Spectral and Energy Efficiency in Cognitive Radio Systems with Unslotted Primary Users and Sensing Uncertainty

Gozde Ozcan, M. Cenk Gursoy, Jian Tang

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


This paper studies energy efficiency (EE) and average throughput maximization for cognitive radio systems in the presence of unslotted primary users. It is assumed that primary user activity follows an ON-OFF alternating renewal process. Secondary users first sense the channel possibly with errors in the form of miss detections and false alarms, and then, start the data transmission only if no primary user activity is detected. The secondary user transmission is subject to constraints on collision duration ratio, which is defined as the ratio of average collision duration to transmission duration. In this setting, the optimal power control policy which maximizes the EE of the secondary users or maximizes the average throughput while satisfying a minimum required EE under average/peak transmit power and average interference power constraints is derived. Subsequently, low-complexity algorithms for jointly determining the optimal power level and frame duration are proposed. The impact of probabilities of detection and false alarm, transmit and interference power constraints on the EE, average throughput of the secondary users, optimal transmission power, and the collisions with primary user transmissions are evaluated. In addition, some important properties of the collision duration ratio are investigated. The tradeoff between the EE and average throughput under imperfect sensing decisions and different primary user traffic are further analyzed.

Original languageEnglish (US)
Article number7892848
Pages (from-to)4138-4151
Number of pages14
JournalIEEE Transactions on Communications
Issue number10
StatePublished - Oct 2017


  • Cognitive radio
  • collision constraints
  • energy efficiency
  • interference power constraint
  • optimal frame duration
  • optimal power control
  • probability of detection
  • probability of false alarm
  • renewal processes
  • throughput
  • unslotted transmission

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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