Research And Implementation Of Algorithm For LTE Downlink Receiving

LTE (Long Term Evolution), as a major project of the3GPP in recent years, withMIMO and OFDM as the key technologies of physical layer, supports larger transmissionbandwidth, higher transmission rate and lower delay. The entire bandwidth can bepartitioned into several subchannels with OFDM technology. And the parallel data streamscan be transmissed on subchannels, which can effectively against frequency selective fading.With the MIMO technology, we can increase the system capacity without increasingthe transmission bandwidth. On the basis of the key technologies of physical layer and LTEphysical layer standards, we study the LTE downlink receiving algorithm, and use theMATLAB to simulate the algorithm.Firstly, the evolution of mobile communication, LTE project’s background andtechnical features are briefly introduced. Secondly, the LTE system and the key technologiesof physical layer (MIMO and OFDM) are described in detail. And then the LTE downlinkreceiving algorithm is carefully studied, and the modules are divised. For those relativelycomplex and important modules, such as channel estimation and MIMO detection, we studythose modules in detail and simulate them. We propose a novel adaptive receiver, and novelfeature lies in the adaptive detection. Adaptive detection principle is based on the channelcondition, choosing the appropriate detection algorithm, namely when the channel conditionis good, using a linear detection, and when channel condition is poor, using a maximumlikelihood detection. The parameters which judge the channel situation are the conditionnumber and the orthogonality defciency. With the time-frequency characteristics of OFDMsystem, we present a simplified adaptive receiver. The simulation results show that, theperformance of simplified adaptive receiver is not reduced very much. Finally, through thesimulation,we can find that the adaptive receiver and the simplified version can improve theperformance of the system, but the complexity of the algorithms are not very high, achievingthe compromise of algorithm complexity and performance.