Research On Small-Cell Higher Order Modulation Enhancement Method In LTE-A System

This paper is mainly aiming at the research on the small-cell higher order modulation technologies in the LTE-A system. Based on the LTE-A Rel.11, the research is made use of to solve the specific problems in the current LTE-A telecommunication system considering the introduction of higher order modulation technology, in order to enhance the higher spectrum efficiency in some specific scenarios. These specific scenarios belong to the scenarios of small cell. This paper mainly includes some contents as follows:the introduction of the higher order modulation in the current LTE-A system, the modelling of EVM and the performance evaluation of the LTE-A system considering different EVM, the new algorithm based on higher order modulation to improve link adaptive and the evaluation of the AMC algorithm.First of all, the paper studies the present development of the wireless communication industry, including LTE and LTE-A system. And then, the paper mainly introduces the key technologies in the LTE/LTE-A system: OFDM and MIMO technology and the basic architecture of LTE/LTE-A system.Secondly, the paper studies the background information and technical principle of the heterogeneous network-small cell. It is concluded that the channel quality in the small cell scenarios can be so good that the higher order modulation (256QAM) can be introduced in the current LTE-A system. Then, the paper tells the diagram of256QAM constellation and bit error rate. Finally, the theory of adaptive modulation and coding technology are studied, including the basic principles, detailed implementation process and the advantages and so on. Thirdly, the paper focuses on the application of the higher order modulation in the LTE-A system and performance improvement to the system. In this paper, the cause of the TX EVM and RX EVM entry are studied. Then some appropriate mathematical methods are used to build the TX EVM and RX EVM algorithm model in the LTE-A system. In order to evaluate the performance improvement of the different combination of the EVM, the LTE-A link level simulation platform and the LTE-A system level simulation platform are builded. Finally, the accurate simulation redults lays the foundation of the analysis of the256QAM and EVM.Forthly, according to the latest3GPP standards, this paper design the CQI/MCS/TBS table for the higher order modulation. Based on the new tables, the new adaptive switching algorithm is put forward. Then, in order to validate the algorithm, some programs in the previous platform are modified. In the end, the simulation results can verity the efficiency of the proposed algorithm and the improvement to the LTE-A system.