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Improving The Performance of Turbo Code by Optimizing QAM Constellation  

Lee, Keun-Hyung (Department of Electronics and Computer Engineering, Chungnam National University)
Lee, Ji-Yeon (Department of Electronics and Computer Engineering, Chungnam National University)
Kang, Dong-Hoon (Department of Electronics and Computer Engineering, Chungnam National University)
Oh, Wang-Rok (Department of Electronics and Computer Engineering, Chungnam National University)
Publication Information
Journal of the Institute of Electronics Engineers of Korea TC / v.46, no.7, 2009 , pp. 39-44 More about this Journal
Abstract
It is well-known that the performance of turbo codes can be improved by allocating different energies per code symbol. In this paper, based on this observation, we propose a joint encoding and modulation scheme for quadrature amplitude modulated turbo code systems. In the proposed scheme, the amount of energy difference between the turbo coded symbols is optimized by optimizing the constellation of quadrature amplitude modulation (QAM). The proposed scheme offers better coding gain compared to the conventional combination of binary turbo code and QAM at the bit error rate of 10$^{-5}$. Also, the performance of binary turbo codes with the proposed QAM constellation for various code symbol mapping strategies are verified.
Keywords
터보 부호;직교진폭변조;성상도 최적화;
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