Adaptive energy-efficient spectrum probing in cognitive radio networks

  • Authors:
  • Zesheng Chen;Chao Chen

  • Affiliations:
  • -;-

  • Venue:
  • Ad Hoc Networks
  • Year:
  • 2014

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Abstract

In cognitive radio networks, secondary users must constantly probe the spectrum to promptly detect the arrival and the departure of primary users (PUs). However, spectrum probing is an energy-consuming process. This indicates the tradeoff between the frequency of spectrum probing and the delay of detecting the PU state change, and highlights the need for energy-conscious spectrum-probing strategies. In this paper, we provide a theoretical framework to find the optimal spectrum-probing methods that minimize the probing delay under a constraint on energy consumption in real stochastic environments. Moreover, we design a practical, sub-optimal adaptive-probing strategy that self-learns the behavior of the PU's dynamics and exploits the proposed optimal probing method. Specifically, we find that the most widely used spectrum-probing scheme, i.e., periodic probing, is not optimal when the arrival rate of the PU state change is not constant or when the distribution of PU channel occupancy/vacancy is not uniform. On the other hand, the derived optimal and adaptive strategies can adapt to the dynamics of PUs and adjust the probing intervals based on the time-varying arrival rate of the PU state changes or the non-uniform distribution of PU channel occupancy/vacancy. Our simulation results show that the optimal spectrum-probing strategies and adaptive-probing methods perform much better and consume much less energy than periodic probing in realistic environments.