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

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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.