Outage probability constrained robust downlink collaborative beamforming

We consider a downlink collaborative relay network where communication between the base station and the terminal node is assisted by a cluster of relay nodes with imperfect channel state information (CSI). The equivalent condition for the probability constraint on the signal-to-noise-ratio (SNR) is derived, by modeling the CSI uncertainties as Gaussian. Though the original problem is quite intractable, it could be effectively solved by working out an semidefinite programming (SDP) iteratively. Subsequently, computer simulations are carried out to validate our approach compared with the non-robust design techniques. Simulation results show that, the quality-of-service (QoS) can be guaranteed in statistical sense for the proposed approach while violated by the non-robust solution.