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Opportunistic scheduling in random beamforming maximizes the sum-rate by allocating resources to the users with the best channel condition, thus leveraging on multiuser diversity/multiplexing gain. Even if the scheduler assigns the resources according to the SINR, the main drawback to the practical deployment of these schemes is the intense feedback to be provided by every user. In this paper we address the sum-rate maximization of downlink multiuser MIMO space division multiple access systems based on 1-bit quantization of SINR feedback where each available spatial beam is assigned to a different user. To minimize signalling, here it is proposed a distributed method to locally estimate the optimal quantization thresholds among the terminals that guarantees a fair allocation of the available resources. Analytical results prove that the distributed scheme is asymptotically (when increasing the number of users) optimal in terms of sum-rate scaling law. Numerical simulations validate the analysis and highlight the capability of the distributed scheme to guarantee fairness constraints.