The WindoWSIL

I stumbled across this interesting article on SmallNetBuilder about the performance of commercial 802.11g devices. To summarize, they used an RF channel emulator between two 802.11g stations to observe the performance of competing devices. The results are, in my opinion, shocking. The best device performs as well as the worst device with over 10 dB more path loss.

As engineers we often believe that better engineering results in more sales and a larger market share…but this isn’t necessarily true. Linksys will sell many, many products due to their brand name recognition, even if the 11g chip they use performs poorly. This brings me to the question, does the average consumer care enough about engineering to make a difference? That is, even if you develop a poorly performing device, as long as it performs well enough it really doesn’t mean much if you can’t market it. I think maybe this situation is unique to wireless LAN, because there is more patience in the performance of WLAN devices. For cell phone chipmakers, if your product drops calls at a high rate, I think you’ll see a consumer reaction. What are all of your thoughts?

As a side note, check out the throughput curve from the figure above. Notice that, at best, you get 23 Mbps of throughput when the PHY rate supports 54 Mbps. This is a point-to-point link using near-field antennas. At best, you won’t even get 50% of the PHY throughput. Clearly, there is much work to be done in improving the 802.11 MAC (even though alot of work was done for the 802.11n standard). You can also get a hint about the link adaptation used from the throughput curve. I suspect the curves that have dips at low path loss must not use SNR-based feedback and maybe an auto-rate fallback method while the others use SNR-based feedback. I cannot confirm this because I don’t know how reliable the testing is, but it seems plausible given some of the observations we’ve seen testing these algorithms in Hydra.

I know this is Bob’s thing, but he’s busy doing real engineering work at the moment.

This semester has gone by extremely quickly. Unbelievably, I’ve been in WSIL for six months already. Amazing.

I’ll first present the latest news. Sumohana Channappayya successfully defended his dissertation and will be heading to San Diego to join the real world as a newly anointed Ph.D. Congratulations, Sumo!

Along similar lines, Caleb Lo and Chan-Byoung Chae both successfully passed quals yesterday. These two, along with Kaibin Huang, are next in line to graduate.

Further, we have published, submitted, or have had accepted numerous papers on topics ranging from prototyping to information theory. In particular, we published the following seven journal papers this semester:

• R. Chen, J. G. Andrews, R. W. Heath, Jr., and A. Ghosh, “Uplink Power Control in Multi-Cell Spatial Multiplexing Wireless Systems,” IEEE Trans. on Wireless, vol. 6, no. 7, pp. 2700-2711, July 2007. [IEEE Xplore]
• A. Forenza, D. J. Love, and R. W. Heath, Jr., “Simplified Spatial Correlation Models for Clustered MIMO Channels with Different Array Configurations,'’ IEEE Trans. on Veh. Tech., vol. 56, no. 4, part 2, pp. 1924-1934, July 2007. [IEEE Xplore]
• K. Huang, R. W. Heath, Jr., and J. G. Andrews, “Space Division Multiple Access with a Sum Feedback Rate Constraint”, IEEE Trans. on Signal Processing, pp 3879-3891, Jul. 2007. [IEEE Xplore]
• B. Mondal and R. W. Heath, Jr., “Quantization on the Grassmann Manifold,'’ IEEE Trans. on Signal Processing, vol. 55, no. 8, pp. 4208-4216, Aug. 2007. [IEEE Xplore]
• V. Raghavan, R. W. Heath, Jr., and A. Sayeed, “Systematic Codebook Designs for Quantized Beamforming in Correlated MIMO Channels,'’ IEEE Journal on Sel. Areas in Comm., Special Issue on Optimization of MIMO Transceivers for Realistic Communication Networks: Challenges and Opportunities, vol. 25, no. 7. pp. 1298-1310, Sept. 2007. [IEEE Xplore]
• M. R. McKay, I. B. Collings, A. Forenza, and R. W. Heath, Jr., “Multiplexing/Beamforming Switching for Coded MIMO in Spatially Correlated Channels Based on Closed-Form BER Approximations,'’ IEEE Transactions on Vehicular Technology, vol. 56, no. 5, part 1. pp. 2555-2567, Sept. 2007. [IEEE Xplore]
• D. Gesbert, M. Kountouris, R. W. Heath, Jr., C. B. Chae, and T. Salzer, ‘Shifting the MIMO Paradigm: From Single User to Multiuser Communications,’ IEEE Signal Processing Magazine, Vol. 24, No. 5, pp. 36-46, Oct., 2007 [IEEE Xplore]
  

Also, first year grad student Alvin Leung taught us all a ping pong lesson in the first annual WSIL ping pong tournament. His skills will surely diminish as grad school takes over his life.

There really was so much more to this semester. In many ways, Fall 07 will be remembered as a semester where a lot of work was put into projects that other semesters will be able to claim to have finished, as this semester did with the above journal papers. We submitted far more journal papers than we published. We welcomed 6 new members and said goodbye to only 1. And we put in hundreds of hours into projects whose payoffs are still months away. In that way, you might say it was a blue-collared semester.

If anyone else has something to add (feel free to toot your own horn), please comment.

Back in the day I used to frequent some grad school discussion boards on the internet. Yes, I’m a loser (I can feel Bob laughing at me already). It really struck me how different the grad school experience is in the rest of the world. For instance, at Ali’s M.S. university in Canada, he had to defend his M.S. thesis. In Australia, they don’t even have to defend their Ph.D. thesis. Even more astounding, in Europe and Australia (and probably several other places), a PhD generally takes three years after a bachelors. And they have no coursework.

On the other hand, in North America, we are required to earn Master’s degrees before our Ph.D. (or Sc.D.), and must take quite a few courses to do so, the exact amount of which varies from school to school. I believe I heard the average time from bachelors to Ph.D. in the U.S. is around 5.5 years.

How can it take more than two more years for us to get our Ph.D.’s relative to other areas of the world? Do we learn more? Are we less prepared? Are our programs less intense? Certainly at least one of these has to be true to some extent.

When Dan Ryan (from CSIRO in Australia) came to visit the WSIL this summer, he said classes are pointless for grad school; we should be able to learn everything we need to know out of a book. What is our response to this?

I’m afraid I only have questions on this topic.

As many of you know, I’m obsessed with overhead these days. I like to think visually and want to organize my thoughts on a poster, kind of like a white board. Here is what I would like to do: Have a virtual poster or white board where I can draw block diagrams and put latex text with equations and references in different movable blocks. Is there a software package (for the MAC) where this can be done? I guess I could use texpoint and powerpoint but then I can’t use bibtex. Any thoughts? Basically I want different objects I can move.

According to a recent University of Chicago study, 49.89% of electrical engineers are ‘very happy’ with their jobs. This was the 11th highest of well over 100 professions. We ranked just below Actor/Director and just above Airline Pilot. Needless to say, we are the happiest engineering profession. Compare our 49.89% “very happy” rating to that of mechanical engineers: 28.2%. How can we be so much happier than them? They’re less happy than waiters, nurses aides, shipping clerks, groundskeepers, and many many other professions. I should note that Computer Programmers also rated very low on this survey.

The data is here.

Last week Google announced Android, an open source platform for mobile software development. Now google has released the software development kit. To top things off the Android Design Challenge is offering a total of $10 million in awards for good mobile software designs. Anybody feel like moving up a few layers and trying this out?

For those of you whom are interested in persian culture or just want to know a bit more about Iran here is short 4-part report from Matt Lauer’s stay in Tehran. This might actually save me from answering a lot of questions given that I’m the first Iranian student of WSIL.

http://www.youtube.com/watch?v=GHBLU6tKb8s&NR=1

I was wondering what you guys use for looking up citations and number of citations of articles. I use google scholar which is beta and not very comprehensive. Has anyone found anything better?

I think my previous posting didn’t in fact get posted. Anyways, given the field we are in, with all the research, papers, deadlines, problems etc, I always enjoy taking a step outside the complexities and chaos of it all and reminding myself how very simple everything is. Down to the very fabric of who I am. And if you’re interested, or enjoy contemplating the subject of simplicity vs. complexity then I recommend you listen to what Dr. John Maeda at MIT has to say about it. You can listen to his talk at www.ted.com. I think you will find the experience both complex, and, well, simplistic!

I’m pleased to announce the creation of several new positions within the WSIL. These positions are a result of appointment (by me) with a term of office of one year, with possible extensions. A description of these positions and the responsibilities is provided below.

• Vice President of Information Technology Administration [Current volunteer is Sanmi] - Deals with questions about computer account access, hardware, etc.
• Vice President of Social Networking [Current volunteer is Takao] - Takes the lead in planning group activities, making reservations, coordinating schedules, thinking of fun and nondestructive activities.
• Vice President of Conference Deadlines [Current volunteer is Caleb] -  Keeps our conference deadlines page up to date. Mentions current deadlines in every group meeting to get everyone motivated.
• Vice President of Local Arrangements [Current volunteer is Kaibin] Helps visiting students, new students in practical arrangements.
• Vice President of Posters, Handouts, and Web Updates [Current volunteer is Chan-Byoung]. Coordinates poster volunteers, handouts, and web updates. Does not do these things themselves, rather serves as point person to apply appropriate pressure to make sure these tasks are done on time.

The main reason to introduce these new assignments is to provide a point-of-contact for different group activities. I’m not sure how other researchers run their groups, but this seems like a sensible approach to me. Are we missing key responsibilities?

Prof. Robert Heath