Software reliability allocation with safety concerns in medical devices

Software reliability allocation is a complicated multiple-criteria decision process which involves many factors such as cost, performance, functional complexity and testing. For medical devices, safety is an extremely critical factor that it must be emphasized in the system software development from the early stages. In this paper, we demonstrate an intuitive approach to incorporate safety into reliability allocation. This approach starts with allocating reliability to software modules associated with specific safety feature through functional decomposition and fault tree analysis, and finalizes the allocation for each software module by considering all safety features. This approach can provide a conservative and practical safety-related reliability allocation in an easy-to-use way at software planning and design stages. The proposed approach is shown in detail with a simplified real case.