Orthogonal convolutional modulation for UWB impulse radio communications

In the context of UWB (ultra-wideband) impulse radio, one of the challenges, for both high and low data-rate applications, is the design of an efficient coding/modulation scheme incorporating forward error correction (FEC) and spreading capabilities. In this paper, we introduce encoding strategies exploiting the trellis structure of orthogonal convolutional codes for generating time-hopping sequences suitable for UWB impulse radio and, at the same time, for mapping the information bits onto the transmitted waveforms. It is shown that this solution improves the Euclidean distance among transmitted signals, without decreasing the corresponding information rate.