Optimized Irregular Variable Length Coding Design for Iteratively Decoded UltraWideBand Time-Hopping Spread-Spectrum Impulse Radio

Irregular Variable Length Coding Design for serial concatenated and iteratively decoded Time-Hopping (TH) Pulse Position Modulation (PPM) UltraWideBand (UWB) Spread-Spectrum (SS) Impulse radio system is considered. The proposed design is capable of low Signal-to-Noise Ratio (SNR) operation in Nakagami-m fading channel amalgamated with joint source and channel coding schemes. A number of component Variable Length Coding (VLC) codebooks with different coding rates are being utilized by IVLC scheme for encoding specific fractions of the input source symbol stream. The EXtrinsic Information Transfer (EXIT) charts are used to select these fractions in order to shape inverted EXIT curve of IVLC according to EXIT curve of the inner decoder match. The proposed scheme can achieve near-zero bit error ratio at low SNR values. This IVLC based scheme provides a gain of up to 0.45 dB over the identical-rate single class VLC based scheme.