96 research outputs found
Distributed Backlog-Aware D2D Communication for Heterogeneous IIoT Applications
Delay and Age-of-Information (AoI) are two crucial performance metrics for
emerging time-sensitive applications in Industrial Internet of Things (IIoT).
In order to achieve optimal performance, studying the inherent interplay
between these two parameters in non-trivial task. In this work, we consider a
Device-to-Device (D2D)-based heterogeneous IIoT network that supports two types
of traffic flows, namely AoI-orientated. First, we introduce a distributed
backlog-aware random access protocol that allows the AoI-orientated nodes to
opportunistically access the channel based on the queue occupancy of the
delay-oriented node. Then, we develop an analytical framework to evaluate the
average delay and the average AoI, and formulate an optimization problem to
minimize the AoI under a given delay constraint. Finally, we provide numerical
results to demonstrate the impact of different network parameters on the
performance in terms of the average delay and the average AoI. We also give the
numerical solutions of the optimal parameters that minimize the AoI subject to
a delay constraint
Indoor Positioning Trends in 5G-Advanced: Challenges and Solution towards Centimeter-level Accuracy
After robust connectivity, precise positioning is evolving into an innovative
component of 5G service offerings for industrial use-cases and verticals with
challenging indoor radio environments. In this direction, the 3GPP Rel-16
standard has been a tipping point in specifying critical innovations, followed
by enhancements in Rel-17+. In this article, we follow this path to elaborate
on the 5G positioning framework, measurements, and methods before shifting the
focus to carrier-phase (CP) measurements as a complementary measure for time-
and angular-based positioning methods toward achieving centimeter-level
accuracy. As this path is not without challenges, we discuss these and outline
potential solutions. As an example of solutions, we study how phase-continuous
reference signaling can counter noisy phase measurements using realistic
simulations in an indoor factory (InF) scenario.Comment: 5 figures, 1 table, under review for possible publication in IEEE
Communications Magazin
Scalability Analysis of a LoRa Network under Imperfect Orthogonality
Low-power wide-area network (LPWAN) technologies are gaining momentum for
internet-of-things (IoT) applications since they promise wide coverage to a
massive number of battery-operated devices using grant-free medium access.
LoRaWAN, with its physical (PHY) layer design and regulatory efforts, has
emerged as the widely adopted LPWAN solution. By using chirp spread spectrum
modulation with qausi-orthogonal spreading factors (SFs), LoRa PHY offers
coverage to wide-area applications while supporting high-density of devices.
However, thus far its scalability performance has been inadequately modeled and
the effect of interference resulting from the imperfect orthogonality of the
SFs has not been considered. In this paper, we present an analytical model of a
single-cell LoRa system that accounts for the impact of interference among
transmissions over the same SF (co-SF) as well as different SFs (inter-SF). By
modeling the interference field as Poisson point process under duty-cycled
ALOHA, we derive the signal-to-interference ratio (SIR) distributions for
several interference conditions. Results show that, for a duty cycle as low as
0.33%, the network performance under co-SF interference alone is considerably
optimistic as the inclusion of inter-SF interference unveils a further drop in
the success probability and the coverage probability of approximately 10% and
15%, respectively for 1500 devices in a LoRa channel. Finally, we illustrate
how our analysis can characterize the critical device density with respect to
cell size for a given reliability target
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