Performance of a nonlinear adaptive SBS-MAP detector usingsoft-statistics for digital transmissions over HF channels

The effectiveness of the adaptive maximum a posteriori (MAP) receiver in Cusani and Mattila is verified for digital HF links between mobile and/or fixed units. Following Cusani and Mattila (1998), a suitable MAP algorithm is employed to compute symbol-by-symbol (SBS) the a posteriori probabilities (APPs) of the channel state; from these, the detected data stream is obtained. The same APPs are employed by an adaptive nonlinear Kalman-like filter to estimate recursively the time-varying channel with fast convergence and good tracking properties, overcoming the delay problem suffered by conventional adaptive MLSE-VA detectors. Computer simulations allow to compare the adaptive SBS-MAP with other receivers (DFE, MLSE) and verify its effectiveness in the HF environment