  In this paper, the problem of optimized beam alignment for wearable
device-to-device (D2D) communications over millimeter wave (mmW) frequencies is
studied. In particular, a noncooperative game is formulated between wearable
communication pairs that engage in D2D communications. In this game, wearable
devices acting as transmitters autonomously select the directions of their
beams so as to maximize the data rate to their receivers. To solve the game, an
algorithm based on best response dynamics is proposed that allows the
transmitters to reach a Nash equilibrium in a distributed manner. To further
improve the performance of mmW D2D communications, a novel quantum game model
is formulated to enable the wearable devices to exploit new quantum directions
during their beam alignment so as to further enhance their data rate.
Simulation results show that the proposed game-theoretic approach improves the
performance, in terms of data rate, of about 75% compared to a uniform beam
alignment. The results also show that the quantum game model can further yield
up to 20% improvement in data rates, relative to the classical game approach.
