Closed Loop Power Control Using Third Order Quadratic Approximator

Abstract

In this paper we introduce a novel bit error rate (BER) feedback transmit power control (TPC) system using a first-time third order quadratic approximation of the power–time curve. This approximation improves the power efficiency of a dual-rate TPC algorithm in terms of reduced total transmit power by smoothing transmit power transients during adaptive iterations. We show that the third order approximator outperforms linear and second order approximators in terms of transmit power savings, sensitivities, error magnitude, and better tracking performance in following reference desired power curves. For the approximator, we determine operational bounds for stability, and demonstrate algorithm behavior using critical valued inputs. In addition we demonstrate value in using a dynamic, rather than static, performance benchmark for quality of service approximation (obtained used scaled maximum acceptable BER), and provide heuristic estimates for the input parameters for the dynamic benchmark.