Energy-Efficient Link Adaptation on a Rayleigh Fading Channel with Receiver CSI

Energy-efficient link adaptation is studied on a slowly varying Rayleigh fading channel assuming perfect CSI at the receiver but no CSI at the transmitter, except for the statistical characterization. Both circuit power and power dissipated in the power amplifier are considered and the energy consumption per bit is minimized over bandwidth, transmission power, and transmission rate. It is shown that the joint optimization of power and rate leads to a point on a curve that connects the two extreme situations that correspond to ignoring the power dissipated in the power amplifier and ignoring the circuit power dissipation, respectively. The first case leads to throughput maximization whereas the second case leads to transmit power minimization. The global optimum depends on the ratio of the power dissipated in the power amplifier to the total power dissipation.