Error protection using PUM codes for future mobile communication systems

Mobile communication systems require error control techniques that improve the link performance in hostile mobile radio environments. The mobile radio channel is particularly dynamic due to multipath fading and Doppler spread. These effects have a strong negative impact on the bit error rate (BER) of any modulation technique. This paper introduces systematic partial unit memory turbo codes (SPUMTCs) as a means of improving the BER in such channels and can be used in conjunction with equalization schemes producing soft information. An iterative maximum a posteriori (MAP) decoding scheme is suggested for multistage trellises. The performance of the SPUMTC is measured and compared to that of the well-established recursive systematic convolutional turbo code (RSCTC) in flat Rayleigh and Ricean fading channels using BPSK modulation. Simulation results show that SPUMTCs have comparable performance to RSCTCs in flat fading channels.