1,357 research outputs found
Capacity scaling law by multiuser diversity in cognitive radio systems
This paper analyzes the multiuser diversity gain in a cognitive radio (CR)
system where secondary transmitters opportunistically utilize the spectrum
licensed to primary users only when it is not occupied by the primary users. To
protect the primary users from the interference caused by the missed detection
of primary transmissions in the secondary network, minimum average throughput
of the primary network is guaranteed by transmit power control at the secondary
transmitters. The traffic dynamics of a primary network are also considered in
our analysis. We derive the average achievable capacity of the secondary
network and analyze its asymptotic behaviors to characterize the multiuser
diversity gains in the CR system.Comment: 5 pages, 2 figures, ISIT2010 conferenc
A Survey on Wireless Security: Technical Challenges, Recent Advances and Future Trends
This paper examines the security vulnerabilities and threats imposed by the
inherent open nature of wireless communications and to devise efficient defense
mechanisms for improving the wireless network security. We first summarize the
security requirements of wireless networks, including their authenticity,
confidentiality, integrity and availability issues. Next, a comprehensive
overview of security attacks encountered in wireless networks is presented in
view of the network protocol architecture, where the potential security threats
are discussed at each protocol layer. We also provide a survey of the existing
security protocols and algorithms that are adopted in the existing wireless
network standards, such as the Bluetooth, Wi-Fi, WiMAX, and the long-term
evolution (LTE) systems. Then, we discuss the state-of-the-art in
physical-layer security, which is an emerging technique of securing the open
communications environment against eavesdropping attacks at the physical layer.
We also introduce the family of various jamming attacks and their
counter-measures, including the constant jammer, intermittent jammer, reactive
jammer, adaptive jammer and intelligent jammer. Additionally, we discuss the
integration of physical-layer security into existing authentication and
cryptography mechanisms for further securing wireless networks. Finally, some
technical challenges which remain unresolved at the time of writing are
summarized and the future trends in wireless security are discussed.Comment: 36 pages. Accepted to Appear in Proceedings of the IEEE, 201
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