Underwater Acoustic Sensor Networks

我的研究是关于水声通信和网络。应用包括地下活动传感器、无人水下航行器、飞机水下定位信标和水下机器人。我专注于节点之间的通信、网络管理和协作。使用声信号进行长距离水下/冰下通信是加拿大环境面临的一个重要挑战，加拿大拥有世界上最长的海岸线，而且经常被冰层覆盖。由于过去的一些实验和理论分析的结果，我相信远程通信是可能的。虽然，它们发生的条件可能因时间和地点而有很大差异。此外，我们处理的是非常衰减的信号。我的研究借鉴了极弱信号通信的科学，可以处理非常高衰减的信道。噪声、幅度、频率和相位变化以及多径传播加剧了这一问题。我的研究重点是数据链路层的设计，包括分帧和高冗余前向纠错。通过深度搜索解码进一步加强。利用关于消息可能内容的知识，例如它们的结构和已部署的节点地址，使用模式匹配和规则来建立接收到的数据包和可信消息之间的关系。为了处理条件的可变性并选择适应信道的协议元素，我使用认知方法，其中协议动态适应信道质量。网络管理提供了远程监控和更新节点状态的能力。这是一个至关重要的特性，因为一旦节点部署在水下/冰下，就很难进行物理访问。远程水下/冰下通信是非常难以实现的。只能交换非常短的数据包。对于这种情况，需要研究非经典的网络管理方法。我开发了一种不需要管理流量的生物启发方法。模仿学习用于在节点间传递设置。每个节点通过观察和模仿它的邻居来学习它的设置。这种方法不会产生流量开销。在水下/冰下环境的恶劣条件下，很难用信息传递信息的情况下，它是有用的。我的研究提供了通信链路和路径，以支持水下节点之间的消息和导航信息交换。我开发无人水下航行器之间的协作协议。探索各种任务，如搜救和监视。核心功能包括对同伴和环境的认识以及合作者之间的工作分配。

My research is about underwater acoustic communications and networks. Applications include subsurface activity sensors, unmanned undersea vehicles, airplane underwater locator beacons and underwater robotics. I focuss on communications, network management and collaboration between nodes. Using acoustic signals, long range underwater/under-ice communication is an important key challenge for the Canadian environment, having the longest coastlines of any country in the world often with ice cover. I believe that long range communications are possible because of the results of a few past experiments and theoretical analysis. Although, the conditions under which they happen may greatly vary according to time and location. Furthermore, we are dealing with awfully attenuated signals. My research draws on the science of extremely weak signal communications that can deal with channels with extraordinarily high attenuation. Noise, amplitude, frequency and phase variations together with multipath propagation exacerbate the problem. The focus of my research is on the design of the data link layer, which includes framing and high redundancy forward error correction. It is strengthened further with deep-search decoding. Leveraging knowledge about possible content of messages, such as their structure and addresses of nodes that have been deployed, pattern matching and rules are used to establish a relationship between a received packet and plausible messages. To deal with the variability of the conditions and select protocols elements that are adapted to the channel, I use the cognitive approach where protocols dynamically adapt to the channel quality. Network management provides the ability to remotely monitor and update the state of nodes. It is a crucial feature because of the difficulty of physical access to nodes once they have been deployed underwater/under-ice. Long range underwater/under-ice communications are very difficult to achieve. Solely very short packets can be exchanged. For such cases, non-classical network management approaches need to be investigated. I develop a bio-inspired approach that does not require management traffic. Learning-by-imitation is used to transfer the settings node-to-node. Every node learns its settings by observing and imitating its neighbors. The approach does not generate traffic overhead. It is useful in cases where it is really hard to convey information using messages, which is expected in the harsh conditions of the underwater/under-ice environment. My research provides communication links and paths to support the exchange of messages and navigation information between underwater nodes. I develop collaboration protocols between unmanned undersea vehicles. Various tasks are explored such as search and rescue and surveillance. Core functions include awareness of peers and environment and distribution of work among collaborators.