Interleave Design Of IDMA System And Some Relatively Analysis Of The Performance

IDMA is a kind of improved CDMA and distinguishes different users by their unique interleaves. IDMA has been a very competitive scheme for future mobile communications because of the better performance in reducing the MAI and low complexity in de-multiplex.IDMA is a kind of technology which is base on interleaves, so the design of interleave has become a hotspot in the IDMA research area. Traditional ways of IDMA interleave design whose main purposes are always to reduce the interleaves' storage and communication bandwidth utilization sometimes based on random interleaves which can't always guarantee a good performance. Although the algorithm introduced by Pupeza I has acquired a very good performance at the only-repeating code IDMA, it doesn't work well in convolution and repeating code IDMA. Through a deep study of the principal of IDMA system, firstly, we introduce a kind of matrix shift interleave design which can replace random interleave completely. And then a kind of improved interleave is proposed: HS-Chaos interleave which is generated based on chaos sequences. And then we compare it with the random interleave. Because of the importing of chaos sequence and S-spread distance, we can say that HS-Chaos interleave is a definite interleave with random character and is more suitable for convolution code IDMA system.There are five chapters in the paper. Firstly it introduces the background and the principal of IDMA. Then it describes 2 kinds of exiting interleave design in detail and gives simulations respectively. And at last we mainly illustrate a novel way of IDMA interleave design and show a large numbers of simulations. We can learn from the results that the matrix shift interleave is very good at saving storage space for the system while getting the same performance as the random interleave. In convolution code IDMA system and under the same simulation condition, HS-Chaos interleave performs better than the random one. As the user only needs to restore their initial value of chaos sequences and some mapping parameters, the storage space and bandwidth of interleaves don't increase so much as the number of users increases.