Study On Bit Interleaved Coded Modulation

Coded Modulation technique is a hot issue in code field in recent 20 years. It appeared in 1982 when Ungerboeck proposed TCM theory. And then it apply widely soon. Coded Modulation technique is a way that combines coding technique with modulation technique to get coding gain in the instance of keeping the power efficiency and frequency efficiency but increasing the complexity of equipment. The performance of TCM over AWGN channel is perfect but it is bad over fading channel.There is an effective method to solve this problem that combines interleave technique with Coded Modulation to get the gain of performance over fading channel. This paper is about a new Coded Modulation technique——BICM (Bit Interleaved Coded Modulation) and BICM_ID (BICM with Iterative Decoding), and their performance of Bit Error Rate in different conditions.First, this paper analyses a BICM model and the BICM_ID model based on combination of convolutional code and 8PSK modulation, and introduces the principle and key technique. Second, this paper design the simulation scheme of BICM for comparing the performance over fading channel and AWGN channel that combine 2/3 rate, 4 states punctured convolutional code with 8PSK modulation, matching block interleave or random interleave, transform through Rayleigh channel or AWGN channel and use the way that combine coherent demodulation with Viterbi decoding in receiver. Design the scheme of BICM_ID that use the Iterative Decoding technique and the scheme of TCM for compare. We use the language C to design the simulation program running under Visual C++6.0.We compare the performance of BICM to TCM, the performance of BICM to BICM_ID and the performance of BICM using block interleave to that using random interleave over Rayleigh channel in simulation scheme. And compare the performance of BICM to TCM and BICM_ID over AWGN channel in addition. The simulation results show that BICM is better than TCM, BICM_ID is better than BICM when the second round decoding. the random interleave is better than the block interleave and the more deep interleave the more performance will be...