MLP/BP-Based Soft Decision Feedback Equalization with Bit-Interleaved TCM for Wireless Applications

Terng-Ren HSU  Chien-Ching LIN  Terng-Yin HSU  Chen-Yi LEE  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E90-A   No.4   pp.879-884
Publication Date: 2007/04/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e90-a.4.879
Print ISSN: 0916-8508
Type of Manuscript: LETTER
Category: Neural Networks and Bioengineering
decision-feedback equalizer (DFE),  intersymbol interference (ISI),  multi-layered perceptron neural network with backpropagation algorithm (MLP/BP),  multi-path fading channel,  and trellis coded modulation (TCM),  

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For more efficient data transmissions, a new MLP/BP-based channel equalizer is proposed to compensate for multi-path fading in wireless applications. In this work, for better system performance, we apply the soft output and the soft feedback structure as well as the soft decision channel decoding. Moreover, to improve packet error rate (PER) and bit error rate (BER), we search for the optimal scaling factor of the transfer function in the output layer of the MLP/BP neural networks and add small random disturbances to the training data. As compared with the conventional MLP/BP-based DFEs and the soft output MLP/BP-based DFEs, the proposed MLP/BP-based soft DFEs under multi-path fading channels can improve over 3-0.6 dB at PER=10-1 and over 3.3-0.8 dB at BER=10-3.