Connectivity of cognitive radio networks: proximity vs. opportunity

ABSTRACT

We address the connectivity of large-scale ad hoc cognitive radio networks, where secondary users exploit channels temporarily and locally unused by primary users and the existence of a communication link between two secondary users depends not only on the distance between them but also on the transmitting and receiving activities of nearby primary users. We introduce the concept of connectivity region defined as the set of density pairs -- the density of the secondary users and the density of the primary transmitters -- under which the secondary network is connected. Using theories and techniques from continuum percolation, we analytically characterize the connectivity region of the secondary network by showing its three basic properties and analyzing its two critical parameters. Furthermore, we reveal the tradeoff between proximity (the number of neighbors) and the occurrence of spectrum opportunities by studying the impact of secondary users' transmission power on the connectivity region of the secondary network, and design the transmission power of the secondary users to maximize their tolerance to the primary traffic load.

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Index Terms

• Computing methodologies

  • Modeling and simulation

    • Simulation theory

      • Systems theory

• Mathematics of computing

  • Information theory

• Theory of computation