Study On Technology Of Self-Organizing Network In LTE-Advanced System

Self-organizing network (SON) is one of the key aspect of LTE/LTE-A systems. SON aims at reducing capital expenditure and operating costs by self-configuring, self-optimizing and self-healing, thus minimizing manual intervention and improving network performance. This paper provides system architecture and functionality of SON based on some background and current research work of SON in LTE/LTE-A. Because self-optimizing works as intermediate link between self-configuring and self-healing, we focus on the key technologies of self-optimizing in SON and research on energy saving(ES) and inter-cell interference coordination (ICIC) in-depth. We propose two innovative algorithms:1. In respect to energy saving, this paper describes the necessity of energy saving and how to adaptively switch off cells according to traffic fluctuation firstly. Then we research the effects of switching off cells on coverage performance through theoretical simulation analysis. An energy efficient algorithm which uses cell switch off technique and joint optimization of electrical and mechanical antenna tilt in heterogeneous network (HetNet) is proposed. It adaptively chooses cells to switch off and helps to absorb the traffic in that region by neighboring cells whose electrical and mechanical antenna tilt will be dynamically adjusted to enable larger coverage areas. This paper describes the algorithm design process in detail. Finally, we compare the old and new methods through simulation. The simulation results show that the proposed scheme can remarkably help maintain coverage and improve energy efficiency.2. In respect to inter-cell interference coordination, this paper describes the strong inter-cell interference caused by the deployment of heterogeneous network firstly. Then we elaborate the principle of cell range expansion (CRE) and almost blanket subframe (ABS), and present some current research work and analyze both advantage and disadvantage of these two techniques. Based on the existing interference coordination algorithms, an enhanced inter-cell interference coordination scheme which jointly optimizes the CRE bias and the ABS ratio is proposed to avoid the interference. The simulation results show that the proposed scheme can effectively help balance the load condition between macrocell and picocell, and improve SINR of UEs belonging to CRE region as well as the system throughput.