Interleave-division multiple access (IDMA) using low-rate layered LDGM codes

We propose the use of low-rate layered LDGM codes to approach the capacity of the AWGN multiple access channel (MAC). To support a high number of users, iterative soft-interference cancellation (SIC) is used at reception. For optimum performance, we design the channel codes to match the extrinsic information transfer (EXIT) function of this detector, which varies with the number of users and modulation format. Simulation results show that the designed codes effectively approach the theoretical limits, outperforming previous IDMA schemes based on turbo-Hadamard codes.