JP3696191B2 - OFDM transceiver - Google Patents

Description

表１は、本実施形態における送信条件設定方法の具体例を示している。受信電界強度は例えば−７０ｄＢｍ未満、−７０ｄＢｍ以上かつ−５０ｄＢｍ未満、−５０ｄＢｍ以上の３レベルに分類される。伝送路応答の特性値が閾値を超えるサブキャリアの全サブキャリアに対する割合Ａは、例えば３０％未満、３０％以上の２レベルに分類される。このような分類によって、変調方式や符号化率を適切な値に設定することができる。
【００２６】
表１の例では、まず受信ＯＦＤＭ信号の受信電界強度が弱くなるほど雑音耐性の大きい変調方式を用い、また符号化率を小さくしている。具体的には、変調方式としてＢＰＳＫ、ＱＰＳＫ、１６ＱＡＭの３つが用意されており、雑音耐性はＢＰＳＫ＞ＱＰＳＫ＞１６ＱＡＭの順で小さくなっている。このように受信電界強度に応じて変調方式および符号化率を選択することによって、安定した通信品質を提供することが可能となり、データ伝送の実効速度を改善することができる。
【００２７】
さらに、本実施形態では伝送路応答の特性値が閾値を超えるサブキャリアの全サブキャリアに対する割合Ａを送信条件の送信条件設定指標として加えることにより、伝送路応答すなわち受信特性が劣悪なサブキャリアが存在する場合、より一層雑音に強い変調方式や符号化率を低く設定することを可能としている。従って、伝送路の電波伝播環境によって激しい周波数選択性フェージングが発生しても、安定した通信品質を提供することができるため、データ伝送の実効速度を飛躍的に改善することが可能となる。
【００２８】
送信条件設定部１２では、受信電界強度や、伝送路応答の特性値が閾値を超えるサブキャリアの全サブキャリアに対する割合Ａに応じて、さらにパケット長や送信電力を設定してもよい。すなわち、受信電界強度が小さくなるに従って、または割合Ａが小さくなるに従って、パケット長を小さくしたり、送信電力を大きくするという設定を行う。このようにしても、同様の効果を得ることができる。すなわち、受信電界強度や割合Ａを送信条件設定指標として設定される送信条件は、変調方式、誤り訂正符号化における符号化率、パケット長および送信電力の少なくとも一つであればよい。
【００２９】
【表２】

表２は、本実施形態における送信条件設定方法の他の具体例を示している。表１に示した受信電界強度と伝送路応答の特性値が閾値を超えるサブキャリアの全サブキャリアに対する割合Ａに加えて、要求通信品質を加味して送信条件（変調方式や符号化率）を設定する方法の一例である。
【００３０】
ここでは、要求通信品質は図１中に示した通信品質設定情報２３によって与えられ、表２の例ではパケットエラーレート（ＰＥＲ）で規定される。ＰＥＲは１％以上か、１％未満かの２レベルで分類される。要求されるＰＥＲの条件が厳しくなるに従って、表２に示すように雑音に強い変調方式を用いたり、符号化率を小さくしたりすることにより、通信品質を向上させて、要求されるＰＥＲを満足するようにすることができる。
【００３１】
上述の説明では、受信電界強度と、伝送路応答の特性値が閾値を超えるサブキャリアの全サブキャリアに対する割合Ａ、さらには要求通信品質を送信条件の送信条件設定指標とし、これら２つまたは３つの送信条件設定指標に従って送信条件を設定するようにしたが、割合Ａのみを送信条件設定指標として送信条件を設定することも可能である。
【００３２】
（第２の実施形態）
次に、図２を用いて本発明の第２の実施形態について説明する。図１と同一部分に同一符号を付して説明すると、本実施形態のＯＦＤＭ送受信装置では、図１中に示したサブキャリア伝送路応答比較部２２がパイロットキャリア伝送路応答比較部２４に置き換えられている点が第１の実施形態と異なる。
【００３３】
第１の実施形態において説明したように、ＦＦＴ部１７の出力のうちデータシンボル中に含まれる既知サブキャリアであるパイロットキャリアは、データサブキャリアの歪み補償に用いられるので、パイロットキャリアの受信特性が劣悪になると、サブキャリア全体の受信特性が劣化する可能性がある。そこで、本実施形態ではパイロットキャリアの受信特性に応じて送信条件を設定することによって通信品質を安定化させ、データ伝送の実効速度を改善する。
【００３４】
伝送路応答算出部２１の出力のうち、パイロットキャリアの伝送路応答の情報はパイロットキャリア伝送路応答比較部２４に入力される。パイロットキャリア伝送路応答比較部２４では、各パイロットキャリアの伝送路応答の所定の特性値を所定の閾値と比較し、特性値が閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂ（特性値が閾値を超えるパイロットキャリアの数／全パイロットキャリアの数）を算出する。ここでいう所定の特性値は、第１の実施形態における各サブキャリアの伝送路応答の特性値と同様に、例えば各パイロットキャリアの伝送路応答の振幅、電力および位相回転の少なくとも一つである。この場合、パイロットキャリア伝送路応答比較部２４では、閾値として例えば全サブキャリアもしくは全パイロットキャリアの平均伝送路応答に対する振幅減衰量、電力減衰量、位相回転量等が用いられる。
【００３５】
パイロットキャリア伝送路応答比較部２４の出力、すなわち伝送路応答の特性値が閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂを示す情報は、送信条件設定部１２に入力される。送信条件設定部１２では、パイロットキャリア伝送路応答比較部２４によって算出される割合Ｂと、受信電界強度測定部２０で求められる受信電界強度を送信条件設定指標として送信条件を設定する。さらに、送信条件設定部１２は必要に応じて通信品質設定情報２３を参照して送信条件を設定する。
【００３６】
【表３】

表３は、本実施形態における送信条件設定部１２での送信条件設定方法の一例を示している。受信電界強度は表１および表２と同様、受信電界強度が−７０ｄＢｍ未満、−７０ｄＢｍ以上かつ−５０ｄＢｍ未満、−５０ｄＢｍ以上の３レベルに分類される。伝送路応答の特性値が閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂは、例えば５０％未満、５０％以上の２レベルに分類される。このような分類によって、変調方式や符号化率を適切に設定することができる。
【００３７】
すなわち、本実施形態によると受信信号の受信電界強度が弱くなるほど雑音に強い変調方式を用い、また符号化率を小さくすることによって、安定した通信品質を供給することが可能となり、データ伝送の実効速度を改善することを可能となる。
【００３８】
また、伝送路応答の特性値が閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂを送信条件の送信条件設定指標として加えることにより、伝送路応答すなわち受信特性が劣悪なパイロットキャリアが存在する場合、より一層雑音に強い変調方式や符号化率を低く設定することができる。これにより、伝送路の電波伝播環境によって激しい周波数選択性フェージングが発生しても、安定した通信品質を提供することができるため、データ伝送の実効速度を飛躍的に改善することが可能となる。
【００３９】
さらに、表３に示すように要求通信品質をＰＥＲで規定し、要求されるＰＥＲが１％以上か１％未満かで送信条件を変えることもできる。すなわち、要求されるＰＥＲの条件に応じて、雑音に強い変調方式を用いたり、符号化率を小さくしたりすることによって、通信品質を安定させることが可能となる。
【００４０】
送信条件設定部１２では、受信電界強度や、伝送路応答の特性値が閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂに応じて、さらにパケット長や送信電力を設定してもよい。すなわち、受信電界強度が小さくなるに従って、または割合Ｂが小さくなるに従って、パケット長を小さくしたり、送信電力を大きくするという設定を行う。このようにしても、同様の効果を得ることができる。すなわち、受信電界強度や割合Ｂを送信条件設定指標として設定される送信条件は、変調方式、誤り訂正符号化における符号化率、パケット長および送信電力の少なくとも一つであればよい。
【００４１】
さらに、上述の説明では受信電界強度と、伝送路応答の特性値が閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂ、さらには要求通信品質を送信条件の送信条件設定指標とし、これら２つまたは３つの送信条件設定指標に従って送信条件を設定するようにしたが、割合Ｂのみを送信条件設定指標として送信条件を設定することも可能である。
【００４２】
（第３の実施形態）
図３に、本発明の第３の実施形態に係るＯＦＤＭ送受信装置の構成を示す。図１および図２と同一部分に同一符号を付して説明すると、本実施形態のＯＦＤＭ送受信装置は第１および第２の実施形態を組み合わせた構成となっている。
【００４３】
すなわち、伝送路応答算出部２１の出力のうち、サブキャリアの伝送路応答の情報はサブキャリア伝送路応答比較部２２に、またパイロットキャリアの伝送路応答の情報はパイロットキャリア伝送路応答比較部２４にそれぞれ入力される。サブキャリア伝送路応答比較部２２は、各サブキャリアの伝送路応答の所定の特性値を第１の閾値と比較し、特性値が第１の閾値を超えるサブキャリアの全サブキャリアに対する割合を算出する。パイロットキャリア伝送路応答比較部２４では、各パイロットキャリアの伝送路応答の所定の特性値を第２の閾値と比較し、特性値が第２の閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合を算出する。
【００４４】
送信条件設定部１２では、サブキャリア伝送路応答比較部２２によって算出される割合Ａと、パイロットキャリア伝送路応答比較部２４によって算出される割合Ｂおよび受信電界強度測定部２０で求められる受信電界強度を送信条件設定指標として送信条件を設定し、さらに必要に応じて通信品質設定情報２３を参照して送信条件を設定する。
【００４５】
【表４】

表４は、本実施形態における送信条件設定部１２での送信条件設定方法の一例を示している。受信電界強度は表１、表２および表３と同様に受信電界強度が−７０ｄＢｍ未満、−７０ｄＢｍ以上かつ−５０ｄＢｍ未満、−５０ｄＢｍ以上の３レベルに分類される。伝送路応答の特性値が第１の閾値を超えるサブキャリアの全サブキャリアに対する割合Ａは、表１および表２と同様に３０％未満、３０％以上の２レベルに分類される。伝送路応答の特性値が第２の閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂは、表３と同様に５０％未満、５０％以上の２レベルに分類される。
【００４６】
このような分類に従って、受信信号の受信電界強度が弱くなるほど雑音に強い変調方式を用い、また符号化率を小さくすることによって、安定した通信品質を提供することができるようになり、データ伝送の実効速度を改善することができる。さらに、伝送路応答の特性値が第１の閾値を超えるサブキャリアの全サブキャリアに対する割合Ａと、伝送路応答の特性値が第２の閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂを送信条件の送信条件設定指標として加えることにより、伝送路応答すなわち受信特性が劣悪なサブキャリアやパイロットキャリアが存在する場合において、より一層雑音に強い変調方式や符号化率を設定することが可能となる。従って、伝送路の電波伝播環境によって激しい周波数選択性フェージングが発生しても、安定した通信品質を提供することができるため、データ伝送の実効速度を飛躍的に改善することが可能となる。
【００４７】
【表５】

表５は、本実施形態における送信条件設定方法の他の具体例を示している。表４に示した受信電界強度と伝送路応答の特性値が第１の閾値を超えるサブキャリアの全サブキャリアに対する割合Ａおよび伝送路応答の特性値が第２の閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂに加えて、要求通信品質を加味して送信条件（変調方式や符号化率）を設定する方法の一例である。要求通信品質は、表２および表３と同様ＰＥＲで規定され、要求されるＰＥＲが１％以上、１％未満の２レベルの分類を追加している。このように要求されるＰＥＲの条件が厳しくなるに従って、雑音に強い変調方式を用いたり、符号化率を小さくしたりすることにより、通信品質を向上させて、要求されるＰＥＲを満足するようにすることができる。
【００４８】
送信条件設定部１２では、受信電界強度や、伝送路応答の特性値が第１の閾値を超えるサブキャリアの全サブキャリアに対する割合Ａおよび伝送路応答の特性値が第２の閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂに応じて、さらにパケット長や送信電力を設定してもよい。すなわち、受信電界強度が小さくなるに従って、または割合ＡもしくはＢが小さくなるに従って、パケット長を小さくしたり、送信電力を大きくするという設定を行うことによって、同様の効果を得ることができる。すなわち、受信電界強度や割合ＡもしくはＢを送信条件設定指標として設定される送信条件は、変調方式、誤り訂正符号化における符号化率、パケット長および送信電力の少なくとも一つであればよい。
【００４９】
さらに、上述の説明では受信電界強度と、伝送路応答の特性値が第１の閾値を超えるサブキャリアの全サブキャリアに対する割合Ａおよび伝送路応答の特性値が第２の閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂに加えて、さらには要求通信品質を送信条件の送信条件設定指標とし、これら３つまたは４つの送信条件設定指標に従って送信条件を設定するようにしている。しかし、割合Ａおよび割合Ｂのみを送信条件設定指標として送信条件を設定することも可能である。
【００５０】
次に、本発明の別の観点による幾つかの実施形態について説明する。
上述した第１、第２および第３の実施形態では、いずれも自局送受信装置に相手局送受信装置から送信されてきたＯＦＤＭ信号に基づいて、自局送受信装置が相手局送受信装置にＯＦＤＭ信号を送信する際の送信条件を設定するための送信条件設定指標（受信電界強度、割合Ａ，Ｂおよび要求通信品質等）を求め、これに基づいて送信条件を設定した。これら第１、第２および第３の実施形態は、自局送受信装置から相手局送受信装置への送信時の伝送路応答と、相手局送受信装置から自局送受信装置への送信時の伝送路応答がほぼ等しい場合（例えば、それぞれの送信周波数帯が等しい場合）に適している。
【００５１】
一方、自局送受信装置から相手局送受信装置への送信時の伝送路応答と、相手局送受信装置から自局送受信装置への送信時の伝送路応答が異なっている場合には、相手局送受信装置から自局送受信装置に送信されてきたＯＦＤＭ信号に基づいて、相手局送受信装置が自局送受信装置に送信を行う際の送信条件を設定するための送信条件設定指標を求め、これに基づいて相手局送信装置の送信条件を設定するようにすればよい。以下、そのような場合の具体例を第４、第５および第６の実施形態で説明する。
【００５２】
（第４の実施形態）
図４は、本発明の第４の実施形態に係るＯＦＤＭ送受信装置（自局送受信装置）の構成を示す図であり、図３に示した第３の実施形態をベースとして構成されている。図３と同一部分に同一符号を付して説明すると、本実施形態は図３における送信条件設定部１２が送信条件設定情報生成部３１に置き換えられ、その出力である送信条件設定情報が送信部１４に入力される点が第３の実施形態と異なっている。
【００５３】
送信条件設定情報生成部３１は、受信電界強度測定部２０、サブキャリア伝送路応答比較部２２およびパイロットキャリア伝送路応答比較部２４の出力を送信条件設定指標として入力する。送信条件設定情報生成部３１は、入力された送信条件設定指標に基づいて、相手局送受信装置が本実施形態のＯＦＤＭ送受信装置（自局送受信装置）に送信を行う際の送信条件（変調方式、符号化率、パケット長および送信電力等）を第３の実施形態における送信条件設定部１２と同様の手順により求める。そして、送信条件設定情報生成部３１は、求められた送信条件に基づいて、相手局装置がその送信条件を設定するための送信条件設定情報を生成する。このようにして生成された送信条件設定情報は、送信部１４を経て相手局送受信装置に送信される。相手局送受信装置では、送信されてきた送信条件設定情報に従って送信条件を設定する。
【００５４】
図５に、本実施形態における相手局送受信装置としてのＯＦＤＭ送受信装置の構成を示す。図４に示したＯＦＤＭ送受信装置から送信されてきた送信条件設定情報は、アンテナ１５および受信部１６を経て送信条件設定部３２に入力される。送信条件設定部３２では、入力された送信条件設定情報に従ってサブキャリア変調部１１に対して変調方式や符号化率を設定し、さらには送信部１４に対して送信電力を設定する。
【００５５】
このように本実施形態では、図４の自局送受信装置において受信電界強度測定部２０、サブキャリア伝送路応答比較部２２およびパイロットキャリア伝送路応答比較部２４が、相手局送受信装置が自局ＯＦＤＭ送受信装置に送信を行う際の送信条件を設定するための送信条件設定指標を求める。送信条件設定情報生成部３１が、この送信条件設定指標に基づき相手局送信装置の送信条件を設定するための送信条件設定情報を生成する。送信部１４が、生成された送信条件設定情報を図５の相手局送受信装置に送信する。相手局送受信装置においては、送信条件設定部３２が、送信されてきた送信条件設定情報に基づいて送信条件を設定する。
すなわち、相手局送受信装置では、送信条件を設定するための送信条件設定情報を生成する動作は実行されない。送信条件設定情報は、自局送受信装置で生成される。
【００５６】
従って、本実施形態によると自局ＯＦＤＭ送受信装置から相手局送受信装置への送信時の伝送路応答と、相手局送受信装置から自局ＯＦＤＭ送受信装置への送信時の伝送路応答が異なっている場合でさえも、相手局送受信装置が最適な送信条件を設定することが可能となり、相手局送受信装置において第３の実施形態と同様の効果を得ることが可能となる。
【００５７】
すなわち、図５の相手局送受信装置において、図４の自局送受信装置の受信電界強度が弱くなるほど雑音に強い変調方式を用い、また符号化率を小さくすることによって、安定した通信品質を提供することができるようになり、データ伝送の実効速度を改善することができる。さらに、伝送路応答の特性値が第１の閾値を超えるサブキャリアの全サブキャリアに対する割合Ａと、伝送路応答の特性値が第２の閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂを送信条件の送信条件設定指標として加えることにより、伝送路応答すなわち受信特性が劣悪なサブキャリアが存在する場合、より一層雑音に強い変調方式や符号化率を設定することが可能となる。従って、伝送路の電波伝播環境によって激しい周波数選択性フェージングが発生しても、安定した通信品質を提供することができるため、データ伝送の実効速度を飛躍的に改善することが可能となる。
【００５８】
本実施形態においては第３の実施形態と同様に、受信電界強度と、伝送路応答の特性値が第１の閾値を超えるサブキャリアの全サブキャリアに対する割合Ａ、伝送路応答の特性値が第２の閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂ、さらには要求通信品質を送信条件の送信条件設定指標とし、これら３つまたは４つの送信条件設定指標に従って送信条件を設定するようにしたが、割合Ａまたは割合Ｂのみ、あるいは割合ＡとＢの両方を送信条件設定指標として送信条件を設定することも可能である。
【００５９】
（第５の実施形態）
図６は、本発明の第５の実施形態に係るＯＦＤＭ送受信装置（自局送受信装置）の構成を示す図である。図４と同一部分に同一符号を付して説明すると、本実施形態は図４における送信条件設定情報生成部３１の出力である送信条件設定情報が送信部１４でなく、サブキャリア変調部１１に入力される点が第３の実施形態と異なっている。
【００６０】
図７は、本実施形態における相手局送受信装置としてのＯＦＤＭ送受信装置の構成を示す図である。図５と同一部分に同一符号を付して説明すると、本実施形態では図６に示したように自局送受信装置において送信条件設定情報がサブキャリア変調部１１に入力される点に対応して、相手局送受信装置においてサブキャリア復調部１８の出力から送信条件設定情報が取り出され、送信条件設定部３２に入力される点が異なっている。
【００６１】
このように送信条件設定情報の送受信はサブキャリア変調部１１およびサブキャリア復調部１８を介して行われるようにしてもよく、これにより第４の実施形態と同様の効果が得られる。
【００６２】
（第６の実施形態）
図８は、本発明の第６の実施形態に係るＯＦＤＭ送受信装置（自局送受信装置）の構成を示す図であり、図３に示した第３の実施形態をベースとして構成されている。図３と同一部分に同一符号を付して説明すると、本実施形態は図３における送信条件設定部１２が送信条件設定指標情報合成部４１に置き換えられ、その出力である送信条件設定指標情報が送信部１４に入力される点が第３の実施形態と異なっている。
【００６３】
送信条件設定指標情報合成部４１は、受信電界強度測定部２０、サブキャリア伝送路応答比較部２２およびパイロットキャリア伝送路応答比較部２４の出力を送信条件設定指標情報として入力して、それらの送信条件設定指標情報を合成する。このようにして生成された送信条件設定指標情報は、送信部１４を経て相手局送受信装置に送信される。相手局送受信装置では、送信されてきた送信条件設定指標情報に従って送信条件を設定する。
【００６４】
図９に、本実施形態における相手局送受信装置としてのＯＦＤＭ送受信装置の構成を示す。図８に示したＯＦＤＭ送受信装置から送信されてきた送信条件設定指標情報は、アンテナ１５および受信部１６を経て送信条件設定指標情報分離部４２に入力される。送信条件設定指標情報分離部４２は、入力された送信条件設定指標に基づいて、本実施形態のＯＦＤＭ送受信装置（自局送受信装置）に送信を行う際の送信条件（変調方式、符号化率、パケット長および送信電力等）を第３の実施形態における送信条件設定部１２と同様の手順により求める。そして、送信条件設定指標情報分離部４２は、求められた送信条件に基づいて、相手局装置がその送信条件を設定するための送信条件設定情報を生成する。その後、送信条件設定指標情報分離部４２は、送信条件設定情報を送信条件設定部４３に出力する。送信条件設定部４３では、入力された送信条件設定指標情報に従って送信条件を設定する。送信条件設定部４３は、送信条件としてサブキャリア変調部１１に対しては変調方式や符号化率を設定し、さらには送信部１４に対しては送信電力を設定する。
【００６５】
このように本実施形態では、図８の自局送受信装置内の送信部１４が、自局送受信装置内における受信電界強度測定部２０、サブキャリア伝送路応答比較部２２およびパイロットキャリア伝送路応答比較部２４からの出力を、相手局送受信装置が自局送受信装置に送信を行う際の送信条件を設定するための送信条件設定指標情報として図９の相手局送受信装置に送信する。相手局送受信装置は、受信した送信条件設定指標情報に基づいて送信条件を設定する。この結果、自局送受信装置から相手局送受信装置への送信時の伝送路応答と、相手局送受信装置から自局送受信装置への送信時の伝送路応答が異なっている場合でも相手局送受信装置が最適な送信条件を設定することが可能となる。従って、相手局送受信装置において第４および第５の実施形態と同様の効果を得ることが可能となる。
本実施形態では、自局送受信装置から相手局送受信装置に送信される情報は、第４および第５の実施形態のように送信条件設定情報ではなく、送信条件設定指標情報である。送信条件設定指標情報は送信条件設定情報に比較してデータ量が少ない。従って、自局送受信装置から相手局送受信装置に送信される送信データ量に関して、本実施形態の方が第４および第５の実施形態の場合よりも少なくなるという効果がある。
【００６６】
本実施形態の変形として、第４および第５の実施形態と同様に受信電界強度と、伝送路応答の特性値が第１の閾値を超えるサブキャリアの全サブキャリアに対する割合Ａ、伝送路応答の特性値が第２の閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂ、さらには要求通信品質を送信条件の送信条件設定指標とし、これら３つまたは４つの送信条件設定指標に従って送信条件を設定することに限定されず、割合Ａまたは割合Ｂのみ、あるいは割合ＡとＢの両方を送信条件設定指標として送信条件を設定することも可能である。
【００６７】
（第７の実施形態）
図１０は、本発明の第７の実施形態に係るＯＦＤＭ送受信装置の構成を示す図であり、図３に示した第３の実施形態のＯＦＤＭ送受信装置に、図９に示したＯＦＤＭ送受信装置の機能を組み合わせた構成となっている。すなわち、図３に示したＯＦＤＭ送受信装置に送信条件設定指標情報分離部５１が追加され、さらに送信条件設定部５２が自局送受信装置内の受信電界強度測定部２０、サブキャリア伝送路応答比較部２２およびパイロットキャリア伝送路応答比較部２４の出力を送信条件設定指標情報として自局送受信装置での送信条件を設定する機能と、相手局送受信装置から送信され、送信条件設定指標情報分離部５１で分離された送信条件設定指標情報に従って自局送受信装置での送信条件を設定する機能を有する。
【００６８】
本実施形態によると、自局送受信装置から相手局送受信装置への送信時の伝送路応答と、相手局送受信装置から自局送受信装置への送信時の伝送路応答がほぼ等しい場合には、第３の実施形態と同様に、自局送受信装置内の受信電界強度測定部２０、サブキャリア伝送路応答比較部２２およびパイロットキャリア伝送路応答比較部２４の出力を送信条件設定指標情報として自局送受信装置での送信条件を設定する。
【００６９】
一方、自局送受信装置から相手局送受信装置への送信時の伝送路応答と、相手局送受信装置から自局送受信装置への送信時の伝送路応答が異なっている場合には、第６の実施形態における図９に示した相手局送受信装置と同様に、自局送受信装置において相手局送受信装置から送信されてきたＯＦＤＭ信号に基づいて、すなわち相手局送受信装置から送信され、送信条件設定指標情報分離部５１で分離された送信条件設定指標情報に従って、送信条件設定部５２によって自局送受信装置での送信条件を設定する。
【００７０】
すなわち、本実施形態によれば自局送受信装置と相手局送受信装置との双方向の伝送路応答が等しい場合と異なる場合の両方に対応して、最適な送信条件を設定することができる。また、本実施形態の変形として、伝送路応答の特性値が第１の閾値を超えるサブキャリアの全サブキャリアに対する割合Ａと伝送路応答の特性値が第２の閾値を超えるパイロットキャリアの全パイロットキャリアに対する割合Ｂのいずれか一方のみ、あるいは両方を送信条件設定指標として送信条件を設定することも可能である。
【００７１】
【発明の効果】
本発明のＯＦＤＭ送受信装置によれば、ＯＦＤＭ信号の各サブキャリアの伝送路応答に応じて送信条件を設定することができ、データ伝送の実効速度を効果的に改善することが可能となる。
【図面の簡単な説明】
【図１】 本発明の第１の実施形態に係るＯＦＤＭ送受信装置の構成を示すブロック図。
【図２】 本発明の第２の実施形態に係るＯＦＤＭ送受信装置の構成を示すブロック図。
【図３】 本発明の第３の実施形態に係るＯＦＤＭ送受信装置の構成を示すブロック図。
【図４】 本発明の第４の実施形態に係るＯＦＤＭ送受信装置（自局送受信装置）の構成を示すブロック図。
【図５】 本発明の第４の実施形態に係るＯＦＤＭ送受信装置（相手局送受信装置）の構成を示すブロック図。
【図６】 本発明の第５の実施形態に係るＯＦＤＭ送受信装置（自局送受信装置）の構成を示すブロック図。
【図７】 本発明の第５の実施形態に係るＯＦＤＭ送受信装置（相手局送受信装置）の構成を示すブロック図。
【図８】 本発明の第６の実施形態に係るＯＦＤＭ送受信装置（自局送受信装置）の構成を示すブロック図。
【図９】 本発明の第６の実施形態に係るＯＦＤＭ送受信装置（相手局送受信装置）の構成を示すブロック図。
【図１０】 本発明の第７の実施形態に係るＯＦＤＭ送受信装置の構成を示すブロック図。
【符号の説明】
１０ 送信データ系列
１１ サブキャリア変調部
１２ 送信条件設定部
１３ ＩＦＦＴ（高速逆フーリエ変換）部
１４ 送信部
１５ アンテナ
１６ 受信部
１７ ＦＦＴ（高速フーリエ変換）部
１８ サブキャリア復調部
１９ 受信データ系列
２０ 受信電界強度測定部
２１ 伝送路応答算出部
２２ サブキャリア伝送路応答比較部
２３ 通信品質設定情報
２４ パイロットキャリア伝送路応答比較部
３１ 送信条件設定情報生成部
３２ 送信条件設定部
４１ 送信条件設定指標情報合成部
４２ 送信条件設定指標情報分離部
４３ 送信条件設定部
５１ 送信条件設定指標情報分離部
５２ 送信条件設定部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an OFDM transmission / reception apparatus in a wireless communication system that transmits an OFDM (Orthogonal Frequency Division Multiplexing) signal.
[0002]
[Prior art]
In general, in a wireless communication system, a transmitted signal is received via a plurality of various paths (multipaths) due to reflection of radio waves by a building or the like, and thus a received signal is distorted. This distortion varies depending on location and time. Under such a propagation environment, the effective speed of data transmission can be maximized by changing transmission conditions such as a modulation scheme and a coding rate in accordance with the propagation environment. Usually, a transmission condition suitable for a propagation environment can be set by obtaining a received electric field strength and a transmission path response from a known reference sequence and data sequence.
[0003]
When the transmitted signal is a broadband signal such as an OFDM signal, frequency selective fading occurs due to multipath. When frequency selective fading occurs, as a result of different received electric field strengths for different subcarriers of a plurality of frequencies constituting an OFDM signal, subcarriers with excellent reception characteristics and inferior subcarriers are mixed. Due to the presence of subcarriers with inferior reception characteristics, the possibility of errors increases even if the average reception field strength and transmission path response of all subcarriers are excellent. Therefore, even if transmission conditions suitable for the average propagation environment of all subcarriers are selected, there may be cases where a large effect cannot be obtained in improving the effective speed of data transmission (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
US Pat. No. 6,175,550
[0005]
[Problems to be solved by the invention]
As described above, in the conventional OFDM transmission / reception apparatus, the transmission condition is set according to the average transmission line response of all subcarriers and the received electric field strength. Therefore, if there is a subcarrier with poor reception characteristics, the set transmission condition is set. However, there is a problem that the effective speed of data transmission cannot be increased.
[0006]
An object of the present invention is to provide an OFDM transmission / reception apparatus capable of improving the effective speed of data transmission by setting an optimum transmission condition according to a transmission path response for each subcarrier.
[0007]
[Means for Solving the Problems]
In order to solve the above problem, an OFDM transceiver apparatus according to the first aspect of the present invention provides:
In an OFDM transceiver apparatus that performs transmission and reception of an OFDM signal having a plurality of subcarriers via a predetermined transmission path with a counterpart station transceiver apparatus,
Receiving means for receiving an OFDM signal transmitted from the counterpart station transceiver;
Transmission path response calculation means for calculating a transmission path response indicating response characteristics of the transmission path to the plurality of subcarriers from the received OFDM signal;
Comparing means for comparing the calculated predetermined characteristic value of the transmission path response with a predetermined threshold, and calculating a ratio of the number of subcarriers whose characteristic value exceeds the threshold to the total number of subcarriers;
Transmission condition setting means for setting a transmission condition when the OFDM transmitter / receiver transmits an OFDM signal to the counterpart station transmitter / receiver based on the transmission condition setting index based on at least the ratio calculated by the comparison means When,
Transmitting means for transmitting an OFDM signal according to a set transmission condition;
Is provided.
[0008]
An OFDM transceiver apparatus according to the second aspect of the present invention is:
In an OFDM transceiver apparatus that performs transmission and reception of an OFDM signal having a plurality of subcarriers via a predetermined transmission path with a counterpart station transceiver apparatus,
Receiving means for receiving an OFDM signal transmitted from the counterpart station transceiver;
Transmission path response calculation means for calculating a transmission path response indicating response characteristics of the transmission path to the plurality of subcarriers from the received OFDM signal;
Comparing means for comparing the calculated predetermined characteristic value of the transmission path response with a predetermined threshold, and calculating a ratio of the number of subcarriers whose characteristic value exceeds the threshold to the total number of subcarriers;
Transmission condition setting for generating transmission condition setting information for setting a transmission condition when the counterpart station transmitting / receiving apparatus transmits an OFDM signal to the OFDM transmitting / receiving apparatus using at least the ratio calculated by the comparison means as a transmission condition setting index Information generating means;
Transmitting means for transmitting the transmission condition setting information to the counterpart station transceiver;
Is provided.
[0009]
An OFDM transceiver apparatus according to the third aspect of the present invention is:
In an OFDM transceiver apparatus that performs transmission and reception of an OFDM signal having a plurality of subcarriers via a predetermined transmission path with a counterpart station transceiver apparatus,
Receiving means for receiving an OFDM signal transmitted from the counterpart station transceiver;
Transmission path response calculation means for calculating a transmission path response indicating response characteristics of the transmission path to the plurality of subcarriers from the received OFDM signal;
Comparing means for comparing the calculated predetermined characteristic value of the transmission path response with a predetermined threshold, and calculating a ratio of the number of subcarriers whose characteristic value exceeds the threshold to the total number of subcarriers;
The transmission condition setting index information is synthesized as a transmission condition setting index when the partner station transmitting / receiving apparatus sets a transmission condition for transmitting an OFDM signal to the OFDM transmitting / receiving apparatus at least for the ratio calculated by the comparison means Transmission condition setting index information combining means;
Transmitting means for transmitting information on the transmission condition setting index to the counterpart station transceiver;
Is provided.
[0010]
According to the above configuration, by setting the optimal transmission condition according to the transmission path response for each subcarrier based on the received OFDM signal, data transmission of data transmitted by the OFDM transceiver apparatus that has received the OFDM signal is performed. Effective speed can be improved.
[0011]
Also, based on the transmission path response for each subcarrier of the OFDM signal received from the counterpart station transceiver, transmission condition setting for setting the transmission condition when the counterpart station transceiver transmits the OFDM signal to the local transceiver Information is transmitted from the local station transmission / reception apparatus to the counterpart station transmission / reception apparatus. The partner station transceiver device can improve the effective speed of data transmission of data transmitted from the partner station transceiver device to the local station transceiver device by setting the transmission condition based on the transmitted transmission condition setting information. It becomes possible.
[0012]
Furthermore, based on the transmission path response for each subcarrier of the OFDM signal received from the counterpart station transceiver, transmission condition setting when the counterpart station transceiver sets a transmission condition when transmitting the OFDM signal to the local transceiver The index is transmitted from the local station transmission / reception device to the counterpart station transmission / reception device. The partner station transceiver device can improve the effective speed of data transmission of data transmitted by the partner station transceiver device by setting the transmission condition based on the transmitted transmission condition setting index. Here, the transmission condition setting index is information serving as an index for setting the transmission condition, and has a smaller data amount than the transmission condition setting information. Therefore, there is an effect that the amount of data transmitted from the local station transmission / reception apparatus to the counterpart station transmission / reception apparatus can be reduced.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The OFDM transmission / reception apparatus according to the embodiment of the present invention is applied to a mobile radio communication system or a wireless LAN system including a base station and a terminal. The OFDM transmission / reception apparatus may be installed in a terminal or a base station. In the former case, the counterpart station transceiver may be an OFDM transceiver installed in a base station, or may be an OFDM transceiver installed in another mobile terminal. In the latter case, the partner station transmitting / receiving apparatus is mounted on a terminal or another base station.
[0014]
(First embodiment)
FIG. 1 is a block diagram showing a configuration of an OFDM transceiver apparatus according to the first embodiment of the present invention. The OFDM transmission / reception apparatus according to the present embodiment has received field strength of an OFDM signal received by the OFDM transmission / reception apparatus (own station transmission / reception apparatus) and characteristic values of transmission line responses respectively corresponding to a plurality of subcarriers constituting the OFDM signal. Is set as a transmission condition setting index, and based on these transmission condition setting indexes, transmission conditions for transmitting an OFDM signal to the counterpart station transmitting / receiving apparatus are set.
[0015]
First, the configuration on the transmission side for the OFDM transmission / reception apparatus (own station transmission / reception apparatus) of the present embodiment to transmit to the counterpart station transmission apparatus will be described.
The transmission data series 10 is converted into a plurality of subcarrier signals orthogonal on the frequency axis by being input to the subcarrier modulation unit 11. The subcarrier modulation unit 11 generates each subcarrier signal based on transmission conditions (for example, modulation scheme, coding rate, packet length, and transmission power) set by the transmission condition setting unit 12 as described later.
[0016]
Each subcarrier signal output from the subcarrier modulation unit 11 is subjected to IFFT processing by an IFFT (Fast Inverse Fourier Transform) unit 13 and converted into a time waveform signal. These time waveform signals are input to the transmission unit 14. The transmission unit 14 adds a preamble including a known signal sequence, a guard time, and the like to each time waveform signal, and further converts the added signal into an analog signal. Thereafter, the transmitter 14 generates an RF band OFDM signal (OFDM modulated signal) by frequency-converting the analog signal in accordance with a predetermined local oscillation signal. The generated OFDM signal is radiated as a radio wave from the antenna 15. In the transmission unit 14, the transmission power of the OFDM signal is set by the transmission condition setting unit 12 as necessary.
[0017]
Next, a description will be given of the configuration on the receiving side for the local station transmitting / receiving apparatus to receive the OFDM signal transmitted from the counterpart station transmitting / receiving apparatus.
The radio wave of the OFDM signal transmitted from the counterpart station transmitting / receiving apparatus is received by the antenna 15. The RF band received OFDM signal received by the antenna 15 is input to the receiving unit 16. In the receiving unit 16, the received OFDM signal is frequency-converted into a baseband signal in accordance with a predetermined local oscillation signal, then analog / digital converted, and time synchronization and frequency synchronization processing are performed.
[0018]
The baseband received OFDM signal output from the receiving unit 16 is input to an FFT (Fast Fourier Transform) unit 17. The FFT conversion window in the FFT unit 17 is set by the synchronization processing of the receiving unit 16. The FFT unit 17 performs FFT processing on the input baseband received OFDM signal for each conversion window set by the receiving unit 16 to generate a plurality of received subcarrier signals. Each generated reception subcarrier signal is demodulated by the subcarrier demodulator 18, thereby reproducing a reception data sequence 19 that is the same as the transmission data sequence of the counterpart station transceiver.
[0019]
The received OFDM signal having an analog waveform output from the receiving unit 16 or the received OFDM signal having a digital waveform after analog / digital conversion is input to the received electric field strength measuring unit 20 where the received electric field strength is measured. Information on the measured received electric field strength is input to the transmission condition setting unit 12.
[0020]
On the other hand, the output from the FFT unit 17 is also input to the transmission path response calculation unit 21. The transmission path response calculation unit 21 uses the preamble added to the received OFDM signal included in the output of the FFT unit 17 to transmit the transmission path response for each subcarrier, that is, transmission from the partner station transmission / reception device to the local station transmission / reception device. Calculate the response characteristics of the road. Information on the transmission path response calculated by the transmission path response calculation unit 21 is input to the subcarrier demodulation unit 18.
[0021]
Among the outputs of the FFT unit 17, the data subcarriers included in the data symbols in the subcarriers are demodulated by the subcarrier demodulating unit 18 with distortion compensation performed by the transmission channel response calculated by the transmission channel response calculating unit 21. The At this time, it is also possible to further compensate for the distortion of the data subcarrier by the pilot carrier that is a known subcarrier included in the data symbol.
[0022]
Information on the transmission path response calculated by the transmission path response calculation unit 21 is also input to the subcarrier transmission path response comparison unit 22. The subcarrier transmission path response comparison unit 22 compares a predetermined characteristic value of the transmission path response of each subcarrier with a predetermined threshold value, and a ratio A (characteristic value is a threshold value) of all subcarriers whose characteristic value exceeds the threshold value. The number of subcarriers exceeding the number of all subcarriers) is calculated. Here, the predetermined characteristic value is, for example, at least one of the amplitude, power, and phase rotation of the transmission path response of each subcarrier. In this case, the subcarrier transmission path response comparison unit 22 uses, for example, an amplitude attenuation amount, power attenuation amount, phase rotation amount, or the like with respect to the average transmission path response of all subcarriers. In the subcarrier transmission line response comparison unit 22, it is not always necessary to compare the characteristic values of the transmission line responses of all subcarriers with the threshold value, and it is assumed that the transmission line responses of neighboring subcarriers are almost equal. A predetermined characteristic value of the channel response of the subcarrier may be compared with a threshold value.
[0023]
The output of the subcarrier transmission path response comparison unit 22, that is, information indicating the ratio A of all subcarriers whose transmission path response characteristic value exceeds the threshold is input to the transmission condition setting unit 12. The transmission condition setting unit 12 sets the transmission condition using the ratio A calculated by the subcarrier transmission path response comparison unit 22 and the received electric field strength obtained by the received electric field strength measuring unit 20 as a transmission condition setting index. Further, the transmission condition setting unit 12 further sets transmission conditions with reference to the communication quality setting information 23 as necessary.
[0024]
Here, the transmission conditions are, for example, a modulation scheme, a coding rate in error correction coding, a packet length, and transmission power when the OFDM transmission / reception apparatus of the present embodiment, which is the local station transmission / reception apparatus, transmits an OFDM signal. In the transmission condition setting unit 12, the ratio A to the total subcarriers of the subcarriers whose transmission channel response characteristic value calculated by the subcarrier transmission channel response comparison unit 22 exceeds the threshold is obtained by the reception electric field strength measurement unit 20. At least one of these transmission conditions is set based on the received electric field strength. Hereinafter, the transmission condition setting method in the transmission condition setting unit 12 will be described more specifically.
[0025]
[Table 1]

Table 1 shows a specific example of the transmission condition setting method in the present embodiment. The received electric field strength is classified into three levels, for example, less than −70 dBm, −70 dBm or more, less than −50 dBm, and −50 dBm or more. The ratio A of the subcarriers whose transmission line response characteristic value exceeds the threshold to the total subcarriers is classified into two levels, for example, less than 30% and 30% or more. By such classification, the modulation scheme and coding rate can be set to appropriate values.
[0026]
In the example of Table 1, first, a modulation scheme with higher noise resistance is used and the coding rate is reduced as the received electric field strength of the received OFDM signal becomes weaker. Specifically, three modulation schemes, BPSK, QPSK, and 16QAM, are prepared, and noise resistance decreases in the order of BPSK>QPSK> 16QAM. Thus, by selecting the modulation method and coding rate according to the received electric field strength, it becomes possible to provide stable communication quality and improve the effective speed of data transmission.
[0027]
Furthermore, in this embodiment, by adding the ratio A of the subcarriers whose transmission path response characteristic value exceeds the threshold to the total subcarriers as a transmission condition setting index of the transmission conditions, subcarriers with poor transmission path response, that is, reception characteristics, can be obtained. When present, it is possible to set a modulation scheme and coding rate that are more resistant to noise to a lower level. Therefore, even if severe frequency selective fading occurs due to the radio wave propagation environment of the transmission path, stable communication quality can be provided, so that the effective speed of data transmission can be dramatically improved.
[0028]
The transmission condition setting unit 12 may further set the packet length and transmission power according to the received electric field strength and the ratio A of all subcarriers whose transmission channel response characteristic value exceeds the threshold value A. That is, the setting is made such that the packet length is reduced or the transmission power is increased as the received electric field strength decreases or as the ratio A decreases. Even if it does in this way, the same effect can be acquired. That is, the transmission condition set using the received electric field strength and the ratio A as a transmission condition setting index may be at least one of a modulation scheme, a coding rate in error correction coding, a packet length, and transmission power.
[0029]
[Table 2]

Table 2 shows another specific example of the transmission condition setting method in the present embodiment. In addition to the ratio A to the total subcarriers of the subcarriers whose received field strength and transmission path response characteristic values shown in Table 1 exceed the threshold value, the transmission conditions (modulation scheme and coding rate) are taken into account in consideration of the required communication quality. It is an example of the method of setting.
[0030]
Here, the required communication quality is given by the communication quality setting information 23 shown in FIG. 1, and is defined by the packet error rate (PER) in the example of Table 2. The PER is classified into two levels of 1% or more or less than 1%. As the required PER conditions become stricter, as shown in Table 2, by using a noise-resistant modulation scheme or by reducing the coding rate, the communication quality is improved and the required PER is satisfied. To be able to.
[0031]
In the above description, the received electric field strength, the ratio A of the subcarriers whose transmission path response characteristic value exceeds the threshold, and the required communication quality are used as the transmission condition setting index of the transmission condition, and these two or three Although transmission conditions are set according to one transmission condition setting index, it is also possible to set transmission conditions using only the ratio A as a transmission condition setting index.
[0032]
(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in FIG. 1 are denoted by the same reference numerals. In the OFDM transmitter / receiver of this embodiment, the subcarrier transmission path response comparison unit 22 shown in FIG. This is different from the first embodiment.
[0033]
As described in the first embodiment, the pilot carrier that is a known subcarrier included in the data symbol in the output of the FFT unit 17 is used for data subcarrier distortion compensation. If it is inferior, the reception characteristics of the entire subcarrier may be degraded. Therefore, in the present embodiment, the transmission condition is set according to the reception characteristics of the pilot carrier, thereby stabilizing the communication quality and improving the effective speed of data transmission.
[0034]
Of the output of the transmission path response calculation unit 21, information on the transmission path response of the pilot carrier is input to the pilot carrier transmission path response comparison unit 24. The pilot carrier transmission line response comparison unit 24 compares a predetermined characteristic value of the transmission line response of each pilot carrier with a predetermined threshold value, and a ratio B (characteristic value is a threshold value) of all pilot carriers whose characteristic value exceeds the threshold value. The number of pilot carriers exceeding / the number of all pilot carriers) is calculated. The predetermined characteristic value here is, for example, at least one of the amplitude, power, and phase rotation of the transmission line response of each pilot carrier, similarly to the characteristic value of the transmission line response of each subcarrier in the first embodiment. . In this case, the pilot carrier transmission line response comparison unit 24 uses, for example, an amplitude attenuation amount, power attenuation amount, phase rotation amount, or the like with respect to the average transmission line response of all subcarriers or all pilot carriers.
[0035]
Information indicating the output B of the pilot carrier transmission line response comparison unit 24, that is, the ratio B of all pilot carriers whose transmission channel response characteristic value exceeds the threshold, to the transmission condition setting unit 12 is input. The transmission condition setting unit 12 sets the transmission condition using the ratio B calculated by the pilot carrier transmission path response comparison unit 24 and the received electric field strength obtained by the received electric field strength measuring unit 20 as a transmission condition setting index. Further, the transmission condition setting unit 12 sets the transmission condition with reference to the communication quality setting information 23 as necessary.
[0036]
[Table 3]

Table 3 shows an example of a transmission condition setting method in the transmission condition setting unit 12 in the present embodiment. Similar to Tables 1 and 2, the received electric field strength is classified into three levels: the received electric field strength is less than −70 dBm, −70 dBm or more, −50 dBm, or −50 dBm or more. The ratio B of pilot carriers whose transmission line response characteristic value exceeds the threshold to all pilot carriers is classified into two levels, for example, less than 50% and 50% or more. By such classification, the modulation scheme and coding rate can be set appropriately.
[0037]
That is, according to the present embodiment, it is possible to supply stable communication quality by using a modulation scheme that is more resistant to noise as the received electric field strength of the received signal becomes weaker, and by reducing the coding rate. It becomes possible to improve the speed.
[0038]
Further, by adding a ratio B of all pilot carriers of the pilot carrier whose transmission line response characteristic value exceeds the threshold as a transmission condition setting index of the transmission condition, when there is a pilot carrier having a poor transmission line response, that is, reception characteristics, It is possible to set the modulation scheme and coding rate that are more resistant to noise to a lower level. As a result, even if severe frequency selective fading occurs due to the radio wave propagation environment of the transmission path, stable communication quality can be provided, so that the effective speed of data transmission can be dramatically improved.
[0039]
Furthermore, as shown in Table 3, the required communication quality is defined by PER, and the transmission condition can be changed depending on whether the required PER is 1% or more or less than 1%. That is, the communication quality can be stabilized by using a noise-resistant modulation scheme or reducing the coding rate in accordance with the required PER conditions.
[0040]
The transmission condition setting unit 12 may further set the packet length and transmission power according to the received electric field strength and the ratio B of all pilot carriers whose pilot channel characteristics exceed the threshold. That is, the setting is made such that the packet length is reduced or the transmission power is increased as the received electric field strength decreases or as the ratio B decreases. Even if it does in this way, the same effect can be acquired. That is, the transmission condition set using the received electric field strength and the ratio B as the transmission condition setting index may be at least one of the modulation scheme, the coding rate in error correction coding, the packet length, and the transmission power.
[0041]
Further, in the above description, the received electric field strength, the ratio B of all pilot carriers whose characteristic value of the channel response exceeds the threshold, and the required communication quality as the transmission condition setting index of the transmission condition, these two or Although the transmission conditions are set according to the three transmission condition setting indexes, it is also possible to set the transmission conditions using only the ratio B as the transmission condition setting indexes.
[0042]
(Third embodiment)
FIG. 3 shows a configuration of an OFDM transceiver apparatus according to the third embodiment of the present invention. The same parts as those in FIGS. 1 and 2 are described with the same reference numerals, and the OFDM transmitting / receiving apparatus according to the present embodiment is configured by combining the first and second embodiments.
[0043]
That is, out of the output of the transmission path response calculation unit 21, the information on the transmission path response of the subcarrier is sent to the subcarrier transmission path response comparison section 22, and the information on the transmission path response of the pilot carrier is sent to the pilot carrier transmission path response comparison section 24. Respectively. The subcarrier transmission path response comparison unit 22 compares a predetermined characteristic value of the transmission path response of each subcarrier with the first threshold value, and calculates a ratio of subcarriers whose characteristic value exceeds the first threshold value to all subcarriers. To do. The pilot carrier channel response comparison unit 24 compares a predetermined characteristic value of the channel response of each pilot carrier with the second threshold value, and calculates the ratio of pilot carriers whose characteristic value exceeds the second threshold value to all pilot carriers. To do.
[0044]
In the transmission condition setting unit 12, the ratio A calculated by the subcarrier transmission path response comparison unit 22, the ratio B calculated by the pilot carrier transmission path response comparison unit 24, and the reception electric field strength obtained by the reception electric field strength measurement unit 20 Is set as a transmission condition setting index, and the transmission condition is set with reference to the communication quality setting information 23 as necessary.
[0045]
[Table 4]

Table 4 shows an example of a transmission condition setting method in the transmission condition setting unit 12 in the present embodiment. Similarly to Tables 1, 2 and 3, the received electric field strength is classified into three levels: the received electric field strength is less than −70 dBm, −70 dBm or more, less than −50 dBm, and −50 dBm or more. The ratio A with respect to all subcarriers of subcarriers whose transmission line response characteristic value exceeds the first threshold is classified into two levels of less than 30% and 30% or more, as in Tables 1 and 2. The ratio B of all pilot carriers whose pilot channel response characteristic value exceeds the second threshold is classified into two levels of less than 50% and 50% or more, as in Table 3.
[0046]
According to such a classification, the use of a modulation scheme that is more resistant to noise as the reception field strength of the received signal becomes weaker, and by reducing the coding rate, it becomes possible to provide stable communication quality, and data transmission. Effective speed can be improved. Further, the ratio A of all subcarriers whose transmission path response characteristic value exceeds the first threshold value and the ratio B of all pilot carriers whose transmission path response characteristic value exceeds the second threshold value are transmitted. By adding a condition as a transmission condition setting index, it is possible to set a modulation scheme and coding rate that are more resistant to noise when there are subcarriers or pilot carriers with poor channel response, that is, reception characteristics. . Therefore, even if severe frequency selective fading occurs due to the radio wave propagation environment of the transmission path, stable communication quality can be provided, so that the effective speed of data transmission can be dramatically improved.
[0047]
[Table 5]

Table 5 shows another specific example of the transmission condition setting method in the present embodiment. The ratio A of the subcarriers whose received field strength and transmission path response characteristic values exceed the first threshold shown in Table 4 to all subcarriers and all pilots of pilot carriers whose transmission path response characteristic values exceed the second threshold This is an example of a method for setting transmission conditions (modulation scheme and coding rate) in consideration of required communication quality in addition to the ratio B to the carrier. The required communication quality is defined by PER as in Tables 2 and 3, and a two-level classification in which the required PER is 1% or more and less than 1% is added. As the required PER conditions become more stringent, the communication quality is improved by satisfying the required PER by using a noise-resistant modulation scheme or by reducing the coding rate. can do.
[0048]
In the transmission condition setting unit 12, the received electric field strength, the ratio A of all subcarriers whose transmission path response characteristic value exceeds the first threshold, and the pilot carrier whose transmission path response characteristic value exceeds the second threshold. The packet length and transmission power may be further set according to the ratio B to all pilot carriers. That is, the same effect can be obtained by setting the packet length to be reduced or the transmission power to be increased as the received electric field strength is reduced or as the ratio A or B is reduced. That is, the transmission condition set using the received electric field strength or the ratio A or B as a transmission condition setting index may be at least one of a modulation scheme, a coding rate in error correction coding, a packet length, and transmission power.
[0049]
Furthermore, in the above description, the received electric field strength, the ratio A of all subcarriers whose transmission channel response characteristic value exceeds the first threshold value, and the pilot carrier whose transmission channel response characteristic value exceeds the second threshold value. In addition to the ratio B for all pilot carriers, the required communication quality is used as a transmission condition setting index for transmission conditions, and the transmission conditions are set according to these three or four transmission condition setting indices. However, it is also possible to set the transmission condition using only the ratio A and the ratio B as the transmission condition setting index.
[0050]
Next, several embodiments according to another aspect of the present invention will be described.
In the first, second, and third embodiments described above, the local station transmission / reception apparatus sends an OFDM signal to the counterpart station transmission / reception apparatus based on the OFDM signal transmitted from the counterpart station transmission / reception apparatus to the local station transmission / reception apparatus. A transmission condition setting index (reception field strength, ratios A and B, required communication quality, etc.) for setting transmission conditions for transmission was obtained, and the transmission conditions were set based on this. In the first, second and third embodiments, the transmission path response at the time of transmission from the local station transmission / reception apparatus to the counterpart station transmission / reception apparatus, and the transmission path response at the time of transmission from the counterpart station transmission / reception apparatus to the local station transmission / reception apparatus. Are suitable (for example, when the respective transmission frequency bands are equal).
[0051]
On the other hand, if the transmission path response at the time of transmission from the local station transmission / reception apparatus to the remote station transmission / reception apparatus is different from the transmission path response at the time of transmission from the remote station transmission / reception apparatus to the local station transmission / reception apparatus, Based on the OFDM signal transmitted from the local station transmission / reception apparatus to the local station transmission / reception apparatus, a transmission condition setting index for setting a transmission condition when the counterpart station transmission / reception apparatus transmits to the local station transmission / reception apparatus is obtained. What is necessary is just to set the transmission conditions of a station transmitter. Hereinafter, specific examples in such a case will be described in the fourth, fifth and sixth embodiments.
[0052]
(Fourth embodiment)
FIG. 4 is a diagram showing a configuration of an OFDM transmission / reception apparatus (own station transmission / reception apparatus) according to the fourth embodiment of the present invention, which is configured based on the third embodiment shown in FIG. The same parts as those in FIG. 3 are denoted by the same reference numerals. In the present embodiment, the transmission condition setting unit 12 in FIG. 3 is replaced with a transmission condition setting information generation unit 31, and the transmission condition setting information as an output thereof is transmitted to the transmission unit. 14 is different from that of the third embodiment.
[0053]
The transmission condition setting information generation unit 31 inputs the outputs of the received electric field strength measurement unit 20, the subcarrier transmission path response comparison unit 22, and the pilot carrier transmission path response comparison unit 24 as a transmission condition setting index. Based on the input transmission condition setting index, the transmission condition setting information generation unit 31 transmits a transmission condition (modulation method, modulation method, transmission) when the counterpart station transmission / reception apparatus performs transmission to the OFDM transmission / reception apparatus (local station transmission / reception apparatus) of the present embodiment. (Coding rate, packet length, transmission power, etc.) are obtained by the same procedure as the transmission condition setting unit 12 in the third embodiment. Then, the transmission condition setting information generating unit 31 generates transmission condition setting information for the counterpart station apparatus to set the transmission condition based on the obtained transmission condition. The transmission condition setting information generated in this way is transmitted to the counterpart station transmission / reception apparatus via the transmission unit 14. The counterpart station transceiver sets the transmission conditions according to the transmitted transmission condition setting information.
[0054]
FIG. 5 shows a configuration of an OFDM transmitter / receiver as a counterpart station transmitter / receiver in the present embodiment. Transmission condition setting information transmitted from the OFDM transmitter / receiver shown in FIG. 4 is input to the transmission condition setting unit 32 via the antenna 15 and the receiving unit 16. The transmission condition setting unit 32 sets a modulation scheme and a coding rate for the subcarrier modulation unit 11 according to the input transmission condition setting information, and further sets transmission power for the transmission unit 14.
[0055]
As described above, in the present embodiment, the reception field strength measurement unit 20, the subcarrier transmission path response comparison unit 22 and the pilot carrier transmission path response comparison unit 24 in the local station transmission / reception apparatus in FIG. A transmission condition setting index for setting a transmission condition for transmission to the transmission / reception apparatus is obtained. The transmission condition setting information generating unit 31 generates transmission condition setting information for setting the transmission condition of the counterpart station transmission apparatus based on the transmission condition setting index. The transmission unit 14 transmits the generated transmission condition setting information to the counterpart station transmission / reception apparatus in FIG. In the counterpart station transmitting / receiving apparatus, the transmission condition setting unit 32 sets the transmission condition based on the transmitted transmission condition setting information.
That is, the counterpart station transmitting / receiving apparatus does not execute an operation for generating transmission condition setting information for setting transmission conditions. The transmission condition setting information is generated by the local transceiver device.
[0056]
Therefore, according to the present embodiment, the transmission path response at the time of transmission from the local station OFDM transmission / reception apparatus to the counterpart station transmission / reception apparatus is different from the transmission path response at the transmission from the counterpart station transmission / reception apparatus to the local station OFDM transmission / reception apparatus. Even so, it becomes possible for the partner station transmitting / receiving apparatus to set an optimum transmission condition, and the partner station transmitting / receiving apparatus can obtain the same effects as those of the third embodiment.
[0057]
That is, the counterpart station transmitting / receiving apparatus in FIG. 5 uses a modulation scheme that is more resistant to noise as the reception electric field strength of the own station transmitting / receiving apparatus in FIG. 4 becomes weaker, and provides a stable communication quality by reducing the coding rate. The effective speed of data transmission can be improved. Further, the ratio A of all subcarriers whose transmission path response characteristic value exceeds the first threshold value and the ratio B of all pilot carriers whose transmission path response characteristic value exceeds the second threshold value are transmitted. By adding a condition as a transmission condition setting index, it is possible to set a modulation scheme and coding rate that are more resistant to noise when there are subcarriers with poor transmission path response, that is, reception characteristics. Therefore, even if severe frequency selective fading occurs due to the radio wave propagation environment of the transmission path, stable communication quality can be provided, so that the effective speed of data transmission can be dramatically improved.
[0058]
In the present embodiment, as in the third embodiment, the received electric field strength, the ratio A of the subcarriers whose transmission path response characteristic value exceeds the first threshold to the total subcarriers, and the transmission path response characteristic value are Although the ratio B of all pilot carriers exceeding the threshold of 2 and the required communication quality are used as transmission condition setting indexes for transmission conditions, the transmission conditions are set according to these three or four transmission condition setting indexes. It is also possible to set the transmission condition using only the ratio A or the ratio B, or both the ratios A and B as the transmission condition setting index.
[0059]
(Fifth embodiment)
FIG. 6 is a diagram showing a configuration of an OFDM transmitter / receiver (own station transmitter / receiver) according to the fifth embodiment of the present invention. The same parts as those in FIG. 4 are denoted by the same reference numerals. In the present embodiment, the transmission condition setting information output from the transmission condition setting information generation unit 31 in FIG. 4 is not transmitted to the transmission unit 14 but to the subcarrier modulation unit 11. The input point is different from the third embodiment.
[0060]
FIG. 7 is a diagram illustrating a configuration of an OFDM transmitter / receiver as a counterpart station transmitter / receiver in the present embodiment. When the same reference numerals are given to the same parts as in FIG. 5, this embodiment corresponds to the point that the transmission condition setting information is input to the subcarrier modulation unit 11 in the local transceiver as shown in FIG. The transmission station setting information is extracted from the output of the subcarrier demodulator 18 and input to the transmission condition setting unit 32 in the counterpart station transmission / reception apparatus.
[0061]
As described above, transmission / reception of the transmission condition setting information may be performed via the subcarrier modulation unit 11 and the subcarrier demodulation unit 18, thereby obtaining the same effect as in the fourth embodiment.
[0062]
(Sixth embodiment)
FIG. 8 is a diagram showing a configuration of an OFDM transmission / reception apparatus (own station transmission / reception apparatus) according to the sixth embodiment of the present invention, which is configured based on the third embodiment shown in FIG. The same parts as those in FIG. 3 are denoted by the same reference numerals. In this embodiment, the transmission condition setting unit 12 in FIG. 3 is replaced with a transmission condition setting index information combining unit 41, and the transmission condition setting index information as an output thereof is changed. The difference from the third embodiment is that it is input to the transmitter 14.
[0063]
The transmission condition setting index information combining unit 41 inputs the outputs of the received electric field strength measuring unit 20, the subcarrier transmission path response comparison unit 22 and the pilot carrier transmission path response comparison unit 24 as transmission condition setting index information, and transmits them. Synthesize condition setting index information. The transmission condition setting index information generated in this way is transmitted to the counterpart station transmission / reception apparatus via the transmission unit 14. In the counterpart station transmitting / receiving apparatus, the transmission condition is set according to the transmitted transmission condition setting index information.
[0064]
FIG. 9 shows a configuration of an OFDM transmitter / receiver as a counterpart station transmitter / receiver in the present embodiment. The transmission condition setting index information transmitted from the OFDM transmitter / receiver shown in FIG. 8 is input to the transmission condition setting index information separating unit 42 via the antenna 15 and the receiving unit 16. Based on the input transmission condition setting index, the transmission condition setting index information separating unit 42 transmits the transmission conditions (modulation method, coding rate, transmission rate) when transmitting to the OFDM transmission / reception apparatus (local station transmission / reception apparatus) of the present embodiment. Packet length, transmission power, and the like) are obtained by the same procedure as the transmission condition setting unit 12 in the third embodiment. Then, the transmission condition setting index information separation unit 42 generates transmission condition setting information for the counterpart station apparatus to set the transmission condition based on the obtained transmission condition. Thereafter, the transmission condition setting index information separation unit 42 outputs the transmission condition setting information to the transmission condition setting unit 43. The transmission condition setting unit 43 sets transmission conditions according to the input transmission condition setting index information. The transmission condition setting unit 43 sets a modulation scheme and a coding rate for the subcarrier modulation unit 11 as a transmission condition, and further sets transmission power for the transmission unit 14.
[0065]
As described above, in the present embodiment, the transmission unit 14 in the local station transmission / reception apparatus in FIG. 8 performs the received electric field strength measurement unit 20, the subcarrier transmission path response comparison unit 22, and the pilot carrier transmission path response comparison in the local station transmission / reception apparatus. The output from the unit 24 is transmitted to the partner station transmitter / receiver in FIG. 9 as transmission condition setting index information for setting a transmission condition when the partner station transmitter / receiver transmits to the host station transmitter / receiver. The partner station transmitting / receiving apparatus sets the transmission condition based on the received transmission condition setting index information. As a result, even if the transmission path response at the time of transmission from the local station transmission / reception apparatus to the remote station transmission / reception apparatus is different from the transmission path response at the time of transmission from the remote station transmission / reception apparatus to the local station transmission / reception apparatus, It is possible to set an optimum transmission condition. Therefore, it is possible to obtain the same effects as those of the fourth and fifth embodiments in the counterpart station transmitting / receiving apparatus.
In this embodiment, the information transmitted from the local station transmission / reception device to the counterpart station transmission / reception device is not transmission condition setting information as in the fourth and fifth embodiments, but transmission condition setting index information. The transmission condition setting index information has a smaller data amount than the transmission condition setting information. Therefore, the present embodiment has an effect that the amount of transmission data transmitted from the local transceiver device to the counterpart transceiver device is smaller than that of the fourth and fifth embodiments.
[0066]
As a modification of this embodiment, as in the fourth and fifth embodiments, the received electric field strength, the ratio A of the subcarriers whose transmission path response characteristic value exceeds the first threshold to the total subcarriers, the transmission path response The ratio B of all the pilot carriers whose characteristic value exceeds the second threshold and the required communication quality are set as transmission condition setting indexes of transmission conditions, and the transmission conditions are set according to these three or four transmission condition setting indexes. The transmission condition can be set by using only the ratio A or the ratio B, or both the ratios A and B as the transmission condition setting index.
[0067]
(Seventh embodiment)
FIG. 10 is a diagram showing a configuration of an OFDM transceiver apparatus according to the seventh embodiment of the present invention. The OFDM transceiver apparatus according to the third embodiment shown in FIG. It has a configuration that combines functions. That is, a transmission condition setting index information separation unit 51 is added to the OFDM transmission / reception apparatus shown in FIG. 3, and the transmission condition setting unit 52 further includes a reception electric field strength measurement unit 20 and a subcarrier transmission path response comparison unit in the local transmission / reception apparatus. 22 and the function of setting the transmission condition in the local station transmission / reception apparatus using the output of the pilot carrier transmission line response comparison section 24 as transmission condition setting index information, and the transmission condition setting index information separation section 51 It has a function of setting a transmission condition in the local transceiver according to the separated transmission condition setting index information.
[0068]
According to the present embodiment, when the transmission path response at the time of transmission from the local station transmission / reception apparatus to the counterpart station transmission / reception apparatus and the transmission path response at the transmission from the counterpart station transmission / reception apparatus to the local station transmission / reception apparatus are substantially equal, Similarly to the third embodiment, the outputs of the reception field strength measuring unit 20, the subcarrier transmission line response comparison unit 22 and the pilot carrier transmission line response comparison unit 24 in the local station transmission / reception apparatus are used as transmission condition setting index information. Set the transmission conditions on the device.
[0069]
On the other hand, when the transmission path response at the time of transmission from the local station transmission / reception apparatus to the remote station transmission / reception apparatus is different from the transmission path response at the time of transmission from the remote station transmission / reception apparatus to the local station transmission / reception apparatus, In the same manner as the counterpart station transmitter / receiver shown in FIG. 9 in the embodiment, based on the OFDM signal transmitted from the counterpart station transmitter / receiver in the own station transmitter / receiver, that is, transmitted from the counterpart station transmitter / receiver, transmission condition setting index information separation According to the transmission condition setting index information separated by the unit 51, the transmission condition setting unit 52 sets the transmission condition in the local transceiver apparatus.
[0070]
That is, according to the present embodiment, it is possible to set an optimum transmission condition corresponding to both the case where the bidirectional transmission path response between the local station transmission / reception apparatus and the counterpart station transmission / reception apparatus is equal. As a modification of the present embodiment, the ratio A of all subcarriers whose transmission channel response characteristic value exceeds the first threshold to all subcarriers and all pilots of pilot carriers whose transmission channel response characteristic value exceeds the second threshold It is also possible to set a transmission condition using only one or both of the ratios B to the carrier as a transmission condition setting index.
[0071]
【The invention's effect】
According to the OFDM transmitting / receiving apparatus of the present invention, it is possible to set transmission conditions according to the transmission path response of each subcarrier of the OFDM signal, and it is possible to effectively improve the effective speed of data transmission.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an OFDM transceiver apparatus according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of an OFDM transmission / reception apparatus according to a second embodiment of the present invention.
FIG. 3 is a block diagram showing a configuration of an OFDM transceiver apparatus according to a third embodiment of the present invention.
FIG. 4 is a block diagram showing a configuration of an OFDM transmission / reception apparatus (own station transmission / reception apparatus) according to a fourth embodiment of the present invention.
FIG. 5 is a block diagram showing a configuration of an OFDM transmitter / receiver device (a partner station transmitter / receiver device) according to a fourth embodiment of the present invention.
FIG. 6 is a block diagram showing a configuration of an OFDM transmission / reception apparatus (own station transmission / reception apparatus) according to a fifth embodiment of the present invention;
FIG. 7 is a block diagram showing a configuration of an OFDM transmission / reception apparatus (partner station transmission / reception apparatus) according to a fifth embodiment of the present invention;
FIG. 8 is a block diagram showing a configuration of an OFDM transmission / reception apparatus (own station transmission / reception apparatus) according to a sixth embodiment of the present invention;
FIG. 9 is a block diagram showing a configuration of an OFDM transmitter / receiver device (a partner station transmitter / receiver device) according to a sixth embodiment of the present invention.
FIG. 10 is a block diagram showing a configuration of an OFDM transmitting / receiving apparatus according to a seventh embodiment of the present invention.
[Explanation of symbols]
10 Transmission data series
11 Subcarrier modulation section
12 Transmission condition setting part
13 IFFT (Fast Inverse Fourier Transform) part
14 Transmitter
15 Antenna
16 Receiver
17 FFT (Fast Fourier Transform) part
18 Subcarrier demodulator
19 Received data series
20 Received electric field strength measurement unit
21 Transmission path response calculation unit
22 Subcarrier transmission line response comparator
23 Communication quality setting information
24 Pilot carrier transmission line response comparator
31 Transmission condition setting information generation unit
32 Transmission condition setting section
41 Transmission condition setting index information synthesis unit
42 Transmission condition setting index information separation unit
43 Transmission condition setting section
51 Transmission condition setting index information separation unit
52 Transmission condition setting section

Claims (12)

In an OFDM transceiver apparatus that performs transmission and reception of an OFDM signal having a plurality of subcarriers via a predetermined transmission path with a counterpart station transceiver apparatus,
Receiving means for receiving an OFDM signal transmitted from the counterpart station transceiver;
Transmission path response calculation means for calculating a transmission path response indicating response characteristics of the transmission path to the plurality of subcarriers from the received OFDM signal;
Comparing means for comparing the calculated predetermined characteristic value of the transmission path response with a predetermined threshold, and calculating a ratio of the number of subcarriers whose characteristic value exceeds the threshold to the total number of subcarriers;
Transmission condition setting means for setting a transmission condition when the OFDM transmitter / receiver transmits an OFDM signal to the counterpart station transmitter / receiver based on the transmission condition setting index based on at least the ratio calculated by the comparison means When,
An OFDM transmission / reception apparatus comprising: transmission means for transmitting an OFDM signal according to a set transmission condition. 2. The OFDM transmission / reception according to claim 1, wherein the transmission condition setting means sets at least one of a modulation scheme used when generating an OFDM signal, a coding rate in error correction coding, a packet length, and transmission power as the transmission condition. apparatus. Means for measuring the received field strength of the OFDM signal from the received OFDM signal;
The OFDM transmission / reception apparatus according to claim 1, wherein the transmission condition setting means sets the transmission condition by adding the measured received electric field strength to the transmission condition setting index. Means for measuring the received field strength of the OFDM signal from the received OFDM signal;
The OFDM transmission / reception apparatus according to claim 1, wherein the transmission condition setting means sets the transmission condition by adding the measured received electric field strength and required communication quality to the transmission condition setting index. In an OFDM transceiver apparatus that performs transmission and reception of an OFDM signal having a plurality of subcarriers via a predetermined transmission path with a counterpart station transceiver apparatus,
Receiving means for receiving an OFDM signal transmitted from the counterpart station transceiver;
Transmission path response calculation means for calculating a transmission path response indicating response characteristics of the transmission path to the plurality of subcarriers from the received OFDM signal;
Comparing means for comparing the calculated predetermined characteristic value of the transmission path response with a predetermined threshold, and calculating a ratio of the number of subcarriers whose characteristic value exceeds the threshold to the total number of subcarriers;
Transmission condition setting for generating transmission condition setting information for setting a transmission condition when the counterpart station transmitting / receiving apparatus transmits an OFDM signal to the OFDM transmitting / receiving apparatus using at least the ratio calculated by the comparison means as a transmission condition setting index Information generating means;
An OFDM transmission / reception apparatus comprising: transmission means for transmitting the transmission condition setting information to the counterpart station transmission / reception apparatus. The transmission path response calculating means calculates a first transmission response indicating a response characteristic of the transmission path with respect to known subcarriers respectively included in an area where data is stored, from a received OFDM signal, and a preamble. Calculating a second transmission response indicating response characteristics of the transmission path to known subcarriers constituting
The comparison means compares the calculated predetermined characteristic value of the first transmission line response with a predetermined threshold, and calculates a ratio of the number of known subcarriers whose characteristic value exceeds the threshold to the total number of known subcarriers. Comparing the predetermined characteristic value of the calculated second transmission line response with a predetermined threshold value, and calculating the ratio of the number of known subcarriers whose characteristic value exceeds the threshold value to the total number of known subcarriers;
The transmission condition setting means uses at least the ratio calculated based on the first and second transmission line responses as a transmission condition setting index, and the OFDM transmitter / receiver transmits OFDM to the counterpart station transmitter / receiver based on the transmission condition setting index. The OFDM transmission / reception apparatus according to claim 1 or 5, wherein a transmission condition for transmitting a signal is set. The transmission path response calculation means calculates a first transmission response indicating response characteristics of the transmission path with respect to known subcarriers respectively included in an area where data is stored, from the received OFDM signal, Calculating a second transmission response indicating a transmission path response indicating response characteristics of the transmission path to a plurality of subcarriers;
The comparison means compares the calculated predetermined characteristic value of the first transmission line response with a predetermined threshold, and calculates a ratio of the number of known subcarriers whose characteristic value exceeds the threshold to the total number of known subcarriers. And comparing the calculated predetermined characteristic value of the second transmission line response with a predetermined threshold value, and calculating the ratio of the number of subcarriers whose characteristic value exceeds the threshold value to the total number of subcarriers,
The transmission condition setting means uses at least the ratio calculated based on the first and second transmission line responses as a transmission condition setting index, and the OFDM transmitter / receiver transmits OFDM to the counterpart station transmitter / receiver based on the transmission condition setting index. The OFDM transmission / reception apparatus according to claim 1 or 5, wherein a transmission condition for transmitting a signal is set. The comparing means uses the first and second transmission line responses as at least one of the amplitude, power, and distortion magnitudes as the predetermined characteristic values of the first and second transmission line responses. The OFDM transmission / reception apparatus according to claim 6 or 7, which is compared with each of the second threshold values. In an OFDM transceiver apparatus that performs transmission and reception of an OFDM signal having a plurality of subcarriers via a predetermined transmission path with a counterpart station transceiver apparatus,
Receiving means for receiving an OFDM signal transmitted from the counterpart station transceiver;
Transmission path response calculation means for calculating a transmission path response indicating response characteristics of the transmission path to the plurality of subcarriers from the received OFDM signal;
Comparing means for comparing the calculated predetermined characteristic value of the transmission path response with a predetermined threshold, and calculating a ratio of the number of subcarriers whose characteristic value exceeds the threshold to the total number of subcarriers;
The transmission condition setting index information is synthesized as a transmission condition setting index when the partner station transmitting / receiving apparatus sets a transmission condition for transmitting an OFDM signal to the OFDM transmitting / receiving apparatus at least for the ratio calculated by the comparison means Transmission condition setting index information combining means;
An OFDM transmission / reception apparatus comprising: transmission means for transmitting information on the transmission condition setting index to the counterpart station transmission / reception apparatus. The transmission path response calculation means calculates response characteristics of the transmission path with respect to known subcarriers each included in an area where data is stored, from the received OFDM signal,
The comparison means compares a predetermined characteristic value of the calculated transmission line response with a predetermined threshold value, and calculates a ratio of the number of known subcarriers whose characteristic value exceeds the threshold value to the total number of known subcarriers. The OFDM transmission / reception apparatus according to claim 1, wherein the comparison apparatus includes: The transmission path response calculation means calculates response characteristics of the transmission path with respect to known subcarriers constituting a preamble from the received OFDM signal,
The comparing means compares a predetermined characteristic value of the calculated transmission line response with a predetermined threshold value, and calculates a ratio of the number of known subcarriers whose characteristic value exceeds the threshold value to the total number of known subcarriers. The OFDM transmission / reception apparatus according to claim 1, wherein the comparison apparatus includes: The comparison means compares at least one of amplitude, power and distortion magnitude of the transmission line response with the threshold value as a predetermined characteristic value of the transmission line response. The OFDM transmitting / receiving apparatus according to 1.

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