Chisheng Zhang

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Spectrum handoff causes performance degradation of the cognitive network when the primary user reclaims its right to access the licensed spectrum. In a multi-hop cognitive network, this problem becomes even worse since multiple links are involved. Spectrum handoff of multiple links seriously affects the network connectivity and routing. In this paper, we(More)
The co-existence and integration of different wireless networks will significantly advance the provision of ubiquitous and high-performance Internet services to mobile users. In this paper, we present HAWK, a real-world implementation of high performance heterogeneous wireless networks for ubiquitous Internet access. We have built a fully featured testbed(More)
The wormhole attack is a severe attack in Wireless Mesh Networks (WMNs). It involves two or more wormhole endpoints colluding to capture traffic from one place in the network and replay it to another faraway place through a secret tunnel, so as to distort network routing. It may lead to even more serious threats such as packet dropping and denial of service(More)
With the popularity of different wireless access technologies for Internet access, the integration of heterogeneous wireless networks is foreseen in the near future. Solutions for secured Internet access in such scenario become an urgent requirement. In this paper, we present SHAWK, a platform for secure integration of heterogeneous advanced wireless(More)
In cognitive networks, spectrum handoff occurs when primary users reclaim their rights to access their licensed spectrum. When links perform spectrum handoff, their communication may be interrupted for a certain period and incurs spectrum handoff delay. Existing work only considered the problem of minimizing spectrum handoff delay of a single link in(More)
Mobile Ad hoc networks typically work in an open un-trusted environment with little physical security, and are vulnerable for different type of security attacks. one attack in ad hoc networks is the wormhole attack that has received a great deal of recent attention. In wormhole attack, an attacker captures the packets from one point in the network and(More)
Wireless networks offer many advantages over wired local area networks such as scalability and mobility. Strategically deployed wireless networks can achieve multiple objectives like traffic offloading, network coverage, and indoor localization. To this end, various mathematical models and optimization algorithms have been proposed to find optimal(More)
As a typical scenario of mobile Internet, a vehicular Internet access network is a network where vehicles exploit wireless technologies to communicate with infrastructure directly or indirectly via other vehicles or road-side units in high speed. Thus, opportunistic interactions through neighboring vehicles and infrastructure networks can be utilized to(More)