Improving the transmission efficiency in the mobile communication systems using turbo codes

This paper applies a variable rate scheme based on rate compatible punctured turbo (RCPT) codes in mobile communication system. This system has been used in Abou-El-Azm and Mohammed (1999) with rate compatible punctured convolutional (RCPC) codes. Turbo code with variable rate is suggested here to improve the transmission efficiency and the performance of the system. We have obtained better results of transmission efficiency and a significant power saving making use of the advantage of RCPT codes compared with the results published in Abou-El-Azm amnd Mohammed. The transmission efficiency is improved by 55.5% and the desired level of BER=10/sup -3/ is sharply reached at E/sub b/N/sub 0/=0.5 dB, however with using RCPC codes, this level is reached 3 dB later on the AWGN channel. Considering the Rayleigh channel, the desired level is reached at E/sub b/N/sub 0/=2 dB using RCPT codes, while it is reached at 6 dB with RCPC codes. The maximum transmission efficiency using RCPT codes is achieved 4 dB and 12 dB lower than RCPC codes on the AWGN and Rayleigh channels respectively.