One Handshake Can Achieve More: An Energy-Efficient, Practical Pipelined Data Collection for Duty-Cycled Sensor Networks

To alleviate long sleep latency due to duty-cycled radio operations, existing collection protocols adopted pipelined scheduling techniques, which stagger the sleep-wakeup schedules of nodes along forwarding paths, requiring accurate time synchronization as underlying support. They either ignored the synchronization issue or just assumed that a local synchronization scheme over non-duty-cycled radios could meet the requirement, however, which may lead to a significant synchronization issue in practice. In this paper, we propose a practical pipelined data collection (PDC) protocol for duty-cycled sensor networks. PDC adopts an inter-layer incorporation of network and media access control layers. It only relies on an RTS/CTS-like handshake with a set of the proposed algorithms, not only for data transmission as commonly utilized, but also for pipelined scheduling and schedule synchronization, data-gathering tree establishment, and network topology control and maintenance, all of which are naturally and seamlessly incorporated together and able to support each other. PDC has been implemented in the Contiki operating system. The testbed evaluations based on two hardware platforms (Z1 and MicaZ) and the compared results with a de facto standard for data collection based on the fully emulated Z1 in Cooja have demonstrated its practicality and efficacy.