Energy-Efficient Joint Sensing Duration, Detection Threshold, and Power Allocation Optimization in Cognitive OFDM Systems

Wenjun Xu, Xuemei Zhou, Chia-Han Lee, Zhiyong Feng, Jiaru Lin

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


This paper investigates an energy efficiency optimization problem in cognitive orthogonal frequency division multiplexing systems. The goal is to maximize the energy efficiency by adapting the sensing duration, detection threshold, and transmit power to the constraints of the energy consumption of the secondary network and the interference to the primary network in a statistical manner. First, the case of identical detection threshold for all subcarriers is considered. In order to circumvent the intractability of the resulting problem, an alternate iteration framework is proposed to iteratively solve the three decoupled subproblems: sensing duration optimization, detection threshold optimization, and power allocation optimization. By exploiting the characteristics of each subproblem, the proposed framework is proved to be convergent. Then, the case with individual detection threshold for each subcarrier is explored. By proving that the optimal detection threshold is the root of a quadratic equation with one unknown variable, the proposed framework can be applied with minor modification. Simulation results show that the proposed alternating optimization framework can approach rapidly to the optimal solution, with less than 1% gap. Compared with the existing schemes, both the cases with identical and individual detection thresholds can achieve a considerable energy efficiency gain, with the latter further outperforming the former.

Original languageEnglish
Article number7577882
Pages (from-to)8339-8352
Number of pages14
JournalIEEE Transactions on Wireless Communications
Issue number12
StatePublished - 1 Dec 2016


  • alternate iteration
  • cognitive OFDM
  • Cognitive radio
  • energy efficiency
  • spectrum uncertainty

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