Round-Robin Scheduling for Orthogonal Beamforming with Limited Feedback

We propose a round-robin scheduling algorithm for orthogonal beamforming with a strict signal to interference-plus-noise ratio (SINR) constraint and limited feedback. The presented algorithm aims at scheduling the users at identical slots over different blocks, in order to reduce the necessary scheduling overhead, and to minimize the maximum delay between serving the same user. Thus, the presented algorithm is especially suited for real-time multimedia traffic. The algorithm allocates the users using orthogonal beamforming based on the quantized feedback provided by the users. The quantized feedback consists of the estimated power that is necessary to fulfill a predefined SINR constraint. Further, we propose an algorithm to design codebooks to quantize the estimated power. Using the feedback, the base station redistributes power from users with spare power to users that lack power so that they fulfill their SINR constraints. The performance of the algorithm is demonstrated through simulations.