The Research Of Ultra Wideband Communication System Based On Chirp Signal

With the development of wireless communication technology, the wide band signal made a great significance in communication history. The emergence of Ultra Wideband was an inevitable phase of the progress. Because of high data rate, low power consumption, unfadable, difficult to capture and penetrating effect, the UWB system has a batter property in dwelling house, medical and industry environment. The chirp signal has been used in RADAR system with its resistance of interference, Doppler Effect and multi-path fading. Shift the chirp signal in UWB system was already been an aspect in the researching field. The chirp signal will be the new candidate of the UWB system with the exception of 1R-UWB, DS-CDMA & MB-OFDM. The novel works are as follows:1. A new method based on the Chirp Signals compression is proposed for the design of the Impulse Radio UWB pulse waveform. Based on the compressibility of the chirp signals passed matched filter and the linearity of the Fourier transform, a new UWB pulse is obtained by superposition of the compressed pulses from different central frequency Chirp signals.2. Research the modulation schemes of Chirp UWB, including binary orthogonal keying (BOK), quaternary bi-orthogonal keying (QBOK), binary phase shift keying (BPSK) andπ/4 differential quaternary phase shift keying (π/4DQPSK). The power spectrum density of these schemes are derived and verified, and their bit error rates are also studied. Proposed a new scheme that the signal envelops could be reshaped by window function. The scheme would depress signal side lobe which could affect the bit error rate.3. Multi-access scheme for Chirp UWB was discussed. Frequency hopping multi-access by pseudo random sequence, multi-slope access and chirp code divide multi-access.4. Real time analog SAW Chirp-Fourier transform devices are adopted to replace the DSP part. According to the parameters of the MB-OFDM UWB system, a MB-OFDM UWB receiver scheme based on the 100% duty cycle M-C-M SAW Chirp-Fourier transform is proposed and the step of signal transformation from input signals is also depicted.5. The chirp-UWB signal source had been designed and realized by using DDS plus PPL. By using stable and high AD converting speed DDS chip, we can obtain the high quality signal by using DDS with PLL. The signal is utly flexible by the programmable of DDS chip. KEY WORDS:UWB,Chirp signal,CFT,DDS...