Channel shortening through bit error rate minimization for UWB systems

Ultra wideband (UWB) communication systems occupy huge bandwidths with very low power spectral densities. This feature make the UWB channels highly rich in resolvable multipaths. To exploit the temporal diversity, the receiver is commonly implemented through a rake. The aim to capture enough signal energy to maintain an acceptable output signal to noise ratio (SNR) dictates a very complicated rake structure with a large number of fingers. Channel shortening or time domain equalizer (TEQ) can simplify the rake receiver design by reducing the number of significant taps in the effective channel. In this paper, we present a TEQ design which minimizes the bit error rate (BER) of the system to perform efficient channel shortening in UWB systems. The performance of the proposed algorithm is compared with a generic TEQ design and other rake structures in UWB channels. It is shown that the proposed algorithm maintains a lower BER along with efficiently shortening the channel.

[1]  Koen Vanbleu,et al.  Bit Error Rate Minimizing Channel Shortening Equalizers for Cyclic Prefixed Systems , 2007, IEEE Transactions on Signal Processing.

[2]  Jianmin Zhang,et al.  Joint impulse response shortening for DMT transceivers , 2002 .

[3]  J. Foerster,et al.  Channel modeling sub-committee report final , 2002 .

[4]  Jinhong Yuan,et al.  Modified channel shortening receiver based on MSSNR algorithm for UWB channels , 2007 .

[5]  Vahid Tarokh,et al.  Channel-shortening multiuser detector for DS-CDMA systems , 2001, IEEE VTS 53rd Vehicular Technology Conference, Spring 2001. Proceedings (Cat. No.01CH37202).

[6]  Syed Imtiaz Husain,et al.  Single Correlator Based UWB Receiver Implemetation Through Channel Shortening Equalizer , 2005, 2005 Asia-Pacific Conference on Communications.

[7]  V. Srinivasa Somayazulu,et al.  RAKE performance for a pulse based UWB system in a realistic UWB indoor channel , 2003, IEEE International Conference on Communications, 2003. ICC '03..

[8]  N. Al-Dhahir,et al.  Efficiently computed reduced-parameter input-aided MMSE equalizers for ML detection: a unified approach , 1996, IEEE Trans. Inf. Theory.

[9]  Zhi Ding,et al.  Second-order statistical approaches to channel shortening in multicarrier systems , 2004, IEEE Transactions on Signal Processing.

[10]  Jinho Choi,et al.  Blind Adaptive Channel Shortening by Unconstrained Optimization for Simplified UWB Receiver Design , 2006, 2006 3rd International Symposium on Wireless Communication Systems.

[11]  William A. Sethares,et al.  A blind adaptive TEQ for multicarrier systems , 2002, IEEE Signal Processing Letters.

[12]  D. D. Falconer,et al.  Adaptive channel memory truncation for maximum likelihood sequence estimation , 1973 .

[13]  G. David Forney,et al.  Maximum-likelihood sequence estimation of digital sequences in the presence of intersymbol interference , 1972, IEEE Trans. Inf. Theory.

[14]  A.A.M. Saleh,et al.  A Statistical Model for Indoor Multipath Propagation , 1987, IEEE J. Sel. Areas Commun..

[15]  Charles E. Rohrs,et al.  Impulse response shortening for discrete multitone transceivers , 1996, IEEE Trans. Commun..

[16]  Changchuan Yin,et al.  Optimal impulse response shortening for discrete multitone transceivers , 1998 .

[17]  Antonio Cantoni,et al.  Properties of the Eigenvectors of Persymmetric Matrices with Applications to Communication Theory , 1976, IEEE Trans. Commun..

[18]  Jinhong Yuan,et al.  Rake Performance after Channel Shortening by Decay Factor Optimization in UWB Channels , 2007, 2007 IEEE 66th Vehicular Technology Conference.

[19]  Francis R. Magee.  A Comparison of Compromise Viterbi Algorithm and Standard Equalization Techniques Over Band-Limited Channels , 1975, IEEE Trans. Commun..

[20]  Richard K. Martin,et al.  Blind, adaptive channel shortening by sum-squared auto-correlation minimization (SAM) , 2002 .