Research On Inter-Cell Interference Coordination Based On Self-Adapting Frequence Reusefor LTE System

LTE is a typical network architecture beyond3G which defined by3GPP, it focus on improving the spectrum efficiency and data speed when the wireless resource is more scarce. As a result of adopting OFDM technology, every sub-carrier is orthogonal, so the intra-cell interference can be eliminated; if the adjacent cell users use the same frequency in the LTE system, it will cause big inter-cell interference and serious influence on the service quality of edge users which will affect the development of the whole system. Therefore the inter-cell interference coordination technology(ICIC) in LTE system becomes the focus of the research in recent years. The ICIC of Release8/9is mainly concentrated in the frequency domain, such like fraction frequency reuse, soft frequency reuse and so on; the ICIC of Release10is divided as ICIC based on Carrier Aggregation and enhance-ICIC based on Almost Blank Sub-frame.Soft frequency reuse technology is known as one of the most popular ICIC scheme. But it’s a static ICIC technology with fixed spectrum distribution and the load distribution is uniform, there is still some optimization space.This paper proposes a load distribution aware and self-adapting frequency reuse scheme for inter-cell interference mitigation and performance optimization in the LTE downlink system. We have considered two scenarios:one is each cell has different number of users and another is each cell has the same number of users but different number of center-users or edge-users. In this scheme, there are two algorithms: self-adapting edge bandwidth allocation and center bandwidth compensation. Both of these algorithms are to allocate the bandwidth corresponds to the distribution of the users in each cell. The goal is to promote the performance of center-users so as to improve the performance of whole system. We realize these two algorithms at the LTE system-level simulation platform, design different parameters and scenarios, realize another two typical algorithms to compare.Through a lot of theory and simulation analysis, we can prove that both of the self-adapting edge bandwidth allocation and the center bandwidth compensation can improve the performance of the LTE downlink system, especially when we combine these two algorithms. And the proposed algorithms have a strong compatibility with the existing static frequency reuse scheme. They do not produce much additional signaling interaction burden when allocating the bandwidth according to the distribution of users. We can also inform that these two algorithms are simple and effective, with low complexity and high practical value.