Study on parameter estimation based on IDMA transmission system
|School||University of Electronic Science and Technology|
|Course||Communication and Information System|
|Keywords||Channel Estimation Time Bias estimation IDMA EM algorithm Multi-user Iterative Detection|
As a newly developed multiple access technique, interleave division multipleaccess(IDMA) has it’s unique advantages. Now IDMA has become one of thecandidate of the4-th generation mobile communication. Research towards IDMA hasalso become a hot issue these years.IDMA uniquely outperforms CDMA in terms of spectral efficiency, maximizedcoding gain and simplification of receiver architecture, because of which, IDMA hasbeen widely focused in acadermia. Great achievement has been made in research towardsome critical technich of IDMA, such as the design of the interleaver, multi-userdetection algorithm, power allocation and so on. However, all of the achievementsabove are based on the assumption that the receiver has known channel stateinformation. On the other hand, among the research topics on IDMA, the uplinksynchronization is always a difficult problem. This article will focus on the parameterestimation in IDMA systerm.The multi-user detection algorithm of IDMA is a kind of iteration algorithm, which isquite similar with EM algorithm. This article will give a new mode of parameterestimation method which will combine IDMA with EM algorithm: channel state andsynchronization parameter estimation based on EM algorithm in the IDMA systerm.We have established an asynchronous IDMA systerm to study the effect of samplingbias. In the systerm, each user has individual randomly produced time bias parameter,which is used to study the bit error rate performance of the systerm. In theory, thesampling bias will bring ISI and multi-access interference to the iterative detectionalgorithm, because of which, the performance of the systerm will be worse than theideal situation. The simulation result has proved it.The main research of this article is the estimation of synchronization patameter andchannel state combining with the iterative multi-user detection of IDMA. Simulationresults indicated that the performance of our systerm is close to the ideal systerm, both of which has low bit error rate.The estimation of parameters in IDMA systerm is a complex issue, we have a longway to go to lead IDMA to a mature technich.