Fault tolerance in a multisensor environment

Replicating sensors is desirable not only to tolerate sensor failures but also to increase the expected accuracy of the ensemble of replicated sensors beyond that obtainable with a single one. Such replication is used in a multisensor environment or in a distributed sensor network. We model a continuous valued sensor as an interval of real numbers containing the physical value of interest. Given n sensors of which at most f of them can suffer arbitrary failures, we present an efficient O(n log n) fault tolerant algorithm whose output is reliable when f < n/2. The output of the algorithm could be a single interval or a set of intervals depending on the nature of the multisensor environment. This algorithm can be used not only to detect all the possibly-faulty sensors but to detect all sets (combinations) of possibly-faulty sensors. We derive a number of results pertaining to the possibly-faulty sensors pointed out by the algorithm which help narrow down the search to detect faulty sensors and to bound the number of intervals needed to construct an accurate and reliable "abstract sensor".