195 research outputs found
Reliable Transmission of Short Packets through Queues and Noisy Channels under Latency and Peak-Age Violation Guarantees
This work investigates the probability that the delay and the peak-age of
information exceed a desired threshold in a point-to-point communication system
with short information packets. The packets are generated according to a
stationary memoryless Bernoulli process, placed in a single-server queue and
then transmitted over a wireless channel. A variable-length stop-feedback
coding scheme---a general strategy that encompasses simple automatic repetition
request (ARQ) and more sophisticated hybrid ARQ techniques as special
cases---is used by the transmitter to convey the information packets to the
receiver. By leveraging finite-blocklength results, the delay violation and the
peak-age violation probabilities are characterized without resorting to
approximations based on large-deviation theory as in previous literature.
Numerical results illuminate the dependence of delay and peak-age violation
probability on system parameters such as the frame size and the undetected
error probability, and on the chosen packet-management policy. The guidelines
provided by our analysis are particularly useful for the design of low-latency
ultra-reliable communication systems.Comment: To appear in IEEE journal on selected areas of communication (IEEE
JSAC
Optimal Adaptive Random Multiaccess in Energy Harvesting Wireless Sensor Networks
Wireless sensors can integrate rechargeable batteries and energy-harvesting
(EH) devices to enable long-term, autonomous operation, thus requiring
intelligent energy management to limit the adverse impact of energy outages.
This work considers a network of EH wireless sensors, which report packets with
a random utility value to a fusion center (FC) over a shared wireless channel.
Decentralized access schemes are designed, where each node performs a local
decision to transmit/discard a packet, based on an estimate of the packet's
utility, its own energy level, and the scenario state of the EH process, with
the objective to maximize the average long-term aggregate utility of the
packets received at the FC. Due to the non-convex structure of the problem, an
approximate optimization is developed by resorting to a mathematical artifice
based on a game theoretic formulation of the multiaccess scheme, where the
nodes do not behave strategically, but rather attempt to maximize a
\emph{common} network utility with respect to their own policy. The symmetric
Nash equilibrium (SNE) is characterized, where all nodes employ the same
policy; its uniqueness is proved, and it is shown to be a local maximum of the
original problem. An algorithm to compute the SNE is presented, and a heuristic
scheme is proposed, which is optimal for large battery capacity. It is shown
numerically that the SNE typically achieves near-optimal performance, within 3%
of the optimal policy, at a fraction of the complexity, and two operational
regimes of EH-networks are identified and analyzed: an energy-limited scenario,
where energy is scarce and the channel is under-utilized, and a network-limited
scenario, where energy is abundant and the shared wireless channel represents
the bottleneck of the system.Comment: IEEE 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
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