Green Cooperative Device–to–Device Communication: a Social–Aware Perspective

As the mobile operators strive to accommodate the increasing load and capacity requirements, direct communication among users' devices, namely, device-to-device (D2D) communication, emerges as an advantageous solution for cellular traffic offloading. However, the formation and the operation of D2D networks are challenging, as D2D peers must satisfy various network-related constraints. Although existing approaches address the D2D communication technical challenges, they usually neglect the fact that devices are used by humans possibly reluctant to communicate with unknown users, introducing an additional constraint. Following the proliferation of social networks and cutting edge mobile devices, social ties among users can promote D2D cooperation. In D2D cooperative communication, multiple devices in close proximity attempt to access the wireless medium. Their interactions at medium access level are affected by the users' social features, as socially connected users are more likely to engage in D2D cooperation. Moreover, the energy consumption of power-constrained mobile devices affects the effectiveness of D2D cooperative communication, stressing the need for incorporating energy awareness in D2D networking. In this paper, we outline the challenges that appear in D2D cooperative networking and medium access control (MAC) design under the influence of social characteristics and the energy consumption concerns that arise in modern D2D networking scenarios. Considering the users' social ties, we present an energy efficient social-aware cooperative D2D MAC protocol as a paradigm of social information inclusion in the green D2D MAC design. Last, we discuss the practical issues of the adoption of social awareness in green D2D cooperation, which may affect the D2D performance in realistic scenarios. Our simulation results demonstrate the effectiveness of exploiting the existence of users' social connections in D2D cooperation, highlighting the need for green social-aware D2D cooperative schemes.