An underwater communication network to remote subsea platforms

该项目的目的是通过开发分布式通信网络，提供对水下传感器的远程访问，以检测海底活动。为了避免入侵者窃听和访问数据，需要在节点之间进行隐蔽传输。此外，为了避免容易被检测到的表面表达（例如浮标），埋在海面以下几米处的网关将用于建立与海面上方的移动的平台的链路。 海底网络将主要依靠声传播在水下节点之间交换和中继信息。 为了扩大范围，将研究不同的网络拓扑结构，并定义一个通信协议，以允许部署自供电节点，用于可能持续数月的任务。 消息将使用短突发来分解，以在多个节点之间共享网络资源。 此外，依赖于不同频率音调集合的自适应调制技术将降低拦截的概率。使用这些调制技术，用户将获得分布在宽带宽上的独特签名，并受到潜艇上可用硬件要求的限制。 将使用特定的编码技术来加密消息，并允许安全和私人链接。 为了将数据从海面以下转发到水面船只，将建立一个跨越空气-水界面的短程中继链路。 为此，将提出一种依靠磁感应的通信链路。 尽管MI传统上被用作潜水员与潜水员通信的10米量级的短程链路，但在这项工作中，MI将用于空气-水界面，并将探索实现几百米的可能性。 为此，先验，分析模型的行为的电磁场，因为它穿过空气-水边界将开发。 一个可重新配置的无线电将被用来优化链路的容量，因为节点之间的距离是变化的。在项目结束时，该网络将部署在海上。

The aim of this project is to provide remote access to underwater sensors deployed for detection of subsea activity through the development of a distributed communication network. To avoid eavesdropping and access of data from intruders, covert transmission between the nodes is required. Also, to avoid a surface expression (for example a buoy) that is easily detected, a gateway buried a few meters below the sea surface will serve to establish a link with a mobile platform above the sea surface. The subsea network will rely primarily on acoustic propagation to exchange and relay information between the underwater nodes. To extend the range, different network topologies will be studied and a communication protocol will be defined to allow deployment of self-powered nodes for missions that can span several months. The messages will be broken up using short burst to share the network resources among multiple nodes. Also, adaptive modulation techniques that rely on a diverse set of frequency tones will reduce the probability of intercept. Using these modulation techniques, the users will be provided unique signatures that are spread over a wide bandwidth, and constrained by the hardware requirements available on submarine vessels. Specific coding techniques will be used to encrypt the message, and allow a secured and private link. To forward the data from below the sea surface to a surface vessel, a short-range relay link will be established that crosses the air-water interface. A communication link relying on magnetic induction (MI) will be proposed for this purpose. Although MI has traditionally been used as a short range link on the order of ten meters for diver-to-diver communication, in this work MI will be used at the air-water interface, and the possibility of achieving a few hundred meters will be explored. For this, a priori, an analytical model of the behaviour of the electro-magnetic fields, as it crosses the air-water boundary will be developed. A reconfigurable radio will be used to optimize the capacity of the link, as the distance between the nodes is varied. At the end of the project, the network will be deployed at sea.