This paper examines the performance of a direct sequence, spread spectrum (DSSS) multiple access (MA) system used over two typical, frequency-selective, fading satellite channels. In an attempt to increase the system efficiency, an adaptive receiver described by Rapajic and Vucetic [1] has been implemented. This system has been combined with soft-decision convolutional coding in order to improve the system performance under the fading conditions relative to the uncoded system and to allow as many simultaneous users as possible. Various code rates have been 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 experimental measurements of fading satellite channels for rural and urban environments.

This paper presents a model for a wide-band fading channel for terrestrial mobile applications. The model is based on the results of measurements made in a heavily built-up urban environment using a 25 MHz signal centred at approximately 2.6 GHz. This paper presents measured impulse responses and details the parameter extraction process used to determine the characteristics of the channel. These parameters are used in the channel simulation package and the output of these simulations are compared to the original data.