Department of Electronics Engineering, Chungnam National University, Daejeon 34134, Republic of Korea.
LIG Nex1, Yongin 16911, Republic of Korea.
Sensors (Basel). 2023 Feb 22;23(5):2447. doi: 10.3390/s23052447.
Time-division multiple access (TDMA)-based medium access control (MAC) protocol has been widely used for avoiding access conflicts in wireless multi-hop ad hoc networks, where the time synchronization among wireless nodes is essential. In this paper, we propose a novel time synchronization protocol for TDMA-based cooperative multi-hop wireless ad hoc networks, which are also called . The proposed time synchronization protocol is based on cooperative relay transmissions to send time synchronization messages. We also propose a network time reference (NTR) selection technique for improving the convergence time and average time error. In the proposed NTR selection technique, each node overhears the user identifier (UID) of other nodes, hop count (HC) from them to itself, and network degree, which denotes the number of 1-hop neighbor nodes. Then, the node with the minimum HC from all other nodes is selected as the NTR node. If there are multiple nodes with the minimum HC, the node with the larger degree is selected as the NTR node. To the best of our knowledge, the proposed time synchronization protocol with the NTR selection is introduced for the first time for cooperative (barrage) relay networks in this paper. Through computer simulations, we validate the proposed time synchronization protocol in terms of the average time error under various practical network scenarios. Furthermore, we also compare the performance of the proposed protocol with the conventional time synchronization methods. It is shown that the proposed protocol significantly outperforms the conventional methods in terms of the average time error and convergence time. The proposed protocol is shown to be more robust against packet loss as well.
时分多址 (TDMA) 为基础的媒体访问控制 (MAC) 协议已被广泛应用于避免无线多跳自组网中的访问冲突，而无线节点之间的时间同步是至关重要的。在本文中，我们提出了一种新颖的基于时分多址的协作多跳无线自组网的时间同步协议，也称为. 所提出的时间同步协议基于协作中继传输来发送时间同步消息。我们还提出了一种网络时间参考 (NTR) 选择技术，以提高收敛时间和平均时间误差。在提出的 NTR 选择技术中，每个节点侦听其他节点的用户标识符 (UID)、从它们到自身的跳数 (HC) 以及网络度，它表示一跳邻居节点的数量。然后，选择来自所有其他节点的 HC 最小的节点作为 NTR 节点。如果有多个 HC 最小的节点，则选择度数较大的节点作为 NTR 节点。据我们所知，本文首次为协作 (弹幕) 中继网络提出了具有 NTR 选择的提议时间同步协议。通过计算机仿真，我们在各种实际网络场景下验证了所提出的时间同步协议的平均时间误差。此外，我们还比较了所提出的协议与传统时间同步方法的性能。结果表明，所提出的协议在平均时间误差和收敛时间方面明显优于传统方法。所提出的协议在数据包丢失方面也表现出更强的鲁棒性。
