  We propose a low-complexity near-optimal wavelength allocation technique for
quantum key distribution access networks that rely on wavelength division
multiple access. Such networks would allow users to send quantum and classical
signals simultaneously on the same optical fiber infrastructure. Users can be
connected to the access network via optical wireless or wired links. We account
for the background noise present in the environment, as well as the Raman noise
generated by classical channels, and calculate the secret key generation rate
for quantum channels in the finite-key setting. This allows us to examine the
feasibility of such systems in realistic scenarios when the secret key exchange
needs to be achieved in a limited time scale. Our numerical results show that,
by proper choice of system parameters for this noisy system, it is possible to
exchange a secret key in tens of seconds. Moreover, our proposed algorithm can
enhance the key rate of quantum channels, especially in high noise and/or high
loss regimes of operation.
