Maritime Wireless Communication: From Propagation to Multi-User Network Topoplogies

海上无线通信具有战略意义；因此，它在科学研究方面有着悠久的历史。在过去的几年里，我们已经被许多合作伙伴，如加拿大海军，要求提供可靠和高速的海外通信。通过使用巧妙的多天线方案，我们将水上可实现的数据速率提高了几个数量级。然而，大多数由他人和我们执行的长期测量活动显示，在收到的功率预测和实际测量之间存在显著差异。海面上的蒸发层引起的折射率梯度引起了对传播的导管效应，这一效应已得到充分的研究，但仍有些难以捉摸。例如，在澳大利亚的大堡礁上，有70公里的非视距连接，年平均功率比预测的要小1000倍，变化甚至与风无关，正如理论所预测的那样。在NSERC Ultra Electronics主席的最后一次活动中，我们还在66公里处获得了意想不到的、令人难以置信的良好非视距连接。如果一个人希望设计一个海上网络，通过增加功率来补偿未知的影响是不可能的，因为它也涉及到对全球网络的更多干扰。因此，在这个问题上，回到射频传播的基础是必要的。因此，我们建议对无线链路和反射过程中波的影响进行深入观察。事实上，我们认为，当范围较长时，掠角很低，只有少数海浪有效地产生反射和衍射。这一假设与通常的散射区域假设形成鲜明对比。我们提出计算分度掠掠和随机产生定向海浪的传播。天文台会进行实际的无线电测量，将海浪高度的实时测量值与接收到的信号功率相关联，以证实结果。在网络层面，研究了随机几何和各种网络拓扑结构，以预测具有可变节点密度的网络的整体性能。提出了在多种海况下，对不同船舶位置和天线高度分布的可实现吞吐量进行评估。在拓扑方面，将考虑网状或Ad-Hoc、点对点和点对多点系统的组合，以最大限度地提高异构网络（HetNet）的性能。海洋对加拿大和科威特至关重要，两国政府最近都在海洋战略上投资了20亿美元。值得注意的是，Ultra electronics TCS是由Giuseppe Marconi爵士于1903年创立的加拿大马可尼公司，因与泰坦尼克号的海外无线通信而闻名，并成为无线电相关诺贝尔奖的第一位获得者。这个提议完全符合我们历史上的无线创造力。

Maritime wireless communication is strategic; as such it has a long history of scientific endeavors. In the past years, we have been solicited by numerous partners, such as the Canadian Navy, to provide reliable and high-speed oversea communications. By using astute multiple antenna schemes, we have enhanced by orders of magnitude the achievable data rates overwater. However, most long range measurement campaigns, performed by others and us, show significant discrepancies between received power predictions and actual measurements. A well-studied, but still somewhat elusive, ducting effect on the propagation is caused by the gradient of refraction index induced by the evaporation layer above the sea. For example, on the great barrier reef in Australia, with a non-line-of-sight link of 70 km, the yearly average power is a thousand times less powerful than predicted, the variations are not even correlated with the wind, as the theory predicts. In the NSERC Ultra Electronics chair's last campaign, we also had an unexpected and unbelievably good non line-of-sight link at 66 km. If one wishes to design a maritime network, a compensation of unknown effects through increased power is not possible since it also involves more interference on the global network. Going back to RF propagation basics is thus imperative on this issue. We thus propose to have an in-depth observation of the wireless link and the effect of waves in the reflection process. In fact, we believe that when the range is long, the grazing angle is so low that only a small number of sea waves effectively produce reflection and diffraction. This hypothesis is in stark contrast to the usual assumption of a scattering area. We propose to compute the propagation with sub-degree grazing and a random generation of directional sea waves. An actual radio measurement will be set-up to confirm the results by correlating real-time wave measurements of sea wave heights and the received signal power. At the network level, stochastic geometry and various network topologies are examined to predict the overall performance of networks with variable node densities. It is proposed to evaluate the achievable throughput for different distributions of ship positions and antenna heights, over multiple sea conditions. In terms of topology, a combination of meshed or Ad-Hoc, point-to-point and point-to-multipoint systems will be considered to maximize the possible Heterogeneous Network (HetNet) performance. The sea is of central importance to Canada and Québec as emphasized recently by both governments investing 2 B$ in maritime strategies. It is worth noting that Ultra electronics TCS has been founded as the Canadian Marconi Company by Sir Giuseppe Marconi in 1903, renowned for oversea wireless communication with the Titanic and as the first recipient of a Radio related Nobel Prize. This proposal is completely aligned with our historical wireless inventiveness.