Improving Age of Information in Wireless Networks With Perfect Channel State Information

Age of information (AoI), defined as the time that elapsed since the last received update was generated, is a newly proposed metric to measure the timeliness of information updates in a network. We consider AoI minimization problem for a network with general interference constraints, and time varying channels. We propose two policies, namely, virtual-queue based policy and age-based policy when the channel state is available to the network scheduler at each time step. We prove that the virtual-queue based policy is nearly optimal, up to a constant additive factor, and the age-based policy is at-most a factor of 4 away from optimality. Comparison with previous work, which derived age optimal policies when channel state information is not available to the scheduler, demonstrates significant improvement in age due to the availability of channel state information. Our analysis relies on the age conservation law and age-square conservation law developed in this paper, which hold more generally and may be of independent interest.