Research On Pilot Design And MIMO Detection Technology In Downlink Of LTE-A System

After more than three years in which3GPP word hard to researched and developed LTE technologies, LTE has become more mature. Based original network architecture and basic technologies in LTE system, some new functions were added in LTE-A system which is the smooth evolution of LTE. It needs to improve certain key technologies of LTE further to implement these functions, especially channel estimation technology and MIMO detection technology.In this paper, it focused on researching the key algorithms of downlink of LTE-A system.Firstly, this paper studies MIMO technologies in LTE-A system. And based on the analysis of the MIMO technologies, it proposes a new transmission program that is PDCCH beam forming. In LTE, PDCCH adopts transmit diversity as transmission mode and maps PDCCH symbols into control channel elements, In LTE-A, the proposed program adopts beam forming as its transmission mode. PDCCH symbols distributed in data region of one subframe, and were not mapped into control region in the unit of control channel element. Simulation results show that compared with PDCCH transmit diversity, PDCCH beam forming get lower BER, it proves that the proposed program is correct.Secondly, this paper still studies reference signal design with the normal CP for the high rank MIMO in LTE-A system. It determines the design principle of reference signal in LTE-A system. Then, it verifies the performance of DMRS pattern of Rank3-4by simulations. Furthermore, it designs DMRS pattern of Rank5-8based on DMSR design principle and DMRS pattern of Rank3-4, and it verifies the feasibility of reference signal design program by computer simulation.Finally, this paper researched MIMO detection algorithms in LTE-A system. By analysis of basic principle of three typical signal detection algorithms, it proposes a new MIMO detection algorithm. Simulation results show that compared with these typical algorithms, the new detection algorithm not only gets perfect performance, but also has lower calculation complexity, it proves that the proposal algorithm is efficient.