Ultra Wideband Communication Rake Receiver

Ultra-wideband (UWB) communication is a novel short-distance wireless communication technique, in which data are transferred using non-sinusoidal pulses with very short duration. It has many advantages, such as high transmission rate, low power consumption, good security, robustness to multipath and low cost. Especially, it does not need extra frequency spectrum, and can coexist with the existing wireless communication systems at the same frequency band, which makes it attract much attention nowadays when the frequency spectrum resource has become more and more precious. This paper focuses on the RAKE receiving technique in UWB communication. RAKE is a technique used widely in wideband CDMA systems to combat multipath fading, in which multipath signals are separated using the good autocorrelation and crosscorrelation characteristics of spread spectrum codes, and thus diversity gain is abtained. In UWB communication, the multipath effects are quite severe, so RAKE is particularly important in UWB communication systems, and is a key technique in UWB communication. From Chapter 1 to Chapter 3 of this paper, the fundamental concept and history of UWB communication, the research status of UWB RAKE receiving technique, the UWB channel model, and some key techniques in the UWB RAKE receiver, such as channel estimation, implementation of high sampling rate and combination, are briefly introduced. These are the fundamentals of researching UWB RAKE receiving. In Chapter 4, the performance of UWB RAKE receivers is analyzed both theoretically and through simulations. The results show unbalanced BERs when transmitting '0'and '1'in TH-PPM systems, and then two solutions are presented. By theoretical analysis and computer simulations, it is proved that both the methods can eliminate the BER imbalance. In Chapter 5, the UWB RAKE receiver using squre-law detection is presented in order to decrease the system complexity. This RAKE receiver makes the transmitted signals orthogonal by changing the modulation index, so that the complicated channel estimation can be omitted at the receiver and the complexity of the receiver is decreased. Then the performance of this RAKE receiver is analyzed by theoretical deduction and computer simulations.