1. FSMA - A Topology-Transparent Scheme for Opportunistic Spectrum Access 
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Contact Hwee-Pink Tan [tanhp(at)tcd(dot)ie], Colman O'Sullivan [cosull13(at)tcd(dot)ie] and Linda Doyle [ledoyle(at)tcd(dot)ie]

Context
With the advent of cognitive radio technology, new paradigms for spectrum access can achieve near-optimal spectrum utilization by letting users sense and utilize available spectrum opportunistically. Recently, graph-coloring models have been used to produce fair, efficient and optimal spectrum allocations for a given network topology. However, topology changes (e.g., due to user mobility or finite call durations) can incur significant signaling traffic to reallocate spectrum, consuming valuable resources.

Overview
We propose a frequency-spread multiple access (FSMA) scheme that is topology-transparent, and numerical results suggest that it is suited for opportunistic spectrum access in a sparsely-connected, low density mobile ad hoc network.

Related Publications

  • Hwee-Pink Tan, Colman O'Sullivan and Linda Doyle. FSMA - A Topology-Transparent Scheme for Opportunistic Spectrum Access. Accepted for publication in 65th IEEE VTC, April 2007.



    • 2. An Interference Temperature Constraints Model for Spectrum Access in Cognitive Radio Networks 
    Contact Hwee-Pink Tan [tanhp(at)tcd(dot)ie], Joe Bater [j(dot)bater(at)4c(dot)ucc(dot)ie], Kenneth N Brown [k(dot)brown(at)4c(dot)ucc(dot)ie], Colman O'Sullivan [cosull13(at)tcd(dot)ie] and Linda Doyle [ledoyle(at)tcd(dot)ie]

    Context
    With the advent of cognitive radio technology, new paradigms for spectrum access can achieve near-optimal spectrum utilisation by letting each user sense and utilise available spectrum opportunistically while regulating the interference it imposes on other users through interference constraints. The standard constraint models are restricting the possible assignment of spectrum between pairs of transmitters. Thus a commonplace analogy to Graph Colouring is used to formulate models of the problem, and algorithms so inspired may be adapted for application to spectrum management. These constraints are generally transmitter-centric (set without direct recourse to the receivers state) and eliminate the possibility of one transmitter interfering with another.

    Overview
    Since interference is a receiver issue we consider receiver-centric constraint models for spectrum access in cognitive radio networks. These models directly consider the potential harmful interference from potential interferers in the network and are line with the recently proposed interference temperature metric. We show that pairwise constraint models are insufficient to the task, but that a more general constraint model captures the problem exactly.

    Related Publications

  • Joe Bater, Kenneth N Brown, Linda Doyle, Colman O'Sullivan and Hwee-Pink Tan. An Interference Temperature Constraints Model for Spectrum Access in Cognitive Radio Networks. Submitted to EURASIP Journal on Wireless Communications and Networking, December 2007.

  • Joe Bater, Hwee-Pink Tan, Kenneth N Brown and Linda Doyle. Maximising Access to a Spectrum Commons using Interference Temperature Constraints. Accepted for publication in ICST Crowncom, August 2007.

  • Joe Bater, Hwee-Pink Tan, Kenneth N Brown and Linda Doyle. Modelling Interference Temperature Constraints for Spectrum Access in Cognitive Radio Networks. Accepted for publication in IEEE CogNet Workshop, June 2007.