Based Turbo Coded Iterative Multiuser Detection Techniques

Multiple access interference and multi-path fading are major impediment to approach excellent performance. Multi-user detection (MUD) and turbo coding are two of the most powerful techniques for enhancing the performance of next generation wide-band code-division multiple-access (CDMA) systems.In this paper, traditional techniques of MUD and Turbo channel coding/decoding are studied first, then some research on iterative MUD are been done. Iterative MUD is a successful application in MUD domain, by joint iterative of MUD and channel decoding, it could enhance the performance of the system. Following, it analyses the iterative structure in MUD, introduces the techniques and development of MUD, studies two kinds of SISO MUD algorithm based on soft MMSE interference cancellation and instantaneous linear MMSE filtering and de-correlating decision feedback ,it analyses the SISO Turbo channel decoding algorithm which makes some improvement in MAP algorithm. The simulation implements the joint iterative of SISO MUD which consists of soft interference cancellation and linear MMSE filtering and SISO channel decoding using MAP algorithm, and compare the performance of iterative MUD in different parameter.Simulation results show that iterations of the system are used to attain large performance improvements that are close to single user performance and to reduce the influence of 'near-and-far'.