Zero signal and last available signal strategies comparison for H∞ control over lossy links

This paper studies the H_∞ performance of networked control systems where control packets are subject to loss. Two commonly-used compensation strategies, namely, the “zero signal” and “last available signal” strategies are compared. The results in this paper show that besides giving simpler equations and being convenient to mathematical analysis, the “zero signal” strategy is never worse than the “last available signal” one. An example is given to show the validity of the proposed result.