Ternary complementary sets for multiple channel DS-UWB with reduced peak to average power ratio

Abstract

We study a multiple channel direct sequence ultrawideband (DS-UWB) system which transmits the same information bit over a set of parallel channels corresponding to a set of orthogonal pulses. It is known that by employing a mutually orthogonal (MO) ternary complementary set of spreading sequences, one can efficiently suppress both multipath and multiuser interference. Similar to a multicarrier DS-CDMA system, the multichannel DS-UWB system can have a high peak to average power ratio (PAPR) which may limit its application. In this paper, we analyze the PAPR of the multichannel UWB system by studying its upper bound. The bound illustrates how column sequences of MO complementary set matrices with small out-off-phase aperiodic autocorrelation functions (ACF) allow for lowering the PAPR. Hence, we develop an algorithm to construct the spreading sequence sets which may result in data sequences with reduced PAPR, while at the same time, preserving the complementarity and orthogonality which alleviate the multipath and multiuser interference.