Research On 64-QAM PTCM And Its Implementation Based On FPGA

The error correcting coding and modulation are designed and implemented respectively in the traditional digital transmission system, the same to decoding and demodulation. In the early 80s, Ungerboeck introduced a new viewpoint, named as Trellis Coded Modulation (TCM), according to the character of modulation /demodulation and error correcting coding. Its basic idea is to adopt encoding method to partition the constellation optimally, so that the maximal distance between the modulated signal vector can be obtained. At the same time, it adopts enough signal vectors to ensure ratio of information transmission. Therefore, it can decrease the code error rate in the receiving terminal without bandwidth expansion. Pragmatic TCM, derived from the punctured codes, can implement different configurations of TCM using an "industry standard"64-state, rate 1/2 convolutional code, it decreases the decoder complexity and increase its general utility in the "wireless Internet". Firstly, this paper dose some research on the principle of TCM ,PTCM and the ACG for coded 64-QAM compared with uncoded 16-QAM in two ways. Secondly, the author simulated BER for uncoded 16-QAM and coded 64-QAM in AWGN. The effect of difference in truncation window length and quantization on the performance is taken into account. The important conclusion was reached from the simulation results .The remainder of the paper deals with the implementation of 64-QAM PTCM based on FPGA. The Viterbi algorithm, in which soft decision decoding is implemented, is studied as the key part in this paper.