Dynamic Transmission Protocols and Advanced Signal Processing Techniques for Wireless Sensor Networks with Cooperative Diversity

无线传感器网络通常被定义为收集和传播数据的小型和低成本传感器的密集无线网络。它们在各种领域都有应用，如系统维护、环境监测、运输、军事目的和在荒凉地区收集信息。传感器网络面临的主要挑战之一是以更高的精度从远程位置监测和控制物理环境。回想一下，传感器网络的独特特征在于节点移动性、频繁的链路故障、有限的链路容量以及传感器设备的有限电池和计算资源，这对可靠通信提出了重大挑战。下面的例子说明了这一建议的动机。举一个动机的例子：考虑一个场景，一排消防员冲进一座燃烧的建筑物进行救援使命。每个消防员都携带一个收发器，他与建筑物外的队长通信并接收命令。这种场景的基本要求是，每个消防员，被视为一个传感器，应该有一个稳定的连接到船长，或一个网络控制中心。这种传感器网络还可能需要支持实时视频流服务，因为消防员可能需要将他所看到的传输到外部进行安全评估。但现实情况是，由于室内环境中的多径衰落，无线链路并不稳定。而对高速高质量真实的时间服务的需求使得满足服务质量要求的任务变得更加具有挑战性，为了满足这种多样化的服务质量要求，我们计划将协作分集技术应用到传感器网络中，这种技术以其抗衰落的能力而闻名。回顾一下，通过使用协作分集，可以以低成本和易于实现的方式实现可靠的传输，这对于传感器网络的应用是理想的。该项目的目的是提高系统的吞吐量和传输鲁棒性的无线传感器网络中应用合作分集。这项建议寻求的解决办法有两个方面。一种是充分利用无线传播的动态特性，设计新的动态协作协议，该特性提供了系统性能的理论上界。第二步是从实际应用的角度出发，设计复杂的DSP算法来实现协同协议所承诺的性能增益。显然这两者是密不可分的，不仅因为无线传感器网络可靠通信的最终目标只有在这两部分的完成下才有可能实现，而且因为这两部分之间的交互是高效系统设计的关键。

Wireless sensor networks are typically defined as dense wireless networks of small and low-cost sensors which collect and disseminate data. They have applications in a variety of fields such as system maintenance, environmental monitoring, transportation, military purposes and gathering information in inhospitable locations. One of the key challenges for sensor networks is to facilitate monitoring and controlling of physical environments from remote locations with better accuracy. Recall that sensor networks are uniquely characterized by node mobility, frequent link failure, limited link capacity, and limited battery and computational resources of sensor devices, which pose significant challenges for reliable communications. The following example illustrates the motivation of this proposal. An example for the motivation: Consider a scenario where a platoon of firemen storm into a building burning for a rescue mission. Each fireman carries a transceiver with which he communicates and receives orders from the captain outside of the building. A basic demand of this scenario is that each fireman, viewed as a sensor, should have a stable connection with the captain, or a network controlling centre. And it is possible that such a sensor network also needs to support a real-time video stream service since a fireman might need to transmit what he sees to outside for safety evaluation. But the reality is that wireless links are not stable due to the multipath fading in the indoor environment. And the demand for high-speed high-quality real time service will make the task to satisfy the required quality of service more challenging.In order to meet such diversified quality of service, we plan to apply cooperative diversity, a technique well known for its ability to combat fading, to sensor networks in this proposal. Recall that, by using cooperative diversity, reliable transmission can be achieved at low cost and with easy implementation, which is ideal for the application of sensor networks. The aim of the project is to increase system throughput and transmission robustness of wireless sensor networks by applying cooperative diversity. The solution this proposal is seeking is two fold. One is to design new dynamic cooperative protocols by fully exploring the dynamic nature of radio propagation, which provides the theoretic upper bound of system performance. Then, the second step is from the practical aspect, where sophistic DSP algorithms shall be devised to realize the performance gain promised by the cooperative protocols. Obviously the two are inseparable not just because the ultimate goal of reliable communication for wireless sensor networks is only possible with the accomplishment of the both two parts, but also because the interaction between the two parts is the key for the efficient system design.