307 research outputs found
Reliable and Low-Latency Fronthaul for Tactile Internet Applications
With the emergence of Cloud-RAN as one of the dominant architectural
solutions for next-generation mobile networks, the reliability and latency on
the fronthaul (FH) segment become critical performance metrics for applications
such as the Tactile Internet. Ensuring FH performance is further complicated by
the switch from point-to-point dedicated FH links to packet-based multi-hop FH
networks. This change is largely justified by the fact that packet-based
fronthauling allows the deployment of FH networks on the existing Ethernet
infrastructure. This paper proposes to improve reliability and latency of
packet-based fronthauling by means of multi-path diversity and erasure coding
of the MAC frames transported by the FH network. Under a probabilistic model
that assumes a single service, the average latency required to obtain reliable
FH transport and the reliability-latency trade-off are first investigated. The
analytical results are then validated and complemented by a numerical study
that accounts for the coexistence of enhanced Mobile BroadBand (eMBB) and
Ultra-Reliable Low-Latency (URLLC) services in 5G networks by comparing
orthogonal and non-orthogonal sharing of FH resources.Comment: 11pages, 13 figures, 3 bio photo
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
A Survey of Scheduling in 5G URLLC and Outlook for Emerging 6G Systems
Future wireless communication is expected to be a paradigm shift from three basic service requirements of 5th Generation (5G) including enhanced Mobile Broadband (eMBB), Ultra Reliable and Low Latency communication (URLLC) and the massive Machine Type Communication (mMTC). Integration of the three heterogeneous services into a single system is a challenging task. The integration includes several design issues including scheduling network resources with various services. Specially, scheduling the URLLC packets with eMBB and mMTC packets need more attention as it is a promising service of 5G and beyond systems. It needs to meet stringent Quality of Service (QoS) requirements and is used in time-critical applications. Thus through understanding of packet scheduling issues in existing system and potential future challenges is necessary. This paper surveys the potential works that addresses the packet scheduling algorithms for 5G and beyond systems in recent years. It provides state of the art review covering three main perspectives such as decentralised, centralised and joint scheduling techniques. The conventional decentralised algorithms are discussed first followed by the centralised algorithms with specific focus on single and multi-connected network perspective. Joint scheduling algorithms are also discussed in details. In order to provide an in-depth understanding of the key scheduling approaches, the performances of some prominent scheduling algorithms are evaluated and analysed. This paper also provides an insight into the potential challenges and future research directions from the scheduling perspective
Open Cell-less Network Architecture and Radio Resource Management for Future Wireless Communication Systems
In recent times, the immense growth of wireless traffic data generated from massive mobile
devices, services, and applications results in an ever-increasing demand for huge
bandwidth and very low latency, with the future networks going in the direction of achieving
extreme system capacity and ultra reliable low latency communication (URLLC). Several
consortia comprising major international mobile operators, infrastructure manufacturers,
and academic institutions are working to develop and evolve the current generation
of wireless communication systems, i.e., fifth generation (5G) towards a sixth generation
(6G) to support improved data rates, reliability, and latency. Existing 5G networks are
facing the latency challenges in a high-density and high-load scenario for an URLLC network
which may coexist with enhanced mobile broadband (eMBB) services. At the same
time, the evolution of mobile communications faces the important challenge of increased
network power consumption. Thus, energy efficient solutions are expected to be deployed
in the network in order to reduce power consumption while fulfilling user demands for
various user densities. Moreover, the network architecture should be dynamic according
to the new use cases and applications. Also, there are network migration challenges for
the multi-architecture coexistence networks.
Recently, the open radio access network (O-RAN) alliance was formed to evolve
RANs with its core principles being intelligence and openness. It aims to drive the mobile
industry towards an ecosystem of innovative, multi-vendor, interoperable, and autonomous
RAN, with reduced cost, improved performance and greater agility. However,
this is not standardized yet and still lacks interoperability. On the other hand, the cell-less
radio access network (RAN) was introduced to boost the system performance required for
the new services. However, the concept of cell-less RAN is still under consideration from
the deployment point of view with the legacy cellular networks. The virtualization, centralization and cooperative communication which enables the cell-less RAN can further
benefit from O-RAN based architecture.
This thesis addresses the research challenges facing 5G and beyond networks towards
6G networks in regard to new architectures, spectral efficiency, latency, and energy efficiency.
Different system models are stated according to the problem and several solution
schemes are proposed and developed to overcome these challenges. This thesis
contributes as follows. Firstly, the cell-less technology is proposed to be implemented
through an Open RAN architecture, which could be supervised with the near real-time
RAN intelligent controller (near-RT-RIC). The cooperation is enabled for intelligent and
smart resource allocation for the entire RAN. Secondly, an efficient radio resource optimization
mechanism is proposed for the cell-less architecture to improve the system
capacity of the future 6G networks. Thirdly, an optimized and novel resource scheduling
scheme is presented that reduces latency for the URLLC users in an efficient resource
utilization manner to support scenarios with high user density. At the same time, this radio
resource management (RRM) scheme, while minimizing the latency, also overcomes
another important challenge of eMBB users, namely the throughput of those who coexist
in such a highly loaded scenario with URLLC users. Fourthly, a novel energy-efficiency
enhancement scheme, i.e., (3 × E) is designed to increase the transmission rate per energy
unit, with stable performance within the cell-less RAN architecture. Our proposed
(3 × E) scheme activates two-step sleep modes (i.e., certain phase and conditional phase)
through the intelligent interference management for temporarily switching access points
(APs) to sleep, optimizing the network energy efficiency (EE) in highly loaded scenarios,
as well as in scenarios with lower load. Finally, a multi-architecture coexistence (MACO)
network model is proposed to enable inter-connection of different architectures through
coexistence and cooperation logical switches in order to enable smooth deployment of a
cell-less architecture within the legacy networks.
The research presented in this thesis therefore contributes new knowledge in the cellless
RAN architecture domain of the future generation wireless networks and makes important
contributions to this field by investigating different system models and proposing
solutions to significant issues.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidenta: Matilde Pilar Sánchez Fernández.- Secretario: Alberto Álvarez Polegre.- Vocal: José Francisco Monserrat del Rí
Radio Resource Management Scheme for URLLC and EMBB coexistence in a Cell-Less Radio Access network
We address the latency challenges in a high-density and high-load scenario for an ultra-reliable and low-latency communication (URLLC) network which may coexist with enhanced mobile broadband (eMBB) services in the evolving wireless communication networks. We propose a new radio resource management (RRM) scheme consisting of a combination of time domain (TD) and frequency domain (FD) schedulers specific for URLLC and eMBB users. We also develop a user ranking algorithm from a radio unit (RU) perspective, which is employed by the TD scheduler to increase the efficiency of scheduling in terms of resource consumption in large-scale networks. Therefore, the optimized and novel resource scheduling scheme reduces latency for the URLLC users (requesting a URLLC service) in an efficient resource utilization manner to support scenarios with high user density. At the same time, this RRM scheme, while minimizing the latency, it also overcomes another important challenge of eMBB users (requesting an eMBB service), namely the throughput of those who coexist in such highly loaded scenario with URLLC users. The effectiveness of our proposed scheme including time and frequency domain (TD and FD) schedulers is analyzed. Simulation results show that the proposed scheme improves the latency of URLLC users and throughput of the eMBB users compared to the baseline scheme. The proposed scheme has a 29% latency improvement for URLLC and 90% signal-to-interference-plus-noise ratio (SINR) improvement for eMBB users as compared with conventional scheduling policies.This work was supported by the European Union H2020 Research and Innovation Programme funded by the Marie Skłodowska-Curie ITN TeamUp5G Project under Grant 813391
Massive MIMO for Internet of Things (IoT) Connectivity
Massive MIMO is considered to be one of the key technologies in the emerging
5G systems, but also a concept applicable to other wireless systems. Exploiting
the large number of degrees of freedom (DoFs) of massive MIMO essential for
achieving high spectral efficiency, high data rates and extreme spatial
multiplexing of densely distributed users. On the one hand, the benefits of
applying massive MIMO for broadband communication are well known and there has
been a large body of research on designing communication schemes to support
high rates. On the other hand, using massive MIMO for Internet-of-Things (IoT)
is still a developing topic, as IoT connectivity has requirements and
constraints that are significantly different from the broadband connections. In
this paper we investigate the applicability of massive MIMO to IoT
connectivity. Specifically, we treat the two generic types of IoT connections
envisioned in 5G: massive machine-type communication (mMTC) and ultra-reliable
low-latency communication (URLLC). This paper fills this important gap by
identifying the opportunities and challenges in exploiting massive MIMO for IoT
connectivity. We provide insights into the trade-offs that emerge when massive
MIMO is applied to mMTC or URLLC and present a number of suitable communication
schemes. The discussion continues to the questions of network slicing of the
wireless resources and the use of massive MIMO to simultaneously support IoT
connections with very heterogeneous requirements. The main conclusion is that
massive MIMO can bring benefits to the scenarios with IoT connectivity, but it
requires tight integration of the physical-layer techniques with the protocol
design.Comment: Submitted for publicatio
Guaranteed Dynamic Scheduling of Ultra-Reliable Low-Latency Traffic via Conformal Prediction
The dynamic scheduling of ultra-reliable and low-latency traffic (URLLC) in
the uplink can significantly enhance the efficiency of coexisting services,
such as enhanced mobile broadband (eMBB) devices, by only allocating resources
when necessary. The main challenge is posed by the uncertainty in the process
of URLLC packet generation, which mandates the use of predictors for URLLC
traffic in the coming frames. In practice, such prediction may overestimate or
underestimate the amount of URLLC data to be generated, yielding either an
excessive or an insufficient amount of resources to be pre-emptively allocated
for URLLC packets. In this paper, we introduce a novel scheduler for URLLC
packets that provides formal guarantees on reliability and latency irrespective
of the quality of the URLLC traffic predictor. The proposed method leverages
recent advances in online conformal prediction (CP), and follows the principle
of dynamically adjusting the amount of allocated resources so as to meet
reliability and latency requirements set by the designer
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