Optimization of spread spectrum systems by cascaded coding

This paper considers methods to reduce the capacity loss of an asynchronous random access spread spectrum (SS) channel. The advantages of the cascaded codec which includes an internal SS codec and a two stage external codec are discussed. It is shown that to improve the performance of a SS channel considerably higher code rates of the internal codec are required and the optimized threshold algorithm (OTA) of decoding in the external codec should be used both with the hard and soft decisions.