  In this paper, we consider queue-aware beamforming control for video
streaming applications in multi-antenna interference network. Using heavy
traffic approximation technique, we first derive the diffusion limit for the
discrete time queuing system. Based on the diffusion limit, we formulate an
infinite horizon ergodic control problem to minimize the average power costs of
the base stations subject to the constraints on the playback interruption costs
and buffer overflow costs of the mobile users. To deal with the queue coupling
challenge, we utilize the weak interference coupling property in the network to
derive a closed-form approximate value function of the optimality equation as
well as the associated error bound using perturbation analysis. Based on the
closed-form approximate value function, we propose a low complexity queue-aware
beamforming control algorithm, which is asymptotically optimal for sufficiently
small cross-channel path gain. Finally, the proposed scheme is compared with
various baselines through simulations and it is shown that significant
performance gain can be achieved.
