BER Performance Improvement of STTD for MC-CDMA using Overlap FDE
نویسندگان
چکیده
あらまし−最近,高速移動無線アクセス技術としてマルチキャリア符号分割マルチアクセス(MC-CDMA)が注目さ れている.MC-CDMA では最小平均二乗誤差 (MMSE)規範に基づいた周波数領域等化(FDE)により厳しい周波数選 択性フェージング環境下においても優れたビット誤り率(BER)特性を得ることができる.従来の周波数領域等化で はブロック間干渉を避けるためにガードインターバル(GI)の挿入が必要であるが,GI 挿入によって伝送効率が低下 してしまう.GI 挿入を必要としない周波数領域等化(Overlap FDE)を用いることにより伝送効率の低下を防ぐことが できる.更に伝送特性を改善する技術として最近,時空間ブロック符号化送信ダイバーシチ(STTD)が注目を集めて いる.従来の GI 挿入を用いる FDE は STTD 復号と容易に組み合わせることができ,優れた BER 特性改善効果が得 られることが報告されている.しかし,Overlap FDE と STTD 復号の併用は非常に困難であり,その BER 特性改善 効果も明らかにされていない.そこで本論文では Overlap FDE を用いる MC-CDMA 下りリンク伝送を対象とした STTD 復号法を提案する.そして,Overlap FDE でも STTD を用いることにより,従来の FDE とほぼ同等の BER 特 性改善効果が得られることを計算機シミュレーションによって明らかにしている.
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تاریخ انتشار 2007