Load balancing algorithm within the small cells of heterogeneous UDN networks: Mathematical proofs

Ultra-Dense Networks (UDNs) can be used to improve coverage. With limited network capacity and the dense development of wireless networks, heterogeneous ultra-dense networks are set to satisfy the increasing demands of mobile users. However, the dense deployment of small cells in the hotspots of UDN networks generates an uneven traffic distribution. To address this problem, this paper proposes novel load balancing approaches implemented within the small cells, which are formed based on the Radio-over-Fiber (RoF) system. To select the best overlapping zone and then the best candidate user to be handed-over between the access points of the small cells, a common zone approach, a worst zone approach and a mixed approach are suggested. The results indicate that the proposed algorithm improves the performance of UDN networks when the load is unbalanced. The balance improvement ratio can reach on average 89.16%.