Improved BDFE Using A Priori Information for Turbo Equalization

Abstract-- Turbo equalization improves communication system performance by iteratively exchanging information between soft-input soft-output (SISO) equalizer and SISO channel decoder. The trellis-based maximum a posteriori probability (MAP) algorithm serves as the optimum SISO equalizer for turbo equalization. However, MAP algorithm is unsuitable for systems with large modulation constellation size and severe inter-symbol interference (ISI) due to its prohibitively high computational complexity. In this paper, an improved SISO block decision feedback equalizer (BDFE) is proposed for low complexity turbo equalization. Unlike other sub-optimum equalizers which perform symbol by symbol detection, the proposed equalizer generates the soft output for each data bit by collecting information from a sequence of samples as in MAP algorithm. The sequencebased equalization is enabled by using not only soft a priori input from channel decoder, but also hard a priori information obtained from BDFE ...

• Type: Journal
• Year: 2008
• Where: TWC
• Authors: Jingxian Wu, Sang-Yick Leong, Kah-Ping Lee, Chengshan Xiao, Jan C. Olivier
• Keywords: Algorithm, MAP Algorithm, Turbo Equalization, TWC 2008