20 research outputs found
Minimizing the Age of Information in Wireless Networks with Stochastic Arrivals
We consider a wireless network with a base station serving multiple traffic
streams to different destinations. Packets from each stream arrive to the base
station according to a stochastic process and are enqueued in a separate (per
stream) queue. The queueing discipline controls which packet within each queue
is available for transmission. The base station decides, at every time t, which
stream to serve to the corresponding destination. The goal of scheduling
decisions is to keep the information at the destinations fresh. Information
freshness is captured by the Age of Information (AoI) metric.
In this paper, we derive a lower bound on the AoI performance achievable by
any given network operating under any queueing discipline. Then, we consider
three common queueing disciplines and develop both an Optimal Stationary
Randomized policy and a Max-Weight policy under each discipline. Our approach
allows us to evaluate the combined impact of the stochastic arrivals, queueing
discipline and scheduling policy on AoI. We evaluate the AoI performance both
analytically and using simulations. Numerical results show that the performance
of the Max-Weight policy is close to the analytical lower bound
Age-Optimal Information Updates in Multihop Networks
The problem of reducing the age-of-information has been extensively studied
in the single-hop networks. In this paper, we minimize the age-of-information
in general multihop networks. If the packet transmission times over the network
links are exponentially distributed, we prove that a preemptive Last Generated
First Served (LGFS) policy results in smaller age processes at all nodes of the
network (in a stochastic ordering sense) than any other causal policy. In
addition, for arbitrary general distributions of packet transmission times, the
non-preemptive LGFS policy is shown to minimize the age processes at all nodes
of the network among all non-preemptive work-conserving policies (again in a
stochastic ordering sense). It is surprising that such simple policies can
achieve optimality of the joint distribution of the age processes at all nodes
even under arbitrary network topologies, as well as arbitrary packet generation
and arrival times. These optimality results not only hold for the age
processes, but also for any non-decreasing functional of the age processes.Comment: arXiv admin note: text overlap with arXiv:1603.0618