Research On Equalization Technology In High Speed Wireless Communication System

Over the last decade, wireless communication technology has shown its growth and potential in global market. Future wireless communication systems are expected to support high speed services to satisfy the increasing needs of users. A fundamental challenge in transmitting high speed datas over radio channels is inter-symbol interference (ISI) caused by multi-path propagation. In order to overcome ISI and decrease bit error rate, equalization technology is widely used in high speed wireless communication system.Among existing equalization technologies, Single-carrier based Frequency Domain Equalization (SC-FDE) exhibits the property of relatively low complexity. It is commended as one of key technologies by many high speed communication systems. So SC-FDE technology will be the main topic of this thesis.Firstly, the principle of ISI is introduced and an overview of equalization technology is shown. Base on that, the theory and algorithm of SC-FDE is researched. Then simulations of high speed communication system with frequency domain equalizer are built. The simulation results show SC-FDE is an effective approach to combat ISI and reduce bit error rate.Secondly, least mean square (LMS) algorithm, which is originally used in time domain equalization, is combined with SC-FDE technology. LMS algorithm is used to update the weights of adaptive frequency domain equalizer. The simulation results demonstrate that LMS algorithm is suitable for euqlizers in frequency domain. The weights of frequency domain equalizer are adjusted by LMS algorithm according to channel characters. Satisfied equalization results can be achieved.In the last part, SC-FDE is implemented in uplink of 3GPP long term evolution (LTE) project. The structure of LTE uplink system is studied and simulated. After that, a LTE system with a frequency domain equalizer is proposed and algorithms of channel estimate are discussed. The simulation results demonstrate the effect of FDE technology in LTE uplink system. Many simulations are done in this thesis based on theory study. Most simulations are built by component Simulink in software Matlab. Others are done by Matlab m code. Figures are wildly used to present and explain the simulation results.