Underwater acoustic sensor networks (UW-ASNs) have been attracting more and more research interests recently due to their various promising applications. In this paper, we focus on the time division multiple access (TDMA) based media access control (MAC) protocol design for UW-ASNs in order to improve the network performance. Different from existing work, we consider a more general underwater communication scenario, where the communication network topology is modeled as a three-dimensional (3-D) scenario and the mobility of sensor nodes is also taken into consideration. We introduce a dynamic and flexible spatial reuse strategy for the TDMA protocol design, and formulate the interference scenario as a dynamic interference-free graph according to the nodes' current position distribution and a preset interference-free threshold. To achieve high spatial reuse efficiency, we propose two interference-free graph (IG) clustering algorithms, which lead to the optimal IG-TDMA protocol and the heuristic IG-TDMA protocol, respectively. The former can achieve the optimal network throughput but may not be feasible for high traffic networks due to its high computational complexity. The latter can achieve near-optimal network performance with much lower computational complexity and thus is more practical. Simulations verify the benefits of our proposed protocols in comparison with the CSMA/CA protocol and some existing TDMA protocols with and without spatial reuse.
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Manuscript received November 29, 2016; revised July 11, 2017; accepted November 12, 2017. Date of publication December 1, 2017; date of current version May 14, 2018. This work was supported in part by the National Science Foundation of China under Grant 61622101 and Grant 61571020, in part by the Ministry National Key Research and Development Project under Grant 2016YFE0123100, and in part by the National Science Foundation under Grant CNS-1343189. The review of this paper was coordinated by Prof. Nei Kato. (Corresponding author: Xiang Cheng.) R. Zhang is with the State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics Engineering and Computer Science, Peking University, Beijing 100080, China, and also with the Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO 80523 USA (e-mail: email@example.com).
- Interference-free graph
- spatial reuse
- underwater acoustic sensor network