LOW COMPLEXITY GENERALIZED PUNCTURED CONVOLUTIONAL CODES FOR OFDM-CDMA BASED MOBILE RADIO COMMUNICATIONS

摘要

In this paper, a novel method of Generalized PuncturedrnConvolutional Codes (GPCC) is investigated forrnOrthogonal Frequency Division Multiplexing (OFDM)rnand Direct Sequence CDMA based future mobile radiornand wireless communications. The GPCCs show betterrnperformance due to the fact that they have reduced trellisrncomplexity. The trellis complexity is directly proportionalrnto the decoding complexity. A minimal and flexible GPCCrntrellis module is developed for the mobile radiorncommunications. It is based on the trade off between trellisrncomplexity and performance requirements by mobile radiornapplications. We have computed some of the lowrncomplexities of GPCC. OFDM based CDMA has inherentrnproperty to combat Inter Symbol Interference (ISI). Wernhave used GPCC for OFDM-CDMA and subsequentlyrnexamined the performance of the system in terms of bitrnerror rate. Our results show an improvement in thernperformance of radio communication. The performancernimprovement is observed ranging from a little over 1% torn10% or more depending upon the code rate selected. Atrnthe end we also analyse the flexible rate selection forrnGPCC so that the better channel utilization and efficiencyrncan be achieved. The flexible rate is particularly suitablernfor varying channel conditions.