Friday, December 12, 2008

Molecular communication: Shameless self promotion

Here's my new paper about molecular communication -- I give an abstract mathematical model and some ways to bound the information rate (both above and below):

A. W. Eckford, “Molecular communication: Physically realistic models and achievable information rates,” arXiv:0812.1554v1 [cs.IT] 8 December 2008 (submitted to IEEE Transactions on Information Theory.)

Comments are always welcome.

Monday, December 1, 2008

This surprised me, but probably shouldn't have.

Today I received a French-language grant from NSERC for review. So that's why they ask you whether you can read and write French.

Thursday, November 13, 2008

Reminding ourselves why we bought a Mac

I dug a 6-year-old laptop out of the closet and brought it to the office. I haven't been a Linux user for several years (or at least, not a Linux administrator -- my desktop runs some flavor of Linux, but is centrally administered by our very able and quick tech staff, so that doesn't count), so for a laugh, I wiped it out and installed the latest Ubuntu -- version 8.10.

Linux has certainly come a long way in the handling of hardware (and it helps that all the hardware on this machine is ancient). Ubuntu recognized and configured both my sound card and my PCMCIA wifi card (yes, the machine is old enough not to have integrated wifi).

But at the first attempt to run Xorg (the windowing system), the resolution was stuck at 800x600 -- Ubuntu apparently failed to recognize the laptop's video driver. The screen's full res is 1024x768, and this is the kind of machine where smaller resolutions are not stretched to the full screen, so I feel like I'm staring at a postage stamp in a sea of blackness.

A little research found that the problem might be solved by running a configuration tool (displayconfig-gtk) and manually specifying the driver. Apparently this was fine for Ubuntu 8.04, but the tool was dropped from 8.10. Here we read:

As Xorg has improved this past year, an unfortunate side effect of these improvements is that it has rendered several design assumptions in displayconfig-gtk obsolete. So, starting with Hardy we are no longer putting displayconfig-gtk forth as a primary configuration tool, and are putting our development focus into the Screen Resolution applet. As a result, we do not plan to fix this ...

So my only recourse is to find and manually change the Xorg configuration files. Thanks, Ubuntu, for a couple of hours of my life that I'll never get back, which may or may not solve the problem.

The whole thing reminds me why I stopped using Linux in the first place, and makes me want to hug my Macbook.

Tuesday, November 11, 2008

Macleans to York: You Suck

The Macleans university rankings are out. York members hoping for some good news are out of luck.

Overall ranking:

"Comprehensive" category: Tied for 9th out of 11 (last year: 8th)

Reputational ranking (and GTA universities for comparison):

"Best overall": 29 out of 48 (U of T: 5, Ryerson: 19, UOIT: 31)
"Highest quality": 27 out of 48 (U of T: 4, Ryerson: 23, UOIT: 43)
"Most innovative": 25 out of 48 (U of T: 8, Ryerson: 15, UOIT: 24)
"Leaders of Tomorrow": 32 out of 48 (U of T: 5, Ryerson: 16, UOIT: 21)

The take home message: In no category do we finish in the top half. In the public eye, we're getting spanked by Ryerson. Ryerson! And we're not much better than a university that didn't exist six years ago.

Friday, November 7, 2008

CUPE 3903 loses the public relations war

Toronto Star editorial strongly criticizing the CUPE 3903 strike:

An article in NOW mildly critical of the strike:

Although the Star is center-left, it's perhaps not so surprising that they would devote editorial space to criticizing CUPE. But it's astonishing that NOW -- known for some fairly hard-core leftist views -- would make anything other than positive comments about the strike.

Tuesday, October 14, 2008

TSE breaks Yahoo's stock ticker, again

Seems Yahoo's stock ticker can't handle moves of greater than 1000 points. Here's a screenshot from this morning (the market opened at around 9065 and, as you can see, was up about 1600 points at the time this was taken). Hooray for volatility!

Monday, October 6, 2008

TSE breaks Yahoo's stock ticker

This morning's 1000-point drop on the Toronto Stock Exchange was so bad, it broke Yahoo's stock ticker (note, the open was around 10,800 points):

Friday, October 3, 2008

Science: Gross and fascinating. (Grosscinating?)

In only the fifth recorded battle between pythons and alligators, we discover the following:

1. "Pythons versus alligators" is a question of legitimate academic interest; and

2. Yes, it is possible for a snake to swallow something so big, that its stomach explodes.

Tuesday, September 16, 2008

Nano-Net Liveblog: Sep 16

9:25 AM: A fascinating plenary lecture by Sylvain Martel on nanorobots capable of communicating with the outside world. He's arguing in favor of combining biological "nanodevices" with electronic intelligence. Some interesting ideas on "motors" formed out of bacterial flagella, using magnetotaxis (following an external magnetic field with an onboard magnetite sensor). He argues that this is a communication channel, since one device can influence its neighbor's magnetic field. Magnetic fields are detectable with external equipment. However, devices may need to cooperate in order to communicate with the outside.

2:09 PM: Neil Gershenfeld's plenary has just begun. "Computer science is one of the worst things ever to happen to computing or science." His problem seems to be with abstraction. I guess the massive global information technological infrastructure isn't good enough for Professor Gershenfeld. At this point I'm inclined to stop listening, as I usually am when somebody makes a ridiculous statement to attract attention. He then contradicts himself by referring to a result of computer science to show a linear-time sort.

2:32 PM: Claim: Locally enforcing constraints leads to global convergence ... ? This seems to be what he is saying, while arguing that asynchronous behavior is irrelevant. It's an incredible claim as it implies that his model ends race conditions forever. He's trying to demonstrate examples of this, but his diagrams are tiny and incomprehensible.

2:53 PM: He starts making more sense talking about problem relaxation to message-passing algorithms. This I can buy: you can relax hard problems to easier problems and solve them much more easily.

3:01 PM: In the end it was an occasionally intriguing but more often frustrating talk. Lots of huge claims and grandiose statements but little clear promise that it will lead to a computing paradigm that will be any more successful than what exists today.

Monday, September 15, 2008

Nano-Net Liveblog: Sep 15

11:22 AM: Interesting keynote by Tatsuya Suda on molecular communication. His group is mainly concerned with the mechanics of communication, and the experimental results are very interesting. A couple of good follow-on presentations by Satoshi Hiyama and Frank Walsh on implementational aspects. However, audience questions are concerned with the lack of obvious applications ... perhaps some applications would focus the research.

2:34 PM: Nice paper by Cooper about random walks on random graphs -- could be a routing solution in cell-scale networks with molecular motors.

3:05 PM: Interesting paper by Bogdan et al. on random walks, with the application of on-chip stochastic routing. Looks like a practical application of the previous paper on random graphs, but in a more regular structure and with a view to practical applications -- also, there are possible modeling extensions to diffusion problems for molecular communication.

Wednesday, August 13, 2008

Thursday, August 7, 2008

Friday, July 11, 2008

ISIT Liveblog: July 11

9:57 AM: My paper is being presented right now in Rateless Codes II. I spent the morning practicing with the speaker.

10:06 AM: The talk is over. Good job Bertrand on your first ISIT talk.

11:07 AM: A very interesting paper by Venkiah et al. on the design of rateless codes over ranges of channel parameters. Their design technique uses EXIT charts and explicitly optimizes the degree sequence over mulitple capacities.

Thursday, July 10, 2008

ISIT Liveblog: July 10

Having some network troubles this morning ...

10:50 AM: Attended "Sensor Networks". The first talk was about optimization of sensor networks on 2-d correlated random fields. The work looks interesting but unfortunately I didn't get much out of the talk.

12:09 PM: Just for fun, I'm sitting in a session on error exponents. There was a very interesting talk on a new class of exponents that beat the Gallager bounds, as well as an easily computable approximation to this bound. The following talk was done on handwritten overhead slides, which I haven't seen in use in about five years. It was about the calculation of error exponents via point processes ... with the overhead slides, it could have been deadly, but the speaker was entertaining and interesting, in spite of the fact that I understood very limited amounts of the talk.

2:56 PM: In "Detection and Estimation": Fascinating paper on inversion of matrices by message-passing over "random fields" using the Gaussian distribution. The method seems quite clever but I didn't exactly follow how the imputed random model is produced ... I will be sure to look this paper up in the proceedings.

4:31 PM: In "Rateless Codes 1": a raptor code-based distributed storage algorithm. Sounds an awful lot like both network coding and peer-to-peer applications that I've heard of before. Also a talk about complexity-performance tradeoffs in rateless codes -- the main idea is to discard any output symbol that is sufficiently unreliable. A paper about "graph-based" LT codes, containing only output degrees 1 and 2.

Wednesday, July 9, 2008

ISIT Liveblog: July 9

11:02 AM: Interesting plenary by Robert Gray on source coding -- it's not really my field, so I was lost on some of the more technical discussion, but it was a nice overview of his work.

12:06 PM: A couple of interesting talks by Urbanke's students on the scaling law for finite-length LDPC code analysis. I was unaware of this work, which has been around since 2003, but it looks like an efficient and accurate way to estimate the performance of short LDPC codes.

It's a half day today, so that's it for the conference until tomorrow ...

Tuesday, July 8, 2008

ISIT Liveblog: July 8

10:07 AM: Sadly missed the plenary. However, I did find the following in this morning's Globe and Mail: Chess boxing! Yes, it's exactly what it sounds like.

10:28 AM: Very interesting talk by Christine Kelley on LDPC code constructions from "voltage graphs", a special algebraic way of representing graph-based codes, which allow easier identification of cycles.

11:03 AM: Neat paper by Ardakani et al on universal LDPC codes -- i.e., designing an LDPC code to converge in two different channels (e.g., BSC and BEC) with the same capacity. An intriguing conjecture: "An LDPC code which converges over two channels with equal capacity will also converge over any channel in the convex hull of those channels" -- they claim this conjecture can be proven for special cases. They also give a set of "basis" subchannels for each capacity, for which each channel can be expressed as a convex combination of those channels.

3:41 PM: I sat in on a session of "Estimation" ... there was a nice paper on entropy estimation, and one on change point estimation, as well as an interesting paper by Loeliger et al. on estimation in 2-d Markov models.

5:51 PM: In "New code constructions", a paper by Grover and Sahai takes a holistic view of power consumed in communication over short range links, combining power used in computation and communication. A neat application for the traditional complexity-performance problem.

Monday, July 7, 2008

ISIT Liveblog: July 7

8:48 AM: I'm in Calderbank's very interesting plenary on sensing and detection in the context of algebraic codes. Carefully designed waveforms with good autocorrelation properties can be used in radar sensing. I saw an earlier version of this talk in Edmonton at CWIT 2007. Calderbank likes Blahut's coding book, and commented: "Classical coding theory and Fourier analysis are two sides of the same coin". But, as a "modern" coding theorist, I'll have to think a bit about what that means.

10:21 AM: Skipping between Iterative Decoding and the Wiretap Channel. Nice talk about bilayer LDPC codes, designed with respect to a rate constraint, in Iterative Decoding. In Wiretap Channels, I saw "Physical Layer Encryption with Stream Ciphers". I'm a little confused about this paper: using ciphers, there seems to be no reason to enhance traditional cryptography with physical layer security; and they claim the eavesdropper can obtain the key via plaintext attacks (which is true traditionally, and what if the transmitted data is compressed or otherwise equiprobable 1/2-1/2?). I think the contribution here is more along the lines of protecting encrypted text with error-correcting codes.

10:35 AM: Neat paper by Gunduz, Erkip and Poor on multiterminal compression with security constraints: eavesdropper can observe a subset of the terminals; only the "decipherer" (i.e., destination) can see all of them.

I think I get the wiretap channel now: given a side channel that is secure (e.g., secured with traditional cryptography, or otherwise private), it is possible to use information theory to make a much larger system private.

12:13 PM: In "Wireless Networks", a very interesting generalization to scaling laws by Ozgur et al., revealing a new operating regime for a wireless network that ignores the area density of nodes.

5:35 PM: Here's something I didn't know (if I remember it right): if z = x+y, then 2^(2H(Z)) >= 2^(2H(X)) + 2^(2H(Y)), with equality if and only if x, y, and z are Gaussian.

Thursday, July 3, 2008

See my paper at ISIT

My paper at ISIT:

Authors: B. Ndzana Ndzana, A. W. Eckford, M. A. Shokrollahi, and G. I. Shamir
Title: Fountain codes for piecewise stationary channels
Session: Fr-AM-6 (Friday, July 11, morning)
Location: Dominion North

See you in Toronto.

Monday, June 16, 2008

Your ISIT guide to Toronto cuisine

For the benefit of ISIT attendees, here are some good places to eat in Toronto. This is not a comprehensive list, but for each place I'm listing, either I have eaten there personally or I'm relaying recommendations from others.

For your reference, I'm also giving maps with directions from the conference site. (The directions are given with driving in mind, so you might find more direct walking routes.)

This list is organized as follows: we begin with assorted restaurants close to the conference venue, then various interesting neighborhoods roughly in order of distance from the conference venue, and we end with some options for high-end cuisine.

Cost estimates, where given, are in Canadian dollars. Roughly speaking, $1 Canadian = $1 US = 0.65 Euro.

A note on tipping for foreign visitors: In Canada, a tip of 15% is expected at any restaurant with table service. Not giving a tip would be considered an insult.

Assorted Restaurants Close to the Conference Venue

General, by type

Best Burrito Anyplace: Try Burrito Boyz, 218 Adelaide St. W., and it will change the way you think about burritos. Try the halibut -- seriously. There are a couple of tables, but it's better to take your order to go. (Suggestion for a sunny day: take your burrito and sit in the grassy courtyard at Metro Hall, two blocks south on King Street.)
Vegan cuisine: Fressen , 478 Queen St. W., is a great vegan restaurant -- and I'm saying this as a committed carnivore.
Crepes: Cafe Crepe, 246 Queen St. W., has good sweet and savoury crepes, to eat in or take out, plus great coffee.
Burgers: Try Hero Burger, 79 Yonge St. (several other locations), for a nouveau-fast-food place making tasty burgers.
Pizza: Amato Pizza, 238 Queen St. W. (several other locations), makes a good slice. For an excellent "traditional" pizza restaurant, try Terroni, 57 Adelaide St. E. (a couple of other locations), but be prepared to pay $30-50 per person.
Italian and Local: Try Il Fornello, 214 King St. W. (several other locations). Famous for devoting part of its menu to an "all-Ontario" selection of local foods.
Defies categorization: The Queen Mother Cafe, 208 Queen St. W., refers to its cuisine as "pan-global", which is not what you might think from its name. Also great desserts.
Asian fusion: East, 240 Queen St. W., is famous for its excellent Pad Thai and spring rolls. (Another location close to the conference venue, under the name Spring Rolls, at 40 Dundas St. W.)
Korean/Japanese: Try HoSu, 254 Queen St. W.
Steak house: There's a local franchise of the good Ruth's Chris Steak House close to the conference venue. This will set you back around $100 for dinner.
American cuisine: Baton Rouge, 218 Yonge St. (access from the street or inside the Eaton Centre) has good burgers, steaks, and other Americana (note, in spite of the name there is not much Cajun cuisine on the menu). Also try: the Pickle Barrel, 312 Yonge St., for a wide-ranging, deli-style menu; and the City Grill, located at the north end of the Eaton Center, for a relaxing drink after a day of talks.
Something completely different: Gandhi Roti, 554 Queen St. W., makes the best roti in the city. Don't know what roti is? All the more reason to go -- get the butter chicken, and take your order to go.


If you're craving something to kick-start your morning, other than the conference coffee and pastries, there are a number of nice options within a short walk of the conference site:

The Senator, 249 Victoria St. -- a lovely old diner that makes great blueberry pancakes.
Fran's, 210 Victoria St. -- a newer place made up to look like an old diner (their original location, from 1940, is no longer operating). Pretty good, but I prefer the Senator.
Le Petit Dejeuner, 191 King St. E. (not open for breakfast Wed-Fri) -- Small space with big flavors, and worth the walk. Excellent crepes and omelettes.
B Espresso Bar, 111 Queen St. E. -- If all you want is coffee and a pastry, try this place, in the style of a modern Italian espresso bar. Great, great coffee.

Nearby restaurant clusters and food courts

Note, these have been less extensively tested by our crack team of restaurant experts.

Eaton Centre food court: A fairly large food court (including some healthy options) is found at the basement level of the Eaton Centre, at the corner of Queen St. W. and Yonge Street.
Financial Core food court: A better food court is found in the basement of the Toronto-Dominion Centre, at the southwest corner of Bay St. and King St. W. (for bonus points, try to find your way there without going outside, using the labyrinth PATH system; warning, you might disappear into a sea of corporate Canada and never be seen again).
Elm Street: Several upscale restaurants along a strip along Elm from Bay Street to Yonge Street.
John Street: A strip of decent restaurants, mostly chains, in the "entertainment district", on John from Richmond to Adelaide (plus a Hooters -- you've been warned).

For a truly Torontonian experience, try a hot dog (affectionately known as "street meat") from one of the ubiquitous sidewalk vendors. They're cheap, tasty, and city licensed.

Baldwin (Neighborhood)

Not too far from the conference site (a pleasant 15 minute walk), Baldwin Street features a short block of small, quirky, mostly inexpensive restaurants.

Eating Garden, 43 Baldwin St. -- A good Chinese restaurant that takes large groups. Voted "best place for a lunch meeting with Frank" by Frank Kschischang's graduate students.
Kon-Nichi-Wa, 31 Baldwin St. -- Not your average sushi place, this Japanese restaurant serves great don and udon dishes.
John's Italian Caffe, 27 Baldwin St. -- Good pasta and panini, with a nice patio.
Yung Sing Pastry Shop, 22 Baldwin St. -- If you're trying to stretch your per diem, and are looking for cheap, tasty food, this place has fed generations of poor University of Toronto students with its famous meat-filled steamed buns.
Kuni Sushi Ya, 20 Baldwin St. -- All you can eat sushi for dinner, enough said. (Note, all you can eat is not available at lunch.)
Vegetarian Haven, 17 Baldwin St. -- Pretty much as the name suggests, and carnivores also think it's delicious.
Matahari Grill, 39 Baldwin St. -- Malaysian cuisine.
Bodega, 30 Baldwin St. -- the most upscale restaurant on the Baldwin strip is a lovely French bistro. Expect to pay $30 per person at lunch, $50-70 at dinner.

Chinatown (Neighborhood)

A short walk from the conference site, Toronto's spectacular Chinatown is found largely along Spadnia Avenue from Queen Street to Dundas Street, and is packed with great Chinese and Vietnamese restaurants.

Lee Garden, 331 Spadina Ave. -- A good place for contemporary Chinese cuisine.
Pho Hung, 350 Spadina Ave. -- Great and cheap Vietnamese noodle soup, as well as other traditional Vietnamese cuisine. Note, this restaurant accepts payment in cash only.
Rol San, 323 Spadina Ave. -- Good dim sum. Must arrive before 11.30 on weekends or be prepared to wait to be seated.
Asian Legend, 418 Dundas St. W. -- Good for Shanghainese food.
Sichuan Garden, 359 Spadina Ave. -- Authentic Sichuan (i.e. spicy) cuisine. Not for the faint of heart.

Kensington Market (Neighborhood)

About a 20 minute walk from the conference venue, but definitely worth a look, is the hip and historical Kensington Market. See here and here for more information on this distinctive neighborhood. (Note, several new restaurants have recently opened here, but I'm reporting only the places I have tried.)

Supermarket, 268 Augusta Ave. -- A hip Asian fusion "tapas" place. Reservations recommended.
Rice Bar, 319 Augusta Ave. -- A tasty noodle place, good for lunch or dinner.
Moonbean Cafe, 30 St. Andrew St. -- An excellent place to take in the bohemian Market lifestyle -- the coffee is great, and so are the light snacks and desserts.

Bloor West "Sushi District" + Little Korea (Neighborhood)

If you're looking for inexpensive (but good) sushi, this is the place for you: a half dozen sushi restaurants on Bloor Street West, all within a few blocks of each other. (Subway access via Spadina or Bathurst stations.)

I have eaten at three of these places, and each is good:

Sushi on Bloor, 515 Bloor St. W.
New Generation Sushi, 493 Bloor St. W.
Tokyo Sushi, 362 Bloor St. W.

If you're in that neighborhood but not in the mood for sushi, Serra, 378 Bloor St. W., is a good and not-too-expensive Italian restaurant; while Dooney's Cafe, 511 Bloor St. W., is a decent bistro.

Another bonus in the neighborhood: walk a few steps west on Bloor Street, past Bathurst Street, to find Toronto's "Little Korea" neighborhood; several restaurants offer traditional Korean barbeque. I particularly recommend Korean Village, 628 Bloor St. W. (After eating there, have walnut cakes for dessert at Hodo Kwaja, 656 Bloor St. W.)

Not on Bloor Street West: If you're in the mood for inventive and upscale sushi, and don't mind paying $70-100 per person for it, try Hiro Sushi, 171 King St. E. The omakase (customized tasting menu) is recommended.

Greektown (Neighborhood)

A nice neighborhood of Greek (and other) restaurants can be found on Danforth Avenue, east of the Don River (subway access via Broadview, Chester, Pape, or Donlands stations -- check the map links).

Astoria Shish Kebob House, 390 Danforth Ave. -- Greek, great grilled meats and calamari, enormous portions.
Megas, 402 Danforth Ave. -- Greek cuisine.
Seven Numbers Danforth, 307 Danforth Ave. (another location on Eglinton). A good, traditional Italian restaurant. So named because companies in Ontario are assigned a seven-digit number if they can't think of a name.
Sakawaya, 867 Danforth Ave. -- T.J.'s favorite Japanese restaurant, with cheap and pretty good sushi and sashimi.
Caffe Demetre, 400 Danforth Ave. (several other locations) -- Serves ice cream, sundaes and coffee.
Embrujo Flamenco Tapas Restaurant, 97 Danforth Ave. -- Spanish restaurant.

India Bazaar (Neighborhood)

The India Bazaar is a neighborhood far from downtown, but worth checking out, on Gerard Street just west of Coxwell. I ate there once, but I can't remember what the place was called -- I only remember that it was great and the neighborhood was really interesting. (Streetcar access via the 506 line.)

Not in the India Bazaar: if you're looking for good Indian food closer to downtown, try The Host, 14 Prince Arthur Ave. Best naan in the city, but a little pricey -- $30 per person, $50 with drinks. (Subway access via St. George station.)

High end cuisine

Toronto has many options for those who enjoy high-end culinary artistry. As you might imagine, such creative cuisine does not come cheap: you should expect to pay $100-150 per person (or more) at any of the following restaurants. In spite of the expense, these restaurants are very popular, and reservations are generally mandatory.

George, 111 Queen St. E. -- Chef Lorenzo Loseto dishes out impeccably executed cuisine in an attractive room on the east side of downtown.
Colborne Lane, 45 Colborne St. -- Chef Claudio Aprile is a student of "molecular gastronomy," and is the most creative of Toronto's current field of chefs.
Thuet, 609 King St. W. -- Chef Marc Thuet's restaurant is an upscale French bistro with a strong Canadian influence.
Scaramouche, 1 Benvenuto Place -- Chef Keith Froggett serves fine cuisine in a room with a beautiful and panoramic view of downtown Toronto. (Ask to be seated in the dining room, rather than the pasta bar.)
C5, 100 Queen's Park -- Take in spectacular architecture, great city views, and modern cuisine at this restaurant in the Royal Ontario Museum.
Lai Wah Heen, 108 Chestnut St. -- Chef Ken Tam serves up the most recent trends in Chinese cuisine.

The weather on Mars

At the site of the Phoenix lander, anyway: Sunny, with a high of -26 C. [CSA via EC Weather Office]

The weather station on Phoenix was designed and built by a Canadian team led by York University researchers. Story here.

Wednesday, June 4, 2008

Paper in TWireless

See my recent paper in IEEE Transactions on Wireless Communications:

A. W. Eckford, J. P. K. Chu, and R. S. Adve, “Low complexity and fractional coded cooperation for wireless networks,” IEEE Trans. Wireless Commun., vol. 7, no. 5, pp. 1917-1929, May 2008. (PDF)

We consider demodulate-and-forward as a low-complexity cooperation technique, and develop a low-complexity "fractional" cooperation scheme, in which every node contributes as much as it can -- possibly not its full resources.

Tuesday, May 27, 2008

My papers from ICC

My two papers from ICC:

A. W. Eckford and S. E. T. Hadley, “On estimating the topology of an adversarial wireless network,” in Proc. IEEE International Conference on Communications (ICC), Beijing, China, 2008. (PDF)

J. P. K. Chu, R. S. Adve, and A. W. Eckford, “Relay selection for low-complexity coded cooperation using the Bhattacharyya parameter,” in Proc. IEEE International Conference on Communications (ICC), Beijing, China, 2008. (PDF)

Wednesday, May 21, 2008

ICC Liveblog: May 22

(11:58 AM) A couple of nice papers in the morning. In WC-31 (Sensor Networks I), there was an interesting talk by Andreas Molisch on "mutual information accumulation" -- sort of like a rateless code across several sensor nodes, with optimization. In CT-09 (Coding and Modulation II), a talk by Natasa Blitvic on a clever low-complexity method for eliminating bad ISI patterns.

ICC Liveblog: May 21

(12:40 PM) Skipped the first morning session to work on my presentation, which was in session WN-11. The talk went quite well, but because the first two presenters did not show up, I ended up presenting early.

(5:28 PM) Interesting paper in CT-05 (Wireless Networks) by Zhu, Guo, and Honig about message-passing algorithms for interference reduction. Also a paper about "aggressive" hybrid ARQ -- I'd like to hear more about this, as I can't tell the difference between this method and the use of rateless codes, like Raptor codes. Also a neat paper about opportunistic scheduling (a.k.a. selection diversity?) with nodes whose signal strengths are independent but non-identically distributed -- surely a practical case that doesn't get much attention in the literature.

I stopped in at WC-28 (Cognitive Networks IV) to hear a bit about the state of the art in cognitive networking. Seems that this community realizes that a fully general radio to exploit free spectrum is not necessarily practical.

Monday, May 19, 2008

ICC Liveblog: May 20

(11:29 AM) Interesting keynote by Prof. Vince Poor on physical layer approaches to network problems, focusing on interaction among nodes. Three issues: "Economorphic" (i.e. competitive) networks, "Sociomorphic" (i.e., cooperative) networks, and physical layer security. Being largely aware of cooperative approaches, I was quite interested in the other two ... Nash equilibria are being used to illustrate fundamental physical tradeoffs in wireless networks, and physical layer security can show the fundamental limits of secure communication.

(4:03 PM) Attended CT01 -- Channel Capacity. Best paper: "Interference alignment and spatial degrees of freedom for the K user interference channel." A clever method for carefully arranging interference so as to align it in time or phase, and can hence be easily discarded (though it seems impractical for any real system).

Tuesday, May 13, 2008

See you in Beijing

I will be in Beijing next week for ICC 2008, where I have two papers:

"Relay selection for low-complexity coded cooperation using the Bhattacharyya parameter"
(in Cooperative Communication I: Session CT-02, May 20, 16:15-18:00, Room 310 BICC)

"On Estimating the Topology of an Adversarial Wireless Network"
(in Wireless Ad Hoc Networks IV: Session WN-11, May 21, 10:45-12:30, Room 311-B BICC)

I will be the speaker for the second paper. Hope to see you there.

Monday, May 5, 2008

Speaking in Zurich: May 13

I'll be in Zurich next week, and am tentatively scheduled to speak at ETH on May 13. (Anyone in Zurich who wants to get together ... send me an email!)

The talk announcement is here. Title and abstract are as follows:

Information theoretic aspects of molecular communication

In molecular communication, messages are transmitted by releasing a pattern of molecules at a transmitter, which propagate through a fluid medium towards a receiver. This form of communication has many advantages for nanotechnological applications, such as simplicity and low energy cost. In this talk, we give a discussion of molecular communication from an information theoretic perspective. Recent progress in molecular communication is surveyed. An idealized channel model is given, along with bounds on mutual information. Using these bounds, we see that surprisingly large amounts of information can be transmitted with tiny amounts of matter. Some applications and future work are also discussed.

Wednesday, April 30, 2008

An experiment with YouTube course delivery

This winter I taught CSE 1030, an introductory computer science course. I'm always looking for new ways to distribute course materials online, and in this class I was lucky enough to have a student who was willing to capture video of the lectures. (Many thanks to Louis St-Amour for his help.)

For the sake of visibility, familiarity, and ease of access, I posted the course video to YouTube. You can see some of the results here.

Overall, reaction was positive, and the availability of video did not seem to impact classroom attendance at all. That may have to do with the quality of YouTube video, which is not great -- for instance, when I use the projection screen in the classroom, it is virtually impossible to make anything out on the screen. However, I see the video as more of a "memory aid" for those who attended the lectures and may wish to review, rather than as a wholesale replacement of the lectures.

On the downside, YouTube restricts videos to 10 minutes and 100 MB. It is possible to get around that by splitting the lecture video into multiple blocks and joining them back together as a playlist, but preparing the video for upload in this way is labour-intensive. I'm told that tools exist to make this easier, so please tell me if you know of one.

In general I'd like to do this again. What was most surprising was that a decent video record of the lectures could be obtained and distributed online at very low cost -- beyond a laptop, which I have anyway, the only equipment we used was a webcam, which can be had for under $200. I'd also like to try distributing the video in iPod format.

I'd love to hear of other experiences with this, as well as suggestions for improvement.

Monday, April 21, 2008

Click here to waste time

My building has a green roof, and for the past few years a family of Canada geese have set up a nest there, just opposite our main seminar room.

Today we set up a webcam to check out their progress. (They tend to do a lot of nothing. It won't be very exciting until the eggs hatch.)

UPDATE: The geese have left and the webcam is now down.

Sunday, March 2, 2008

Look for my paper ...

My recent paper in IEEE Transactions on Communications (PDF):

X. Jin, A. W. Eckford, and T. E. Fuja, "LDPC codes for non-coherent block fading channels with correlation: Analysis and design," IEEE Trans. Commun., vol. 56, no. 1, pp. 70-80, Jan. 2008.

The paper is about density evolution and code design for LDPC codes on block fading channels, where the channel coefficients are correlated between blocks. This is a realistic model for OFDM or frequency hopping spread spectrum.