1,404 research outputs found
On Throughput Maximization of Grant-Free Access with Reliability-Latency Constraints
Enabling autonomous driving and industrial automation with wireless networks
poses many challenges, which are typically abstracted through reliability and
latency requirements. One of the main contributors to latency in cellular
networks is the reservation-based access, which involves lengthy and
resource-inefficient signaling exchanges. An alternative is to use grant-free
access, in which there is no resource reservation. A handful of recent works
investigated how to fulfill reliability and latency requirements with different
flavors of grant-free solutions. However, the resource efficiency, i.e., the
throughput, has been only the secondary focus. In this work, we formulate the
throughput of grant-free access under reliability-latency constraints, when the
actual number of arrived users or only the arrival distribution are known. We
investigate how these different levels of knowledge about the arrival process
influence throughput performance of framed slotted ALOHA with -multipacket
reception, for the Poisson and Beta arrivals. We show that the throughput under
reliability-latency requirements can be significantly improved for the higher
expected load of the access network, if the actual number of arrived users is
known. This insight motivates the use of techniques for the estimation of the
number of arrived users, as this knowledge is not readily available in
grant-free access. We also asses the impact of estimation error, showing that
for high reliability-latency requirements the gains in throughput are still
considerable.Comment: Accepted for publication in ICC'201
Performance Analysis of a System with Bursty Traffic and Adjustable Transmission Times
In this work, we consider the case where a source with bursty traffic can
adjust the transmission duration in order to increase the reliability. The
source is equipped with a queue in order to store the arriving packets. We
model the system with a discrete time Markov Chain, and we characterize the
performance in terms of service probability and average delay per packet. The
accuracy of the theoretical results is validated through simulations. This work
serves as an initial step in order to provide a framework for systems with
arbitrary arrivals and variable transmission durations and it can be utilized
for the derivation of the delay distribution and the delay violation
probability.Comment: ISWCS 201
Internet of Things and Sensors Networks in 5G Wireless Communications
The Internet of Things (IoT) has attracted much attention from society, industry and academia as a promising technology that can enhance day to day activities, and the creation of new business models, products and services, and serve as a broad source of research topics and ideas. A future digital society is envisioned, composed of numerous wireless connected sensors and devices. Driven by huge demand, the massive IoT (mIoT) or massive machine type communication (mMTC) has been identified as one of the three main communication scenarios for 5G. In addition to connectivity, computing and storage and data management are also long-standing issues for low-cost devices and sensors. The book is a collection of outstanding technical research and industrial papers covering new research results, with a wide range of features within the 5G-and-beyond framework. It provides a range of discussions of the major research challenges and achievements within this topic
Internet of Things and Sensors Networks in 5G Wireless Communications
This book is a printed edition of the Special Issue Internet of Things and Sensors Networks in 5G Wireless Communications that was published in Sensors
Internet of Things and Sensors Networks in 5G Wireless Communications
This book is a printed edition of the Special Issue Internet of Things and Sensors Networks in 5G Wireless Communications that was published in Sensors
Frameless ALOHA with Reliability-Latency Guarantees
One of the novelties brought by 5G is that wireless system design has
increasingly turned its focus on guaranteeing reliability and latency. This
shifts the design objective of random access protocols from throughput
optimization towards constraints based on reliability and latency. For this
purpose, we use frameless ALOHA, which relies on successive interference
cancellation (SIC), and derive its exact finite-length analysis of the
statistics of the unresolved users (reliability) as a function of the
contention period length (latency). The presented analysis can be used to
derive the reliability-latency guarantees. We also optimize the scheme
parameters in order to maximize the reliability within a given latency. Our
approach represents an important step towards the general area of design and
analysis of access protocols with reliability-latency guarantees.Comment: Accepted for presentation at IEEE Globecom 201
A Comprehensive Overview on 5G-and-Beyond Networks with UAVs: From Communications to Sensing and Intelligence
Due to the advancements in cellular technologies and the dense deployment of
cellular infrastructure, integrating unmanned aerial vehicles (UAVs) into the
fifth-generation (5G) and beyond cellular networks is a promising solution to
achieve safe UAV operation as well as enabling diversified applications with
mission-specific payload data delivery. In particular, 5G networks need to
support three typical usage scenarios, namely, enhanced mobile broadband
(eMBB), ultra-reliable low-latency communications (URLLC), and massive
machine-type communications (mMTC). On the one hand, UAVs can be leveraged as
cost-effective aerial platforms to provide ground users with enhanced
communication services by exploiting their high cruising altitude and
controllable maneuverability in three-dimensional (3D) space. On the other
hand, providing such communication services simultaneously for both UAV and
ground users poses new challenges due to the need for ubiquitous 3D signal
coverage as well as the strong air-ground network interference. Besides the
requirement of high-performance wireless communications, the ability to support
effective and efficient sensing as well as network intelligence is also
essential for 5G-and-beyond 3D heterogeneous wireless networks with coexisting
aerial and ground users. In this paper, we provide a comprehensive overview of
the latest research efforts on integrating UAVs into cellular networks, with an
emphasis on how to exploit advanced techniques (e.g., intelligent reflecting
surface, short packet transmission, energy harvesting, joint communication and
radar sensing, and edge intelligence) to meet the diversified service
requirements of next-generation wireless systems. Moreover, we highlight
important directions for further investigation in future work.Comment: Accepted by IEEE JSA
5g new radio access and core network slicing for next-generation network services and management
In recent years, fifth-generation New Radio (5G NR) has attracted much attention owing to its potential in enhancing mobile access networks and enabling better support for heterogeneous services and applications. Network slicing has garnered substantial focus as it promises to offer a higher degree of isolation between subscribers with diverse quality-of-service requirements. Integrating 5G NR technologies, specifically the mmWave waveform and numerology schemes, with network slicing can unlock unparalleled performance so crucial to meeting the demands of high throughput and sub-millisecond latency constraints.
While conceding that optimizing next-generation access network performance is extremely important, it needs to be acknowledged that doing so for the core network is equally as significant. This is majorly due to the numerous core network functions that execute control tasks to establish end-to-end user sessions and route access network traffic. Consequently, the core network has a significant impact on the quality-of-experience of the radio access network customers. Currently, the core network lacks true end-to-end slicing isolation and reliability, and thus there is a dire need to examine more stringent configurations that offer the required levels of slicing isolation for the envisioned networking landscape.
Considering the factors mentioned above, a sequential approach is adopted starting with the radio access network and progressing to the core network. First, to maximize the downlink average spectral efficiency of an enhanced mobile broadband slice in a time division duplex radio access network while meeting the quality-of-service requirements, an optimization problem is formulated to determine the duplex ratio, numerology scheme, power, and bandwidth allocation. Subsequently, to minimize the uplink transmission power of an ultra-reliable low latency communications slice while satisfying the quality-of-service constraints, a second optimization problem is formulated to determine the above-mentioned parameters and allocations. Because 5G NR supports dual-band transmissions, it also facilitates the usage of different numerology schemes and duplex ratios across bands simultaneously. Both problems, being mixed-integer non-linear programming problems, are relaxed into their respective convex equivalents and subsequently solved.
Next, shifting attention to aerial networks, a priority-based 5G NR unmanned aerial vehicle network (UAV) is considered where the enhanced mobile broadband and ultra-reliable low latency communications services are considered as best-effort and high-priority slices, correspondingly. Following the application of a band access policy, an optimization problem is formulated. The goal is to minimize the downlink quality-of-service gap for the best-effort service, while still meeting the quality-of-service constraints of the high-priority service. This involves the allocation of transmission power and assignment of resource blocks. Given that this problem is a mixed-integer nonlinear programming problem, a low-complexity algorithm, PREDICT, i.e., PRiority BasED Resource AllocatIon in Adaptive SliCed NeTwork, which considers the channel quality on each individual resource block over both bands, is designed to solve the problem with a more accurate accounting for high-frequency channel conditions.
Transitioning to minimizing the operational latency of the core network, an integer linear programming problem is formulated to instantiate network function instances, assign them to core network servers, assign slices and users to network function instances, and allocate computational resources while maintaining virtual network function isolation and physical separation of the core network control and user planes. The actor-critic method is employed to solve this problem for three proposed core network operation configurations, each offering an added degree of reliability and isolation over the default configuration that is currently standardized by the 3GPP.
Looking ahead to potential future research directions, optimizing carrier aggregation-based resource allocation across triple-band sliced access networks emerges as a promising avenue. Additionally, the integration of coordinated multi-point techniques with carrier aggregation in multi-UAV NR aerial networks is especially challenging. The introduction of added carrier frequencies and channel bandwidths, while enhancing flexibility and robustness, complicates band-slice assignments and user-UAV associations. Another layer of intriguing yet complex research involves optimizing handovers in high-mobility UAV networks, where both users and UAVs are mobile. UAV trajectory planning, which is already NP-hard even in static-user scenarios, becomes even more intricate to obtain optimal solutions in high-mobility user cases
5G Wireless Network Slicing for eMBB, URLLC, and mMTC: A Communication-Theoretic View
The grand objective of 5G wireless technology is to support three generic
services with vastly heterogeneous requirements: enhanced mobile broadband
(eMBB), massive machine-type communications (mMTC), and ultra-reliable
low-latency communications (URLLC). Service heterogeneity can be accommodated
by network slicing, through which each service is allocated resources to
provide performance guarantees and isolation from the other services. Slicing
of the Radio Access Network (RAN) is typically done by means of orthogonal
resource allocation among the services. This work studies the potential
advantages of allowing for non-orthogonal sharing of RAN resources in uplink
communications from a set of eMBB, mMTC and URLLC devices to a common base
station. The approach is referred to as Heterogeneous Non-Orthogonal Multiple
Access (H-NOMA), in contrast to the conventional NOMA techniques that involve
users with homogeneous requirements and hence can be investigated through a
standard multiple access channel. The study devises a communication-theoretic
model that accounts for the heterogeneous requirements and characteristics of
the three services. The concept of reliability diversity is introduced as a
design principle that leverages the different reliability requirements across
the services in order to ensure performance guarantees with non-orthogonal RAN
slicing. This study reveals that H-NOMA can lead, in some regimes, to
significant gains in terms of performance trade-offs among the three generic
services as compared to orthogonal slicing.Comment: Submitted to IEE
- …