Research And Applications Of Pulse Random Jitter Spectrum Smoothing Technique In IR-UEB Systems

Impulse Radio Ultra-wide Band (IR-UWB) is a wireless radio communicationtechnology, which uses some low duty cycle narrow pulses as information carriers totransmit the users’ information. IR-UWB system has many unique advantages, such as ahigher data rate, the lower power and system complexity, so IR-UWB technology shows abroad application prospects in many fields.IR-UWB signal occupies a large frequency bandwidth which shared with othernarrow-band systems, so it will inevitably affect the normal work of narrow-band radiocommunication systems. The results of traditional UWB interference analysis show thatUWB signals have a feature as a low noise floor in a very wide frequency bandwidth,however, the study in recent years shows that IR-UWB transmitted signal contains a largenumber of discrete peaks, which have a higher power more than the continuous spectralcomponents in the Power Spectrum Density (PSD) of IR-UWB signals, so once thesediscrete peaks captured by narrow-band receiver, the narrow-band system will suffer agreater interference. In addition, in order to avoid these high amplitudes of discrete peaksexceeding the limit of FCC Mask, the transmitter had to reduce the overall transmittedpower, resulting in many unfavorable factors, such as, a lower system spectrum utilization,a poor reliability of information transmission and a shorter communication distance.Therefore, under the restrictions of FCC Mask, it has become a major challenge that howto smooth power spectrum of the transmitted signal and how to improve the transmittedpower in IR-UWB systemsTraditional IR-UWB signal power spectrum smoothing program primarily focused onthe design and optimization of PSD by using spread spectrum technology of TimeHopping (TH) and Direct Sequence (DS). However, the TH technology needs an extratime slice to make the radiation pulse have a distribution random jitter, and DS technologyalso needs a longer time for encoding users’ information. Thus, it will affect thetransmission rate of users’ information and system implementation complexity.To solve these problems, this paper presented a novel solution, which called pulsejitter spectrum smoothing technique, to smooth the signal power spectrum of IR-UWBtransmitted signals, which can be used for the application of IR-UWB communicationsystems. Pulse jitter spectral smoothing technique can smooth power spectrum oftransmitted signals by using one or more random variables to modulate the frequency, phase and other parameters of pulse carrier in order to achieve random jitter of pulsecarrier. Because it does not change the time location of pulse and doesn’t need additionalinformation coding and detecting or removing the random jitter of transmitted pulses inthe energy detection receivers of IR-UWB systems, it has a lower system complexity andhigher data rate. This paper studied the basic principle of pulse jitter spectrum smoothingtechnique through theoretical analysis and computer simulation, and the result showed thatpulse jitter spectrum smoothing technique can optimize the power spectrum signature andtransmitted power of IR-UWB transmitted signals. Then, the pulse jitter spectrumsmoothing technique was applied into the Code-Shifted Reference IR-UWB system, andthe final result of theoretical analysis and computer simulation showed that the systemperformance of Code-Shifted Reference IR-UWB system was improved well.