Decision-Feedback Differential Detection in Impulse-Radio Ultra-Wideband   Systems
  In this paper we present decision-feedback differential detection (DF-DD) schemes for autocorrelation-based detection in impulse-radio ultra-wideband (IR-UWB) systems, a signaling scheme regarded as a promising candidate in particular for low-complexity wireless sensor networks. To this end, we first discuss ideal noncoherent sequence estimation and approximations thereof based on block-wise multiple-symbol differential detection (MSDD) and the Viterbi algorithm (VA) from the perspective of tree-search/trellis decoding. Exploiting relations well-known from tree-search decoding, we are able to derive the novel decision-feedback differential detection (DF-DD) schemes. A comprehensive comparison with respect to performance and complexity of the presented schemes in a typical IR-UWB scenario reveals---along with novel insights in techniques for complexity reduction of the sphere decoder applied for MSDD---that sorted DF-DD achieves close-to-optimum performance at very low, and in particular constant receiver complexity. 
Andreas Schenk and Robert F.H. Fischer
cs.IT math.IT