Energy impact of outdoor small cell backhaul in green heterogeneous networks

Small cells (SCs) are expected to be densely deployed during the next few years to enhance the network capacity of future heterogeneous networks (HetNets). Due to their dense deployment, not all SCs are expected to have a direct connection to the core network. As a result, some SCs will forward their traffic to the neighboring SCs until they reach the core network, thus forming a multi-hop backhaul (BH) network. Due to the large number of BH links, the BH is expected to be one of the main challenges that future HetNets will have to face. At the same time, traffic demands are growing exponentially resulting in higher energy consumption. Therefore, how to achieve high network energy efficiency becomes of utmost importance. To that end, in this paper, we study the role of BH in future outdoor HetNets aiming to answer to whether or not it could constitute an energy bottleneck for the HetNet. To gain insights, we study the BH energy consumption impact compared to the access network under different traffic distribution scenarios and BH technologies.