eDirect: Energy-Efficient D2D-Assisted Relaying Framework for Cellular Signaling Reduction

Mobile Instant Messaging (IM) apps, such as WhatsApp and WeChat, frequently send heartbeat messages to remote servers to maintain their always-online status. Periodic heartbeat messages are small in size, but their transmissions incur heavy signaling traffic due to frequently establishing and releasing communication channels between Base Stations (BSs) and smartphones, known as the signaling storm. Meanwhile, smartphones also need to activate the cellular data communication module frequently for transmitting short heartbeat messages, resulting in substantial energy consumption. To address these issues, we present eDirect, an energy-efficient D2D-assIsted Relaying framEwork for Cellular signaling reducTion. eDirect selects active smartphones as relays to opportunistically collect heartbeat messages from nearby smartphones using energy-efficient D2D communication. The collected heartbeat messages are transmitted to the BS in an aggregated manner to reduce cellular signaling traffic. Based on the beating frequencies and deadlines of the collected heartbeat messages, eDirect schedules transmissions of the collected heartbeat messages to minimize signaling overhead and energy consumption while meeting the deadline constraints. We implement and evaluate our solution on Android smartphones. The results from real-world experiments show that our solution reduces signaling traffic by at least 50% and energy consumption by up to 36%.