Feedback Power Control with Bit Error Outage Probability QoS Measure on the Rayleigh Fading Channel

We propose to use the probability of instantaneous bit error outage (IBEO) as a new performance measure in the design of an actual feedback power control system. It is defined as the probability that the instantaneous bit error probability (IBEP) exceeds an IBEP threshold. We propose the IBEO-based power control law where the transmitted power is adjusted according to the variations of the channel such that the IBEO probability is kept within some quality of service (QoS)-specified threshold. It ensures that in the long term, no more than a certain fraction of received bits would have IBEP exceeding some IBEP threshold. Therefore, the instantaneous QoS is guaranteed. Based on a practical system model with channel estimation and prediction, we develop the traditional average bit error probability (ABEP)-based power control law and the new IBEO-based power control law. For both laws, we derive explicit ABEP and IBEO probability results. The IBEO-based law shows a remarkable gain over the ABEP-based law in terms of IBEO probability, and sacrifices only a little in the ABEP performance.