13 research outputs found
Peak Age of Information Distribution for Edge Computing with Wireless Links
Age of Information (AoI) is a critical metric for several Internet of Things
(IoT) applications, where sensors keep track of the environment by sending
updates that need to be as fresh as possible. The development of edge computing
solutions has moved the monitoring process closer to the sensor, reducing the
communication delays, but the processing time of the edge node needs to be
taken into account. Furthermore, a reliable system design in terms of freshness
requires the knowledge of the full distribution of the Peak AoI (PAoI), from
which the probability of occurrence of rare, but extremely damaging events can
be obtained. In this work, we model the communication and computation delay of
such a system as two First Come First Serve (FCFS) queues in tandem,
analytically deriving the full distribution of the PAoI for the M/M/1 - M/D/1
and the M/M/1 - M/M/1 tandems, which can represent a wide variety of realistic
scenarios.Comment: Preprint version of the paper accepted for publication in the
Transactions on Communication
Age-of-Information Dependent Random Access for Massive IoT Networks
As the most well-known application of the Internet of Things (IoT), remote
monitoring is now pervasive. In these monitoring applications, information
usually has a higher value when it is fresher. A new metric, termed the age of
information (AoI), has recently been proposed to quantify the information
freshness in various IoT applications. This paper concentrates on the design
and analysis of age-oriented random access for massive IoT networks.
Specifically, we devise a new stationary threshold-based age-dependent random
access (ADRA) protocol, in which each IoT device accesses the channel with a
certain probability only when its instantaneous AoI exceeds a predetermined
threshold. We manage to evaluate the average AoI of the proposed ADRA protocol
mathematically by decoupling the tangled AoI evolution of multiple IoT devices
and modeling the decoupled AoI evolution of each device as a Discrete-Time
Markov Chain. Simulation results validate our theoretical analysis and affirm
the superior age performance of the proposed ADRA protocol over the
state-of-the-art age-oriented random access schemes.Comment: Accepted to appear at INFOCOM 2020 Workshop on Age of Informatio
On the Role of Preemption for Timing Metrics in Coded Multipath Communication
Recent trends in communication networks have focused on Quality of Service
(QoS) requirements expressed through timing metrics such as latency or Age of
Information (AoI). A possible way to achieve this is coded multipath
communication: redundancy is added to a block of information through a robust
packet-level code, transmitting across multiple independent channels to reduce
the impact of blockages or rate fluctuation. The number of these links can grow
significantly over traditional two-path schemes: in these scenarios, the
optimization of the timing metrics is non-trivial, and latency and AoI might
require different settings. In particular, packet preemption is often the
optimal solution to optimize AoI in uncoded communication, but can
significantly reduce the reliability of individual blocks. In this work, we
model the multipath communication as a fork-join D/M/(K,N)/L queue, where K
blocks of information are encoded into N>K redundant blocks. We derive the
latency and Peak AoI (PAoI) distributions for different values of the queue
size L. Our results show that preemption is not always the optimal choice, as
dropping a late packet on one path might affect the reliability of the whole
block, and that minimizing the PAoI leads to poor latency performance.Comment: Submitted for publication to the IEEE Transactions on Communication