知の参照信号（例えば冗長性の低い乱数）で除算して得られる相関ベクトルである。ここでは、図５（a）に示すような位相α１を有する第１の相関値（相関ベクトルＡ）が得られたと想定する。前半トレーニング相関算出部４は、上述したように相関ベクトルＡを算出して上りSNR補正値算出部９に出力する。  Specifically, the first correlation value is a correlation vector obtained by dividing the first half training signal t1 by a known reference signal (for example, a random number with low redundancy). Here, it is assumed that a first correlation value (correlation vector A) having a phase α1 as shown in FIG. The first-half training correlation calculation unit 4 calculates the correlation vector A as described above and outputs the correlation vector A to the uplink SNR correction value calculation unit 9.

次に、後半トレーニング相関算出部５は、上記出力信号ｙに含まれる後半トレーニング信号ｔ２を基に第２の相関値を算出し、上りSNR補正値算出部９に出力する（ステップＳ３）。第２の相関値とは、後半トレーニング信号ｔ２を参照信号で除算して得られる相関ベクトルである。ここでは、図５（b）に示すような位相α２を有する第２の相関値（相関ベクトルＢ）が得られたと想定する。後半トレーニング相関算出部５は、上述したように相関ベクトルＢを算出して上りSNR補正値算出部９に出力する。  Next, the second half training correlation calculation unit 5 calculates a second correlation value based on the second half training signal t2 included in the output signal y, and outputs the second correlation value to the uplink SNR correction value calculation unit 9 (step S3). The second correlation value is a correlation vector obtained by dividing the latter half training signal t2 by the reference signal. Here, it is assumed that a second correlation value (correlation vector B) having a phase α2 as shown in FIG. The second half training correlation calculation unit 5 calculates the correlation vector B as described above and outputs it to the uplink SNR correction value calculation unit 9.

なお、上記のように、１つのアップリンクバースト信号に含まれる前半トレーニング信号ｔ１及び後半トレーニング信号ｔ２を基に相関ベクトルを算出することに限らず、例えば、前半トレーニング信号ｔ１を所定のタイミングで間欠的に取得して、各前半トレーニング信号における相関ベクトルを求めても良い。  Note that, as described above, the present invention is not limited to calculating the correlation vector based on the first training signal t1 and the second training signal t2 included in one uplink burst signal. For example, the first training signal t1 is intermittent at a predetermined timing. The correlation vector in each first-half training signal may be obtained.

一方、出力信号ｙは復調部６にて復調され、復調信号として上りSNR算出部８に出力される。上りSNR算出部８は、上記復調信号を基に、上りSNR値を算出し、上りSNR補正値算出部９に出力する（ステップＳ４）。  On the other hand, the output signal y is demodulated by the demodulator 6 and output to the uplink SNR calculator 8 as a demodulated signal. The uplink SNR calculation unit 8 calculates an uplink SNR value based on the demodulated signal and outputs it to the uplink SNR correction value calculation unit 9 (step S4).

そして、上りSNR補正値算出部９は、上記第１の相関値（相関ベクトルＡ）及び第２の相関値（相関ベクトルＢ）に基づいて、上りSNR値を補正して上りSNR補正値を生成する（ステップＳ５）。具体的には、まず、上りSNR補正値算出部９は、図６（a）に示すように、相関ベクトルＢを相関ベクトルＡで除算して、前半トレーニング信号ｔ１を受信した時間から後半トレーニング信号ｔ２を受信した時間までの間に生じる受信信号（アップリンクバースト信号）の位相回転量α０を算出する。 Then, the uplink SNR correction value calculation unit 9 corrects the uplink SNR value based on the first correlation value (correlation vector A) and the second correlation value (correlation vector B) to generate an uplink SNR correction value. (Step S5). Specifically, first, the uplink SNR correction value calculation unit 9 divides the correlation vector B by the correlation vector A as shown in FIG. 6A, and starts the second half training signal from the time when the first training signal t1 is received. A phase rotation amount α 0 of a received signal (uplink burst signal) generated until the time t2 is received is calculated.

ここで、例えばＱＰＳＫ変調方式の場合の信号シンボル座標を図６（b）に示す。この図において、Ｓはシンボル情報を含む信号の振幅であり、ｎはノイズ振幅である。上記位相回転量α０を考慮すると、図６（ｂ）は図６（ｃ）のように表される。つまり、上記信号振幅Ｓは、α０の位相回転によりＳ’に減少する。また、Ｓ’＝Ｓ・sin（４５°−α０）である。このような位相回転はフェージングが発生した通信環境下で生じるものである。つまり、この位相回転量α０を考慮して上りSNR値を補正することにより、フェージングをも加味して変調方式を決定することが可能となる。 Here, FIG. 6B shows signal symbol coordinates in the case of the QPSK modulation method, for example. In this figure, S is the amplitude of the signal including symbol information, and n is the noise amplitude. In consideration of the phase rotation amount α 0 , FIG. 6B is expressed as FIG. That is, the signal amplitude S is reduced to S 'by the phase rotation of the alpha 0. Further, S ′ = S · sin (45 ° −α 0 ). Such phase rotation occurs in a communication environment where fading has occurred. That is, by correcting the uplink SNR value in consideration of this phase rotation amount α 0 , it becomes possible to determine the modulation method in consideration of fading.

位相回転量α０を考慮した上りSNR補正値は下記（１）式で表される。
上りSNR補正値＝Ｓ’／ｎ＝Ｓ・sin（４５°−α０）／ｎ
＝上りSNR値・sin（４５°−α０） ・・・・（１）
すなわち、上りSNR算出部８から取得した上りSNR値にsin（４５°−α０）、つまり補正値を乗算することにより、上りSNR補正値を算出することができる。このように、上りSNR補正値算出部９は、位相回転量α０を算出した後、上記（１）に基づいて上りSNR補正値を算出して端末側変調方式決定部１０に出力する。 The uplink SNR correction value in consideration of the phase rotation amount α 0 is expressed by the following equation (1).
Uplink SNR correction value = S ′ / n = S · sin (45 ° −α 0 ) / n
= Upstream SNR value • sin (45 ° −α 0 ) (1)
That is, the uplink SNR correction value can be calculated by multiplying the uplink SNR value acquired from the uplink SNR calculation unit 8 by sin (45 ° −α 0 ), that is, the correction value. As described above, the uplink SNR correction value calculation unit 9 calculates the phase rotation amount α 0 , calculates the uplink SNR correction value based on the above (1), and outputs it to the terminal side modulation scheme determination unit 10.

なお、上記のように、上りSNR補正値を算出する際に、図７に示すテーブルを用いても良い。つまり、位相回転量α０の値に応じたsin（４５°−α０）、つまり補正値の値を予めテーブルとして記憶しておき、位相回転量α０を算出した後、このテーブルから補正値を読み出して上りSNR値に乗算するようにしても良い。また、図７において、位相回転量α０が±４５°の場合の値を記載していないが、この場合、強制的に最も変調レートの低い変調方式を用いる。 As described above, the table shown in FIG. 7 may be used when calculating the uplink SNR correction value. That is, sin (45 ° −α 0 ) corresponding to the value of the phase rotation amount α 0 , that is, the value of the correction value is stored in advance as a table, and after calculating the phase rotation amount α 0 , the correction value is calculated from this table. May be read and multiplied by the uplink SNR value. In FIG. 7, the value when the phase rotation amount α 0 is ± 45 ° is not described, but in this case, the modulation scheme having the lowest modulation rate is forcibly used.

端末側変調方式決定部１０は、上記上りSNR補正値に基づいて無線通信端末Ｔ側、つまりアップリンク側の変調方式を決定し、当該変調方式を示す端末変調方式情報を送信データに多重化する（ステップＳ６）。以下、上りSNR補正値を用いた変調方式の決定方法を具体的に説明する。図８は、各変調方式におけるSNR値とBER（ビット誤り率：Bit Error Rate）との関係を示す特性図である。この特性図に基づき、SNR値として上りSNR補正値を使用して、BERが閾値Ｌ以下となる変調方式を決定する。ここで、上記閾値Ｌは、この無線通信システムにおいて最低限要求されるビット誤り率である。  The terminal-side modulation scheme determination unit 10 determines a modulation scheme on the radio communication terminal T side, that is, the uplink side based on the uplink SNR correction value, and multiplexes terminal modulation scheme information indicating the modulation scheme with transmission data. (Step S6). Hereinafter, a method of determining the modulation scheme using the uplink SNR correction value will be specifically described. FIG. 8 is a characteristic diagram showing the relationship between the SNR value and BER (Bit Error Rate) in each modulation scheme. Based on this characteristic diagram, an uplink SNR correction value is used as the SNR value, and a modulation scheme in which the BER is equal to or less than the threshold value L is determined. Here, the threshold value L is a bit error rate required at the minimum in this wireless communication system.

このような端末変調方式情報を含む送信データは、無線通信端末Ｔに送信され、当該無線通信端末Ｔの復調部２４、復号化部２６により受信データに変換される。そして、無線通信端末Ｔの変調部２８は、受信データに含まれる端末変調方式情報が示す変調方式で送信データの変調を行う。  Transmission data including such terminal modulation scheme information is transmitted to the radio communication terminal T, and is converted into reception data by the demodulation unit 24 and the decoding unit 26 of the radio communication terminal T. Then, the modulation unit 28 of the radio communication terminal T modulates the transmission data with the modulation scheme indicated by the terminal modulation scheme information included in the received data.

〔基地局Ｂ側の変調方式を決定する場合〕
次に、基地局Ｂ側、つまりダウンリンク側の変調方式を決定する場合の動作について、図９のフローチャートを用いて説明する。 [When determining the modulation system on the base station B side]
Next, the operation for determining the modulation method on the base station B side, that is, the downlink side will be described with reference to the flowchart of FIG.

まず、無線通信端末Ｔ（具体的にはアンテナ２０）は、基地局Ｂから送信されるバースト信号（ダウンリンクバースト信号）を受信する（ステップＳ１０）。アンテナ２０にて受信されたダウンリンクバースト信号は、ＲＦ送受信部２１において増幅され、ベースバンド信号へ変換後デジタル信号に変換され、受信信号として前半トレーニング相関算出部２２、後半トレーニング相関算出部２３及び復調部２４に出力される。   First, the radio communication terminal T (specifically, the antenna 20) receives a burst signal (downlink burst signal) transmitted from the base station B (step S10). The downlink burst signal received by the antenna 20 is amplified by the RF transmission / reception unit 21, converted to a baseband signal, converted to a digital signal, and received as a first-half training correlation calculation unit 22, second-half training correlation calculation unit 23, and It is output to the demodulator 24.

前半トレーニング相関算出部２２は、上記と同様に受信信号に含まれる前半トレーニング信号ｔ１を基に第１の相関値を算出する（ステップＳ１１）。また、後半トレーニング相関算出部２３は、上記受信信号に含まれる後半トレーニング信号ｔ２を基に第２の相関値を算出する（ステップＳ１２）。一方、受信信号は復調部２４にて復調され、復調信号として下りSNR算出部２５及び復号化部２６に出力される。下りSNR算出部２５は、上記復調信号を基に、下りSNR値を算出する（ステップＳ１３）。  The first-half training correlation calculation unit 22 calculates the first correlation value based on the first-half training signal t1 included in the received signal as described above (step S11). Further, the latter half training correlation calculating unit 23 calculates a second correlation value based on the latter half training signal t2 included in the received signal (step S12). On the other hand, the received signal is demodulated by the demodulator 24 and output to the downlink SNR calculator 25 and the decoder 26 as a demodulated signal. The downlink SNR calculator 25 calculates a downlink SNR value based on the demodulated signal (step S13).

これらダウンリンクに関する第１の相関値、第２の相関値及び下りSNR値を示す情報は送信データに多重化され、基地局Ｂに送信される（ステップＳ１４）。そして、基地局Ｂにおいて、ダウンリンクに関する第１の相関値、第２の相関値及び下りSNR値を示す情報が含まれた受信データは、下りSNR補正値算出部１１に入力される。下りSNR補正値算出部１１は、上りSNR補正値算出部９と同様な処理により、ダウンリンクに関する第１の相関値、第２の相関値及び下りSNR値に基づいて下りSNR補正値を算出し、基地局側変調方式決定部１２に出力する。基地局側変調方式決定部１２は、上記下りSNR補正値に基づいて基地局Ｂ側、つまりダウンリンク側の変調方式を決定し、当該変調方式を示す基地局変調方式情報を変調部１４に出力する（ステップＳ１５）。変調部１４は、基地局変調方式情報が示す変調方式にて送信データを変調する。  Information indicating the first correlation value, the second correlation value, and the downlink SNR value related to the downlink is multiplexed with transmission data and transmitted to the base station B (step S14). In the base station B, the received data including information indicating the first correlation value, the second correlation value, and the downlink SNR value related to the downlink is input to the downlink SNR correction value calculation unit 11. The downlink SNR correction value calculation unit 11 calculates the downlink SNR correction value based on the first correlation value, the second correlation value, and the downlink SNR value related to the downlink by the same process as the uplink SNR correction value calculation unit 9. And output to the base station side modulation scheme determination unit 12. Based on the downlink SNR correction value, the base station side modulation scheme determination unit 12 determines a modulation scheme on the base station B side, that is, the downlink side, and outputs base station modulation scheme information indicating the modulation scheme to the modulation unit 14 (Step S15). Modulator 14 modulates transmission data using a modulation scheme indicated by base station modulation scheme information.

以上のように、本実施形態によれば、フェージングが発生した通信環境下であっても、当該フェージングの影響を加味した上りまたは下りSNR補正値を基に決定した変調方式を使用することにより、誤り率特性の劣化を効果的に防止してスループットの向上を実現することが可能である。  As described above, according to the present embodiment, even in a communication environment in which fading occurs, by using a modulation scheme determined based on an uplink or downlink SNR correction value that takes into account the effect of the fading, It is possible to effectively improve the throughput by effectively preventing the deterioration of the error rate characteristics.

なお、本発明は、上記実施形態に限定されるものではなく、例えば以下のような変形例が考えられる。   In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.

（１）上記実施形態では、下りSNR補正値算出部１１及び基地局側変調方式決定部１２を基地局Ｂに設けたが、これに限らず、これらを無線通信端末Ｔ側に設け、無線通信端末側にて下りSNR補正値を算出し、基地局側変調方式を決定して基地局変調方式情報を基地局Ｂに送信しても良い。なお、無線通信端末Ｔの信号処理負担を軽減するためには、下りSNR補正値算出部１１及び基地局側変調方式決定部１２は基地局Ｂに設けることが好ましい。 (1) In the above-described embodiment, the downlink SNR correction value calculation unit 11 and the base station side modulation scheme determination unit 12 are provided in the base station B. However, the present invention is not limited thereto, and these are provided on the radio communication terminal T side. The terminal side may calculate the downlink SNR correction value, determine the base station side modulation scheme, and transmit the base station modulation scheme information to the base station B. In order to reduce the signal processing burden on the radio communication terminal T, the downlink SNR correction value calculation unit 11 and the base station side modulation scheme determination unit 12 are preferably provided in the base station B.

（２）上記実施形態では、間欠的に取得したトレーニング信号間の位相回転量に基づいて回線品質情報を補正したが、これに限らず、上記トレーニング信号間のベクトル変化量と
受信したバースト信号のシンボル座標における隣接するシンボル間の距離とを算出し、シンボル間の距離の２乗をベクトル変化量の２乗で除算した値を補正値とし、当該補正値を乗算することで回線品質情報を補正しても良い。このように、シンボル間の距離の２乗をベクトル変化量の２乗で除算した値は、フェージングの影響により符号間干渉を起こすまでのシンボル座標上の距離にどれだけのマージンがあるかを示すものである。従って、この値を補正値として、回線品質情報に乗算することでフェージングの影響を加味した上りまたは下りSNR補正値を基に変調方式を決定することができる。 (2) In the above embodiment, the channel quality information is corrected based on the phase rotation amount between training signals acquired intermittently. However, the present invention is not limited to this, and the amount of vector change between the training signals and the received burst signal The distance between adjacent symbols in symbol coordinates is calculated, the value obtained by dividing the square of the distance between symbols by the square of the vector change amount is used as a correction value, and the correction value is multiplied to correct the line quality information. You may do it. As described above, the value obtained by dividing the square of the distance between symbols by the square of the vector change amount indicates how much margin is in the distance on the symbol coordinates until intersymbol interference occurs due to the influence of fading. Is. Therefore, by using this value as a correction value and multiplying the channel quality information, the modulation scheme can be determined based on the uplink or downlink SNR correction value taking the influence of fading into consideration.

（３）上記実施形態では、回線品質情報としてSNRを用いたが、これに限らず、CNR（Carrier to Noise Ratio）、SINR(Signal to Interference and Noise Ratio)、CINR(Carrier to Interference and Noise Ratio)、SIR（Signal to Interference power Ratio）、CIR(Carrier to Interference power Ratio)等を用いても良い。 (3) In the above embodiment, SNR is used as channel quality information. However, the present invention is not limited to this, but CNR (Carrier to Noise Ratio), SINR (Signal to Interference and Noise Ratio), CINR (Carrier to Interference and Noise Ratio) SIR (Signal to Interference power Ratio), CIR (Carrier to Interference power Ratio), or the like may be used.

本発明の一実施形態に係わる基地局の構成ブロック図である。It is a block diagram of the configuration of a base station according to an embodiment of the present invention. 本発明の一実施形態に係わる無線通信端末の構成ブロック図である。1 is a configuration block diagram of a wireless communication terminal according to an embodiment of the present invention. 本発明の一実施形態に係わる無線通信システムにおける無線通信端末側の変調方式を決定する場合のフローチャートである。It is a flowchart in the case of determining the modulation system by the side of the radio | wireless communication terminal in the radio | wireless communications system concerning one Embodiment of this invention. 本発明の一実施形態に係わる無線通信システムにおける変調方式決定方法を示す第１説明図である。It is 1st explanatory drawing which shows the modulation system determination method in the radio | wireless communications system concerning one Embodiment of this invention. 本発明の一実施形態に係わる無線通信システムにおける変調方式決定方法を示す第２説明図である。It is 2nd explanatory drawing which shows the modulation system determination method in the radio | wireless communications system concerning one Embodiment of this invention. 本発明の一実施形態に係わる無線通信システムにおける変調方式決定方法を示す第３説明図である。It is 3rd explanatory drawing which shows the modulation system determination method in the radio | wireless communications system concerning one Embodiment of this invention. 本発明の一実施形態に係わる無線通信システムにおける変調方式決定方法を示す第４説明図である。It is the 4th explanatory view showing the modulation system decision method in the radio communications system concerning one embodiment of the present invention. 本発明の一実施形態に係わる無線通信システムにおける変調方式決定方法を示す第５説明図である。It is 5th explanatory drawing which shows the modulation system determination method in the radio | wireless communications system concerning one Embodiment of this invention. 本発明の一実施形態に係わる無線通信システムにおける基地局側の変調方式を決定する場合のフローチャートである。It is a flowchart in the case of determining the modulation system by the side of the base station in the radio | wireless communications system concerning one Embodiment of this invention.

符号の説明Explanation of symbols

１…アンテナ素子、２、２１…ＲＦ送受信部、３…信号処理部、４、２２…前半トレーニング相関算出部、５、２３…後半トレーニング相関算出部、６、２４…復調部、７、２６…復号化部、８…上りSNR算出部、９…上りSNR補正値算出部、１０…端末側変調方式決定部、１１…下りSNR補正値算出部、１２…基地局側変調方式決定部、１３、２７…符号化部、１４、２８…変調部、２０…アンテナ











DESCRIPTION OF SYMBOLS 1 ... Antenna element 2, 21 ... RF transmission / reception part, 3 ... Signal processing part, 4, 22 ... First half training correlation calculation part, 5, 23 ... Second half training correlation calculation part, 6, 24 ... Demodulation part, 7, 26 ... Decoding unit, 8 ... Uplink SNR calculation unit, 9 ... Uplink SNR correction value calculation unit, 10 ... Terminal side modulation method determination unit, 11 ... Downlink SNR correction value calculation unit, 12 ... Base station side modulation method determination unit, 13, 27: Encoder, 14, 28 ... Modulator, 20 ... Antenna











Claims (13)

送信信号に含まれるトレーニング信号間の変化を算出する算出部と、
前記送信信号から回線品質情報を取得する回線品質取得部と、
前記算出部の算出結果に基づいて前記回線品質情報を補正する回線品質情報補正部と、
当該回線品質情報補正部にて補正された回線品質情報に基づいて無線通信端末側の変調方式を決定する変調方式決定部と
を具備することを特徴とする基地局。 A calculation unit for calculating a change between training signals included in the transmission signal;
A line quality acquisition unit for acquiring line quality information from the transmission signal;
A line quality information correction unit that corrects the line quality information based on a calculation result of the calculation unit;
A base station comprising: a modulation scheme determining unit that determines a modulation scheme on the wireless communication terminal side based on the channel quality information corrected by the channel quality information correcting unit. 前記回線品質情報補正部は、前記トレーニング信号間の位相回転量に基づく補正値を前記回線品質情報に乗算することで当該回線品質情報を補正することを特徴とする請求項１記載の基地局。   The base station according to claim 1, wherein the channel quality information correcting unit corrects the channel quality information by multiplying the channel quality information by a correction value based on a phase rotation amount between the training signals. 前記回線品質情報補正部は、位相回転量に応じた前記補正値をテーブルとして予め記憶しており、当該テーブルから前記補正値を読み出して前記回線品質情報に乗算することで当該回線品質情報を補正することを特徴とする請求項２記載の基地局。   The line quality information correction unit stores the correction value corresponding to the phase rotation amount in advance as a table, and reads the correction value from the table and multiplies the line quality information by correcting the line quality information. The base station according to claim 2, wherein: 前記算出部は、前記トレーニング信号間のベクトル変化量を算出し、前記送信信号のシンボル座標における隣接するシンボル間の距離を算出し、
前記回線品質取得部は、前記シンボル間の距離の２乗を前記ベクトル変化量の２乗で除算した値を補正値として算出する
ことを特徴とする請求項１記載の基地局。 The calculation unit calculates a vector change amount between the training signals, calculates a distance between adjacent symbols in the symbol coordinates of the transmission signal,
The base station according to claim 1, wherein the channel quality acquisition unit calculates a correction value obtained by dividing the square of the distance between the symbols by the square of the vector change amount. 前記回線品質情報は、信号または搬送波と雑音との比、もしくは信号または搬送波と干渉波を含む雑音との比であることを特徴とする請求項１〜４のいずれかに記載の基地局。  5. The base station according to claim 1, wherein the channel quality information is a ratio of a signal or carrier wave to noise, or a ratio of a signal or carrier wave to noise including an interference wave. 受信信号に含まれるトレーニング信号間の変化を算出する算出部と、
前記受信信号から回線品質情報を取得する回線品質取得部と、
前記算出部の算出結果に基づいて前記回線品質情報を補正する回線品質情報補正部と、
当該回線品質情報補正部にて補正された回線品質情報に基づいて基地局側の変調方式を決定する変調方式決定部と
を具備することを特徴とする無線通信端末。 A calculation unit for calculating a change between training signals included in the received signal;
A line quality acquisition unit for acquiring line quality information from the received signal;
A line quality information correction unit that corrects the line quality information based on a calculation result of the calculation unit;
A radio communication terminal comprising: a modulation scheme determining unit that determines a modulation scheme on the base station side based on the channel quality information corrected by the channel quality information correcting unit. 前記回線品質情報補正部は、前記トレーニング信号間の位相回転量に基づく補正値を回線品質情報に乗算することで前記回線品質情報を補正することを特徴とする請求項６記載の無線通信端末。   The wireless communication terminal according to claim 6, wherein the channel quality information correction unit corrects the channel quality information by multiplying the channel quality information by a correction value based on a phase rotation amount between the training signals. 前記回線品質情報補正部は、位相回転量に応じた前記補正値をテーブルとして予め記憶しており、当該テーブルから補正値を読み出して前記回線品質情報に乗算することで当該回線品質情報を補正することを特徴とする請求項７記載の無線通信端末。   The line quality information correction unit stores the correction value corresponding to the phase rotation amount in advance as a table, and corrects the line quality information by reading the correction value from the table and multiplying the line quality information. The wireless communication terminal according to claim 7. 前記算出部は、前記トレーニング信号間のベクトル変化量を算出し、前記受信信号のシンボル座標における隣接するシンボル間の距離を算出し、
前記回線品質取得部は、前記シンボル間の距離の２乗を前記ベクトル変化量の２乗で除算した値を補正値として算出する
ことを特徴とする請求項６記載の無線通信端末。 The calculation unit calculates a vector change amount between the training signals, calculates a distance between adjacent symbols in symbol coordinates of the reception signal,
The wireless communication terminal according to claim 6, wherein the channel quality acquisition unit calculates a correction value by dividing a square of the distance between the symbols by a square of the vector change amount. 前記回線品質情報は、信号または搬送波と雑音との比、もしくは信号または搬送波と干渉波を含む雑音との比であることを特徴とする請求項６〜９のいずれかに記載の無線通信端末。  10. The radio communication terminal according to claim 6, wherein the channel quality information is a ratio of a signal or carrier wave to noise, or a ratio of a signal or carrier wave to noise including an interference wave. 請求項１〜５のいずれかに記載の基地局と、請求項６〜１０のいずれかに記載の無線通信端末とを具備し、互いに決定した変調方式にて通信を行うことを特徴とする無線通信システム。   A radio comprising the base station according to any one of claims 1 to 5 and the radio communication terminal according to any one of claims 6 to 10, and performing communication using a mutually determined modulation scheme. Communications system. 前記基地局に、無線通信端末側で補正された回線品質情報に基づいて基地局側の変調方式を決定する変調方式決定部を備えることを特徴とする請求項１１記載の無線通信システム。   12. The radio communication system according to claim 11, wherein the base station includes a modulation scheme determining unit that determines a modulation scheme on the base station side based on channel quality information corrected on the radio communication terminal side. 前記無線通信端末に、基地局側で補正された回線品質情報に基づいて無線通信端末側の変調方式を決定する変調方式決定部を備えることを特徴とする請求項１１または１２に記載の無線通信システム。






The radio communication terminal according to claim 11 or 12, wherein the radio communication terminal includes a modulation scheme determining unit that determines a modulation scheme on the radio communication terminal side based on channel quality information corrected on the base station side. system.






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