Fault Coverage Ratio Research Articles

Availability requirement for a fault-management server in high-availability communication systems

This paper investigates the availability requirement for the fault management server in high-availability communication systems. This study shows that the availability of the fault management server does not need to be 99.999% in order to guarantee a 99.999% system availability, as long as the fail-safe ratio (the probability that the failure of the fault management server does not bring down the system) and the fault coverage ratio (probability that the failure in the system can be detected and recovered by the fault management server) are sufficiently high. Tradeoffs can be made among the availability of the fault management server, the fail-safe ratio, and the fault coverage ratio to optimize system availability. A cost-effective design for the fault management server is proposed.

The Influence of Masking Phenomenon on Coverage Capability of Single Fault Test Sets in PLA's

It is relatively easy to generate a complete single contact fault detection test set Tc for a PLA. However such a test set may fail to detect all multiple faults due to the phenomenon of masking. In previous papers attempting to quantitatively predict the multiple fault coverage capability of a single fault detection test set Tc in PLA's, it was proved that every multiple contact fault in an irredundant PLA is detected by Tc if the multiple fault does not contain any four-way masking cycle. In this correspondence, the masking relations are studied in detail and it is shown that Tc in fact detects a signifilcant percentage of faults with four-way masking. Based on these results more realistic bounds of the coverage capability of Tc are determined. It is shown that the multiple fault coverage ratio of Tc increases with the increasing number m of rows of a PLA and for m = 24 Tc detects 99 percent of all contact faults of size 8 or less.

Combinatorial Approach to Multiple Contact Faults Coverage in Programmable Logic Arrays

The increasing number of applications of programmable logic arrays (PLA's) has evoked the development of test generation methods for these circuits. There are known methods for complete single contact fault detection test set generation. These test sets fail to detect all multiple faults in a PLA due to the phenomenon of masking. In this correspondence, we present a method to quantitively predict the multiple fault coverage capability of a single fault detection test set in a PLA. The method enables us to determine the coverage ratio, which is defined as the ratio of the number of multiple contact faults detected by a single fault test T c to the total number of all multiple faults. It is shown that the multiple fault coverage ratio of T c drops with an increasing size of faults, and most unexpectedly, the ratio increases with an increasing number of rows. The number of crosspoints in one product line has very little influence on the ratio.