Soft Metrics and EXIT Chart Analysis of Noncoherent MFSK with Diversity Reception

A convolutionally encoded noncoherent M-ary Frequency Shift Keying (MFSK) modulation scheme using diversity reception is considered. A novel technique of generating soft information for Soft Decision Decoding (SDD) of noncoherent MFSK is derived assuming various channel models. Furthermore, the convergence behavior of the MFSK receiver is investigated using Extrinsic Information Transfer (EXIT) charts. It is demonstrated that the expressions derived for SDD of the MFSK scheme are useful for exploiting the beneficial effects of diversity. We also demonstrate that EXIT chart analysis provides accurate insights into the system´s iterative decoding behavior.