Performance of Super-Orthogonal Convolutional Coding for Ultra-Wideband Systems in Multipath and Multiuser Channels

This paper investigates the application of super-orthogonal convolutional codes (SOCC) to a direct-sequence based ultra- wideband (DS-UWB) system under a realistic environment including inter-symbol interference (ISI) and multiuser interference (MUI). The effect of MUI and ISI on the performance of SOCC is analyzed by using both maximum ratio combining (MRC) RAKE receiver and minimum mean-squared error (MMSE) RAKE receiver followed by matched filter receiver. The analysis shows that in the case of employing simple MRC-RAKE receiver, the performance of SOCC is ffected by MUI and ISI because of the short length of the spreading sequence. In order to combat MUI and ISI, a code-hopping scheme is proposed in conjunction with SOCC. The results show that SOCC scheme outperforms the higher-rate conventional convolutional coded scheme for multipath and multiple access channels. Furthermore, the use of MMSE-RAKE receiver to suppress interference is analyzed and the subsequent increase of the system capacity is observed.

[1]  A. Viterbi.  CDMA: Principles of Spread Spectrum Communication , 1995 .

[2]  Pål K. Frenger,et al.  Code-spread CDMA using maximum free distance low-rate convolutional codes , 1998, IEEE Trans. Commun..

[3]  M. L. Welborn.  System considerations for ultra-wideband wireless networks , 2001, Proceedings RAWCON 2001. 2001 IEEE Radio and Wireless Conference (Cat.No.01EX514).

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

[5]  Andrew J. Viterbi,et al.  Very Low Rate Convolutional Codes for Maximum Theoretical Performance of Spread-Spectrum Multiple-Access Channels , 1990, IEEE J. Sel. Areas Commun..

[6]  Paul H. Siegel,et al.  A comparison of long versus short spreading sequences in coded asynchronous DS-CDMA systems , 2001, IEEE J. Sel. Areas Commun..

[7]  John G. Proakis,et al.  Digital Communications , 1983 .

[8]  P. Shaft,et al.  Low-Rate Convolutional Code Applications in Spread-Spectrum Communications , 1977, IEEE Trans. Commun..

[9]  Masoumeh Nasiri-Kenari,et al.  Performance analysis of time-hopping spread-spectrum multiple-access systems: uncoded and coded schemes , 2002, IEEE Trans. Wirel. Commun..

[10]  Wayne E. Stark,et al.  Performance of ultra-wideband communications with suboptimal receivers in multipath channels , 2002, IEEE J. Sel. Areas Commun..

[11]  Masoumeh Nasiri-Kenari,et al.  Low-rate convolutionally encoded time-hopping spread spectrum multiple access systems , 2000, 11th IEEE International Symposium on Personal Indoor and Mobile Radio Communications. PIMRC 2000. Proceedings (Cat. No.00TH8525).