Key Technologies Of Lte/Lte-a System

To meet the requirements of the IMT-A, LTE physical layer technology is based on MIMO-OFDM. Through the Multi-antenna technology, spatial being regard as another new resources, achieving higher spectral efficiency. Beside, multi-user MIMO technology further improve the performance of the system. By Orthogonal Frequency Division Multiplexing, LTE system has a good control of the intra-cell interference, but if the adjacent cell using the same frequency resources, it will bring the inter-cell interference seriously affect system performance, especially in heterogeneous scenario, inter-cell interference coordination is required to improve the performance of the cell-edge users. The contents are as follows:System level simulation platform is built to verify the performance of several typical scenarios in the LTE system involving single-user, multi-user as well as heterogeneous network scenario. Each scenario is a combination of MIMO techniques, scheduling, link adaptation techniques and so on.This paper focuses on the LTE multi-user MIMO precoding and scheduling algorithm. Selection criteria of starting user based on semi-static scheme considering the potential user’s interference present in this paper is compared with the traditional selection of the best single-user. It’s proved that this algorithm can improve the performance of the semi-static users selection without cause any increase in the complexity, and the performance increase is more pronounced when the number of users is large. In addition, semi-static users selection will loss the performance when the number of user is large, this paper presents an algorithm named several times semi-static user selection have a tradeoff of performance and complexityTo share the load of the macro basestation, users belong to macro basestation access to the low power node through range extension technique in heterogeneous scenario, but this brings a strong interference of the macro base station in the cell edge. By almost blanks subframe (ABS) scheme, it is possible to alleviate the strong interference of the cell edge, but it will cause a decrease the schedule opportunity of macrocell. Low power almost blank subframe (LP-ABS) can appropriately improve the throughput of the macrocell user, and also reduce the interference on the edge of the low-power node user. An inter-cell interference coordination scheduling algorithm by exchanging CQI and RSRP information is presented, which can improve the average cell spectral efficiency and cell edge user spectral efficiency, and able to adapt to changes in the distribution of users and business.