Using Turbo Codes and Non-Gaussian Interference to Improve Spectral Efficiency in M-ary Optical CDMA Networks

摘要

We considers turbo-coded optical CDMA network transmission when single-user detection and single-user decoding are performed at the receiver. We use turbo codes, M-ary optical spreading codes and soft-decision demodulation to achieve very high spectral efficiencies over 0.4 bits per optical CDMA chip. In particular, we consider recently-proposed M-ary OCDMA transmission with non-equiprobable chips. We observe for this approach that the multi-user interference has a strongly reduced and uniquely non-Gaussian structure. Consequently, we propose a novel soft-decision single-user optical CDMA signal detector that takes advantage of this specific interference structure. We also present simulation results of a turbo-coded M-ary OCDMA network transmission that allows above mentioned spectral efficiencies.