Key Technologies Of Lte Uplink Virtual Mimo Channel Estimation

In2011, smart phones13%proportion of all cell phones contributed78%of totalmobile data, which indicates the growing demand for data services other than voiceservices. So this requires the mobile communication system to have a bigger systemcapacity and higher data rates. Virtual MIMO technology had become an important wayto improve the LTE system throughputs, by assigning the same time-frequencyresources for multiple users and fully using of space resources.On the other hand, due to the noise, inter-cell interference, and the interferenceeffects between the pairing users, the radio propagation channel environment is quitecomplex, which seriously affect the useful signal transmission. In order to rebuilttransmitted signal at the receiver as accurate as possible, accurate channel fadinginformation is needed. So it is necessary to study a perfect channel estimation algorithmin virtual MIMO system.Firstly, for single user LTE uplink system, we find out how much the channelestimation algorithm impact the system performance. Also, we analysis the channelestimated algorithm itself, and proposed a DFT-Based method. By doing IDFTtransform, take the channel information received into time domain. In order to retain theuseful channel information energy, we then filter out some noise, by which, it performbetter in BER, comparing to the LS algorithm.Secondly, considering the multi-user LTE uplink virtual MIMO system, since theorthogonally among different user reference signals cannot be guarantee, we address theDFT-Based channel estimation algorithm with the aid of SNR information. Quitedifferent from single user time-domain fixed window method, by using SNR basedadaptive window algorithm, we enhance significantly the performance of lower poweruser in virtual MIMO pairing. For both symmetric resource pairing and asymmetricresources pairing cases, the paper gives the formula and derivation of the SINR beforeand after the pairing of virtual MIMO.Finally, according to the LTE uplink system protocol specific specification, a Matlabbased simulation platform has been built. For both single-user and multi-user in virtualMIMO scene, with different channel information and the moving speeds, we address thesimulation performance and analysis of all channel estimation algorithm mentionsbefore.This paper studies the channel estimation technology in the multi-user LTE uplinkvirtual MIMO scenarios. It enriches the existing channel estimation methods, and hassomehow theoretical and practical value. The research can be directly used in themulti-user LTE uplink virtual MIMO pairing system, thus to reduce the complexity andimprove system performance.