  Motivated by the inherent value of packets arising in many cyber-physical
applications (e.g., due to precision of the information content or an alarm
message), we consider status update systems with update packets carrying values
as well as their generation time stamps. Once generated, a status update packet
has a random initial value and a deterministic deadline after which it is not
useful (ultimate staleness). In our model, value of a packet decreases in time
(even after reception) starting from its generation to ultimate staleness when
it vanishes. The value of information (VoI) at the receiver is additive in that
the VoI is the sum of the current values of all packets held by the receiver.
We investigate various queuing disciplines under potential dependence between
value and service time and provide closed form expressions for average VoI at
the receiver. Numerical results illustrate the average VoI for different
scenarios and the contrast between average age of information (AoI) and average
VoI.
