A Spectrum Access with User Cooperation in Heterogeneous Cognitive Radio Networks

Cognitive radio system consists of multiple wireless accesses that cover overlapping area, and cognitive terminals that use one or more of the wireless accesses simultaneously. In cognitive radio systems, secondary users can share the spectrum with the primary user as long as the quality of service (QoS) of the primary system is guaranteed. However, the system throughput of the cognitive system will be limited when the QoS requirement is stringent. We had proposed the architecture of the cognitive radio system, the inter-system handover protocols and packet format designed to achieve fast handover among the radio systems.