CAPACITY OF A CODED DIRECT-SEQUENCE SPREAD-SPECTRUM SYSTEM OVER FADING SATELLITE CHANNELS USING AN ADAPTIVE LMS-MMSE RECEIVER

This paper examines the performance of a direct sequence, spread spect rum (DSSS) multiple access (MA) system used over two typical, frequenc y-selective, fading satellite channels. In an attempt to increase the system efficiency, an adaptive receiver described by Rapajic and Vucet ic [1] has been implemented. This system has been combined with soft-d ecision convolutional coding in order to improve the system performanc e under the fading conditions relative to the uncoded system and to al low as many simultaneous users as possible. Various code rates have be en examined and the results are given. This paper specifically focuses on DSSS-MA systems with low spreading ratios. The satellite channels used in this paper were produced by models developed as a result of ex perimental measurements of fading satellite channels for rural and urb an environments.