Family of time-hopping sequences with no-hit and few-hit zone for quasi-synchronous THSS-UWB systems

In this paper, based on the known frequency-hopping (FH) sequences and conventional time-hopping (TH) sequences, three sets of TH sequences with no-hit zone (NHZ) or few-hit zone (FHZ) are proposed. Different from conventional TH sequences design, the presented NHZ and FHZ TH sequences suitable for quasi-synchronous time-hopping spread spectrum ultra wideband (QS THSS-UWB) systems can be mutually orthogonal (or almost orthogonal) within NHZ (or FHZ). The QS THSS-UWB systems employing the proposed NHZ or FHZ TH sequences can eliminate or reduce multiple-access interference (MAI) and multipath interference when the shifts between sequences are in the range of NHZ (or FHZ).