36,390 research outputs found
Age-Optimal Updates of Multiple Information Flows
In this paper, we study an age of information minimization problem, where
multiple flows of update packets are sent over multiple servers to their
destinations. Two online scheduling policies are proposed. When the packet
generation and arrival times are synchronized across the flows, the proposed
policies are shown to be (near) optimal for minimizing any time-dependent,
symmetric, and non-decreasing penalty function of the ages of the flows over
time in a stochastic ordering sense
Status Updates in a multi-stream M/G/1/1 preemptive queue
We consider a source that collects a multiplicity of streams of updates and
sends them through a network to a monitor. However, only a single update can be
in the system at a time. Therefore, the transmitter always preempts the packet
being served when a new update is generated. We consider Poisson arrivals for
each stream and a common general service time, and refer to this system as the
multi-stream M/G/1/1 queue with preemption. Using the detour flow graph method,
we compute a closed form expression for the average age and the average peak
age of each stream. Moreover, we deduce that although all streams are treated
equally from a transmission point of view (they all preempt each other), one
can still prioritize a stream from an age point of view by simply increasing
its generation rate. However, this will increase the sum of the ages which is
minimized when all streams have the same update rate
Optimizing Age-of-Information in a Multi-class Queueing System
We consider the age-of-information in a multi-class queueing system,
where each class generates packets containing status information. Age of
information is a relatively new metric that measures the amount of time that
elapsed between status updates, thus accounting for both the queueing delay and
the delay between packet generation. This gives rise to a tradeoff between
frequency of status updates, and queueing delay. In this paper, we study this
tradeoff in a system with heterogenous users modeled as a multi-class
queue. To this end, we derive the exact peak age-of-Information (PAoI) profile
of the system, which measures the "freshness" of the status information. We
then seek to optimize the age of information, by formulating the problem using
quasiconvex optimization, and obtain structural properties of the optimal
solution
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