New Soft-decision Decoding Techniques for Adaptive Decision-Feedback Differential Detection

In this paper, two soft-decision decoding techniques for decision-feedback differential detection (DF-DD) scheme using adaptive linear prediction with maximum ratio combining (MRC) diversity are proposed. These techniques can contribute to considerably reduce the irreducible error floor due to the Doppler spread in a mobile multi-path fading. Error propagation of conventional DF-DD can be corrected by adaptive linear prediction technique. Combined MRC diversity and adaptive DF-DD can produce performance gain compared to conventional DF-DD with MRC diversity. Furthermore, this paper proposes two new applications in soft-decision decoding which overcomes the limitation that DF-DD could be used only in the hard- decision based system. The BER performance is investigated by computer simulations in the time-varying Typical Urban (TU) fading channel.