Energy efficiency of optically backhauled LTE: A case study

Nowadays, we are witnesses of fast penetration of high data-rate cellular networks such as the Long Term Evolution (LTE). With increasing average access data rates in mobile networks, also the requirements on networks providing backhaul for the wireless infrastructure are increasing. New radio interfaces are already capable of providing hundreds of Mbps over a single radio link between a base station and a user, which means that the future backhaul network should be able to provide a connection to base station sites in the order of Gbps. As optical access networks are able to provide a very high bandwidth practically almost independent on distance as well as high energy efficiency, it seems that a combination of mobile wireless access with optical access networks is a very promising integrated approach for a sustainable and efficient next generation ubiquitous access network. Wireless cellular and optical wired access networks provide synergies and complementary features. The main benefits of using a kind of wireless access are mobility and ubiquity while optical access networks provide high data rates, low power consumption and robustness. In this paper, we investigate various options for deploying LTE in urban areas with a particular emphasis on energy efficiency. For the purpose of evaluation, we apply an access network model to estimate both power consumption and achievable access data rates for various deployment scenarios and show results of a case study for the city of Vienna. The considered deployment scenarios are assessed regarding their potential for improving energy efficiency.