771 research outputs found
CN2F: A Cloud-Native Cellular Network Framework
Upcoming 5G and Beyond 5G (B5G) cellular networks aim to improve the
efficiency and flexibility of mobile networks by incorporating various
technologies, such as Software Defined Networking (SDN), Network Function
Virtualization (NFV), and Network Slicing (NS). In this paper, we share our
findings, accompanied by a comprehensive online codebase, about the best
practice of using different open-source projects in order to realize a flexible
testbed for academia and industrial Research and Development (R&D) activities
on the future generation of cellular networks. In particular, a Cloud-Native
Cellular Network Framework (CN2F) is presented which uses OpenAirInterface's
codebase to generate cellular Virtual Network Functions (VNFs) and deploys
Kubernetes to disperse and manage them among some worker nodes. Moreover, CN2F
leverages ONOS and Mininet to emulate the effect of the IP transport networks
in the fronthaul and backhaul of real cellular networks. In this paper, we also
showcase two use cases of CN2F to demonstrate the importance of Edge Computing
(EC) and the capability of Radio Access Network (RAN) slicing
Split Federated Learning for 6G Enabled-Networks: Requirements, Challenges and Future Directions
Sixth-generation (6G) networks anticipate intelligently supporting a wide
range of smart services and innovative applications. Such a context urges a
heavy usage of Machine Learning (ML) techniques, particularly Deep Learning
(DL), to foster innovation and ease the deployment of intelligent network
functions/operations, which are able to fulfill the various requirements of the
envisioned 6G services. Specifically, collaborative ML/DL consists of deploying
a set of distributed agents that collaboratively train learning models without
sharing their data, thus improving data privacy and reducing the
time/communication overhead. This work provides a comprehensive study on how
collaborative learning can be effectively deployed over 6G wireless networks.
In particular, our study focuses on Split Federated Learning (SFL), a technique
recently emerged promising better performance compared with existing
collaborative learning approaches. We first provide an overview of three
emerging collaborative learning paradigms, including federated learning, split
learning, and split federated learning, as well as of 6G networks along with
their main vision and timeline of key developments. We then highlight the need
for split federated learning towards the upcoming 6G networks in every aspect,
including 6G technologies (e.g., intelligent physical layer, intelligent edge
computing, zero-touch network management, intelligent resource management) and
6G use cases (e.g., smart grid 2.0, Industry 5.0, connected and autonomous
systems). Furthermore, we review existing datasets along with frameworks that
can help in implementing SFL for 6G networks. We finally identify key technical
challenges, open issues, and future research directions related to SFL-enabled
6G networks
Integration of hybrid networks, AI, Ultra Massive-MIMO, THz frequency, and FBMC modulation toward 6g requirements : A Review
The fifth-generation (5G) wireless communications have been deployed in many countries with the following features: wireless networks at 20 Gbps as peak data rate, a latency of 1-ms, reliability of 99.999%, maximum mobility of 500 km/h, a bandwidth of 1-GHz, and a capacity of 106 up to Mbps/m2. Nonetheless, the rapid growth of applications, such as extended/virtual reality (XR/VR), online gaming, telemedicine, cloud computing, smart cities, the Internet of Everything (IoE), and others, demand lower latency, higher data rates, ubiquitous coverage, and better reliability. These higher requirements are the main problems that have challenged 5G while concurrently encouraging researchers and practitioners to introduce viable solutions. In this review paper, the sixth-generation (6G) technology could solve the 5G limitations, achieve higher requirements, and support future applications. The integration of multiple access techniques, terahertz (THz), visible light communications (VLC), ultra-massive multiple-input multiple-output ( μm -MIMO), hybrid networks, cell-free massive MIMO, and artificial intelligence (AI)/machine learning (ML) have been proposed for 6G. The main contributions of this paper are a comprehensive review of the 6G vision, KPIs (key performance indicators), and advanced potential technologies proposed with operation principles. Besides, this paper reviewed multiple access and modulation techniques, concentrating on Filter-Bank Multicarrier (FBMC) as a potential technology for 6G. This paper ends by discussing potential applications with challenges and lessons identified from prior studies to pave the path for future research
Signal Processing and Learning for Next Generation Multiple Access in 6G
Wireless communication systems to date primarily rely on the orthogonality of
resources to facilitate the design and implementation, from user access to data
transmission. Emerging applications and scenarios in the sixth generation (6G)
wireless systems will require massive connectivity and transmission of a deluge
of data, which calls for more flexibility in the design concept that goes
beyond orthogonality. Furthermore, recent advances in signal processing and
learning have attracted considerable attention, as they provide promising
approaches to various complex and previously intractable problems of signal
processing in many fields. This article provides an overview of research
efforts to date in the field of signal processing and learning for
next-generation multiple access, with an emphasis on massive random access and
non-orthogonal multiple access. The promising interplay with new technologies
and the challenges in learning-based NGMA are discussed
Compressive Sensing-Based Grant-Free Massive Access for 6G Massive Communication
The advent of the sixth-generation (6G) of wireless communications has given
rise to the necessity to connect vast quantities of heterogeneous wireless
devices, which requires advanced system capabilities far beyond existing
network architectures. In particular, such massive communication has been
recognized as a prime driver that can empower the 6G vision of future
ubiquitous connectivity, supporting Internet of Human-Machine-Things for which
massive access is critical. This paper surveys the most recent advances toward
massive access in both academic and industry communities, focusing primarily on
the promising compressive sensing-based grant-free massive access paradigm. We
first specify the limitations of existing random access schemes and reveal that
the practical implementation of massive communication relies on a dramatically
different random access paradigm from the current ones mainly designed for
human-centric communications. Then, a compressive sensing-based grant-free
massive access roadmap is presented, where the evolutions from single-antenna
to large-scale antenna array-based base stations, from single-station to
cooperative massive multiple-input multiple-output systems, and from unsourced
to sourced random access scenarios are detailed. Finally, we discuss the key
challenges and open issues to shed light on the potential future research
directions of grant-free massive access.Comment: Accepted by IEEE IoT Journa
Decentralized Ultra-Reliable Low-Latency Communications through Concurrent Cooperative Transmission
Emerging cyber-physical systems demand for communication technologies that enable seamless interactions between humans and physical objects in a shared environment. This thesis proposes decentralized URLLC (dURLLC) as a new communication paradigm that allows the nodes in a wireless multi-hop network (WMN) to disseminate data quickly, reliably and without using a centralized infrastructure. To enable the dURLLC paradigm, this thesis explores the practical feasibility of concurrent cooperative transmission (CCT) with orthogonal frequency-division multiplexing (OFDM). CCT allows for an efficient utilization of the medium by leveraging interference instead of trying to avoid collisions. CCT-based network flooding disseminates data in a WMN through a reception-triggered low-level medium access control (MAC). OFDM provides high data rates by using a large bandwidth, resulting in a short transmission duration for a given amount of data.
This thesis explores CCT-based network flooding with the OFDM-based IEEE 802.11 Non-HT and HT physical layers (PHYs) to enable interactions with commercial devices. An analysis of CCT with the IEEE 802.11 Non-HT PHY investigates the combined effects of the phase offset (PO), the carrier frequency offset (CFO) and the time offset (TO) between concurrent transmitters, as well as the elapsed time. The analytical results of the decodability of a CCT are validated in simulations and in testbed experiments with Wireless Open Access Research Platform (WARP) v3 software-defined radios (SDRs). CCT with coherent interference (CI) is the primary approach of this thesis.
Two prototypes for CCT with CI are presented that feature mechanisms for precise synchronization in time and frequency. One prototype is based on the WARP v3 and its IEEE 802.11 reference design, whereas the other prototype is created through firmware modifications of the Asus RT-AC86U wireless router. Both prototypes are employed in testbed experiments in which two groups of nodes generate successive CCTs in a ping-pong fashion to emulate flooding processes with a very large number of hops. The nodes stay synchronized in experiments with 10 000 successive CCTs for various modulation and coding scheme (MCS) indices and MAC service data unit (MSDU) sizes. The URLLC requirement of delivering a 32-byte MSDU with a reliability of 99.999 % and with a latency of 1 ms is assessed in experiments with 1 000 000 CCTs, while the reliability is approximated by means of the frame reception rate (FRR). An FRR of at least 99.999 % is achieved at PHY data rates of up to 48 Mbit/s under line-of-sight (LOS) conditions and at PHY data rates of up to 12 Mbit/s under non-line-of-sight (NLOS) conditions on a 20 MHz wide channel, while the latency per hop is 48.2 µs and 80.2 µs, respectively. With four multiple input multiple output (MIMO) spatial streams on a 40 MHz wide channel, a LOS receiver achieves an FRR of 99.5 % at a PHY data rate of 324 Mbit/s. For CCT with incoherent interference, this thesis proposes equalization with time-variant zero-forcing (TVZF) and presents a TVZF receiver for the IEEE 802.11 Non-HT PHY, achieving an FRR of up to 92 % for CCTs from three unsyntonized commercial devices. As CCT-based network flooding allows for an implicit time synchronization of all nodes, a reception-triggered low-level MAC and a reservation-based high-level MAC may in combination support various applications and scenarios under the dURLLC paradigm
Optimization of 5G Second Phase Heterogeneous Radio Access Networks with Small Cells
Due to the exponential increase in high data-demanding applications and their services per
coverage area, it is becoming challenging for the existing cellular network to handle the massive
sum of users with their demands. It is conceded to network operators that the current
wireless network may not be capable to shelter future traffic demands. To overcome the challenges
the operators are taking interest in efficiently deploying the heterogeneous network.
Currently, 5G is in the commercialization phase. Network evolution with addition of small
cells will develop the existing wireless network with its enriched capabilities and innovative
features. Presently, the 5G global standardization has introduced the 5G New Radio (NR) under
the 3rd Generation Partnership Project (3GPP). It can support a wide range of frequency
bands (<6 GHz to 100 GHz).
For different trends and verticals, 5G NR encounters, functional splitting and its cost evaluation
are well-thought-out. The aspects of network slicing to the assessment of the business
opportunities and allied standardization endeavours are illustrated. The study explores the
carrier aggregation (Pico cellular) technique for 4G to bring high spectral efficiency with the
support of small cell massification while benefiting from statistical multiplexing gain. One
has been able to obtain values for the goodput considering CA in LTE-Sim (4G), of 40 Mbps
for a cell radius of 500 m and of 29 Mbps for a cell radius of 50 m, which is 3 times higher
than without CA scenario (2.6 GHz plus 3.5 GHz frequency bands).
Heterogeneous networks have been under investigation for many years. Heterogeneous network
can improve users service quality and resource utilization compared to homogeneous
networks. Quality of service can be enhanced by putting the small cells (Femtocells or Picocells)
inside the Microcells or Macrocells coverage area. Deploying indoor Femtocells for 5G
inside the Macro cellular network can reduce the network cost. Some service providers have
started their solutions for indoor users but there are still many challenges to be addressed.
The 5G air-simulator is updated to deploy indoor Femto-cell with proposed assumptions with
uniform distribution. For all the possible combinations of apartments side length and transmitter
power, the maximum number of supported numbers surpassed the number of users
by more than two times compared to papers mentioned in the literature. Within outdoor environments,
this study also proposed small cells optimization by putting the Pico cells within
a Macro cell to obtain low latency and high data rate with the statistical multiplexing gain of
the associated users.
Results are presented 5G NR functional split six and split seven, for three frequency bands
(2.6 GHz, 3.5GHz and 5.62 GHz). Based on the analysis for shorter radius values, the best
is to select the 2.6 GHz to achieve lower PLR and to support a higher number of users, with
better goodput, and higher profit (for cell radius u to 400 m). In 4G, with CA, from the
analysis of the economic trade-off with Picocell, the Enhanced multi-band scheduler EMBS
provide higher revenue, compared to those without CA. It is clearly shown that the profit of
CA is more than 4 times than in the without CA scenario. This means that the slight increase
in the cost of CA gives back more than 4-time profit relatively to the ”without” CA scenario.Devido ao aumento exponencial de aplicações/serviços de elevado débito por unidade de
área, torna-se bastante exigente, para a rede celular existente, lidar com a enormes quantidades
de utilizadores e seus requisitos. É reconhecido que as redes móveis e sem fios atuais
podem não conseguir suportar a procura de tráfego junto dos operadores. Para responder
a estes desafios, os operadores estão-se a interessar pelo desenvolvimento de redes heterogéneas
eficientes. Atualmente, a 5G está na fase de comercialização. A evolução destas
redes concretizar-se-á com a introdução de pequenas células com aptidões melhoradas e
características inovadoras. No presente, os organismos de normalização da 5G globais introduziram
os Novos Rádios (NR) 5G no contexto do 3rd Generation Partnership Project
(3GPP). A 5G pode suportar uma gama alargada de bandas de frequência (<6 a 100 GHz).
Abordam-se as divisões funcionais e avaliam-se os seus custos para as diferentes tendências
e verticais dos NR 5G. Ilustram-se desde os aspetos de particionamento funcional da rede à
avaliação das oportunidades de negócio, aliadas aos esforços de normalização. Exploram-se
as técnicas de agregação de espetro (do inglês, CA) para pico células, em 4G, a disponibilização
de eficiência espetral, com o suporte da massificação de pequenas células, e o ganho
de multiplexagem estatística associado. Obtiveram-se valores do débito binário útil, considerando
CA no LTE-Sim (4G), de 40 e 29 Mb/s para células de raios 500 e 50 m, respetivamente,
três vezes superiores em relação ao caso sem CA (bandas de 2.6 mais 3.5 GHz).
Nas redes heterogéneas, alvo de investigação há vários anos, a qualidade de serviço e a utilização
de recursos podem ser melhoradas colocando pequenas células (femto- ou pico-células)
dentro da área de cobertura de micro- ou macro-células). O desenvolvimento de pequenas
células 5G dentro da rede com macro-células pode reduzir os custos da rede. Alguns prestadores
de serviços iniciaram as suas soluções para ambientes de interior, mas ainda existem
muitos desafios a ser ultrapassados. Atualizou-se o 5G air simulator para representar a
implantação de femto-células de interior com os pressupostos propostos e distribuição espacial
uniforme. Para todas as combinações possíveis do comprimento lado do apartamento, o
número máximo de utilizadores suportado ultrapassou o número de utilizadores suportado
(na literatura) em mais de duas vezes. Em ambientes de exterior, propuseram-se pico-células
no interior de macro-células, de forma a obter atraso extremo-a-extremo reduzido e taxa de
transmissão dados elevada, resultante do ganho de multiplexagem estatística associado.
Apresentam-se resultados para as divisões funcionais seis e sete dos NR 5G, para 2.6 GHz,
3.5GHz e 5.62 GHz. Para raios das células curtos, a melhor solução será selecionar a banda
dos 2.6 GHz para alcançar PLR (do inglês, PLR) reduzido e suportar um maior número de
utilizadores, com débito binário útil e lucro mais elevados (para raios das células até 400 m).
Em 4G, com CA, da análise do equilíbrio custos-proveitos com pico-células, o escalonamento
multi-banda EMBS (do inglês, Enhanced Multi-band Scheduler) disponibiliza proveitos superiores
em comparação com o caso sem CA. Mostra-se claramente que lucro com CA é mais
de quatro vezes superior do que no cenário sem CA, o que significa que um aumento ligeiro
no custo com CA resulta num aumento de 4-vezes no lucro relativamente ao cenário sem CA
NB-IoT via non terrestrial networks
Massive Internet of Things is expected to play a crucial role in Beyond 5G (B5G) wireless communication systems, offering seamless connectivity among heterogeneous devices without human intervention. However, the exponential proliferation of smart devices and IoT networks, relying solely on terrestrial networks, may not fully meet the demanding IoT requirements in terms of bandwidth and connectivity, especially in areas where terrestrial infrastructures are not economically viable.
To unleash the full potential of 5G and B5G networks and enable seamless connectivity everywhere, the 3GPP envisions the integration of Non-Terrestrial Networks (NTNs) into the terrestrial ones starting from Release 17. However, this integration process requires modifications to the 5G standard to ensure reliable communications despite typical satellite channel impairments.
In this framework, this thesis aims at proposing techniques at the Physical and Medium Access Control layers that require minimal adaptations in the current NB-IoT standard via NTN. Thus, firstly the satellite impairments are evaluated and, then, a detailed link budget analysis is provided.
Following, analyses at the link and the system levels are conducted. In the former case, a novel algorithm leveraging time-frequency analysis is proposed to detect orthogonal preambles and estimate the signals’ arrival time. Besides, the effects of collisions on the detection probability and Bit Error Rate are investigated and Non-Orthogonal Multiple Access approaches are proposed in the random access and data phases.
The system analysis evaluates the performance of random access in case of congestion. Various access parameters are tested in different satellite scenarios, and the performance is measured in terms of access probability and time required to complete the procedure. Finally, a heuristic algorithm is proposed to jointly design the access and data phases, determining the number of satellite passages, the Random Access Periodicity, and the number of uplink repetitions that maximize the system's spectral efficiency
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