Timing Channels with Multiple Identical Quanta

We consider mutual information between release times and capture times for a set of M identical quanta traveling independently from a source to a target. The quanta are immediately captured upon arrival, first-passage times are assumed independent and identically distributed and the quantum emission times are constrained by a deadline. The primary application area is intended to be inter/intracellular molecular signaling in biological systems whereby an organelle, cell or group of cells must deliver some message (such as transcription or developmental instructions) over distance with reasonable certainty to another organelles, cells or group of cells. However, the model can also be applied to communications systems wherein indistinguishable signals have random transit latencies.Comment: 24 pages, 3 figures, Submitted to JSAC Special Issue on Nanoscale and Molecular Networkin

Inscribed Matter Communication: Part II

This paper is Part II of a two-paper set which develops a finest-grain per-molecule timing treatment of molecular communication. We first consider a simple one-molecule timing channel with a molecule launch deadline, similar to but different from previous work ("Bits Through Queues") where the constraint was mean launch time. We also derive a number of results related to the {\em ordering entropy}, a key quantity which undergirds the capacity bounds for the molecular timing channel, both with and without token data payloads. We then conclude with an upper bound on molecular timing-channel capacity.Comment: 12 pages, 2 figures, 1 Table, in review at IEEE Transactions on Molecular Biological and Multiscale Communicatio

Inscribed Matter Communication: Part I

We provide a fundamental treatment of the molecular communication channel wherein "inscribed matter" is transmitted across a spatial gap to provide reliable signaling between a sender and receiver. Inscribed matter is defined as an ensemble of "tokens" (molecules, objects, and so on) and is inspired, at least partially, by biological systems where groups of individually constructed discrete particles ranging from molecules through membrane-bound structures containing molecules to viruses and organisms are released by a source and travel to a target -- for example, morphogens or semiochemicals diffuse from one cell, tissue or organism diffuse to another. For identical tokens that are neither lost nor modified, we consider messages encoded using three candidate communication schemes: a) token timing (timed release), b) token payload (composition), and c) token timing plus payload. We provide capacity bounds for each scheme and discuss their relative utility. We find that under not unreasonable assumptions, megabit per second rates could be supported at femtoWatt transmitter powers. Since quantities such as token concentration or bin-counting are derivatives of token arrival timing, individual token timing undergirds all molecular communication techniques. Thus, our modeling and results about the physics of efficient token-based information transfer can inform investigations of diverse theoretical and practical problems in engineering and biology. This work, Part I, focuses on the information theoretic bounds on capacity. Part II develops some of the mathematical and information-theoretic ideas that support the bounds presented here.Comment: 20 pages, 6 figures, 1 Table in revision at IEEE Journal on Molecular, Biological and Multiscale Communicatio