Resource allocation for OFDMA cognitive radios under channel uncertainty

Seung Jun Kim, Nasim Yahya Soltani, Georgios B. Giannakis

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


A resource allocation problem for a cognitive radio base station (CR-BS) communicating with multiple CR mobile stations (MSs) is considered in the downlink, which relies on orthogonal frequency-division multiple access (OFDMA). To protect the incumbent primary user (PU) system operating over the same frequency band, the interference inflicted to the PU receiver must be regulated. Since the channel gain estimates from the CR-BS to the PU receiver are typically uncertain in practice, a robust interference power constraint is advocated. Although the latter translates to a second-order cone constraint, the overall optimization problem for joint transmit-power and subcarrier allocation is non-convex, and coupled over all subcarriers in general. To circumvent the resulting computational hurdle, a tight polyhedral approximation of the second-order cone is employed. Practical finite-alphabet constellations are adopted and total weighted achievable rate is maximized. It is shown that a near-optimal solution can be obtained based on the Lagrangian dual.

Original languageEnglish (US)
Article number6552842
Pages (from-to)3578-3587
Number of pages10
JournalIEEE Transactions on Wireless Communications
Issue number7
StatePublished - 2013


  • Cognitive radios
  • channel uncertainty
  • optimization
  • resource allocation


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