Connectivity of Underlay Cognitive Radio Networks with Directional Antennas

Qiu Wang, Hong Ning Dai*, Orestis Georgiou, Zhiguo Shi, Wei Zhang

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

14 Citations (Scopus)


In underlay cognitive radio networks (CRNs), the connectivity of secondary users (SUs) is difficult to be guaranteed due to the existence of primary users. Most prior studies only consider cognitive radio networks equipped with omni-directional antennas causing high interference at SUs. We name such CRNs with omni-directional antennas as Omn-CRNs. Compared with an omni-directional antenna, a directional antenna can concentrate the transmitting/receiving capability at a certain direction, consequently resulting in the less interference. In this paper, we investigate the connectivity of SUs in CRNs with directional antennas (named as Dir-CRNs). In particular, we derive closed-form expressions of the connectivity of SUs of both Dir-CRNs and Omn-CRNs, thus enabling tractability. We show that the connectivity of SUs is mainly affected by two constraints: the spectrum availability of SUs and the topological connectivity of SUs. Extensive simulations validate the accuracy of our proposed models. Meanwhile, we also show that Dir-CRNs can have higher connectivity than Omn-CRNs mainly due to the lower interference, the higher spectrum availability, and the higher topological connectivity brought by directional antennas. Moreover, we also extend our analysis with considering transmission power efficiency. The simulation results show that Dir-CRNs require less transmission power to establish links than Omn-CRNs. We further investigate the throughput capacity of SUs, which is shown to heavily depend on the connectivity of SUs.

Original languageEnglish
Article number8334605
Pages (from-to)7003-7017
Number of pages15
JournalIEEE Transactions on Vehicular Technology
Issue number8
Early online date10 Apr 2018
Publication statusPublished - 1 Aug 2018


  • Cognitive radio networks
  • connectivity
  • directional antennas
  • spectrum availability
  • stochastic geometry


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