Research On Key Techniques And Implementations Of Impulse Radio Ultra Wideband Transceiver

The Federal Communications Commission(FCC) has approved the use of the unlicensed band with the frequencies ranging from 3.1 GHz to 10.6 GHz in the commercial ultra-wideband(UWB) wireless communication systems. This invoked a surge in research on the UWB communication technology. Impulse Radio UWB(IR-UWB) is a promising UWB communication technique having a simple architecture. In the IR-UWB systems, short duration pulses are usually adopted as exciting signals. In the meanwille, high cost, high power consumption, great size and so on are the difficult problems of UWB. Especially for a large number of mobile terminal equipments using and meeting the needs of all types of personnels and equipments, including portable wearable device requirements. Therefore, the cost and power consumption requirements are indeed demanded. Some studies have been done for practical applications of IR-UWB technique.1. Concerned with the timing and synchronization for impulse radio-ultra wideband(IR-UWB) communication and positioning system, we improved the traditional sliding correlation algorithms and proposed a novel synchronization algorithm based on quadratic enveloping. Get the quadratic enveloping of correlation output firstly, then establish a fine synchronization interval based the center of the highest point of quadratic enveloping, do sliding correlation in the fine synchronization and take the peak point to estimate time delay.The simulation results show that the algorithms have good synchronization performance while reduce the number of integrator branch significantly, has very strong practicability.2. A compressive sensing reconstruction algorithm based on the minimization of the smooth approximation to the zero norm estimation: SALZ(Smooth Approximate0 l norm) algorithm is proposed. The approximate function of this algorithm has a very steep descent rate near the most advantage. In the ideal case, the convergence speed is very fast. In two or three steps, we can approximate the optimal solution with high accuracy when we have get the results close to the optimal solution. Finally, the SALZ algorithm is compared with the LASSO algorithm by some simulations formwhich we can find the SALZ's computational complexity is lower than LASSO, and the performance is better than LASSO also.3. Compressive sensing(CS) usually provide a feasible way to reduce the sampling speed of ultra-wideband(UWB) communication system channel estimation using the sparsity of UWB channel. An novel UWB channel estimation algorithm based on CS and factor graph model of UWB channel is proposed in this paper utilizing generalized approximate message passing(GAMP) and mean field(MF)theories. The proposed algorithm combines the low complexity of GAMP and the advantage of processing exponential prior distribution of MF which not only bring down the sampling speed for received UWB signals significantly, but also get the precise UWB channel estimation value in reconstruction with lower algorithm complexity. Simulation results show that the proposed GAMP-MF sparse channel estimation algorithm has better performance, lower complexity and faster convergence speed comparing with the channel estimation algorithms with OMP or LASSO.4. Based on step recovery characteristics of stepped recovery diode(SRD) at reverse biased, a Second-order Derivative Ultra-wideband(UWB) gaussian pulse generator is designed in this paper. Compared with previous generators based on SRD,a novel structure is adopted in the proposed one. The generator is composed of a shunt SRD, a series SRD, three RC networks and a short-circuited microstrip stub. In the proposed generator, the RC networks substitute for DC bias, the shunt SRD works as edge sharpener while series SRD generates short gaussian pulse, and the short-circuited microstrip stub is utilized for shaping the second-order derivative pulse. The circuit is simulated by Advanced Design System(ADS) and fabricated.Measured results indicate that the pulse duration is about 800 ps, and the peak-to-peak magnitude is 1.2 volt. Good symmetry has been shown in the measured pulse, and the ringing level is approximately-16 dB.5. A novel compact printed monopole ultra-wideband(UWB) antenna featured with the band notch is proposed in this paper. The proposed antenna consists of a two-step beveled radiant patch and a truncated ground plane, which can provide a good impedance matching from 3.1 GHz to 10.6 GHz. In order to generate theband-notched characteristics, two symmetrical slots are embedded along with the microstrip feeding line, resulting in a band notch from 5.05 GHz to 5.85 GHz.Accordingly, the mutual electromagnetic interference between the UWB and Wireless Local Area Network(WLAN) radio communication systems can be eliminated. In addition, it is shown how the slots integrated on the ground plane improve the radiation patterns. The experimental measurements are found to be in good agreement with the numerical simulations.6. Design and implementation of a UWB transceiver system have been done for verification. The validity of the system is verified by the analysis of the two-order derivative Gauss pulses transmitted transmitting and receiving in actual measurements.