Analysis of energy efficiency in fading channels under QoS constraints

• Published in: IEEE transactions on wireless communications Vol. 8; no. 8; pp. 4252 - 4263
• Main Authors: Gursoy, M.C., Deli Qiao, Velipasalar, S.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-08-2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Channels; Delay; effective capacity; Energy efficiency; Energy levels; Energy requirements; Energy resources; energy-bandwidthdelay tradeoff; Exact sciences and technology; Fading; Fading channels; Information analysis; minimum bit energy; Mobile communication; Multimedia communication; Operation, maintenance, reliability; Quality of service; Radiocommunications; Receivers; Spectra; spectral efficiency; statistical quality of service (QoS) constraints; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Transmitters; Transmitters. Receivers; Wideband; wideband slope; Wireless communication; Fading channels; Performance evaluation; effective capacity; wideband slope; energy-bandwidth-delay tradeoff; Two channel system; Wireless telecommunication; Transmitter; statistical quality of service QoS constraints; Wide band; Energetic efficiency; energy efficiency; spectral efficiency; Telecommunication channels; minimum bit energy; Minimum energy; Delay time; Service quality
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2009.081105

Energy efficiency in fading channels in the presence of Quality of Service (QoS) constraints is studied. Effective capacity, which provides the maximum arrival rate that a wireless channel can sustain while satisfying statistical QoS 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. Through this analysis, energy requirements under QoS constraints are identified. The analysis is conducted under two assumptions: perfect channel side information (CSI) available only at the receiver and perfect CSI available at both the receiver and transmitter. In particular, it is shown in the low-power regime that the minimum bit energy required under QoS constraints is the same as that attained when there are no such limitations. However, this performance is achieved as the transmitted power vanishes. Through the wideband slope analysis, the increased energy requirements at low but nonzero power levels in the presence of QoS constraints are determined. A similar analysis is also conducted in the wideband regime. The minimum bit energy and wideband slope expressions are obtained. In this regime, the required bit energy levels are found to be strictly greater than those achieved when Shannon capacity is considered. Overall, a characterization of the energy-bandwidth-delay tradeoff is provided.