| The surge in the amount of data traffic and continuous improvement of people’s communication needs bring great challenge to improvement and innovation of wireless mobile communication system in network architecture, network bandwidth, and advanced physical layer technologies. To address this challenge, heterogeneous network is adopted in the current commercial fourth generation mobile communication system and the fifth generation mobile communication system under research and development. In heterogeneous network, a variety of low-emission power small base stations are deployed within the macrocell, such as micro base stations, pico base stations, femto base stations and relays. Network capacity and user experience are improved by the dense deployment of networks. However a large number of stations have led great energy consumption and sophisticated cell interference, which bring higher challenge to network resource allocation and handover scheduling. It is very urgent and necessary to research resource management in heterogeneous networks. In this paper, energy efficient resource allocation and handover scheduling mechanism are researched by theoretical analysis and simulation in heterogeneous network.Firstly, this article summarizes the energy-saving technologies of heterogeneous network in recent study, focusing on the network resource allocation and handover scheduling.Single-cell OFDMA network is the basic unit of heterogeneous network. In multi-user OFDMA network, the downlink resource allocation model based on energy efficiency is built and analyzed. The objective is to maximize energy efficiency of the total network while ensuring each user’s minimum data rate. Through the analysis of resource allocation mathematical model, best channel quality subcarrier adjustment algorithm(BCSA) inspired by MDSA is designed to ensure the performance of the network energy efficiency while reducing computational complexity. Different from general methods of completing subcarrier allocation with once assignment, BCSA determines the initial subcarrier allocation via the principle of best channel quality. Then the subcarrier allocation between the user with the maximum energy efficiency and the user with the minimum energy efficiency is continually adjusted until the energy efficiency of the entire network gradually converges.Then in typical heterogeneous network scenario with macro stations and micro base stations, resource allocation and handover scheduling are jointly considered. Resource allocation and handover scheduling mechanism model is analyzed to maximize the network energy efficiency with each user’s data rate requirement. The resource management issue in heterogeneous network is decomposed into two sub-problems which are switching scheduling and resource allocation. In the sub-problem of switching scheduling, the considerations during the process of switch scheduling are analyzed and the sleep judgment condition of micro stations is obtained through mathematical derivation. Centralized user switching scheduling algorithm called CUSA is designed based on the sleeping of micro stations. The network energy consumption is further saved through centralized switching scheduling. In the sub-problem of resource allocation, BCSA is adopted. Different from general strategies of considering resource allocation or handover scheduling separately, JSRA algorithm is formed by effectively jointing BCSA and CUSA, fully saving network energy from multiple parts of the network to further improve the energy efficiency of heterogeneous network. |
