Analysis of Energy Efficiency in Fading Channels Under QoS Constraints

Energy efficiency in fading channels in the presence of QoS constraints is studied. Effective capacity, which provides the maximum constant arrival rate that a given process can support while satisfying statistical delays constraints, is considered. Spectral efficiency - bit energy tradeoff is analyzed in the low-power and wideband regimes by employing the effective capacity formulation, rather than the Shannon capacity, and energy requirements under QoS constraints are identified. The analysis is conducted for the case in which perfect Channel Side Information (CSI) is available at the receiver and also for the case in which perfect CSI is available at both the receiver and transmitter.