Date Added: Apr 2011
In Cognitive Radio (CR) networks, the perceived reduction of application layer Quality of Service (QoS), such as multimedia distortion, by secondary users may impede the success of CR technologies. Most previous work in CR networks ignores application layer QoS. In this paper, the authors take an integrated design approach to jointly optimize multimedia intra refreshing rate, an application layer parameter, together with access strategy, and spectrum sensing for multimedia transmission in a CR system with time varying wireless channels. Primary network usage and channel gain are modeled as a finite state Markov process. With channel sensing and channel state information errors, the system state cannot be directly observed. They formulate the QoS optimization problem as a Partially Observable Markov Decision Process (POMDP).