Soft-limiter receivers for coded DS/DPSK systems

The performance of a soft-limiter metric and a quantized soft-limiter metric is evaluated for coded DS/DPSK (direct sequence/differential phase shift keying) in the presence of worst case pulse jamming and background noise. The metrics are easy to implement and do not require jammer state information. Instead they rely on the use of receiver thresholds, which must be adjusted according to the code rate and the received bit-energy-to-background-noise ratio. The performance of the metrics is evaluated by using the cutoff rate criterion and a number of specific convolutional and block codes. It is shown that the metrics can offer a significant soft-decision decoding gain and can perform to within 0.5-1.5 dB of the maximum-likelihood soft-decision metric with perfect jammer state information.<
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