distributed control; Power control; quality of service Closed-loop structures; Comprehensive evaluation; Control gains; Discrete time version; Distributed control; Distributed Power-Allocation; Integral action; Power allocation strategies; Power control algorithm; Proportional controller; Stability margins; Stability regions; Time varying; Time-varying delay; Tracking problem; Universal mobile telecommunication systems; Unknown channel; Work study; Algorithms; Automation; Control system stability; Distributed parameter control systems; Electrical engineering; Mobile telecommunication systems; Power control; Process control; Quality of service; Time varying control systems