Study On Turbo-MTCM Scheme

Turbo-TCM is a bandwidth-efficient coded-modulation scheme, which has near-capacity performance on the AWGN channel. It has an overall structure similar to binary Turbo codes, but employs Trellis Coded Modulation (TCM) codes as component codes. However, the performance of TCM on the fading channel is not as good as that on the AWGN channel, as the Hamming distance and the product distance of symbol are not taken into account in the design of TCM. Therefore, a trellis coded-modulation technique referred to as Multiple Trellis Coded Modulation (MTCM) is proposed wherein more than one channel symbol per trellis branch is transmitted, so it can achieve better performance on the fading channel than TCM. Besides, MTCM can obtain performance gain over TCM with the same number of trellis state and spectrum efficiency. Accordingly, we propose a novel coded-modulation scheme, which is a combination of Turbo codes with MTCM, called Turbo-MTCM, and expect it to achieve more performance gain relative to Turbo-TCM.The primary principles of TCM and Turbo-TCM are introduced, and the methods for the design of MTCM which can achieve optimum performance on the fading channel and the AWGN channel discussed respectively. Based on this, the preliminary theory of the encoding and decoding of Turbo-MTCM are put forward, followed by an analysis of the problem to realize the scheme: the design of feedback encoder for MTCM. Thus, the recursive representation of convolutional codes together with the design principle of the component codes of CT-TCM are studied for reference. According to this, the encoder of Turbo-MTCM is designed. Finally, the simulation results of Turbo-TCM and Turbo-MTCM on the AWGN channel and the fading channel are presented. As a result, research work which remains to be studied further is analyzed.