Papers at CWIT: PDFs and video

I posted earlier about my papers at CWIT.  I finally got around to uploading the PDFs and video.


J. P. K. Chu, A. W. Eckford, and R. S. Adve, “Distributed optimization of the Bhattacharyya parameter in wireless relay networks,” in Proc. 12th Canadian Workshop on Information Theory, Kelowna, BC, 2011. [PDF] (Video not available.)

L. Cui and A. W. Eckford, “The delay selector channel: Definition and capacity bounds,” in Proc. 12th Canadian Workshop on Information Theory, Kelowna, BC, 2011. [PDF]


Presentation video for the Cui/Eckford paper:

 

Jeffrey Simpson, do your research

Good news, everyone! Jeffrey Simpson has solved all that ails the university sector in Ontario: it turns out that those lazy professors need to stop doing their airy-fairy research and get their butts in front of the classroom.  Oh, and we also need heavy-handed government intervention to make this happen.

Simpson's column betrays an almost complete lack of understanding of the modern university, not to mention the role and importance of research.  I would invite Simpson to check the research page of any university in Ontario, listing high-profile and news-making results (e.g., U of T, York). Perhaps in his next column, Simpson can let us know which of these results he would trade against smaller class sizes for undergraduates, from the innovative and censorship-fighting Citizen Lab to the breakthroughs of the University Health Network to environment-saving advances in clean energy.  Or perhaps he can let us know which of the many innovative spin-off companies arising from university research Ontario can do without (at U of W alone, valued at nearly $1 billion annually in a 2001 report).

Simpson also fails to understand that there is no tension between research and teaching. Indeed, at the graduate level, research is teaching: graduate students learn the difficult process of developing new knowledge through research, under the close guidance of a supervising professor.  From personal experience, I can say that graduate supervision is a rewarding but time-consuming process; one that Simpson completely ignores.

I could go on, but I've got a lot of research work to do this afternoon! I'm working on an innovative communication technique for nanorobots that may one day revolutionize drug delivery and make invasive surgery obsolete -- take that, taxpayers! Meanwhile, before writing his next column, I suggest Simpson do a bit of the research he hates so much and acquaint himself with what universities actually do in 2011.

On Slepian-Wolf compression, in memory of Jack Wolf

Jack Keil Wolf, one of the giants of information theory, passed away last month.  His obituary was carried in the New York Times.

Wolf's signature contribution was in distributed data compression.  Say you're trying to retrieve two files, X and Y, from separate servers on a network. One strategy would be to compress both files individually to their entropy, H(X) and H(Y), and download them; this requires H(X)+H(Y) bits.  This is as good as you can do if X and Y are statistically independent.  However, if they are dependent, compressing X and Y together can be done at the joint entropy H(X,Y), which is less than H(X)+H(Y). But what can be done by the two servers, since neither has access to both X and Y?

Meeting of the minds

At CWIT in Kelowna, here are the only three Canadians to be president of the IEEE Information Theory Society.  From left to right: Professors Vijay Bhargava, Ian Blake, and Frank Kschischang.

Two papers at CWIT

I have two papers at this week's Canadian Workshop on Information Theory in Kelowna:

1. Lu Cui and Andrew W. Eckford, "The delay selector channel: Definition and capacity bounds"
Session: Coding and Information Theory I, Wednesday May 18, 9:00-10:40 AM

This is work from Lu's master's thesis [PDF]. The "delay selector channel" is a discrete-time channel model that captures some of the features of molecular communication with Brownian motion. The main contribution of this paper is a closed-form lower bound on the channel capacity.

2. Josephine P. K. Chu, Andrew W. Eckford, and Raviraj S. Adve, "Distributed optimization of the Bhattacharyya parameter in wireless relay networks"
Session: Relay Assisted Communication, Thursday May 19, 2:00-3:20 PM

This is work from Josephine's Ph.D. thesis. We give an iterative, distributed solution to the non-convex multi-source, multi-relay resource allocation problem, where the objective is to optimize the Bhattacharyya parameter for each source's transmission.


Paper PDFs will be posted shortly. I will be in Kelowna and presenting both papers.

A quick exercise on divergent sequences

I have a sequence and I'm trying to show that it converges.  Here's my attempt to turn a morning of frustration into a blog post.

Let s(j), j = 1, 2, ..., be a sequence of real numbers with the following properties:

• There exist constants a and b such that a <= s(j) <= b for all j.
• In the limit as j goes to infinity, s(j) - s(j-1) = 0.

Conjecture: Any sequence s(j) satisfying these properties is convergent.

Your job: Disprove the conjecture by providing a counterexample.

There are many possible answers, but I give one in the comments.

Seminar in Ottawa: Information-theoretic problems in molecular and nanoscale communication

I'll be in Ottawa this Thursday and Friday: Thursday I'll be the external examiner at the Ph.D. defense of one of Yongyi's students, and Friday I'll be giving a seminar on some of my recent molecular communication work. Details follow.

Time: Friday, April 29, 11 AM

Title: Information-theoretic problems in molecular and nanoscale communication

Abstract: Recent advances in MEMS/NEMS and systems biology have made it possible to manufacture customized nanoscale devices, such as swarms of nanorobots.  However, manufacturing is not enough: a significant remaining challenge is to solve the communication problem among these devices, which would allow them to coordinate their actions.  Furthermore, the nanoscale communication environment is rather different from the systems that are usually studied by information and communication theorists.  In this talk, I will introduce the nanoscale communication problem from an information-theoretic perspective, focusing on molecular communication, which mimics the way in which microorganisms communicate.  Mathematical models and achievable-rate results will be presented, and important open problems will be discussed.