  Mode-pairing quantum key distribution (MP-QKD) is an easy-to-implement scheme
that transcends the Pirandola--Laurenza--Ottaviani--Banchi bound without using
quantum repeaters. In this paper, we present an improvement of the performance
of MP-QKD using an advantage distillation method. The simulation results
demonstrate that the proposed scheme extends the transmission distance
significantly with a channel loss exceeding 7.6 dB. Moreover, the scheme
tolerates a maximum quantum bit error rate of 8.9%, which is nearly twice that
of the original MP-QKD. In particular, as the system misalignment error
increases, the expandable distance of the proposed scheme also increases. The
proposed system is expected to promote the practical implementation of MP-QKD
in a wide range of applications, particularly in scenarios involving high
channel losses and system errors.
