Differential Encoding for Real-Time Status Updates

For many applications in sensor networks and cyber-physical systems, receiving timely information is of utmost importance. In this article, we study data transmission schemes for a single source, sending periodic updates to a receiver through an unreliable channel. We consider two schemes that exploit the temporal correlation in the source messages, to send differential information to the receiver. Taking advantage of the receiver feedback in the first scheme, the source can decide between the differential and the actual information, to be sent at each transmission opportunity. Contrastingly, in the second scheme without any feedback, the source periodically sends the actual information, interspersed with differential messages. We observe that the differential encoding improves the timeliness performance, only if the receiver feedback is available.