Multi-dimensional EXIT analysis for iterative multi-user detection with unequal power allocation

A multi-dimensional extrinsic information transfer analysis of multi-power level multi-user detectors is proposed as a tool to better understand the convergence behavior of iterative decoding schemes. We develop a K dimensional EXIT chart in order to analyze a system with K power levels. We state a conjecture that predicts the convergence point of the system. We show through simulation our analysis closely matches the simulation results. The tools discussed here provides a new insight to receiver performance analysis and can be used to design near capacity achieving multi-user systems.