Mapping of Turbo Encoded bits with 64-QAM modulator for spectral efficiency in LTE

Abstract: In turbo-coded transmission systems, several ways of allocating the bits generated by the turbo encoder can be considered. Thus the bits generated by turbo encoder can occupy different positions in the modulator input symbol. In this paper, we have considered the performance of transmission systems, in terms of bit/frame error rate with respect to signal to noise ratio (BER/FER vs SNR) for both single binary turbo code of the LTE standard with coding rates 1/3 and 2/3 and also double binary turbo code of the DVB-RCS2 with coding rate 2/3. The simulation results show that different investigated allocation methods affect the performance of bit/frame error rate with respect to signal to noise ratio of the turbo coded system. The simulation result provides certain conclusions for the selection of best allocation methods, both in waterfall region and error floor region.

Keywords: turbo codes, modulation, QAM, LTE.