Proactive protection scheme for Small Backoff Window attack over Cognitive Radio Networks

As a novel technique to enhance the spectrum utilization by allowing Secondary Users (SUs) with an opportunistic manner to access available spectrum resource, cognitive radio has attracted much academic and industrial attentions. However, the common available spectrum resource will motivate certain Normal SUs (NSUs) to become selfish (called Greedy Cognitive Radios, GCRs). In particular, these GCRs deliberately revise the MAC protocol parameters and adopt Small Backoff Window (SBW) attack to gain the high priority of spectrum usage. In this paper, we propose a proactive protection scheme in Distributed Cognitive Radio Networks (DSRNs) to constrain this unfair competition, while guarantee the fairness and Quality of Service (QoS) of independent NSUs' transmission. In the proposed scheme, GCRs with high priority are allowed to access spectrum resource, while satisfying two prior rules: Rule 1, GCRs are required to prolong the transmission time of each packet in exchange for the high priority on spectrum usage; Rule 2, GCRs allow NSUs to transmit data with themselves simultaneously in certain slots. Simulation results show the proposed proactive protection scheme can effectively improves NSUs' throughput over DCRNs.