IDMA Key Technology Of Communication System

Interleave-Division Multiple Access (IDMA) was recently proposed by Prof. Li Ping coming from the City University of Hong Kong. It originates from CDMA, so many advantages are inherited from CDMA technology. IDMA uses low rate code and uses random interleavers to separate different users. It removes the spreading sequences and allows a very simple chip-by-chip iterative TURBO MUD strategy. But the key issues technologies of the IDMA technology depend on the assumption that the receiver has known the exact channel information, while it is impossible in the practical communication system.In this paper, an IDMA simulation system on the platform of VC 6.0 was designed. It involves wireless channel model, transmitter which concludes repeat coding, BPSK modulating, random interleaving and receiver which consists channel estimation and iterative detection. In addition, we have a deep study on the channel estimation and the main works are listed bellow:(1) Based on EM algorithm, we propose a combination channel estimation approach. Furthermore, we compare the channel estimation performance of the extrinsic information feedback with that of the posteriori information feedback. We have the conclusion that channel estimation has better estimation result by the posteriori information feedback and we give the academic explanation.(2) Based on the superimposed training channel estimation, we present the optimal power allocation strategy by maximizing the effective signal-to-noise ratio. Furthermore, compared with the different power allocation strategies from the aspect of MSE, BER and channel capacity, the power allocation algorithm in this paper is effective.(3) We analyze the linear interpolation, Gaussian interpolation and cubic-spline interpolation algorithms based on the pilots under 3-path Jakes channel model. Then we give performance evaluation at different channel environment. Furthermore, the optimal interval design rule of the linear interpolation and the Gaussian interpolation is presented and the experiential value for the optimal pilot interval is also given from lots of simulation results.