Robust multicast beamforming for spectrum sharing-based cognitive radios

Yongwei Huang, Qiang Li, Wing Kin Ma, Shuzhong Zhang

Research output: Contribution to journalArticlepeer-review

77 Scopus citations


We consider a robust downlink beamforming optimization problem for secondary multicast transmission in a multiple-input multiple-output (MIMO) spectrum sharing cognitive radio (CR) network. The minimization of transmit power is formulated subject to both quality-of-service (QoS) constraints on the secondary receivers and interference temperature constraints on the primary users, under the assumption of imperfect channel state information (CSI). The problem is a nonconvex quadratically constrained quadratic program (QCQP), and in general it is hard to achieve the global optimality. As a compromise, we present two randomized approximation algorithms for the problem via convex optimization techniques. Apart from the general setting of the robust beamforming problem, we identify one interesting special case, the robust problem of which can be solved efficiently. Simulation results are presented to demonstrate the performance gains of the proposed algorithms over an existing robust design.

Original languageEnglish (US)
Article number6026260
Pages (from-to)527-533
Number of pages7
JournalIEEE Transactions on Signal Processing
Issue number1
StatePublished - Jan 1 2012


  • Imperfect channel state information
  • MIMO cognitive radio networks
  • robust multicast beamforming
  • semidefinite programming relaxation
  • spectrum sharing

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