  Subcarrier assignment is of crucial importance in wideband cognitive radio
(CR) networks. In order to tackle the challenge that the traditional
optimization-based methods are inappropriate in the dynamic spectrum access
environment, an independent Q-learning-based scheme is proposed for the case
that the secondary users (SUs) cannot exchange information while a
collaborative Q-learning-based scheme is proposed for the case that information
can be exchange among SUs. Simulation results show that the performance
achieved with the proposed collaborative Q-learning-based assignment is better
than that obtained with the proposed independent Q-learning-based assignment at
the cost of the computation cost.
