Social stability enhanced mobile D2D relay networks: An optimal stopping approach

Device-to-device (D2D) relay network is regarded as a promising technology to meet the drastically increasing demands on local-based communication services. The relay devices on users with social behaviors will inevitably cause the negative effects on the stability of D2D communications. To improve the stability of the communication over mobile relays, we exploit users' social information in terms of contact duration to characterize the social stabilities of potential relays. Furthermore, with optimal stopping theory, we propose a joint social-physical relay re-selection scheme. This scheme takes into account the mobility of the currently selected relay as well as the social stability and physical conditions of potential relays. This can avoid the interruption of relayed communication and achieve the long-term increase of the relayed data traffic. Our scheme is shown to exhibit the stage-dependent policy structure that is adaptive for different mobility and social stability. This structure indicates that the relay re-selection scheme can achieve the tradeoff between the cost of relay probing and the amount of relayed data traffic. We conduct extensive simulations to demonstrate the superiority of our proposed scheme compared with other baseline schemes. The impact of social stability and mobility on the performance are revealed by our simulation results.