Fault Masking By Probabilistic Voting

In this study, we introduced a probabilistic voter, regarding symbol probabilities in decision process besides majority consensus. Conventional majority voter is independent of functionality of redundant modules. In our study, proposed probabilistic voter is designed corresponding to functionality of the redundant module. We tested probabilistic voter for 3 and 5 redundant modules with random transient errors inserted the wires and it was seen from simulation results that Multi-Modular Redundancy (M-MR) with Probabilistic Voting (PV) had been shown better availability performance than conventional majority voter. Keyword: Fault Tolerance, Fault Masking,Voting Algorithm. Introduction: Majority voting is the most common voting technique used in Multi-Modular Redundancy (M-MR) for fault masking in digital systems. [1-4] The most basic one is bit-bybit majority voting, in which voter algorithm selects the most common output. In the Table 1, truth table of conventional bit-by-bit majority voting for Triple Modular Redundancy (TMR) was given to demonstrate output selection from redundant modules according to majority consensus. In this table, y1, y2 and y3 are output of modules and y represents voter output. General architecture of M-MR system was shown in the Figure 1. In older studies, conventional majority voter was seen to capable of masking single errors which occurs when one of three modules is faulty. Table 1. Conventional bit-by-bit majority voting [3] y1 y2 y3 y 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 1 1 1 0 1 1 1 1 1 Figure 1. Block diagram of the Multi-Modular Redundancy Conventional bit-by-bit majority voting made its decision according to majority consensus at outputs of redundant modules to select the most reliable results. It does not consider any information based on symbol probabilities derived from functionality of Module