A QoS-Based Cross-Tier Cooperation Resource Allocation Scheme over Ultra-Dense HetNets

An ultra-dense network (UDN) can increase the system throughput by deploying a mass of low-power nodes and can greatly increase the spectral efficiency and energy efficiency at local hot spots. However, due to the random deployment of a large number of base stations (BSs), severe inter-cell interference may occur, which hinders the development of resource allocation technology, especially on the computational complexity. In this paper, we propose a quality of service (QoS)-based cross-tier cooperation transmission scheme over the UDN. In order to mitigate the interference and improve the entire network throughput, a non-convex problem is formulated. To solve this problem, first, we define the cooperation signal-to-interference-plus-noise ratio (SINR) threshold that represents the ratio of transmission power of macro BS and SBS, and we utilize the stochastic geometry theory to analyze the effect of cooperation SINR threshold on the number of user equipment. Then, we use the dedicated channel to decrease the cross-tier interference according to the fractional frequency refused mechanism. To reduce the computational complexity, this resource allocation scheme is divided into two parts, i.e., subcarrier allocation and power allocation, and we also consider the QoS requirement. The simulation results verify that our proposed scheme has better performance than the other two existing algorithms while QoS is guaranteed.