Robust and energy-efficient user association and traffic routing in B5G HetNets

Next-generation cellular networks, i.e., beyond fifth generation (B5G) and sixth generation (6G) networks,aim at significantly increasing capacity by deploying a massive number of small cells (SCs) and leveragingmillimeter wave (mmWave) links that have large bandwidth availability. However, as optical connectionsto a large number of base stations (BSs) are not cost effective, wireless backhaul (BH) links may be usedto connect SCs to the core network using mmWave frequencies and forming multihop mesh BH paths. Whilevery flexible in deployment, the uncertainty in user demand, which varies over time and place, makes networkplanning and management challenging. In this work, we propose novel algorithms to solve the joint problemof energy-efficient user association, BH traffic routing and BS/BH link on/off switching. We first formulatean exact model assuming user traffic demand uncertainty leveraging -robustness theory. As the model isintractable for large-scale instances, we develop a novel greedy robust heuristic (P-HEUR), which includesa robustifying step to effectively cope with demand uncertainty. Our evaluation demonstrates that P-HEURprovides robust and energy-efficient solutions quickly for different scenarios and traffic demand uncertaintylevels, and it significantly outperforms state-of-the-art approaches while achieving up to 83% of the optimalcapacity, even in the most demanding scenarios in terms of traffic load and demand uncertainty, with up to200k times lower complexity