Special Issue "Optical Communications and Networking Solutions for the Support of C-RAN in 5G Environments"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Optics and Lasers".

Deadline for manuscript submissions: closed (15 October 2018).

Special Issue Editors

Prof. Dr. Vincenzo Eramo
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Guest Editor
Department of Engineering of Information, Electronics and Telecommunications, University of Rome “La Sapienza”, Rome 00184, Italy
Interests: telecommunication networks; all-optical networks; internet switching architectures; network function virtualization
Special Issues and Collections in MDPI journals
Prof. Dr. Marco Listanti
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Guest Editor
Department of Engineering of Information, Electronics and Telecommunications, University of Rome “La Sapienza”, Rome 00184, Italy
Interests: Telecommunication networks; Internet; Networking; Network protocols
Special Issues and Collections in MDPI journals
Dr. Francesco Giacinto Lavacca
Website
Guest Editor
Department of Engineering of Information, Electronics and Telecommunications, University of Rome “La Sapienza”, Rome 00184, Italy
Interests: optical networking; network function virtualization
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

The widespread availability of mobile devices, such as tablets and smartphones, has led to a quick increase in mobile data traffic over the last few years. Furthermore, based on different studies and predictions, it is possible to conclude that, beyond 2020, mobile networks will be asked to support more than 1000 times today's traffic volumes. Demands for higher mobile networks capacity, increased data rates and for a larger number of simultaneously-connected devices are just few of the requirements posed in the evolution of radio access networks. Other fundamental factors are energy saving and cost of systems, latency, spectrum availability and spectral efficiency. Naturally, one of the solutions to deal with the very high capacity and coverage demand is the strong radio site densification (e.g. through small, pico, femto cells), that could be also obtained by different deployment architectures. Cloud Radio Access Network (C-RAN) or centralized RAN can be seen as a promising solution to deal the 5G requirements. Traditional C-RANs are organized as a three-element network: a distributed unit (DU), a central unit (CU) and a fronthaul network interconnecting CUs and DUs. The CU provides baseband signal processing functions and the DU provides the radio frequency (RF) signal transmission and reception functions. The C-RAN architecture enables Base Stations to be deployed flexibly and cost-effectively, and is capable of performance enhancement through the use of coordinated multi-point transmission and reception (CoMP). The in-phase and quadrature (IQ) samples of the baseband signals are transmitted in the fronthaul network across a common public radio interface (CPRI).

We invite investigators to submit original research articles in which solutions for the bandwidth saving in fronthaul networks are proposed and evaluated especially for the support of 5G traffic and system requirements. Potential topics include, but are not limited to:

  • Compression techniques for the reduction in bit-rate of the CPRI flows;
  • Functional split between DU and CU;
  • 5G fronthaul network architectures based on technologies such as Ethernet, OTN, etc..;
  • QoS support in the frontaul network;
  • Optical modulation systems for the fronthaul network;
  • Techniques for the virtualization of the functionalities in the CU.

Prof. Dr. Vincenzo Eramo
Prof. Dr. Marco Listanti
Dr. Francesco Giacinto Lavacca
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Radio access network
  • 5G environment
  • CPRI
  • Virtualization
  • Ethernet
  • OTN
  • WDM

Published Papers (8 papers)

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Editorial

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Open AccessEditorial
Optical Communications and Networking Solutions for the Support of C-RAN in a 5G Environment
Appl. Sci. 2019, 9(3), 414; https://doi.org/10.3390/app9030414 - 26 Jan 2019
Cited by 1
Abstract
The widespread availability of mobile devices such as tablets and smartphones has led to fast-increasing mobile data traffic in the last few years [...] Full article

Research

Jump to: Editorial

Open AccessArticle
Impact of the Maximum Number of Switching Reconfigurations on the Cost Saving in Network Function Virtualization Environments with Elastic Optical Interconnection
Appl. Sci. 2019, 9(23), 5167; https://doi.org/10.3390/app9235167 - 28 Nov 2019
Abstract
Network Function Virtualization is based on the virtualization of the network functions and it is a new technology allowing for a more flexible allocation of cloud and bandwidth resources. In order to employ the flexibility of the technology and to adapt its use [...] Read more.
Network Function Virtualization is based on the virtualization of the network functions and it is a new technology allowing for a more flexible allocation of cloud and bandwidth resources. In order to employ the flexibility of the technology and to adapt its use according to the traffic variation, reconfigurations of the cloud and bandwidth resources are needed by means of both migration of the Virtual Machines executing the network functions and reconfiguration of circuits interconnecting the Virtual Machines. The objective of the paper is to study the impact of the maximum number of switch reconfigurations on the cost saving that the Networking Function Virtualization technology allows us to achieve. The problem is studied in the case of a scenario with an elastic optical network interconnecting datacenters in which the Virtual Machines are executed. The problem can be formulated as an Integer Linear Programming one introducing a constraint on the maximum number of switch reconfigurations but due to its computational complexity we propose a low computational complexity heuristic allowing for results close to the optimization ones. The results show how the limitation on the number of possible reconfigurations has to be taken into account to evaluate the effectiveness in terms of cost saving that the Virtual Machine migrations in Network Function Virtualization environment allows us to achieve. Full article
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Open AccessArticle
Optimizing C-RAN Backhaul Topologies: A Resilience-Oriented Approach Using Graph Invariants
Appl. Sci. 2019, 9(1), 136; https://doi.org/10.3390/app9010136 - 02 Jan 2019
Cited by 4
Abstract
At the verge of the launch of the first commercial fifth generation (5G) system, trends in wireless and optical networks are proceeding toward increasingly dense deployments, supporting resilient interconnection for applications that carry higher and higher capacity and tighter latency requirements. These developments [...] Read more.
At the verge of the launch of the first commercial fifth generation (5G) system, trends in wireless and optical networks are proceeding toward increasingly dense deployments, supporting resilient interconnection for applications that carry higher and higher capacity and tighter latency requirements. These developments put increasing pressure on network backhaul and drive the need for a re-examination of traditional backhaul topologies. Challenges of impending networks cannot be tackled by star and ring approaches due to their lack of intrinsic survivability and resilience properties, respectively. In support of this re-examination, we propose a backhaul topology design method that formulates the topology optimization as a graph optimization problem by capturing both the objective and constraints of optimization in graph invariants. Our graph theoretic approach leverages well studied mathematical techniques to provide a more systematic alternative to traditional approaches to backhaul design. Specifically, herein, we optimize over some known graph invariants, such as maximum node degree, topology diameter, average distance, and edge betweenness, as well as over a new invariant called node Wiener impact, to achieve baseline backhaul topologies that match the needs for resilient future wireless and optical networks. Full article
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Open AccessArticle
Analysis of 5G New Radio Uplink Signals on an Analogue-RoF System Based on DSP-Assisted Channel Aggregation
Appl. Sci. 2019, 9(1), 47; https://doi.org/10.3390/app9010047 - 24 Dec 2018
Cited by 2
Abstract
The 3rd Generation Partnership Project (3GPP) is in the process of developing 5th generation (5G) radio access technology, the so-called new radio (NR). The aim is to achieve the performance requirements forIMT-2020 radio interface technology. In this paper, we focus on the analysis [...] Read more.
The 3rd Generation Partnership Project (3GPP) is in the process of developing 5th generation (5G) radio access technology, the so-called new radio (NR). The aim is to achieve the performance requirements forIMT-2020 radio interface technology. In this paper, we focus on the analysis of the transmission of 5G NR uplink physical channels, such as physical uplink shared channel (PUSCH) and physical uplink control channel (PUCCH), dedicated for data and control channels, respectively, as specified in the 3GPP standard, using digital signal processing (DSP)-assisted frequency division multiple access (FDMA) and time division multiple access (TDMA) channel aggregation techniques on an analogue radio-over-fiber (A-RoF) architecture. We verified that there is ~34% spectral efficiency gain and lower error vector magnitude (EVM) achieved using the TDMA technique. Full article
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Open AccessArticle
A Genetic Algorithm for VNF Provisioning in NFV-Enabled Cloud/MEC RAN Architectures
Appl. Sci. 2018, 8(12), 2614; https://doi.org/10.3390/app8122614 - 13 Dec 2018
Cited by 5
Abstract
5G technologies promise to bring new network and service capacities and are expected to introduce significant architectural and service deployment transformations. The Cloud-Radio Access Networks (C-RAN) architecture, enabled by the combination of Software Defined Networking (SDN), Network Function Virtualization (NFV) and Mobile Edge [...] Read more.
5G technologies promise to bring new network and service capacities and are expected to introduce significant architectural and service deployment transformations. The Cloud-Radio Access Networks (C-RAN) architecture, enabled by the combination of Software Defined Networking (SDN), Network Function Virtualization (NFV) and Mobile Edge Computing (MEC) technologies, play a key role in the development of 5G. In this context, this paper addresses the problems of Virtual Network Functions (VNF) provisioning (VNF-placement and service chain allocation) in a 5G network. In order to solve that problem, we propose a genetic algorithm that, considering both computing resources and optical network capacity, minimizes both the service blocking rate and CPU usage. In addition, we present an algorithm extension that adds a learning stage and evaluate the algorithm performance benefits in those scenarios where VNF allocations can be reconfigured. Results reveal and quantify the advantages of reconfiguring the VNF mapping depending on the current demands. Our methods outperform previous proposals in the literature, reducing the service blocking ratio while saving energy by reducing the number of active core CPUs. Full article
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Open AccessArticle
C-RAN Traffic Aggregation on Latency-Controlled Ethernet Links
Appl. Sci. 2018, 8(11), 2279; https://doi.org/10.3390/app8112279 - 18 Nov 2018
Cited by 2
Abstract
Centralized/Cloud Radio Access Networks (C-RAN) are deployed in converged fixed-mobile networks to exploit the flexibility coming from joint application of Network Function Virtualization (NFV) and Software Defined Networking (SDN). In this context, optical links connecting C-RAN nodes, possibly based on the Ethernet standards, [...] Read more.
Centralized/Cloud Radio Access Networks (C-RAN) are deployed in converged fixed-mobile networks to exploit the flexibility coming from joint application of Network Function Virtualization (NFV) and Software Defined Networking (SDN). In this context, optical links connecting C-RAN nodes, possibly based on the Ethernet standards, may carry traffic with different requirements in terms of latency and throughput. This paper considers the problem of traffic aggregation on C-RAN optical Ethernet links with latency control for fronthaul traffic and throughput capability for backhaul traffic. Integrated hybrid network technique is applied to show how time transparency can be enforced for Ethernet encapsulated Common Public Radio Interface (CPRI) traffic while allowing statistical multiplexing of backhaul traffic. Simulation results show the effectiveness of segmentation of backhaul traffic to allow exploitation of the available bandwidth even with high capacity CPRI options. Full article
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Open AccessArticle
Traffic-Estimation-Based Low-Latency XGS-PON Mobile Front-Haul for Small-Cell C-RAN Based on an Adaptive Learning Neural Network
Appl. Sci. 2018, 8(7), 1097; https://doi.org/10.3390/app8071097 - 06 Jul 2018
Cited by 2
Abstract
In this paper, we propose a novel method for low-latency 10-Gigabit-capable symmetric passive optical network (XGS-PON) mobile front-haul for small cell cloud radio access network (C-RAN) based on traffic estimation. In this method, the number of packets that arrive to the optical network [...] Read more.
In this paper, we propose a novel method for low-latency 10-Gigabit-capable symmetric passive optical network (XGS-PON) mobile front-haul for small cell cloud radio access network (C-RAN) based on traffic estimation. In this method, the number of packets that arrive to the optical network unit (ONU) buffer from the remote radio unit (RRU) link is predicted using an adaptive learning neural network function integrated into the dynamic bandwidth allocation (DBA) module at the optical line terminal (OLT). By using this predictive method, we are able to eliminate the additional DBA processing delay and the delay required for reporting ONU buffer occupancy to the OLT. As a result, the latency is as low as required for mobile front-haul in C-RAN architecture. The performance of the new method is evaluated by means of simulation under XGS-PON standard. The simulation results confirmed the capability of the proposed method of achieving the latency requirement for mobile front-haul while outperforming some other XGS-PON standard compliant algorithms that are optimized to support mobile front-haul and backhaul traffic. Full article
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Open AccessFeature PaperArticle
Dimensioning Models of Optical WDM Rings in Xhaul Access Architectures for the Transport of Ethernet/CPRI Traffic
Appl. Sci. 2018, 8(4), 612; https://doi.org/10.3390/app8040612 - 12 Apr 2018
Cited by 12
Abstract
The Centralized Radio Access Network (C-RAN) provides a valid solution to overcome the problem of traditional RAN in scaling up to the needed processing resource and quality expected in 5G. The Common Public Rate Interface has been defined to transport traffic flows in [...] Read more.
The Centralized Radio Access Network (C-RAN) provides a valid solution to overcome the problem of traditional RAN in scaling up to the needed processing resource and quality expected in 5G. The Common Public Rate Interface has been defined to transport traffic flows in C-RAN and recently some market solutions are available. Its disadvantage is to increase by at least 10 times the needed bandwidth and for this reason its introduction will be gradual and will coexist with traditional RAN solutions in which Ethernet traffic is carried towards the radio base stations. In this paper, we propose an Xhaul optical network architecture based on Optical Transport Network (OTN) and Dense Wavelength Division Multiplexing (DWDM) technologies. The network allows for a dynamic allocation of the bandwidth resources according to the current traffic demand. The network topology is composed of OTN/DWDM rings and the objective of the paper is to evaluate the best configuration (number of rings and number of wavelengths needed) to both to minimize the cost and to provide an implementable solution. We introduce an analytical model for the evaluation of the number of wavelengths needed in each optical ring and provide some results for 5G case studies. We show how, although the single ring configuration provides the least cost solution due to the high statistical multiplexing advantage, it is not implementable because it needs switching apparatus with a too high number of ports. For this reason, more than one ring is needed and its value depends on several parameters as the offered traffic, the number of Radio Remote Units (RRU), the percentage of business sub-area and so on. Finally, the analytical model allows us to evaluate the advantages of the proposed dynamic resource allocation solution with respect to the static one in which the network is provided with a number of wavelengths determined in the scenario in which the radio station works at full load. The bandwidth saving can be in the order of 90% in a 5G traffic scenario. Full article
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