A distributed algorithm for robust transmission in multicell networks with probabilistic constraints

This paper studies a robust beamforming optimization problem of minimizing total transmit power in a distributed manner in the presence of imperfect channel state information (CSI) in multicell interference networks. Due to the fact that worst- case is a rare occurrence in practical network, this problem is constrained to satisfying a set of signal-to-interference-plus-noise-ratio (SINR) requirements at user terminals with certain SINR outage probabilities. This problem is numerically intractable due to the cross-link coupling effect among base stations (BSs) operating under the same frequency bandwidth and the robust constraints that involve instantaneous CSI uncertainties. The intractable problem is first converted to a semidefinite programming form with linear matrix inequality constraints via Schur complement, S-procedure and semidefinite relaxation technique, and then decomposed into a set of independent subproblems at individual BSs and solved via subgradient iterations with a light inter-BS communication overhead. Simulation results demonstrate the advantage of the proposed strategy in terms of providing larger SINR operational range as compared with recent proposed designs.