<To be printed on letterhead>
April 22, 2009
U.S. Department of Homeland Security
U.S. Citizenship and Immigration Services
Dear Sir/Madam:
This letter is written in support of Dr. Shu Du’s I-140 Immigrant Petition as an outstanding researcher. I came to know Dr. Du’s scientific research work entirely through his publications. I would like to share my expert opinion on his outstanding research work in this letter.
To start let me explain my own background and qualifications. I am a Professor of Computer Science of UniversityCollegeCork inIreland. I was Head of Department from 2000-2004. Before I joined UCC in 1999, I was a Principal Technical Staff Member with AT&T Labs Research (in Florham Park, NJ, USA), and I also worked at Bell Labs Research (in Murray Hill, NJ, USA). I became a Fellow of the British Computer Society in 2005 and a Life Fellow of the Cambridge University Philosophical Society in 2000. I hold a Ph.D. in Computer Science from the University of Cambridge, and have over 20 years research experience and over 70 peer-reviewed publications.My research interests are in computer systems and networking, and especially their use for new applications that involve mobility/wireless and multimedia. I am an Editor for ACM/Springer Multimedia Systems Journal and for Elsevier Computer Networks Journal. Currently, I direct the Mobile & Internet Systems Laboratory (MISL), a group of about 10 researchers and students that are investigating a range of systems and networking research issues, the majority focused on wireless and sensor networks. Given my background and research experience in wireless sensor networks I am in an ideal position to judge Dr. Du’s achievements and contributions.
Dr. Du has carried out some outstanding research, which is considered a major breakthrough in several fields of mobile ad hoc networks and wireless sensor networks and is having widespread impact on these areas.
One of Dr. Du’s papers, “Safari: A Self-Organizing, Hierarchical Architecture for Scalable Ad Hoc Networking” has been published in Ad Hoc Networks Journal, one of the most significant journals in mobile ad hoc networks. With this work, Dr. Du has joined the very few pioneering researchers who have addressed the scalability problem in mobile ad hoc networks. Dr. Du solved the scalability problem by using hierarchical virtual coordinate-guided routing, which has demonstrated significantly improved performance than the other protocols. His work is undoubtedly a pioneering breakthrough in scalability study of mobile ad hoc networks.
Another of Dr. Du’s paper, “RMAC: A Routing-Enhanced Duty-Cycle MAC Protocol for Wireless Sensor Networks” has been published in INFOCOM’07, one of the most highly-selective and highly-cited international conferences in telecommunications. In this work, Dr. Du investigated the latency problem introduced by duty-cycling in wireless sensor networks. He has proposed an absolutely new way to explore the cross-layer information to optimize network performance, as routing layer information is used by MAC to make medium access reservation and packet delivery scheduling. His continuation work, "DW-MAC: A Low Latency, Energy Efficient Demand-Wakeup MAC Protocol for Wireless Sensor Networks" has been published in MobiHoc’08, another prestigious international conference in the mobile and wireless networking field. In this work, his original idea of cross-layer optimization has been extended from unicast traffic to broadcast traffic, which has further completed his vision in the design. With these two papers, Dr. Du has created a new direction for cross-layer optimization between the medium access layer and the routing layer for wireless networks. I fully believe more researchers will continue Dr. Du’s exploration in this new direction and will make further significant advances in sensor network research.
I want to provide another example of Dr. Du’s remarkable research achievements. In one of Dr. Du’s paper, “Design and Performance of PRAN: A System for Physical Implementation of Ad Hoc Network Routing Protocols” published in a top journal in mobile and wireless networking, IEEE Transactions on Mobile Computing, Dr. Du and his colleagues developed a new testbed platform for the real implementation of ad hoc network protocols so that the simulation code developed for a protocol can be used unmodified to get a real implementation of the same protocol in Linux and FreeBSD. This research work is very important in advancing the research in mobile ad hoc networks. It is because numerous researchers have been using simulations exclusively for their study in ad hoc networks and very few people have ever tried to implement their protocols in real operating systems like Linux or FreeBSD to test their protocols in the real world due to the unfortunate fact that not many researchers have the expertise or resources to complete a real implementation. Now, with the new testbed platform, researchers who rely on the simulations can now get their real-world implementation in no time. This is a truly wonderful piece of research work.
Dr. Du has a very special combination of strong research abilities in theoretical networking and practical skills in programming and implementations, which makes him especially unique compared against other researchers. Dr. Du’s research achievements, extraordinary research abilities, and professional knowledge and skills have placed him in the very top position in the field of wireless networking and helped him gain an outstanding reputation recognized by the international scientific community as well. His international recognition can be easily observed by his presence as technical program committee member of several key international conferences and as an invited reviewer for prestigious journals in wireless networking.
I hope my opinion about Dr. Du’s outstanding research achievements will assist your decision about his immigration petition. If I can be of any further help, please feel free to contact me.
Yours faithfully,
Cormac J. Sreenan, Ph.D.
Professor of Computer Science