Simulation Researches On Applications Of Distributed Antenna In LTE-a System

With the increase of demands on wireless communication services, providing high-rate and diversified services is the trend of the development of wireless networks. While demand on the data rate is far from being satisfied, the scarcity of available radio resource is becoming increasingly serious, which requires that the spectrum efficiency should be continually enhanced. Traditional cellular systems make use of various technologies, such as cell-splitting and sectorization, to improve the spectrum efficiency. However, a variety of new problems, such as frequent handover, complex spectrum planning, extra interference, higher cost, may arise, which deteriorates the practical sense of these technologies to a great extent. On the contrary, distributed antenna system (DAS) is capable of enhancing the spectrum efficiency while avoiding or even ameliorating these problems.As the smooth evolution of LTE system, LTE-A system doesn't only inherited various advanced physical-layer transmission technologies, such as OFDM and MIMO, from LTE system, but also employs other new technologies, including carrier aggregation, enhanced MIMO, relay technology, distributed antenna technology and so on, to extend available spectrum and improve the spectrum efficiency, especially that of the cell-edge users.Research focus of the thesis is on DAS, that could extend the cell coverage, save transmition power, reduce inter-cell interference, improve SINR, alleviate near-far effect, resist shadow fading and increase system capacity. Based on the guidelines on LTE system-level simulation proposed by IMT-A, an LTE system-level simulation platform is designed and established, which employs the wrap-around configuration of 19 sites, each with 3 cells. In accordance with the overall block diagram of the LTE system-level simulation model, function modules involving base station, antenna station, antenna selection and power allocation are designed and implemented in the thesis.Based on the simulation platform, the antenna selection and antenna power allocation algorithms of downlink DAS are simulated and analyzed. After comparing the performance and complexity of various antenna selection algorithms, the thesis chooses the antenna selection algorithm based on Frobenius norm and the classical water-filling power allocation algorithm. The system average spectrum efficiency and cell-edge spectrum efficiency are simulated and analyzed in the context of different total transmitting antenna number and active transmitting antenna number. It's shown that DAS technology can improve the system average spectrum efficiency and cell-edge users'performance.