The Research Of Interference Suppression Technology In LTE-Advanced Heterogeneous Network

In order to meet the higher demand of future wireless communication market, LTE-advanced system comes into being. To further improve the capacity of system, heterogeneous networks have become a new feature of the LTE-Advanced. For example, applying some low-power nodes such as relay nodes, femto nodes, micro nodes and pico nodes in the original macro network in order to improve indoor coverage, increase network capacity and enhance users perception. However, the introduction of heterogeneous nodes will bring new interference problems inevitably, and these problems may greatly deteriorate the overall performance of the LTE-Advanced heterogeneous networks. Therefore, how to suppress the interferences between new heterogeneous nodes and macro network has become the focus of the industry. It's important for the development of next mobile communication system to suppress interferences in the heterogeneous network reasonably.This paper introduces the LTE-A key technology, LTE-A heterogeneous network development, interference scenarios and interference suppression technology related knowledge in detail. For LTE-Advanced heterogeneous networks, this paper mainly studies the interference coordination schemes in relay and femto systems, including schemes selection and improvement. The main work and achievements are divided into the following two aspects.Firstly, for LTE-Advanced relay system, this article mainly aimed at the uplink interference of the network. In this paper, we propose an interference coordination scheme which joints frequency coordination with power control for inner-cell and inter-cell. Compared with previous traditional interference coordination schemes, this new scheme considers enhancing user satisfaction under the premise of increasing system throughput and cell edge user rate. What's more, it tries to combine frequency coordination and power control to reduce the uplink interference of LTE-Advanced relay system for the first time by the methods of users type determination, dynamic spectrum allocation and power control. Here, user type determination is based on OI and RSRP, dynamic spectrum allocation is based on HII, and power control is based on RSRP correction.Secondly, for LTE-Advanced femto system, we mainly focus on the downlink interference of the network. By studying the advantages and disadvantages of the existing interference suppression schemes, this article presents a inter-cell interference coordination scheme based on SFR. The old and new schemes have been carried on the simulation respectively. The simulation results show that this solution decreases the interference between femto nodes and macro users in the system, and reduce the interference from other neighboring femto nodes and eNodeBs to femto users at the same time, improving the throughput of the whole system, as same as the average throughput of cell edge users.