Time-Energy Limited Feedback Algorithms for Multiuser Diversity Scenarios on Nakagami Fading Channels

• Published in: IEEE transactions on communications Vol. 60; no. 4; pp. 1045 - 1057
• Main Authors: Filio, O., Kontorovich, V., Ramos-Alarcon, F.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.04.2012; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Base stations; Equations; Exact sciences and technology; Fading; Joints; level crossing theory; Mathematical model; Multiuser diversity; Nakagami distribution; Nakagami fading channels; non-fade durations; Signal to noise ratio; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Fading channels; Level crossing; Performance evaluation; Multiple access; High performance; Polling; Nakagami fading channels; Feedback regulation; Scheduling; Algorithm; Multiuser diversity; level crossing theory; non-fade durations; Nakagami fading; Time domain method
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/TCOMM.2012.022912.090686

Preserving a reduced feedback load in Multiuser Diversity systems is crucial. By establishing either single or multiple thresholds only in the energy domain, the Selective Multiuser Diversity (SMUD) schemes achieve a reduced feedback load while maintaining a high capacity performance. This paper introduces an enhanced joint time-energy domain scheduling approach for SMUD systems that maximizes the total spectral efficiency and preserves a minimal feedback load with just a few thresholds in the joint domain. This joint domain capitalizes on the energy and the non-fade duration statistics in order to establish a feedback policy that is focused on those users who have good channel condition and preserve it for a predetermined amount of time, providing thus an automatically more rational and fair use of the resources without a sophisticated scheduling with large polling/decision times. The analysis of this enhanced approach for the general case of Nakagami fading channels is developed and expressions for the average system capacity and the average feedback load are presented. The tradeoff between the feedback load and the spectral efficiency gain is analyzed. Two main scenarios are studied; the first when there are two thresholds in the energy domain side and one in the time domain side; the second when there are two thresholds in both domains.