Optimal Spreading Mechanism with Different Modulation Techniques Using Random Interleaver in IDMA System

The Interleave-Division Multiple-Access (IDMA) scheme is known for property of orthogonality amongst its user-specific interleavers. The interleavers are, therefore, referred has the core heart of IDMA Transceivers. Now-a-days, the IDMA scheme is being thought as a strongest candidate for radio access in cellular mobile communication systems. It is attractive for wireless access due to its numerous advantages over TDMA, FDMA and CDMA and other multiple access schemes. In this paper, IDMA system is being simulated using random interleaver foe each user. On comparing various spreading techniques including repition, Gold code and Walsh code spreading, it is observed from simulation results, that the performance is almost similar for all the spreading mechanisms. However, from implementation point of view, repition spreading is concluded as optimum mechanism because it requires less memory, less computational complexity, easy implementation and also defines larger number of users as compared to Gold code and Walsh code for same spreading length. In this paper, the performance analysis of iterative IDMA receivers have been evaluated with BPSK & QPSK modulation techniques employing random interleavers in uncoded and rate ½ convolutional coded conditions with Additive White Gaussian Noise (AWGN) channel. During the simulation, it has been observed that IDMA system with QPSK modulation techniques employing QPSK outperforms its counterpart BPSK optimally.