Hu´s algorithm application for task scheduling in N-version software for satellite communications control systems

Ensuring the reliable operation of satellite communications control systems is an important objective. The reliability of such control systems is largely determined by the level of reliability of their software. The N-version programming has been one of the topical approaches to increase the reliability of the software. The N-version software is based on software redundancy that requires a larger amount of execution time. Satellite communications systems are real-time applications for which any increase in the software execution time is critical. Hu´s scheduling algorithm is suggested for solving this task. The proposed approach allows for generation of an optimal execution schedule for versions of the N-version software of the control system of a satellite communications system. The schedule has the advantage of using a reduced time for task solving. The paper presents a solution to determination of the minimum execution time to run the N-version of the control system of a satellite communications system for a given number of processors. The paper shows a procedure for determination of the number of processors required in the minimum time for execution of a task flow.