Analysis Of Uwb Systems With Narrowband Interference And Coexistence

Interference and coexistence issues need to be carefully taken into account to guarantee the specified QoS for all existing radio services sharing the same spectrum. Impulse radio ultra-wideband signal isgenerated by sub-nanosecond pulses that spread the signal energy over an extremely wide frequency bandwidth. Since the working frequency band of UWB systems overlap with most of the other existing wireless systems, it is unavoidable to give rise to the mutual interference between UWB radios and narrowband systems nearby. Therefore, it is of great importance to solve the coexistence and compatibility problem before implementing commercial applications.Based on impulse ultra-wideband system, this thesis has a research on interference performance between UWB system and narrowband system. And smooth power spectrum density and adaptive pulse waveform design techniques were studied to reduce systems interfere with each other, improve spectrum utilization and achieve coexistence in this thesis. It mainly focuses on:(1)First of all, interference of multiple UWB systems on narrowband system was theoretical analyzed by using UWB system aggregate interference analysis methods. What's more, interference performance simulations of UWB systems on GSM900 and 802.11a WLAN system wad made under the FCC regulations limited and refer to the working parameters of both narrowband systems. The simulating results show that there will be a greater interference to the narrowband users when the UWB users reached a certain level.(2) And then, power spectral density of the DS-UWB signal model was analyzed and the relevant simulations of influence on discrete spectrum by different pulse repetition frequency and DS code were made. The simulating results show that smooth power spectrum will be improved by adjusting the pulse repetition frequency or selecting a different DS code. So that feasibility specific program was proposed to reduce the inference of UWB system to narrowband system.(3) Finally, under the UWB system platform of adaptive narrowband interference suppression based on CR technology, UWB transmitter pulse waveform was optimizing designed by using proposed adaptive pulse waveform algorithm which based on combination of Chirp pulse compression. The simulating results show that generated pulse waveform by the algorithm could meet the needs of different spectrum emission mask. By the way, the flexibility of UWB system against narrowband interference was increased and the coexistence between the UWB system and narrowband system was achieved.