Opportunistic-based dynamic interference coordination in dense small cells deployment

Dense deployment of small cells is considered as a key enabling technique for the emerging 5G cellular networks. However, the dense and random deployments of femtocells in ultra-dense network (UDN) induce severe intercell inference that in turn reduces spectral efficiency. Traditional frequency reuse scheme is not fit for the dynamic network topology. In this paper, we propose a flexible resource reuse scheme based on opportunistic algorithm to coordinate interference. The scheme dynamically adjusts the number of reused sub-channels and determines which sub-channel should be reused with the variation of interference. Due to strong interference, some subchannels that cannot be reused will be allocated orthogonally. For those reused channels, the scheme selects best users to improve the sum rate, which will match resources with appropriate users. Hence, it can be seen as an optimization of enhanced inter-cell interference coordination (eICIC). Additionally, with the density of small cells increasing, non-ideal backhaul will be deployed extensively. However, the limited backhaul capacity constrains the throughput of small cells. We investigate the impact of backhaul on the sum rate. Our simulation shows that with the variation of signal-to-noise-ratio (SNR), the optimal reuse ratio is different. The sum rate of optimal reuse ratio is higher than traditional orthogonal allocation. In practical, we can choose the reuse ratio in respond to the interference situation. Besides, even when the backhaul capacity is constrained, the performance of our scheme is still better than orthogonal allocation.