A stability with optimality analysis of consensus-based distributed filters for discrete-time linear systems

In this paper we investigate how stability and optimality of consensus-based distributed filters depend on the number ofconsensus steps in a discrete-time setting for both directed and undirected graphs. By introducing two new algorithms, asimpler one based on dynamic averaging of the estimates and a more complex version where local error covariance matrices areexchanged as well, we are able to derive a complete theoretical analysis. In particular we show that dynamic averaging alonesuffices to approximate the optimal centralized estimate if the number of consensus steps is large enough and that the numberof consensus steps needed for stability can be computed in a distributed way. These results shed light on the advantages aswell as the fundamental limitations shared by all the existing proposals for this class of algorithms in the basic case of lineartime-invariant systems, that are relevant for the analysis of more complex situations.