Pre-coding Technology Based On Limited Channel Feedback

In the future,the wireless communication systems with higher-speed and QoS is needed.So the development direction of wireless communication systems is high spectrum efficiency and high-performance.MIMO Pre-coder technology provide an effective solution for future wireless communication.MIMO is multi-antenna technology, which can significantly improve the system capacity and spectrum efficiency; Pre-coder is a signal processor at the transmitter side by using channel characteristics, which can improve transmission.MIMO and Pre-coder are worth studying and challenging,because of its high system performance.This thesis gives a detailed introduction on the basic knowledge of MIMO and pre-coder.MIMO and pre-coder are the techniques in keeping with future developent trend.In generally,the signal appears random because the influence of space fading,the result is the communication performance declines.This thesis make an introduction on the Rayleigh fading and Rician fading,then gives a simulation result that shows the fading is bad for the system performance.Diversity and combination are the methods that can decline fading.This text introduces three kinds of basic diversity and four kinds of combination,including their principle and gain.This text emphasizes on the MIMO.It gives the MIMO system model,capacity formula and the system capacity with fast/slowly fading.Then the MIMO system model with antenna correlation is introduced and the correlate capacity is given.Then we simulate the channel capacity with different characteristics of the antenna-related. The method to access CSIT is introduced,and the capacity is compared between perfect CSI and partial CSI.Multi-antenna is one of the most important techniques in the future wireless communication system.Its efficient application in downlink of multi-user Cell system is an interesting problem.Given the consideration of cost and feasibility of the system,this thesis will focus on the multi-antenna multi-user diversity system with limited feedback.The concept of beam-forming and traditional model are given,and multi-user diversity is also introduced.To improve the system throughput performance and fairness among users,this thesis expends Random beam-forming to launch arbitrary beams and get its formulas,then simulate its performance with Monte Carlo method,the results show that the method can improve system throughout and fairness.