Metric (unit)

Queueing theory

Service (business)

Computer network

Mathematics

Markov chain

Poisson distribution

Algorithm

Distributed computing

Statistics

Mathematical optimization

Variety (cybernetics)

Machine learning

Engineering

Queue

Economy

Artificial intelligence

Management

Markov process

Economics

Operations management

Computer science

Performance metric

Exponential distribution

Real-time computing

State (computer science)

IEEE Transactions on Information Theory

We examine multiple independent sources providing status updates to a monitor through simple queues. We formulate an age of information (AoI) timeliness metric and derive a general result for the AoI that is applicable to a wide variety of multiple source service systems. For first-come first-served and two types of last-come first-served systems with Poisson arrivals and exponential service times, we find the region of feasible average status ages for multiple updating sources. We then use these results to characterize how a service facility can be shared among multiple updating sources. A new simplified technique for evaluating the AoI in finite-state continuous-time queuing systems is also derived. Based on stochastic hybrid systems, this method makes AoI evaluation to be comparable in complexity to finding the stationary distribution of a finite-state Markov chain.

The Age of Information: Real-Time Status Updating by Multiple Sources