Convergence analysis of iterative detectors for narrow-band multiple access

Convergence analysis of iterative detectors for narrow-band multiple access is performed using extrinsic information transfer charts. The system has no bandwidth expansion, so K users use the same bandwidth as a single user. The load (the number of bits used per channel) of the system is therefore higher than the load in, for example, conventional CDMA systems. The analysis provides useful guidelines on how to combine outer codes with the chosen mapper for different loads of the system. Both memoryless mappers and differential mappers are evaluated. We present the limitations of the system measured with the maximum number of users and the required SNR for different scenarios.