Javaid Nadeem, Ahmed Farwa, Wadud Zahid, Alrajeh Nabil, Alabed Mohamad Souheil, Ilahi Manzoor
COMSATS Institute of Information Technology, Islamabad 44000, Pakistan.
University of Engineering & Technology, Peshawar 25000, Pakistan.
Sensors (Basel). 2017 Aug 1;17(8):1762. doi: 10.3390/s17081762.
Underwater wireless sensor networks (UWSNs) facilitate a wide range of aquatic applications in various domains. However, the harsh underwater environment poses challenges like low bandwidth, long propagation delay, high bit error rate, high deployment cost, irregular topological structure, etc. Node mobility and the uneven distribution of sensor nodes create void holes in UWSNs. Void hole creation has become a critical issue in UWSNs, as it severely affects the network performance. Avoiding void hole creation benefits better coverage over an area, less energy consumption in the network and high throughput. For this purpose, minimization of void hole probability particularly in local sparse regions is focused on in this paper. The two-hop adaptive hop by hop vector-based forwarding (2hop-AHH-VBF) protocol aims to avoid the void hole with the help of two-hop neighbor node information. The other protocol, quality forwarding adaptive hop by hop vector-based forwarding (QF-AHH-VBF), selects an optimal forwarder based on the composite priority function. QF-AHH-VBF improves network good-put because of optimal forwarder selection. QF-AHH-VBF aims to reduce void hole probability by optimally selecting next hop forwarders. To attain better network performance, mathematical problem formulation based on linear programming is performed. Simulation results show that by opting these mechanisms, significant reduction in end-to-end delay and better throughput are achieved in the network.
水下无线传感器网络（UWSN）促进了各个领域中广泛的水生应用。然而，恶劣的水下环境带来了诸如低带宽、长传播延迟、高误码率、高部署成本、不规则拓扑结构等挑战。节点移动性和传感器节点的不均匀分布会在UWSN中产生空洞。空洞的产生已成为UWSN中的一个关键问题，因为它严重影响网络性能。避免空洞的产生有利于在一个区域实现更好的覆盖、减少网络中的能量消耗并提高吞吐量。为此，本文重点关注特别是在局部稀疏区域中空洞概率的最小化。两跳自适应逐跳矢量转发（2hop-AHH-VBF）协议旨在借助两跳邻居节点信息来避免空洞。另一种协议——基于质量转发的自适应逐跳矢量转发（QF-AHH-VBF），基于复合优先级函数选择最优转发器。由于选择了最优转发器，QF-AHH-VBF提高了网络的有效吞吐量。QF-AHH-VBF旨在通过最优选择下一跳转发器来降低空洞概率。为了获得更好的网络性能，基于线性规划进行了数学问题公式化。仿真结果表明，通过采用这些机制，网络中的端到端延迟显著降低，吞吐量得到提高。
