A comparison of trellis coded versus convolutionally coded spread-spectrum multiple-access systems
- 1 May 1990
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Journal on Selected Areas in Communications
- Vol. 8 (4), 628-640
- https://doi.org/10.1109/49.54459
Abstract
A system model is proposed that allows one to apply both trellis coding and PN spreading sequence to the data symbols to be transmitted. Rate n/n+1, trellis codes using 2n+1-point MPSK signal constellations are investigated when Gold sequences are used for PN spreading. Performance in an additive white Gaussian noise (AWGN) channel is investigated, with 5-20 users transmitting simultaneously. Using the criteria of equal complexity and throughput, the performance of the trellis codes in a SSMA (spread spectrum multiple access) environment is compared to that of medium-rate to low-rate convolutional codes through the use of a generalized transfer function bound. The average degradation due to the interuser interference is determined by the method of moments. The validity of approximating the interuser interference as a Gaussian random variable is also investigated. The numerical results illustrate that for a given complexity, chip rate and throughput, low-rate convolutional codes provide the best performance in an SSMA system. As lower-rate convolutional codes are used, there is an increase in the effective interuser interference due to the greater cross-correlation effects from using shorter PN sequences, or alternatively from the effects of partial cross-correlation. However, this increased degradation is more than overcome by the increased distance properties of the low-rate codesKeywords
This publication has 17 references indexed in Scilit:
- On the performance evaluation of trellis codesIEEE Transactions on Information Theory, 1987
- Trellis Coded Modulation for 4800-9600 bits/s Transmission Over a Fading Mobile Satellite ChannelIEEE Journal on Selected Areas in Communications, 1987
- Direct-Sequence Spread Spectrum with DPSK Modulation and Diversity for Indoor Wireless CommunicationsIEEE Transactions on Communications, 1987
- Trellis Coding with Asymmetric ModulationsIEEE Transactions on Communications, 1987
- Performance of Low-Complexity Channel Coding and Diversity for Spread Spectrum in Indoor, Wireless CommunicationAT&T Technical Journal, 1985
- Bit Error Rate Evaluation for Spread-Spectrum Multiple-Access SystemsIEEE Transactions on Communications, 1984
- High-Level Modulation and Coding for Nonlinear Satellite ChannelsIEEE Transactions on Communications, 1984
- Partial Correlation Effects in Direct-Sequence Spread-Spectrum Multiple-Access Communication SystemsIEEE Transactions on Communications, 1984
- Computing the Distribution of a Random Variable via Gaussian Quadrature RulesBell System Technical Journal, 1982
- Channel coding with multilevel/phase signalsIEEE Transactions on Information Theory, 1982