Enabling green heterogeneous cellular networks via balanced dynamic planning

Network operators exploit temporal and spatial fluctuations in call traffic load to save energy by switching off their lightly loaded base stations (BSs), a technique that is referred to as dynamic planning. Research efforts in the literature focus on satisfying the mobile users' service quality in the downlink while implementing dynamic planning. However, the impact of dynamic planning on the service quality of uplink users is overlooked. In this context, switching off a nearby femto BS and associating uplink mobile users to a faraway macro BS might lead to service quality degradation due to longer transmission distance, and hence, larger transmission power. In turn, this could lead to violation of the minimum required uplink throughput and in severe cases this could result in mobile terminal battery depletion, and hence, call dropping. In this chapter, we quantify the impact of dynamic planning on mobile users' service quality for data calls in both uplink and downlink. Then, we propose dynamic planning frameworks with balanced energy efficiency that account for the service quality of mobile users both at the downlink and uplink based on a two timescale decision problem. Simulation results demonstrate that the balanced dynamic planning frameworks can save energy for the network operators and provide service quality guarantee for mobile users in the downlink and the uplink as compared with an unbalanced (traditional) dynamic planning benchmark.