I'm third author on this paper, and Sachin and Ravi rightly deserve most of the credit. However, we got a writeup in Technology Review, so I thought I would blog a bit about the paper.
In molecular communication, a transmitter sends a message to a receiver by releasing a pattern of molecules into a shared medium. One way to communicate using molecules is to use timing -- i.e., releasing a molecule at different times to express different messages. Using Brownian motion, the timing message is distorted by the random propagation time from transmitter to receiver.
My original work on molecular communication (1, 2) considered the case of drift-free Brownian motion. In this paper, we extend these results into Brownian motion with drift -- it's a much easier case to deal with, since the first arrival distribution without drift has a very heavy tail, as well as infinite mean. We also have some nice results about modulation: even when multiple molecules are available, pulse position modulation turns out to work quite well if the drift velocity is low.
The paper was submitted to IEEE Trans. Nanobioscience, and we're expecting the first reviews back any day now.