Asymmetric Uplink-Downlink Assignment for Energy-Efficient Mobile Communication Systems

Mobile operators are facing increasing energy prices to operate their networks. At the same time, the demand for broadband wireless access is steadily increasing, driven by the success of smart phones and new services like machine-to-machine communication. In this paper we propose and evaluate a novel asymmetric user assignment scheme, which enables operators to save energy, while satisfying the capacity demands. The main innovation is to separate the association of users to base stations in uplink and downlink, such that in macro/micro overlay scenarios parts of the radio access network can be switched off. Based on system-level simulations we show that our scheme enables energy savings of up to 15% and 60% over typical macro and micro cell deployments, respectively. We further discuss its technical feasibility and implications on the system design. All numerical results are obtained in accordance with the guidelines and requirements of IMT-Advanced systems.