  To reap the active and passive beamforming gain in an intelligent reflecting
surface (IRS)-aided wireless network, a typical way is to first acquire the
channel state information (CSI) relying on the pilot signal, and then perform
the joint beamforming design. However, it is a great challenge when the
receiver can neither send pilot signals nor have complex signal processing
capabilities due to its hardware limitation. To tackle this problem, we study
in this paper an IRS-aided wireless energy transfer (WET) network and propose
two joint beamforming design methods, namely, the channel-estimationbased
method and the distributed-beamforming-based method, that require only one-bit
feedback from the energy receiver (ER) to the energy transmitter (ET).
Specifically, for the channelestimation-based method, according to the feedback
information, the ET is able to infer the cascaded ET-IRS-ER channel by
continually adjusting its transmit beamformer while applying the analytic
center cutting plane method (ACCPM). Then, based on the estimated cascaded CSI,
the joint beamforming design can be performed by using the existing
optimization techniques. While for the distributed-beamforming-based method, we
first apply the distributed beamforming algorithm to optimize the IRS
reflection coefficients, which is theoretically proven to converge to a local
optimum almost surely. Then, the optimal ET's transmit covariance matrix is
obtained based on the effective ET-ER channel learned by applying the ACCPM
only once. Numerical results demonstrate the effectiveness of our proposed
one-bitfeedback-based joint beamforming design schemes while greatly reducing
the requirement on the hardware complexity of the ER. In particular, the high
accuracy of our IRS-involved cascaded channel estimation method exploiting
one-bit feedback is also validated.
