Performance of a nonlinear adaptive SBS-MAP detector using soft-statisticsfor digital transmissions over HF channels

The effectiveness of the recently proposed adaptive Maximum A Posteriori (M AP) receiver in Cusani and Mattila is verified for digital HF links between mobile and/or tired units. Following Cusani and,Mattila, a suitable MAP al gorithm is employed to compute Symbol-by-Symbol (SBS) the A Posteriori Prob abilities (APP's) of the channel state; from these, the detected data strea m is obtained. The same APP's are employed by an adaptive nonlinear Kalman- like filter to estimate recursively the time-varying channel with fast conv ergence 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 it s effectiveness in the HF environment.