A new soft metric for FH/DPSK systems with coding and diversity in the presence of partial-band noise jamming

A scheme is proposed to generate a soft metric based on L hard decision diversity outputs. The performance of this scheme is studied and compared with existing schemes. The target system used for investigation is a slow frequency-hopped differential phase shift keying (FH/DPSK) system in the presence of partial band noise jamming (PBNJ). It is shown that a significant improvement in L-diversity hard decision systems can be achieved. It is demonstrated that, by using the proposed soft metric, the almost ideal performance can be achieved for FH/DPSK systems in the presence of PBNJ without relying on any jammer state information; nor is optimization for quantization step size or threshold needed in order to achieve a satisfactory performance