FPGA Implementation of Rake Receiver in Broadband Micro-power Wireless Communication System

Abstract

Aiming at the problem that receiver performance is seriously degraded by multipath fading in multipath channel, a three-finger Rake receiver design scheme is proposed, based on Chirp spread spectrum technology for multipath search, delay estimation and phase estimation. Firstly, the windowed algorithm is adopted in multipath search to improve the accuracy of multipath search. Secondly, detecting the spacing between multipath peaks can realize the delay estimation of multipath signals. Finally, the multipath signals are merged to enhance the receiving effect, significantly improving the system’s block error rate performance under the multipath channel environment. Matlab simulation shows that adding a Rake receiver in the system can improve performance by about 1.2dB. A multi-switching mechanism is applied in FPGA implementation, in order to reduce the hardware power consumption. FPGA simulation results verify rationality and correctness of the design, indicating that the system meets the requirements of block error rate less than 1% in actual transmission, when the signal-to-noise ratio is -2dB.