Soft Output Detector for Convolutionally Encoded Parity Bit Selected Multicarrier Direct-Sequence Spread Spectrum System

In this paper the authors investigate the performance of the Parity Bit selected MultiCarrier Direct Sequence Spread Spectrum (PB-MC-DS-SS) system using Log Likelihood Ratio (LLR). In this system information bits are convolutionally encoded prior to being used in the parity bit selected MC-DS-SS system. Reliability of the detected bits in the receiver is calculated in the form of LLRs and then used as the input of a soft input Viterbi decoder. The performance of the proposed system is compared to conventional coded multicarrier spread spectrum systems where no parity bit selected spreading sequence is used.