144 research outputs found
Caching-Aided Collaborative D2D Operation for Predictive Data Dissemination in Industrial IoT
Industrial automation deployments constitute challenging environments where
moving IoT machines may produce high-definition video and other heavy sensor
data during surveying and inspection operations. Transporting massive contents
to the edge network infrastructure and then eventually to the remote human
operator requires reliable and high-rate radio links supported by intelligent
data caching and delivery mechanisms. In this work, we address the challenges
of contents dissemination in characteristic factory automation scenarios by
proposing to engage moving industrial machines as device-to-device (D2D)
caching helpers. With the goal to improve reliability of high-rate
millimeter-wave (mmWave) data connections, we introduce the alternative
contents dissemination modes and then construct a novel mobility-aware
methodology that helps develop predictive mode selection strategies based on
the anticipated radio link conditions. We also conduct a thorough system-level
evaluation of representative data dissemination strategies to confirm the
benefits of predictive solutions that employ D2D-enabled collaborative caching
at the wireless edge to lower contents delivery latency and improve data
acquisition reliability
Capacity and Outage of Terahertz Communications with User Micro-mobility and Beam Misalignment
User equipment mobility is one of the primary challenges for the design of
reliable and efficient wireless links over millimeter-wave and terahertz bands.
These high-rate communication systems use directional antennas and therefore
have to constantly maintain alignment between transmitter and receiver beams.
For terahertz links, envisioned to employ radiation patterns of no more than
few degrees wide, not only the macro-scale user mobility (human walking, car
driving, etc.) but also the micro-scale mobility - spontaneous shakes and
rotations of the device - becomes a severe issue. In this paper, we propose a
mathematical framework for the first-order analysis of the effects caused by
micro-mobility on the capacity and outage in terahertz communications. The
performance of terahertz communications is compared with and without
micro-mobility illustrating the difference of up to 1 Tbit/s or 75%. In
response to this gap, it is finally shown how the negative effects of the
micro-mobility can be partially addressed by a proper adjustment of the
terahertz antenna arrays and the period of beam realignment procedure.Comment: Accepted to IEEE Transactions on Vehicular Technology on April 9,
2020. Copyright may be transferred without further notice after which this
version may become non-availabl
Analysis of Intelligent Vehicular Relaying in Urban 5G+ Millimeter-Wave Cellular Deployments
The capability of smarter networked devices to dynamically select appropriate
radio connectivity options is especially important in the emerging
millimeter-wave (mmWave) systems to mitigate abrupt link blockage in complex
environments. To enrich the levels of diversity, mobile mmWave relays can be
employed for improved connection reliability. These are considered by 3GPP for
on-demand densification on top of the static mmWave infrastructure. However,
performance dynamics of mobile mmWave relaying is not nearly well explored,
especially in realistic conditions, such as urban vehicular scenarios. In this
paper, we develop a mathematical framework for the performance evaluation of
mmWave vehicular relaying in a typical street deployment. We analyze and
compare alternative connectivity strategies by quantifying the performance
gains made available to smart devices in the presence of mmWave relays. We
identify situations where the use of mmWave vehicular relaying is particularly
beneficial. Our methodology and results can support further standardization and
deployment of mmWave relaying in more intelligent 5G+ "all-mmWave" cellular
networks.Comment: 6 pages, 8 figures. The paper has been accepted for IEEE GLOBECOM
2019. Copyright may be transferred without notice, after which this version
may no longer be accessibl
Counter Waves Link Activation Policy for Latency Control in In-Band IAB Systems
3GPP’s Integrated Access and Backhaul (IAB) architecture is expected to deliver a cost-efficient option for deploying 5G New Radio (NR) systems. However, IAB relies on multi-hop wireless communications, and packet latency therefore becomes a critical metric in such systems. Latency minimization in the in-band backhauling regime involves dynamical scheduling of active transmission links so as to avoid half-duplex conflicts, which brings significant control overheads. In this paper, by using the formalism of Markov decision processes (MDP), we identify a general fixed link activation policy and the associated policy design algorithm for tree-shaped in-band IAB systems with half-duplex constraints. The proposed policy, named “counter waves”, does not require signalling between the IAB donor and nodes and provides stable low latency for low-to-medium traffic conditions spanning up to 60% of the capacity region of the system.Peer reviewe
Hover or Perch: Comparing Capacity of Airborne and Landed Millimeter-Wave UAV Cells
On-demand deployments of millimeter-wave (mmWave) access points (APs) carried
by unmanned aerial vehicles (UAVs) are considered today as a potential solution
to enhance the performance of 5G+ networks. The battery lifetime of modern
UAVs, though, limits the flight times in such systems. In this letter, we
evaluate a feasible deployment alternative for temporary capacity boost in the
areas with highly fluctuating user demands. The approach is to land UAV-based
mmWave APs on the nearby buildings instead of hovering over the area. Within
the developed mathematical framework, we compare the system-level performance
of airborne and landed deployments by taking into account the full operation
cycle of the employed drones. Our numerical results demonstrate that the choice
of the UAV deployment option is determined by an interplay of the separation
distance between the service area and the UAV charging station, drone battery
lifetime, and the number of aerial APs in use. The presented methodology and
results can support efficient on-demand deployments of UAV-based mmWave APs in
prospective 5G+ networks.Comment: Accepted to IEEE Wireless Communications Letters on July 20, 2020.
Copyright may be transferred without further notice after which this version
may become non-availabl
An Accurate Approximation of Resource Request Distributions in Millimeter Wave 3GPP New Radio Systems
The recently standardized millimeter wave-based 3GPP New Radio technology is
expected to become an enabler for both enhanced Mobile Broadband (eMBB) and
ultra-reliable low latency communication (URLLC) services specified to future
5G systems. One of the first steps in mathematical modeling of such systems is
the characterization of the session resource request probability mass function
(pmf) as a function of the channel conditions, cell size, application demands,
user location and system parameters including modulation and coding schemes
employed at the air interface. Unfortunately, this pmf cannot be expressed via
elementary functions. In this paper, we develop an accurate approximation of
the sought pmf. First, we show that Normal distribution provides a fairly
accurate approximation to the cumulative distribution function (CDF) of the
signal-to-noise ratio for communication systems operating in the millimeter
frequency band, further allowing evaluating the resource request pmf via error
function. We also investigate the impact of shadow fading on the resource
request pmf.Comment: The 19th International Conference on Next Generation Wired/Wireless
Networks and Systems (New2An 2019
Performance Assessment of an ITU-T Compliant Machine Learning Enhancements for 5Â G RAN Network Slicing
Network slicing is a technique introduced by 3GPP to enable multi-tenant operation in 5 G systems. However, the support of slicing at the air interface requires not only efficient optimization algorithms operating in real time but also its tight integration into the 5 G control plane. In this paper, we first present a priority-based mechanism enabling defined performance isolation among slices competing for resources. Then, to speed up the resource arbitration process, we propose and compare several supervised machine learning (ML) techniques. We show how to embed the proposed approach into the ITU-T standardized ML architecture. The proposed ML enhancement is evaluated under realistic traffic conditions with respect to the performance criteria defined by GSMA while explicitly accounting for 5 G millimeter wave channel conditions. Our results show that ML techniques are able to provide suitable approximations for the resource allocation process ensuring slice performance isolation, efficient resource use, and fairness. Among the considered algorithms, polynomial regressions show the best results outperforming the exact solution algorithm by 5–6 orders of magnitude in terms of execution time and both neural network and random forest algorithms in terms of accuracy (by 20–40 %), sensitiveness to workload variations and training sample size. Finally, ML algorithms are generally prone to service level agreements (SLA) violation under high load and time-varying channel conditions, implying that an SLA enforcement system is needed in ITU-T's 5 G ML framework.publishedVersionPeer reviewe
- …