  In free-space quantum key distribution (QKD) between moving parties, e.g.,
free-space QKD via satellite, the reference frame rotation and fluctuation
degrades the performance of QKD. Reference-frame-independent QKD (RFI-QKD)
provides a simple but efficient way to overcome this problem. While there has
been a number of theoretical and experimental studies on RFI-QKD, the
experimental verification of the robustness of RFI-QKD over other QKD protocols
under the reference frame rotation and fluctuation is still missing. Here, we
have constructed a free-space QKD system which can implement BB84, six-state,
and RFI-QKD protocols, and compared their performances under the reference
frame rotation and fluctuation. With the theoretical analysis and experimental
data, we have successfully verified the robustness of RFI-QKD protocol over
other QKD protocols in the presence of reference frame rotation and
fluctuation.
