The multicode interleaved DSSS system for high speed wireless digital communications

An intersymbol interference (ISI) free spread spectrum system, named multicode interleaved direct sequence spread spectrum (MCI-DSSS) system, is proposed in this paper. By combining the multicode direct sequence spreading and block interleaving together, this system is able to provide high-speed data transmission over severe multipath frequency-selective fading channel While the ISI is resolved by the orthogonality of the code set used in the multicode spreading, high degree path diversity is exploited to overcome the significant dispersion of the channel which may have a delay spread much longer than one bit duration, Another advantage of this MCI-DSSS system over conventional multicode and multicarrier systems is its higher power efficiency as constant envelope modulations can be applied to the binary MCI-DSSS baseband signal. The principle of the multicode interleaved direct sequence spreading and the MCI-DSSS system models are described. The selection of practical code sets in relation to the system structures is summarized and numerical results are given