Extrinsic Information Transfer Charts for Narrow-Band Multiple Access

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