Network Optimisation in 5G Networks: A Radio Environment Map Approach

Network densification has been a driven force for boosting capacity throughout the different generation of cellular networks. In the current 5G networks, extreme densification is a core technology to meet the ever-increasing capacity demand by reusing the spectrum over the spatial domain. As the cell density increases, so does the handover rate, diminishing the user throughput that could potentially undermine the prospective capacity gains. Furthermore, advanced interference mitigation techniques are needed to cope with the co-channel interference, adding extra backhaul traffic. In this paper, we propose a cell-association strategy based on radio environment maps for dense 5G networks that maximises the average user throughput across the network. By exploiting the stored channel states and user location, we connect cellular users to the optimal tier dynamically. Based on stochastic geometry, the association probability and the coverage probability have been derived for dense 5G networks, where the base stations' locations follow Poisson Point Processes. Moreover, the user throughput and backhaul traffic are evaluated to assess its performance in dense 5G networks. The proposed technique is validated via Monte Carlo simulations and compared to different cell-association techniques. Results show that our scheme finds a balance between the coverage probability and the handover rate by numerical optimisation. In particular, it increases the average user throughput by 65% over the traditional approach, and it reduces the amount of overhead up to 68% over the other cell-association strategies.