Reverse CDMA link based on noise-like spreading sequences and fading mitigation

Abstract

This paper presents a theoretical model of a reverse CDMA link that uses noise-like spreading sequences in the case when AWGN and flat fading are present in the channel. It is known fact that the fading can be mitigated by the use of a block interleaver/deinterleaver structure. However, how to mitigate fading in a CDMA link that uses noise-like spreading sequences is not investigated and reported yet. For the proposed model, the expressions for the probability of error are derived and compared with the previously derived expression for the system that uses binary and non-binary chaotic sequences. It was shown that the degradation in the BER performances of the CDMA system in the presence of fading can be reduced applying interleaver/deinterleaver blocks to be close to the level of AWGN influence.Theory. KeywordsNoise based CDMA, probability of error derivation, non-binary spreading sequences, noise-like sequences.