We study the problem of user association, i.e., determining which base station (BS) a user should associate with, in a dense millimeter wave (mmWave) network. In our system model, in each time slot, a user arrives with some probability in a region with a relatively small geographical area served by a dense mmWave network. Our goal is to devise an association policy under which, in each time slot in which a user arrives, it is assigned to exactly one BS so as to minimize the weighted average amount of time that users spend in the system. The above problem is a restless multi-armed bandit problem and is provably hard to solve. We prove that the problem is Whittle indexable, and based on this result, propose an association policy under which an arriving user is associated with the BS having the smallest Whittle index. Using simulations, we show that our proposed policy outperforms several user association policies proposed in prior work.

翻译：我们研究用户的关联问题,即确定一个用户应该与哪个基站(BS)在一个密度毫米波(mmWave)网络中联系。在我们的系统模型中,每个时间档中,一个用户都有可能到达一个相对较小的地理区域,由一个密度毫米Wave网络服务的区域。我们的目标是制定一项联合政策,在用户到达的每一个时间档中,它被完全分配给一个BS,以便尽可能减少用户在系统中花费的加权平均时间。上面的问题是一个无休止的多臂强盗问题,而且很难解决。我们证明,这个问题是可以按惠特尔指数的,并以此结果为基础,提出一个联合政策,使抵达的用户与拥有最小惠特尔指数的BS相联系。我们用模拟来显示,我们提出的政策比先前工作中提出的几个用户关联政策要好得多。