  This paper investigates the impact of the channel state information (CSI) and
antenna correlation at the multi-antenna relay on the performance of wireless
powered dual-hop amplify-and-forward relaying systems. Depending on the
available CSI at the relay, two different scenarios are considered, namely,
instantaneous CSI and statistical CSI where the relay has access only to the
antenna correlation matrix. Adopting the power-splitting architecture, we
present a detailed performance study for both cases. Closed-form analytical
expressions are derived for the outage probability and ergodic capacity. In
addition, simple high signal-to-noise ratio (SNR) outage approximations are
obtained. Our results show that, antenna correlation itself does not affect the
achievable diversity order, the availability of CSI at the relay determines the
achievable diversity order. Full diversity order can be achieved with
instantaneous CSI, while only a diversity order of one can be achieved with
statistical CSI. In addition, the transmit antenna correlation and receive
antenna correlation exhibit different impact on the ergodic capacity. Moreover,
the impact of antenna correlation on the ergodic capacity also depends heavily
on the available CSI and operating SNR.
