  The design and analysis of diffusive molecular communication systems
generally requires knowledge of the environment's physical and chemical
properties. Furthermore, prospective applications might rely on the timely
detection of changes in the local system parameters. This paper studies the
local estimation of channel parameters for diffusive molecular communication
when a transmitter releases molecules that are observed by a receiver. The
Fisher information matrix of the joint parameter estimation problem is derived
so that the Cramer-Rao lower bound on the variance of locally unbiased
estimation can be found. The joint estimation problem can be reduced to the
estimation of any subset of the channel parameters. Maximum likelihood
estimation leads to closed-form solutions for some single-parameter estimation
problems and can otherwise be determined numerically. Peak-based estimators are
proposed for low-complexity estimation of a single unknown parameter.
