  Assuming noisy feedback channels, this paper investigates the data
transmission efficiency and robustness of different automatic repeat request
(ARQ) schemes using adaptive power allocation. Considering different
block-fading channel assumptions, the long-term throughput, the delay-limited
throughput, the outage probability and the feedback load of different ARQ
protocols are studied. A closed-form expression for the power-limited
throughput optimization problem is obtained which is valid for different ARQ
protocols and feedback channel conditions. Furthermore, the paper presents
numerical investigations on the robustness of different ARQ protocols to
feedback errors. It is shown that many analytical assertions about the ARQ
protocols are valid both when the channel remains fixed during all
retransmission rounds and when it changes in each round (in)dependently. As
demonstrated, optimal power allocation is crucial for the performance of noisy
ARQ schemes when the goal is to minimize the outage probability.
