  This paper considers the resource allocation problem in an Orthogonal
Frequency Division Multiple Access (OFDMA) based cognitive radio (CR) network,
where the CR base station adopts full overlay scheme to transmit both private
and open information to multiple users with average delay and power
constraints. A stochastic optimization problem is formulated to develop flow
control and radio resource allocation in order to maximize the long-term system
throughput of open and private information in CR system and ensure the
stability of primary system. The corresponding optimal condition for employing
full overlay is derived in the context of concurrent transmission of open and
private information. An online resource allocation scheme is designed to adapt
the transmission of open and private information based on monitoring the status
of primary system as well as the channel and queue states in the CR network.
The scheme is proven to be asymptotically optimal in solving the stochastic
optimization problem without knowing any statistical information. Simulations
are provided to verify the analytical results and efficiency of the scheme.
