Multicell Downlink Beamforming with Imperfect Channel Knowledge at Both Transceiver Sides

In this letter, we design downlink beamforming vectors for a multicell network when only imperfect channel state information (CSI) is available at both base stations (BS) and mobile users (MU). We consider two different optimization criteria, i.e., minimizing the total downlink transmit power subject to quality of service (QoS) constraints at each MU and maximizing the worst-case effective signal-to-interference-plus-noise ratio (SINR) subject to BS power constraints. To solve the optimization problems, the imperfect CSI embedded QoS constraints are converted to linear matrix inequalities (LMI) with the aid of S-procedure, and then a semidefinite relaxation (SDR) approach is applied. Numerical results are provided to corroborate the proposed studies.