Optimizing Data Transmission Power for ARQ Energy Efficiency under Imperfect CSI
In this paper, we study the issue of optimizing the data transmission power (energy per symbol) for minimizing the expected energy required to successfully deliver a packet to the destination in a wireless point-to-point link through automatic repeat request (ARQ). We focus on the system that has a slow fading wireless channel and employs a pilot symbol-assisted modulation (PSAM) scheme along with a channel estimation scheme based on the minimum mean square error (MMSE) criterion. We derive the expected energy as a function of the data transmission power. Then, we derive a closed-form expression of the data transmission power that minimizes that function.