  MillimeterWave communications in the 60 GHz band are considered one of the
key technologies for enabling multi-gigabit wireless access. However, the high
propagation loss in such a band poses major obstacles to the optimal
utilization of the wireless resources, where the problem of efficient client
association to access points (APs) is of vital importance. In this paper, the
client association in 60 GHz wireless access networks is investigated. The AP
utilization and the quality of the rapidly vanishing communication links are
the control parameters. Because of the tricky non-convex and combinatorial
nature of the client association optimization problem, a novel solution method
is developed to guarantee balanced and fair resource allocation. A new
distributed, lightweight and easy to implement association algorithm, based on
Lagrangian duality theory and subgradient methods, was proposed. It is shown
that the algorithm is asymptotically optimal, that is, the relative duality gap
diminishes to zero as the number of clients increases. Both theoretical and
numerical results evince numerous useful properties of the algorithm, such as
fast convergence, scalability, time efficiency, and fair execution in
comparison to existing approaches. It is concluded that the proposed solution
can be applied in the forthcoming 60 GHz wireless access networks.
