CAP: A ContAct based Proximity service via opportunistic device-to-device relay

The research progress of 5G has brought a number of novel technologies to meet the multi-dimensional demands. Device-to-Device (D2D) communication is a way to no longer treat the User Equipments (UEs) as terminal, but rather as a part of network (known as helpers) for service provisioning. Such a way potentially increases the coverage and also expands the capacity of cellular network. In this paper, we propose a generic framework for Proximity as a Service (PaaS) with demands of service continuity, namely ContAct based Proximity (CAP) via opportunistic D2D communication. Mainly, fruitful contact information (e.g., contact duration, frequency and interval) is captured as a key metric, to handle an ubiquitous and PaaS through the optimal selection of helpers. The nature of CAP is evaluated under the Helsinki city scenario, with key factors influencing the service demands (e.g., success ratio, disruption duration and frequency). Simulation results show the advantage of CAP, in both success ratio and continuity of the service. This work is the first one to evaluate LTE-Direct and WiFi-Direct in opportunistic proximity services.