Despite many existing research on data forwarding in low-duty-cycle wireless sensor networks (WSNs), relatively little work has been done on energy-efficient data forwarding with probabilistic delay bounds. Probabilistic delay guarantees (i.e., delay bounded data delivery with reliability constraints) are of increasing importance for many delay-constrained applications, since deterministic delay bounds are prohibitively expensive to guarantee in WSNs. However, radio duty-cycling and unreliable wireless links pose challenges for achieving the probabilistic delay guarantee in WSNs. In this paper, we propose EEAF, a novel energy-efficient adaptive forwarding technique tailored for low-duty-cycle WSNs with unreliable wireless links. We show the existence of path diversity in low-duty-cycle WSNs, where delay-optimal routing and energy-optimal routing are likely following different paths. The key idea of EEAF is to exploit the intrinsic path diversity to provide probabilistic delay guarantees while minimizing transmission cost. In EEAF, an early arriving packet will be adaptively switched to the energy-optimal path for energy conservation. Delay quantiles are derived at each node in a distributed manner and are used as the guidelines in the adaptive forwarding decision making. Extensive testbed experiment and large-scale simulation show that EEAF effectively reduces the transmission cost by 12%25% with probabilistic delay guarantees under various network settings. In addition, we extend the EEAF technique with data aggregation for event-based traffic scenarios. Evaluation using publicly available WSN event traffic traces yields very encouraging results with up to 40% energy saving in probabilistic delay bounded data delivery.
Bibliographical noteFunding Information:
Manuscript received August 31, 2019; revised January 19, 2020; accepted March 29, 2020. Date of publication April 17, 2020; date of current version July 10, 2020. This work was supported in part by NSFC under Grant 61972253, Grant 61672349, and Grant U190820096, and in part by the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning. This article was presented in part at the IEEE SECON’15. The associate editor coordinating the review of this article and approving it for publication was G. Fodor. (Corresponding author: Linghe Kong.) Long Cheng and Yongjia Song are with the Department of Industrial Engineering, Clemson University, Clemson, SC 29634 USA (e-mail: firstname.lastname@example.org; email@example.com).
- Wireless sensor networks
- adaptive forwarding
- probabilistic delay guarantee