Ultra Wideband Wireless Communication Systems Under Narrowband Interference and Noisy Environments

Ultra wide-band is considered to be one of the most promising short range wireless communication technologies. This is due to its high data rate capability, very fine time-domain resolution allowing for location and tracking applications, resistance to dense multi-path environment and jamming. Despite its enviable benefits, the unlicensed usage of a very wide spectrum that overlaps with the spectra of narrowband technologies brings about interference related concerns. Therefore, significant researches have been carried out to quantify the interference issue in both sides.;The thesis presents bit error rate analyses for impulse radio, when subjected to narrowband interference over Log-normal fading as well as the IEEE802.15.3a fading channel models.;We modeled the narrowband interference signal as the standard IEEE802.lla wireless local area network, which is considered one of the main threats to ultra wide-band communication systems. It is shown that the presence of narrowband interference signal can severely deteriorate the performance of impulse radio ultra wideband communication systems.;To this end, an interference canceller scheme is proposed and its average bit error rate performance is investigated in various channel models. The studied channel models are the additive white Gaussian noise, Nakagami-m, Log-normal flat and frequency selective fading channels in addition to the ultra wide-band channel models developed by the IEEE802.15.3a task group.;This thesis investigates the impact of in-band narrowband interference signals on the performance of impulse radio ultra wide-band communication systems and proposes a mitigation technique to solve such problem.;A noticeable performance enhancement to UWB communication systems can be achieved with the use of the interference canceller scheme. Specifically, for an average probability of symbol error equals to 0.05, the signal to noise ratio degradation is reduced to be less than 6 dB at bit error rate equals to 1 x 10-4 in AWGN channel. While in a Log-normal fiat fading channel, the degradation is less than 2 dB at bit error rate = 1 x 10-3. In the CM1 IEEE802.15.3a UWB channel model, the degradation is less than 3 dB at bit error rate equals to 1 x 10-3.;The effectiveness of all these analytical performance evaluations of the canceller scheme are supported by simulation. The performance of the proposed canceller scheme is also investigated in various scenarios of operation such as the presence of symbol timing error and the presence of multiple narrowband interference signals. The impact of multiple access interference on the performance of such canceller is also presented.;Finally, we gave a comparison with the performance obtained by using a "Notch filter" based case, characterized by different quality factors. The comparison is done in two scenarios: perfectly tuned and de-tuned notch filter.