A Novel Modulation Waveform on Ultra-Wideband Based Cognitive Radio Systems

Cognitive radio (CR) permits to satisfy the necessity of more efficiency in the radio spectrum occupation. An important task of CR is dynamic spectrum management of the transmitted signal to avoid the interference to/from the existent licensed in-band applications. We propose an adaptive modulation waveform for ultra-wideband (UWB) based CR systems in this paper. By controlling the time intervals between a series of impulses, the interference to/from the narrowband (NB) applications with different central frequencies can be suppressed. The proposed scheme can realize dynamic spectrum utilization in the UWB based CR systems without complex frequency processing of the traditional CR schemes. Hereby it can reduce the system complexity. We discuss the design algorithm of the proposed scheme and evaluate the coexistence performance of the proposed system with several NB applications by simulation. The simulation results certify that this adaptive modulation waveform is one of the good candidates for UJWB based CR schemes.