Research On The Integrated Method Of Heterogeneous Cellular Networks

Currently, with the popularization of 4G network, people begin to use this new technology. However, wireless multimedia services lead to increase the network traffic, and the burden on the cellular network system is also increasing. The operator deploys many small cells in order to offload macro cell traffic, which has become a major means to solve the network overload. Small cell is a short-range, low-power and easy-deploy wireless access point. Deploying of small cells in the mainstream of macro cell composes the integration of heterogeneous networks, and that can effectively improve the network system capacity, indoor depth coverage and user perception.In addition, since the different network architecture between small cell and macro cell, the handover and cell access become the main problems of integration of heterogeneous network. Although the deployment of small cell could meet the growing of high data rate requirement, dense small cell will lead to frequent handover, especially for high speed moving users, some handover is completely unnecessary. Compared to macro cell, the transmission power of the small cell is relatively low, so users are more likely to access macro cell, which makes the original congestion macro cell network become more serious, the utilization of small cell will be reduced, and CRE will also bring the problem of interference of heterogeneous networks.For the problem of handover between heterogeneous networks, a multi-criteria handover decision algorithm based on X2 interface is proposed.The algorithm can realize the interconnection between base stations based on X2 interface, which simplifies the handover process, and the corresponding signaling cost is reduced. Taking into account the handover of high speed mobile users, the time of accessing small cell decides the handover to small cell combining with RSRQ and available bandwidth. Experimental results show that the method can effectively reduce the number of handover of high speed mobile users as well as the system signaling cost.For the problem of low utilization ratio of small cell, an adaptive offset cell access method based on load is proposed. This algorithm can dynamically increase or decrease offset value by setting the load factor and using the characteristics of logarithmic function, and determine the offload timing and the degree of freedom of user equipment. The experimental results show that the proposed algorithm can enhance small cell utilization, alleviate the macro cell load pressure and improve the average throughput of the system.For the problem of interference of CRE, an e ICIC optimization algorithm based on ABS is proposed, and provides an objective function to optimize the performance of the system by achieving the optimal offset and ABS%. Experimental results show that the algorithm can enhance small cell utilization, mitigate the interference effect, and significantly improve the user data rate fairness and system network capacity.