Conference Paper

Time-Efficient Layer-2 Auto-Configuration for Cognitive Radios.

Conference: International Conference on Parallel and Distributed Computing Systems, PDCS 2005, November 14-16, 2005, Phoenix, AZ, USA
Source: DBLP

ABSTRACT timeslots, where is the maximum number of nodes deployed, is the maximum number of available channels for communication and is the diameter of the network. Assuming all nodes are aware of and , we present both diameter-aware and diameter-unaware versions of the algorithm. For highly sparse networks like linear chain topology where , with and , the diameter- aware conguration protocol terminates within and the diameter-unaware version terminates within .

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    ABSTRACT: In multi-hop cognitive radio networks, the communication links among the cognitive nodes fail easily with the dynamic appearances of the licensed users. We propose an approach to compute the weight of the available channels intersections. The cognitive nodes compare the weights of different routing paths and update the route-table to reduce the re-routing times caused by the network changing, in order to reduce packet loss rate in cognitive radio networks. Simulation results show that in a multi-hop cognitive radio network with frequent change of the licensed users and uneven distribution of the available spectrum, our protocol provides less packet loss rate in the communication channels and proper overhead in the control channel. KeywordsCognitive Radio Network-Routing Protocol-Spectrum Assignment-Packet Loss Rate-Overhead
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    ABSTRACT: We study oblivious deterministic gossip algorithms for multi-channel radio networks with a malicious adversary. In a multi-channel network, each of the n processes in the system must choose, in each round, one of the c chan- nels of the system on which to participate. Assuming the adversary can disrupt one channel per round, preventing communication on that channel, we establish a tight bound of max " " (1 )n c 1 + logc n "" on the number of rounds needed to solve the -gossip problem, a parameterized generalization of the all-to-all gossip problem that requires (1 )n of the "rumors" to be success- fully disseminated. Underlying our lower bound proof lies an interesting con- nection between -gossip and extremal graph theory. Specifically, we make use of Turan's theorem, a seminal result in extremal combinatorics, to reason about an adversary's optimal strategy for disrupting an algorithm of a given duration. We then show how to generalize our upper bound to cope with an adversary that can simultaneously disrupt t < c channels. Our generalization makes use of se- lectors: a combinatorial tool that guarantees that any subset of processes will be "selected" by some set in the selector. We prove this generalized algorithm opti- mal if a maximum number of values is to be gossiped. We conclude by extending our algorithm to tolerate traditional Byzantine corruption faults.
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    ABSTRACT: Recent disasters, including the 9/11 terrorist attacks, Hurricane Katrina, the London subway bombings, and the California wildfires, have all highlighted the limitations of current mobile communication systems for public safety first responders. First, in a point-to-point configuration, legacy radio systems used by first responders from differing agencies are often made by competing manufacturers and may use incompatible waveforms or channels. In addition, first responder radio systems, which may be licensed and programmed to operate in frequency bands allocated within their home jurisdiction, may be neither licensed nor available in forward-deployed disaster response locations, resulting in an operational scarcity of usable frequencies. To address these problems, first responders need smart radio solutions which can bridge these disparate legacy radio systems together, can incorporate new smart radio solutions, or can replace these existing aging radios. These smart radios need to quickly find each other and adhere to spectrum usage and access policies. Second, in an infrastructure configuration, legacy radio systems may not operate at all if the existing communications backbone has been destroyed by the disaster event. A communication system which can provide a new, temporary infrastructure or can extend an existing infrastructure into a shaded region is needed. Smart radio nodes that make up the public safety infrastructure again must be able to find each other, adhere to spectrum usage policies, and provide access to other smart radios and legacy public safety radios within their coverage area. This work addresses these communications problems in the following ways. First, it applies cognitive radio technology to develop a smart radio system capable of rapidly adapting itself so it can communicate with existing legacy radio systems or other smart radios using a variety of standard and customized waveforms.

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