UWB signaling for CR and coherent receivers and localization with weak received signals

Pulsed ultrawideband (UWB) signaling is widely used in indoor localization networks, in which data communications often occur concurrently. The receivers in such a network often have different complexity, performance, and energy consumption requirements. The goal of this paper is to design a coded-reference (CR) UWB scheme that enables simultaneous data transmission and high-precision localization while receivers with different performance and complexity requirements can flexibly choose their own operation modes. We start with the Barker codes and construct a set of orthogonal codes for CR signaling; compared with existing schemes, these codes have the desired autocorrelation properties required for high-precision timing extraction when the received signal is weak (transmission over a long distance). We also modify an existing hybrid coherent-transmitted-reference modulation format and apply the orthogonal codes designed so that both coherent and CR receivers can demodulate the same transmitted data while the fine-timing information required for high-precision localization is carried inherently in the transmitted signal. Timing synchronization and error performances of the proposed system are analyzed and simulated.