Research On The Technology Of RAKE Receiver In TD-SCDMA System

The RAKE receiving technology is one of the key technologies in CDMA communication system. It can distinguish multi-path interferences from the received signals. Then using some optimum combination principle, it can overcome multi-path fading and improve the reliability and perfoermance of the system. Through integration with other technologies and structural optimization, RAKE receiver technology shows real potential for increasing system capacity, spectrum efficiency and so on. Thus it becomes one of the research hotspots in current mobile communication field.This paper deals with RAKE receiver applying for TD-SCDMA system, and analyzes the performance and shortcoming of conventional RAKE receiver. Based on those work, a method of TD RAKE receiver with multi-path signals coherent demodulation is proposed, and the performance comparison between conventional RAKE receiver and new RAKE receiver proposed is also performed. The simulation results show that RAKE receiver performace can be improved by using that new receiver with simple structure and easy implementation. In addition, due to its complexity, smart antenna RAKE receiver is discussed simply in this paper, while smart antenna directional receiver is primary researched. This paper gives the specific implementation schemes of smart antenna directional receiver on radio frequency(RF), intermediate frequency(IF) and baseband respectively. The simulation results show that smart antenna directional receiver in baseband could not utilize coherent demodulation to inhibit multi-path interference(MPI) and multi-access interference(MAI), whose gain of SNR(G_SA) would change with the location of MS, so it is difficult to obtain stable system performance. G_SA of smart antenna directional receiver implemented in radio is maximal, but it is very difficult to be realized. Consequently, smart antenna directional receiver implemented in intermediate frequency would have the highest cost-performance ratio.