Session-Based Cooperation in Cognitive Radio Networks: A Network-Level Approach

Currently, the cooperation-based spectrum access in cognitive radio networks (CRNs) is implemented via cooperative communications based on link-level frame-based cooperative (LLC) approach, where individual secondary users (SUs) independently serve as relays for primary users (PUs) in order to gain spectrum access opportunities. Unfortunately, this LLC approach cannot fully exploit spectrum access opportunities to enhance the throughput of CRNs and fails to motivate PUs to join the spectrum sharing processes. To address these challenges, we propose a network-level session-based cooperative (NLC) approach, where SUs are grouped together to cooperate with PUs session by session, instead of frame by frame, for spectrum access opportunities of the corresponding group. To articulate our NLC approach, we further develop an NLC scheme under a cognitive capacity harvesting network architecture. We formulate the cooperative mechanism design as a cross-layer optimization problem with constraints on primary session selection, flow routing and link scheduling. Through extensive simulations, we demonstrate the effectiveness of the proposed NLC approach.