The problem of using acknowledgement messages for reducing the effects of packet loss on the performance of a networked control system (NCS) is considered. A sampling and transmission strategy is proposed and the model of the NCS with a Markovian communication state is precisely determined which provides the necessary tools for exact NCS analysis and design. The results can be used efficiently to design simple and practical controllers like PID by minimizing the value of a performance measure. During an example, an $H_{infty}$ performance measure of an NCS is optimized to design controllers, compare between them and evaluate them from both control and communication points of view.