Energy-Efficient Power and LNA Control for Wireless Multi-Channel Communication

Simultaneous communications over parallel channels is a prominent scheme in modern wireless system. Intuitive multi-channel solution allocates one independent RF chain (including LNA, low-noise amplifier) to each separate channel, causing high implementation cost. Alternatively, low-cost RF uses one single LNA to cover all parallel channels and save implementation cost. Nevertheless, such structure introduces challenges in the control of shared LNA gain (as well as channel power allocation), especially when adapting to independent fadings across parallel channels. Under shared-LNA strucutre, and to maximize energy efficiency, this paper proposes a sub-gradient framework that optimizes both shared-LNA gain and channel power values under multiple system constraints, including Tx power, ADC saturation, baseband SNR, and LNA gain. We discuss algorithm properties including convergence performance, step size selection, and solution accuracy. Simulation results confirm that, optimized energy efficiency through our algorithm can outperform intuitive strategies by 20% to 160%. Finally, impacts of various system parameters are studied as well.