Researchs In Low Complexity And Low Power IR-UWB Receiver Technology

Impulse Radio Ultra-Wideband (IR-UWB) communication uses low duty cycle narrow pulses to transmit information. It has technique advantages on low power, low cost, low spectrum density and high data rate. And that makes it very suitable for high speed wireless communication, wireless personal area network and wireless sensor network applications. Since these applications are sensitive to cost, power consumption and volume, IR-UWB has high demand on low complexity and low power. Yet because of the short duration and ultra wideband of the pulse signal, traditional solutions for IR-UWB are unefficient in low power and low cost.In this paper, we investigate the design of low complexity and low cost receivers in IR-UWB communication systems. Study on the complexity and power of IR-UWB communication systems shows that the key problem is the receiver's design. And the main problems are the correlating integrator and synchronization in analog receivers while the high speed analog to digital conversion in all digital receivers. Considering the specialties of IR-UWB, we propose some solutions to these problems.To solve the correlation integral problem in analog receivers, we consider the low duty cycle of IR-UWB signal, and propose a low complexity equivalent integrating method. The performance analysis shows that the method induces a SNR degradation lower than 0.15dB in typical communication systems.With respect to the synchronization difficulties for narrow pulses, we notice that the energy of the pulses is mostly concentrated. An orthogonal sinusoid correlation synchronization method based on correlation window is presented. The mathematical model and the transfer function are derived. We demonstrate by simulation that the synchronaztion method is able to achieve pulse synchronization fast and efficiently.Noticing the high instantaneous SNR and the low order modulation of pulses, we propose a low resolution sampling method as the solution to the high speed analog to digital conversion in all digital receivers. We study the basic theories and practice technologies of representational mono bit sampling receiver. Study on the capacity of the mono bit sampled additive white Gaussian noise channel shows that BPSK is the best modulation when the SNR is low and high order modulation brings proceeds when the SNR is high. The analysis of the maximum likelihood receiver shows that the mono bit receiver has 1.96dB SNR distortion in dense multi path channel. And when the sampling resolution increases one bit, we have 1.4 dB SNR gain. For the practice technologies we present optimized iterative channel estimation and maximum likelihood synchronization methods. And that makes the mono bit receiver realizable. The simulation results show that in typical channel the practical mono bit receiver can reach the theoretical limit.This paper provides instructions in the design of low complexity and low cost IR-UWB receivers, especially the low resolution sampling all digital receivers.