Self-encoded spread spectrum and multiple access communications

Spread spectrum and code-division multiple access systems traditionally have employed deterministic pseudo-random sequences for signal spreading and de-spreading. Although random sequences have often been used for the purpose of analysis, they cannot be practically implemented because data recovery at the receiver requires a knowledge of the sequences that have been generated in the transmitter. We present a novel spread spectrum communication system for secure transmissions of digital information. The approach is based on the unconventional self encoding principles that we have developed for the modulation and detection of spread spectrum signals. The proposed system does not use pseudo-random codes, and is unique in that traditional transmit and receive code generators based on maximal-length sequences of chaotic signals are not needed. In fact, the enhanced transmission security arises not only due to the spread-spectrum nature of the signal, but also from the stochastic nature of the unique spectrum spreading and de-spreading processes. This paper describes the self-encoded system and presents the theoretical and simulation results of the system performance in additive-white Gaussian noise and Rayleigh fading channels. We discuss the application of self-encoded spread spectrum to multiple access communications.