  Predictor antenna (PA) system is referred to as a system with two sets of
antennas on the roof of a vehicle, where the PAs positioned in the front of the
vehicle are used to predict the channel state observed by the receive antennas
(RAs) that are aligned behind the PAs. In this work, we study the effect of
spatial mismatch on the accuracy of channel state information estimation, and
analyze the delay-constrained average rate of hybrid automatic repeat request
(HARQ)-based PA systems. We consider variable-length incremental redundancy
(INR) HARQ protocol, and derive a closed-form expression for the maximum
average rate subject to a maximum delay constraint. Moreover, we study the
effect of different parameters such as the vehicle speed, the antenna distance
and the rate allocation on the system performance. The results indicate that,
compared to the open-loop case, the delay-limited average rate is considerably
improved with our proposed PA-HARQ scheme.
