Density Evolution Analysis of Turbo Product Codes

摘要

Turbo product codes (TPC) are a promising approach for power- efficient communications, particularly in satellite and terrestrial wireless systems. These codes use an iterative decoding method similar to turbo codes. TPCs have been shown to have a bit error rate (BER) performance within a couple of dB of turbo codes without the error floor, however other performance measures of turbo product codes are not well developed. This thesis applies the Extrinsic Information Transfer (EXIT) chart analysis, developed for turbo codes, to turbo product codes. The EXIT chart analysis allows for examination of the evolution of the probability densities of the information passed from iteration to iteration of the decoder. The analysis begins with the EXIT chart analysis for two-dimensional TPCs, similar to the turbo code results, and then extends the analysis to three-dimensional TPCs. Binary phase-shift keying (BPSK) and Gaussian minimum-shift keying (GMSK) modulations are examined in both an unfaded additive white Gaussian noise (AWGN) as well as Rayleigh faded channel. In addition, BER results are predicted in the low E (sub b)/N (sub o) region, convergence thresholds determined, and lastly a new code construction for a rate 1/2 TPC is designed.