  This paper studies robust resource allocation algorithm design for a
multiuser multiple-input single-output (MISO) cognitive radio (CR) downlink
communication network. We focus on a secondary system which provides unicast
secure wireless layered video information to multiple single-antenna secondary
receivers. The resource allocation algorithm design is formulated as a
non-convex optimization problem for minimization of the total transmit power at
the secondary transmitter. The proposed framework takes into account a quality
of service (QoS) requirement regarding video communication secrecy in the
secondary system, the imperfection of the channel state information (CSI) of
potential eavesdroppers (primary receivers) at the secondary transmitter, and a
limit for the maximum tolerable received interference power at the primary
receivers. Thereby, the proposed problem formulation exploits the
self-protecting architecture of layered transmission and artificial noise
generation to ensure communication secrecy. Semidefinite programming (SDP)
relaxation is employed to derive a resource allocation algorithm which finds
the global optimal solution to the formulated problem. Simulation results
demonstrate significant transmit power savings and robustness against CSI
imperfection for the proposed resource allocation algorithm for layered
transmission compared to baseline schemes with traditional single-layer
transmission.
