Study On Antenna And Signal Design In Pulsed Ultra-wideband Communication Systems

This thesis studies the impacts of antenna systems and pulses on the bit error rate (BER) of ultra-wideband (UWB) communication systems, and the mutual interference effects between UWB and narrowband (NB) communication systems, then proposes two signal design methods to reduce the mutual interference.First, the impacts of antenna systems and pulses on the BER of UWB systems are investigated. The closed-form expression for the BER is derived, then the impacts of antenna systems and pulses on the BER of UWB systems are discussed theoretically and illustrated by simulation results. It is shown that, improving the processing gain corresponding to the antenna system and pulses can reduce the BER of the UWB system. Furthermore, enhancing the transmission efficiency of the antenna system, as well as the fidelity between the received and template pulses will improve the processing gain of the UWB system.Next, the interference effects of UWB signal on NB systems are studied. The expression of the signal-to-noise ratio (SNR) of the NB system is derived, and the influences of UWB and NB signal parameters on the SNR is discussed theoretically and illustrated by simulation results. The study shows that enhancing the transmission rate of the NB system, as well as the power spectral density (PSD) of the UWB signal in the bandwidth of the NB system, will result in the higher BER of the NB system.Then, the interference effects of NB signal on UWB systems are studied. The expression of the SNR of the UWB system is derived, and the influences of UWB and NB signal parameters on the SNR is discussed theoretically and illustrated by simulation results. The study shows that enhancing the transmission rate of the UWB system, as well as the PSD of the UWB signal in the bandwidth of the NB signal,will result in the higher BER of the UWB system.At last, two signal design methods are proposed to reduce the mutual interference between UWB and NB systems. The first method presents a class of time hopping (TH) codes and the method for selecting signal parameters, while the second method proposes the signal design to reduce the mutual interference independently of TH codes. Simulation results demonstrate that both methods can reduce the mutual interference effectively.