Transmit Diversity Study Based On LTE-A System

The LTE-Advanced was accepted by the International Telecommunic-ation Union (ITU) as4G mobile communication international standard system in October2010, to become one of the IMT-A (4G) technology. The system based on Orthogonal Frequency Division Multiplexing and Multi-Input Multi-Output technology, integrated other key technologies such as Carrier Aggregation, Relay, and fully adopted and optimized packet data transmission, the goal is to meet and exceed the ITU-R IMT-A standards and compatible with the LTE system to enhance the technologi-cal competitiveness,and reduce the operator’s network upgrade version. In view of this, the paper will deeply study the uplink and downlink transmit diversity techniques based on understanding the multi-antenna theory and LTE-A protocols, will build the uplink and downlink transmit diversity simulation platform and make simulation to analysis the performance of the various diversities.The following work will be completed:(1) The paper will establish a multi-antenna system model based on studying the general model of transmit diversity techniques, then the impact of channel capacity and multi-antenna gain for LTE-A system performance will be analysised, and also a LTE-A system uplink and downlink transmit diversity simulation platform will be built.(2) In the downlink LTE system, SFBC transmit diversity for2antennas and SFBC-SFTD for4antennas will be theoretically analysised and simulated by comparison.The results shows that:At the downlink, SFBC is the most appropriate scheme for2antennas transmit diversity, can achieve better performance compared to other schemes,also SFBC-FSTD for4antennas.(3) Based on research on downlink4antennas SFBC-SFTD transmit diversity, the downlink8antennas SFBC-FSTD transmit diversity for LTE-A system will be proposed,the paper will analysis its feasibility and implementation principle, and also a simulation will be done. The simulation results show that:SFBC-FSTD can be used as a solution to solve downlink8antennas transmit diversity, It can obtain bit error rate performance promotion compared to the4antennas diversity.(4) This paper will study transmit diversity shame for PUCCH. A transmit diversity scheme based on PUCCH space orthogonal resources will be proposed, based on analysising the characteristics and drawbacks of the STBC,CDD and FSTD diversity,the simulation for which will be done.simulation results show that:the scheme proposed achieves good diversity gain, improves channel link error rate performance and afters good backward compatibility, which fulfill the requirements of uplink transmit diversity scheme.Finally, this paper will summarize all the works and present further research ideas.