Enhanced Interference Coordination Technology In Multi-Layer Heterogeneous Networks

With the explosive development of mobile Internet industry, data service is going through explosive growth in mobile communication field. The demand of data rate is gradually increasing nowadays.The three most important scenarios in mobile Internet era are indoor environment, low-speed mobile scenario and hotspot coverage scenario. Multi-layer heterogeneous wireless network is proposed to reduce load of macro-layer, and improve indoor coverage and performance of cell edge users. Low power nodes (e.g. Picocell, Femtocell, Relay) are introduced to the network compared to the traditional Macrocell. When cell deployment becomes denser and more complicated, how to solve the inter-layer and intra-layer interference problem is important. How to improve resource utilization with limited resources has been a hot area of research.This paper focuses on interference coordination in a LTE-A (Long Term Evolution-Advanced) multi-layer heterogeneous network. The performance under different deployment of smallcell is evaluated. Then, interference coordination algorithms in frequency domain, time domain and power control aspect are proposed. Finally, system level simulation platform is used to evaluate and analyze the performance of the proposed algorithms.The system capacity is analyzed in this paper. In a MIMO (Multi Input Multi Output) system, the channel analysis method and capacity calculation formula are given. Furthermore, the location of small cell is evaluated by simulation. The evaluation of average spectrum efficiency and cell edge spectrum efficiency is provided under different coordination techniques, i.e. soft frequency reuse, orthogonal, full reuse in frequency domain and different CRE bias when combined with time domain interference coordination. According to the simulation results, optimal deployment of small cells and performance comparison under different interference coordination techniques are provided.A frequency domain interference coordination algorithm is proposed. Through calculation of average transmission ability of associated users and fairness of users, edge users and center users are repartitioned. Low power nodes will dynamically adjust the frequency transmit range and transmit power, reducing interference to macro users. Simulation results show that the algorithm is able to improve average throughput while increasing edge throughput.A power control scheme, combined with time domain interference coordination is also discussed. After ABS (Almost Blank Sub frame) is applied, each low power node will estimate the throughput variance in terms of channel quality information of center users, edge users and macro users in vicinity. According to the estimation result, low power nodes will adjust transmit power on different resource blocks respectively. This method can reduce amount of calculation at macro side and improve the performance of edge users while ensuring the fairness of users.