Serial concatenation schemes for PSK waveforms vs. turbo codes

Abstract

For radio communication systems, powerful error correction codes are necessary to operate in noisy and fading channel conditions. Iterative forward error correction schemes like Turbo codes can achieve near Shannon capacity performance on memory-less channels and also perform well on correlated fading channels. The key to the excellent decoding performance of the Turbo coding systems is the BCJR algorithm in conjunction with the iterative processing of soft information. A very popular modulation technique is Differential Phase Shift Key (DPSK) which is not only a simple non-coherent modulation and demodulation technique; it is also a recursive rate one code. Combining DPSK with a single convolutional code structure as an iterative inner outer forward error correction system can provide excellent Turbo like performance. Bit Interleaved Coded Modulation with Iterative Demodulation (BICM-ID), another powerful iterative technique achieves near Turbo code performance with significantly less mips. We will also introduce and compare with the latter systems yet another novel iterative scheme that utilizes coherent demodulation in conjunction with convolutional codes. This new system can easily be extended to higher order modulations such as 16 and 64 Quadrature Amplitude Modulation (QAM) while only requiring modest amounts of processing power. Monte Carlo simulation results will be shown for the Additive White Gaussian Noise (AWGN) channels.