As Matt has announced, the Sensys 2009 preliminary program has been released. I’m proud to say that it includes a contribution from our group on Mercury, a wearable sensor network for high-fidelity motion analysis. This is largely Konrad’s work (in fact, his thesis work), but I was peripherally involved and the Mercury download manager architecture borrows heavily from Lance. It’s a solid engineering effort and I’m pleased that it was accepted &mdash particularly as its good exposure for both Konrad and Bor-rong, both of whom are graduating next month.

I am disappointed, however, that our Draft paper didn’t make the cut. I blogged recently about the paper submission and my feelings about it pre-decision. After the decision came down I think I went through the usual post-rejection phases: anger, depression, careful consideration[1. Facilitated by reviews.], acceptance, imagination, reinvigoration. While the reviews weren’t quite as helpful as I would have liked, Jason and I are up and spinning together an NSDI’10 submission and are exploring some exciting new directions for the work. Given that this is the last piece of real research I imagine I’m going to get a chance to do before pulling together my thesis this winter and then (hopefully) interviewing next spring, I plan on enjoying one more trip out. As Suzanna put it, despite the inevitable feelings of failure that accompany a paper rejection, I had wanted to write an NSDI’10 paper, and that would have actually been quite hard had I had to spend August tightening up a Sensys’09 submission. That said, I would have loved to be able to get up at a fall conference and give a talk, particularly with the job market looming, but I guess I’ll have to hope people remember best talk award at Sensys’08.

Personal mutterings aside, this post was supposed to be a preliminary look at the Sensys’09 program, particularly in light of the comments Matt has made about the process on his blog. At first glance, most of the papers seem to break down into some well-defined categories[2. Note that I'm breaking these down by their titles, which can be misleading.]:

  • No MAC Papers (!): perhaps this is a function of Matt and Jie as program chairs, or maybe the community is finally just really tired of the (IMO) largely useless proliferation of MAC protocols, almost all of which were never compared against other research MAC protocols or ever canonicized in the standard TinyOS distribution. I remember during a question Matt asked at either Sensys’08 or Sensys’06 he argued that really what we needed was a MAC sMACdown, i.e. a paper that would actually compare a number of contributed MAC protocols using a consistent set of experiments, methodologies and benchmarks. Don’t see that paper, but it seems like the MAC sMACdown just ended up taking a slightly different form this year. No complaints here.
  • Multiple Link/Routing Protocol Papers: maybe these are what replaces MAC protocol papers for the next few years. Just based on the titles I see “ADB: An Efficient Multihop Broadcast Protocol based on Asynchronous Duty-Cycling in Wireless Sensor Networks”, “Collection Tree Protocol”, “M&M: Multilevel Markov Model for Wireless Link Simulation in Sensor Networks”, “Explicit and precise rate control for wireless sensor networks” and “Bursty Traffic over Bursty Links”; “The Case For A Network Protocol Isolation Layer” may be making an architectural contribution or may fall into this category. So it seems like we have at least one dedicated routing session, with a number of papers focusing on link-level dynamics and/or simulation.
  • Time Synchronization: several years after the FTSP and Firefly Sensys papers — which I mention here due to my familiarity, not due to any seminality — another batch of papers addressing time synchronization are here. “Optimal Clock Synchronization in Networks”, “Low-power clock synchronization using electromagnetic energy radiating from AC power lines”, and “A Tale of Two Synchronizing Clocks” look like they compromise a dedicated time synchronization session.
  • Applications: Sensys has a strong history of application papers, and this year is no exception, with “Canopy Closure Estimates with GreenOrbs: Long-Term Large-Scale Sensing in the Forest”, “DCNet: A High-Fidelity Data Center Sensing Network”, “Suelo: Human-assisted Sensing for Exploratory Soil Monitoring Studies”, “Mercury: A Wearable Sensor Network Platform for High-Fidelity Motion Analysis”, “Experiences with A High-Fidelity Wireless Building Energy Auditing Network” and “VTrack: Accurate, Energy-Aware Traffic Delay Estimation Using Mobile Phones” all seeming to present application case studies or present experiences deploying real systems. I probably have a more mixed view of application papers than my CV would suggest. Some I find extremely interesting and edifying. Others seem to have impressed reviewers with a complete, well-engineering system, but really don’t contribute many or any new ideas. That said, based on the titles alone I see a number of projects represented here that I’ve known about and am excited to hear and read more about.
  • Programming/Debugging: this category includes “FIND: Faulty Node Detection for Wireless Sensor Networks”, “TOSThreads: Safe and Non-Invasive Preemption in TinyOS”, “Darjeeling, A Feature-Rich VM for the Resource Poor”, “Macrodebugging: Providing Abstract Views of System State”, and “Evaluating A BASIC Approach To Sensor Network Node Programming”.

Interesting that only one paper — “Achieving Range-Free Localization Beyond Connectivity” — out of the 21 accepted escapes this categorization. I haven’t tried a similar title-based categorization for other preliminary programs at other conferences, but part of me wonders if this is a function of the topically-based decision making process that Matt seems to imply went on at the PC meeting. I don’t have enough experience with program committees to know whether or not this is standard operating procedure, but I wonder how you combat the danger of category-driven selection, namely that you don’t get the strongest 21 papers but rather the strongest three routing protocol papers, the strongest three programming/debugging papers, the strongest six application case studies, and so on. The other danger of early categorization is that papers that span multiple areas or don’t fit cleanly into boxes end up being left out.

Specifically, I’m disappointed this year to see a program bereft of architectural approaches to reducing power consumption. I’m willing to presume that some of the programming papers may address this more directly, but one of the more exciting things (for me) about the past few years of Sensys was the emergence of papers like Levels (Sensys’07), Eon (Sensys’07), Pixie (Sensys’08) and of course Lance[3. This list is obviously too tilted towards our own work at Harvard, and plenty of other good papers in this area exist.] which took large-scale, top-down approaches to controlling network-wide power consumption. (Or were getting there, slowly.) I’m hoping that as I learn more about the papers that were accepted a broader focus on energy will emerge from papers where it is not evident in the title, but as of now I’m disappointed that this area seems poorly represented.