Toward Reliable Contention-aware Data Dissemination in Multi-hop Cognitive Radio Ad Hoc Networks

This paper introduces a new channel selection strategy for reliable contentionaware data dissemination in multi-hop cognitive radio network. The key challenge here is to select channels providing a good tradeoff between connectivity and contention. In other words, channels with good opportunities for communication due to (1) low primary radio nodes (PRs) activities, and (2) limited contention of cognitive ratio nodes (CRs) acceding that channel, have to be selected. Thus, by dynamically exploring residual resources on channels and by monitoring the number of CRs on a particular channel, SURF allows building a connected network with limited contention where reliable communication can take place. Through simulations, we study the performance of SURF when compared with three other related approaches. Simulation results confirm that our approach is effective in selecting the best channels for efficient and reliable multi-hop data dissemination

Distributed Clustering in Cognitive Radio Ad Hoc Networks Using Soft-Constraint Affinity Propagation

Absence of network infrastructure and heterogeneous spectrum availability in cognitive radio ad hoc networks (CRAHNs) necessitate the self-organization of cognitive radio users (CRs) for efficient spectrum coordination. The cluster-based structure is known to be effective in both guaranteeing system performance and reducing communication overhead in variable network environment. In this paper, we propose a distributed clustering algorithm based on soft-constraint affinity propagation message passing model (DCSCAP). Without dependence on predefined common control channel (CCC), DCSCAP relies on the distributed message passing among CRs through their available channels, making the algorithm applicable for large scale networks. Different from original soft-constraint affinity propagation algorithm, the maximal iterations of message passing is controlled to a relatively small number to accommodate to the dynamic environment of CRAHNs. Based on the accumulated evidence for clustering from the message passing process, clusters are formed with the objective of grouping the CRs with similar spectrum availability into smaller number of clusters while guaranteeing at least one CCC in each cluster. Extensive simulation results demonstrate the preference of DCSCAP compared with existing algorithms in both efficiency and robustness of the clusters

Cloned Access Point Detection and Point Detection and Prevention Mechanism in IEEE 802.11 Wireless Mesh Networks

IEEE 802.11 Wireless Mesh Network (WMN) is an emerging low cost, decentralized community-based broadband technology, which is based on self-healing and multi-hop deployment of Access Points (APs), so that to increase the coverage area with maximum freedom to end-users to join or leave the network from anywhere anytime having low deployment and maintenance cost. Such kind of decentralized structure and multihop architecture increases its security vulnerabilities especially against the APs. One of such possible security attack is the placement of cloned AP to create serious performance degradation in IEEE 802.11 WMN. In this paper, we discuss the different security vulnerabilities of AP in IEEE 802.11 WMN along with possible research directions. We also propose a mutual cooperation mechanism between the multi-hop APs and serving gateway so that to detect and prevent the possibility of cloned AP. In this way the large scale exploitation of IEEE 802.11 WMN can be eliminated