A cascade packet-combining scheme employing cyclic shift delay for cooperative MIMO-OFDM transmission

摘要

本稿ではMIMO－OFDM協調伝送において，目的局での受信特性の改善を目的とした連接型パケット合成復調方法を提案する．提案方法はMLDでの信号分離の前にパケット合成を行うpre－MLD合成方法とMLDで信号分離された各データストリームのビット信号に対してパケット合成を行うpost－MLD方法を連接的に用いる．2ホップ伝送の中継局に巡回シフト遅延を適用した場合の評価を行った．PER特性では，従来のpost－MLD方法と比較してPER＝0．01において所要E_b/N_oが約0．5dB改善する．更に，Decode－and－forward（DF）型中継を用いた場合にpost－MLD方法と比較して，中継局と目的局の受信電力比において約4．1dBの改善が得られることを示す.%This paper describes a simple cascade packet-combining scheme with maximum likelihood detection (MLD) for packet-based cooperative multiple-input multiple-output with orthogonal frequency division multiplexing (MIMO-OFDM) transmission. The proposed cascade combining scheme sequentially applies the pre-MLD approach, which simply combines the multiplexed sub-stream signals before MLD processing, and the post-MLD combining approach, which combines the bit signals after the sub-streams are separated by MLD processing. In addition, we consider cyclic shift delay (CSD) processing at the relay terminal of the two-hop transmission to improve the performance of the pre-MLD part. First, we assess the ideal relay strategy; it is shown that the proposed scheme improves the required E_b/N_o by approximately 0.5 dB over the post-MLD scheme. Second, we employ the decode-and-forward (DF) strategy. It is found that the proposed scheme offers about 4.1dB improvement in the received power ratio of the relay terminal to the destination terminal at PER = 0.01.