The conventional architecture for short-range, low-power, wireless hardware integrates a radio transceiver and a general-purpose microcontroller. However, microcontrollers have limited computational power and hence, restrict the kinds of algorithms that can be implemented. Moreover, closed radio architectures prevent the direct access to the physical layer needed for many novel applications. The emergence of low-power FPGAs with their efficient duty cycling support presents an opportunity to create a novel wireless platform to overcome these limitations. The project develops a highly flexible hardware/software architecture for mobile wireless networking based on low-power FPGA devices. High performance DSP and other algorithms can be implemented directly in hardware, while the rest of the code runs on a soft processor core inside the FPGA. This flexible hardware/software boundary increases the complexity of software development that is eased via sophisticated development tool support and an extensive software component library that the project is also developing. The small inexpensive platform offers two orders of magnitude higher performance than current microcontroller-based hardware at equivalent power for many applications. Hence, it will stimulate research in novel protocols and enable new applications not possible today. A competition for undergraduate students will be organized in which winners will receive the hardware, software, training, and mentorship needed to carry out their ideas during a paid summer internship at Vanderbilt.
This grant supported the development of a radically new wireless sensor network platform (MarmotE) enabling the design, development and experimentation with novel and innovative methods for wireless communication, sensing and localization on resource constrained nodes. Over the past decade, wireless sensor network research relied on highly-integrated radio chips with built-in and fixed modulation and radio protocol stacks. The new platform uses Flash-based reconfigurable logic components for implanting radio communication and sensing thus it allows for smarter wireless sensor networks to be built by using the latest results from software radio research. These smart nodes are able to change their communication patterns on-the-fly based on environmental factors and application-specific requirements. The open-source MarmotE platform includes a tested and refined modular hardware design and all necessary software components, all of these available on the project website (https://sites.google.com/site/marmoteplatform/). The researchers of this project also developed two essential services enabled by the new platform. First, the Code Division Multiple Access (CDMA) channel access method was adopted to create adaptive reliable wireless links for collecting data from the battery operated sensor nodes. The CDMA approach – not supported by traditional WSN radios – also enables highly efficient duty-cycling of the transmitter radios, further increasing the lifetime of the wireless nodes. Second, by leveraging the versatile radio architecture, we demonstrated a highly accurate (centimeter-level) ranging and localization approach for wireless sensors. The ranging method is based on our previous results utilizing radio interferometry, however, the MarmotE platform decreased the time and energy required by several magnitudes while significantly increased the reliability and accuracy of the method. There are broad potential benefits of these methods, in terms of operational life, reliability, scalability and accuracy in home automation, industrial control, healthcare, structural health monitoring and in many other domains where distributed sensing is used today. The project also reached out to undergraduate students with diverse ethnic, economic and academic background. During our summer internship program in 2012 these students developed solid and practical knowledge of software radios and of the basic principles of digital communication. Our research team (Team MarmotE) qualified to participate in the DARPA Spectrum Challenge, a national competition for innovative software radio protocols that can best use a given communication channel in the presence of other dynamic users and interfering signals. Our team won 1st place in the first tournament in 2013 (http://dtsn.darpa.mil/spectrumchallenge/PreliminaryEventResults.aspx) and reached the semifinals in the final tournament in 2014. The developed protocols and know-how will benefit future communication networks in heavily congested and contested environments both in civilian and military applications. The MarmotE platform also won 1st place in the 2013 Software Defined Radio Design Challenge (http://groups.winnforum.org/p/cm/ld/fid=366) which took place at Virginia Tech and organized by the Wireless Innovation Forum. The project concluded with the PhD dissertation defense of the graduate student sponsored by this award. His thesis provides a detailed summary of the efforts and results of the project. Also, our results were published and resulted in five conference and two workshop papers, two book chapters and two journal publications.
