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Message Passing Algorithm for Space Time Block Coded MIMO Detection in Fast Fading Channels
Thesis

Message Passing Algorithm for Space Time Block Coded MIMO Detection in Fast Fading Channels

Chen, Ting-Wei
Masters, 國立清華大學, 電機工程學系
2009

Abstract

時空碼 多天線收發 正交分頻多工 資訊傳遞演算法 space time block code MIMO OFDM message passing algorithm
It has been shown that space-time block coded orthogonal frequency-division multiplexing (STBC-OFDM) system is capable to achieve full diversity in MIMO detection. The STBC-OFDM system assumes a quasi-static block fading channel over the codeword. When the channel is fast fading, the assumption is no longer valid. The co-channel interference (CCI) and inter-carrier interference (ICI) in fast fading channel introduce severe performance degradation. Several ICI cancellation methods have been proposed. However, performances are still unsatisfactory even with considerable computation complexity. Recently, ICI selfcancellation methods are proposed. Although these methods can mitigate ICI efficiently, the techniques of ICI self-cancellation need to decrease the transmission rate or the bandwidth efficiency by 50 percents. In this work, we propose an interleaved message passing algorithm (MPA) with ICI cancellation for MIMO detection to achieve the CCI problem and reduce ICI jointly. The MIMO channel model is represented as a factor graph, and the co-channel MPA (CC-MPA) converges co-channel information with few inner iterations. An neighboring ICI cancellation (NIC) uses the prior information to reduce neighboring ICI effect with outer iteration. Interleaving channel structure can make CC-MPA obtain the received signal without ICI earlier. Moreover, we develope a SR-controller to skip unnecessary computations. The proposed scheme does not decrease any transmission rate or reduce the bandwidth efficiency. Significant BER improvement is achieved through few iterations. The simulation results show that the proposed scheme achieves near maximum likelihood sequence decoder error performance with low complexity for STBC-OFDM in fast fading channels.

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