Research On Inter-cell Interference Control And Energy Saving Scheme For Small Cell Networks

During the last decade, the wireless communication technology has developed rapidly. Due to high data load in wireless networks and increasingly rigid environmental standards, the dramatically rising energy consumption in the mobile cellular networks has attracted more and more attention. High energy consumption not only increases the operator’s operating costs, but also leads to the deterioration of the environment. A promising approach to improve energy efficiency is to use a multi-tier structure with short-range and low-power small cell base stations (BSs), which operate in conjunction with traditional macrocells. In the multi-tier structure networks, large cells provide mobility support and ubiquitous coverage, while smaller cells take connectivity closer to users thereby increasing data rate with less energy consumption. Because of the small coverage radius and the small short between the BSs, the inter-cell interference (ICI) is more serious in small cell networks. As a result of the existence of the macrocell BS, there is cross-tier interference in the multi-tier heterogeneous networks.ICI and Energy saving are two important issues in the future generation cellular networks. Among ICI control technologies, the ICI coordination technology is more flexible because it does not depend on the underlying communication technologies. So the ICI coordination based on frequency resource allocation is adopted in this paper. Since BSs are responsible for60-80%of the whole network energy consumption, and a BS consumes more than90%of its peak energy even when there is little traffic, BS sleep mode is considered to save energy in this paper. ICI and Energy saving are studied separately in most of previous works. Since these two important issues have great impacts on user quality of service and energy consumption, they should be jointly studied and optimized in a common framework. Therefore, in one-tier small cell networks and multi-tier heterogeneous networks, a common framework is proposed to dynamically allocate spectral resource to mitigate ICI and to save energy by BS sleep mode at the same time in this paper, and the objective function is built to maximize the whole network energy efficiency. At the same time, fairness among users is considered.In addition, most of the previous works use centralized schemes to solve ICI and energy saving problems, which needs to collect all the information in the networks to make decision. But centralized schemes may suffer from signaling overhead, outdated dynamic information, poor scalability issues and so on. In the small cell networks, the proposed optimization problem is simplified into a linear programming problem, and then, a distributed scheme is designed by primal decomposition and projected subgradient method, in which each cell only needs the information of its own and its neighboring cell to solve the optimization independently. Future work is to design a distributed scheme for the heterogeneous networks.