Throughput Performance of MC-CDMA HARQ with Adaptive Variable Spreading Factor
نویسندگان
چکیده
あらまし 次世代の移動無線通信では,高速高品質のパケット伝送が求められている.ところで,無線アクセスとして MC-CDMA が有力視 されている.無線パケット伝送では,誤り訂正符号化と自動再送(ARQ)を組み合わせたハイブリッド ARQ(HARQ)が重要な技術である.本 稿では,再送ごとにマルチキャリア(MC-)CDMA の拡散率を変え,周波数ダイバーシチ効果と符号化効果をうまく利用することでスループ ットを向上させるMC-CDMA HARQ を提案している.計算機シミュレーションにより周波数選択性フェージング環境下におけるスループッ トを求め,再送回数によらず常に固定の拡散率を用いる HARQ との比較を行っている.シミュレーション結果より,提案方式は再送回数を 減らすことができ,平均受信 Es/N0 全体に渡って従来の HARQ より良好なスループット特性が得られることを示している.特に多値変調 (16QAM,64QAM)を用いる場合に有効であることも示している. キーワード MC-CDMA, HARQ, 拡散率,周波数ダイバーシチ,符号化利得
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تاریخ انتشار 2005