In this paper, we study an optimal user scheduling with minimum beam alignment overhead in millimeter wave networks. The problem is posed as constrained Markov decision process (CMDP) with the goal of minimizing the average beam alignment overhead subject to the average rate constraint on each user. Under a certain assumption on the rate function of the users, by using a structural result derived from the Lagrangian formulation of the CMDP, we show that the optimal policy should keep scheduling the users that are scheduled in the previous time slot unless an abrupt change in the beam direction occurs. Using this result, the complexity of the problem decreases to polynomial in the number of users. In addition, we provide a heuristic deterministic algorithm that achieves (1+ϵ)({1}+\epsilon) approximation of the optimal solution, with smaller ϵ\epsilon at the cost of longer transmission interval of each user. Lastly, to deal with the case where the assumption on the rate function does not hold due to beam conflicts between the users, we consider a system model that accounts for an angular channel information. A new CMDP is formulated for the problem and a heuristic algorithm based on the age information is proposed.

中文翻译：

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具有大量移动用户的毫米波网络中的用户调度和波束对准


在本文中，我们研究了毫米波网络中波束对准开销最小的最佳用户调度。该问题被提出为约束马尔可夫决策过程（CMDP），其目标是在每个用户的平均速率约束下最小化平均波束对准开销。在用户速率函数一定的假设下，通过使用 CMDP 的拉格朗日公式导出的结构结果，我们表明最优策略应该继续调度在前一个时隙中调度的用户，除非情况突然发生变化。发生光束方向。使用这个结果，问题的复杂性降低到用户数量的多项式。此外，我们提供了一种启发式确定性算法，可以实现最优解的 (1+ϵ)({1}+\epsilon) 近似，较小的 ϵ\epsilon 以每个用户的传输间隔较长为代价。最后，为了处理由于用户之间的波束冲突而导致速率函数的假设不成立的情况，我们考虑考虑角度信道信息的系统模型。针对该问题制定了新的CMDP，并提出了基于年龄信息的启发式算法。