Cognitive MIMO relaying networks with primary user's interference and outdated channel state information

Yuzhen Huang, Fawaz S. Al-Qahtani, Caijun Zhong, Qihui Wu, Jinlong Wang, Hussein Alnuweiri

Research output: Contribution to journalArticle

35 Citations (Scopus)


In this paper, we propose transmit antenna selection with maximal ratio combining (TAS/MRC) in dual-hop decode-and-forward spectrum-sharing relaying networks with the primary user's interference and outdated channel state information (CSI). In this network, a single antenna that maximizes the received SNR is selected at the secondary transmitter, and the MRC is adopted at the secondary receiver. To efficiently evaluate the impact of key parameters on the system performance, we derive the exact analytical expression for the outage probability of the secondary network in a Rayleigh fading channel. Moreover, we present simple asymptotic expressions for the outage probability in a high SNR regime, which reveal practical insights on the achievable diversity order and coding gain. The findings suggest that whether the outdated CSI concerning the secondary transmission links has significant impact on the outage probability of the system depends on the interference power constraint at primary receivers. Specifically, under the proportional interference power constraint, the achievable diversity order is affected by imperfect CSI regarding the secondary transmission links, and the diversity-multiplexing tradeoff is independent of the primary network. However, under the fixed interference power constraint, the error floor is displayed, and the achievable diversity order reduces to zero regardless of the CSI concerning the secondary transmission links.

Original languageEnglish
Article number6935092
Pages (from-to)4241-4254
Number of pages14
JournalIEEE Transactions on Communications
Issue number12
Publication statusPublished - 1 Dec 2014



  • Cognitive radio
  • MIMO
  • outdated channel state information (CSI)
  • relay

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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