Iterative switched-decoding for interleave-division multiple-access systems
Yi Hong, Lars Kildehoj Rasmussen · 2007
Abstract — We consider an interleave-division multiple-access (IDMA) system with multiple users transmitting over a shared additive white Gaussian noise channel. At the transmitter, the information sequence of each user is encoded by a low rate code, corresponding to the concatenation of a convolutional code and a repetition code. We propose an iterative partial decoding scheme, where a receiver only decodes parts of the joint concatenated repetition-convolutional code at the first few iterations, before progressively including more and more code structure into the decoding process. By decoding only parts of the concatenated code, the resulting extrinsic information transfer (EXIT) curve for the partially decoded code is different from the EXIT curve for the fully decoded code. To demonstrate the general scheme, we focus on an iterative switched-decoding scheme in which a receiver only decodes the repetition code at a fixed initial number of iterations, and switches to decode the entire joint repetition and convolutional code. It is shown by simulation that the proposed scheme guarantees fast decoding convergence at low decoding complexity. 1 I.