Signaling and QoS control in resilient cognitive radio networks

Cognitive radio networks aim to allow nodes to be aware of their radio environment. Therefore, cognitive radio equipment can select the best frequency band and modulation to communicate with any surrounding node. This enables efficient spectrum sharing and the transmission parameters optimization according to the needed quality of service. In this article, we firstly present a physical layer signaling protocol that allows cognitive radio nodes to discover their neighbors in a transparent manner, by sharing their frequency hopping sequences. This protocol allows discovering a new node in less than one second and at low cost, under realistic scenarios, using a Software Defined Radio (SDR). Then we present a MAC layer signaling protocol which is based on the RTS/CTS handshake mechanism, defined in the IEEE 802.11 standard. This signaling mechanism enables the cognitive radio nodes to negotiate spectrum allocation and to select the best modulation for a transmission. We finally associate to this protocol, a transmission parameters (which have an impact on QoS) control function. Our proposal therefore improves wireless nodes capabilities in order to define a resilient network capable of providing and maintaining a certain level of QoS.