Network functions virtualization (NFV) is a new network architecture framework where network function that traditionally used dedicated hardware (middleboxes or network appliances) are now implemented in software that runs on top of general purpose hardware such as high volume server. NFV emerges as an initiative from the industry (network operators, carriers, and manufacturers) in order to increase the deployment flexibility and integration of new network services with increased agility within operator’s networks and to obtain significant reductions in operating expenditures and capital expenditures. NFV promotes virtualizing network functions such as transcoders, firewalls, and load balancers, among others, which were carried out by specialized hardware devices and migrating them to software-based appliances. One of the main challenges for the deployment of NFV is the resource allocation of demanded network services in NFV-based network infrastructures. This challenge has been called the NFV resource allocation (NFV-RA) problem. This paper presents a comprehensive state of the art of NFV-RA by introducing a novel classification of the main approaches that pose solutions to solve it. This paper also presents the research challenges that are still subject of future investigation in the NFV-RA realm.

Resource Allocation in NFV: A Comprehensive Survey

With the advent of cloud computing, many new networking concepts have been introduced to simplify network management and bring innovation through network programmability. The emergence of the software-defined networking (SDN) paradigm is one of these adopted concepts in the cloud model so as to eliminate the network infrastructure maintenance processes and guarantee easy management. In this fashion, SDN offers real-time performance and responds to high availability requirements. However, this new emerging paradigm has been facing many technological hurdles; some of them are inherent, while others are inherited from existing adopted technologies. In this paper, our purpose is to shed light on SDN related issues and give insight into the challenges facing the future of this revolutionary network model, from both protocol and architecture perspectives. Additionally, we aim to present different existing solutions and mitigation techniques that address SDN scalability, elasticity, dependability, reliability, high availability, resiliency, security, and performance concerns. Copyright © 2017 John Wiley & Sons, Ltd.

Software-defined networking (SDN): a survey

Wireless networks are passing through a transition phase for the past few years now and this transition is giving a way towards the convergence of all IP-based networks to form the Next Generation Networks (NGNs). With the proliferation of these networks in daily life, users' needs are also increasing and service operators are offering different services to satisfy their customers for a better grade of service and an elevated quality of experience (QoE). However, a single operator cannot fulfill the huge demands of the users especially, if a user is nomadic. In nomadism, a user traverses number of available networks that might contain cellular or wireless data networks, usually known as heterogeneous wireless networks. These networks offer various services from email to live video streaming depending upon their capacity and nature. During this traversing procedure, a user switches among different networks to satisfy his/her needs in terms of quality of service. This process is commonly known as a vertical handover or handoff (VHO) due to the involvement of heterogeneous wireless networks in it. An extensive work has been carried out in this field in order to fulfill user demands for better QoS and QoE. In this paper, we give a detailed state-of-the-art of these existing vertical handover decision mechanisms that aim at providing ubiquitous connectivity to the mobile users. We have categorized these vertical handover measurement and decision schemes on the basis of their employed techniques and parameters. Also, we present a comprehensive summary of their advantages and drawbacks. This paper gives its readers an overview of the active research initiatives in the area of handover decision making process in heterogeneous wireless networks and identifies the challenges behind the seamless services provisioning during mobility.

Enabling Vertical Handover Decisions in Heterogeneous Wireless Networks: A State-of-the-Art and A Classification

Machine-to-Machine (M2M) communications

Software-defined networking (SDN) features the decoupling of the control plane and data plane, a programmable network and virtualization, which enables network infrastructure sharing and the "softwarization" of the network functions. Recently, many research works have tried to redesign the traditional mobile network using two of these concepts in order to deal with the challenges faced by mobile operators, such as the rapid growth of mobile traffic and new services. In this paper, we first provide an overview of SDN, network virtualization, and network function virtualization, and then describe the current LTE mobile network architecture as well as its challenges and issues. By analyzing and categorizing a wide range of the latest research works on SDN and virtualization in LTE mobile networks, we present a general architecture for SDN and virtualization in mobile networks (called SDVMN) and then propose a hierarchical taxonomy based on the different levels of the carrier network. We also present an in-depth analysis about changes related to protocol operation and architecture when adopting SDN and virtualization in mobile networks. In addition, we list specific use cases and applications that benefit from SDVMN. Last but not least, we discuss the open issues and future research directions of SDVMN.

/pdf/sdn-and-virtualization-based-lte-mobile-network-3wo0c9ct2m.pdf

SDN and Virtualization-Based LTE Mobile Network Architectures: A Comprehensive Survey

The maturity reached by virtualisation technology enabled great innovation for efficient applications and services development and delivery, independent of the underlying hardware equipment, especially with the large deployment of off-the-shelf hardware based cloud infrastructures. In order to take advantage of this technology, the existing network functions have to be developed and adapted to the new paradigm. However, traditional telecom services are still implemented on dedicated hardware resulting in high deployment and maintenance costs compared to the other already cloudified services. ETSI Network Functions Virtualisation (NFV) aims to fill this gap by applying to telecom the virtualisation technologies. This paper introduces a set of three software architectures for efficient virtualisation of IP Multimedia Subsystem (IMS) in different operator environments responding to the high level requirements of the ETSI NFV use case for virtualizing operator core network functions. Additionally, a management architecture for simplifying the deployment and runtime orchestration of such a virtual service on top of a cloud infrastructure is presented. Furthermore, one of the IMS software architectures was implemented based on the Fraunhofer FOKUS Open IMS Core, measured and evaluated on top of an OpenStack cloud.

http://www.mobile-cloud-networking.eu/site/index.php?process=download&id=203&code=af77df7fd695755012110be92ed540420292e05b

Cloudified IP Multimedia Subsystem (IMS) for Network Function Virtualization (NFV)-based architectures

Mobile network operators in Europe mostly have rolled out 3G networks and are now looking into the deployment of the IP Multimedia Subsystem (IMS) which provides an overlay architecture for IP based core networks. The IMS offers a standardized way to develop new and appealing applications and may serve as a blueprint for convergent Next Generation Networks. As with the introduction of any new technology, there comes the need to measure its performance and capabilities.

The Open IMS Core project introduced in this paper offers the core network functionality of an IMS for testing the performance of the central IMS network entities, the IMS Call Session Control Functions. The project's target was to build an implementation based upon open source tools that is fully conformant to existing IMS standards which may be re-used in other IMS related projects. In its setup the Open IMS Core resembles future IMS networks at the needed detail level and allowed to produce first IMS performance results.

Design and implementation of an open IMS core

The IP Multimedia Subsystem (IMS) as defined by the 3GPP emerges as blueprint for a central architecture to provide Next Generation Network (NGN) services. As overlay architecture for IP based access networks, it provides standardized interfaces to services which will merge the advantages of traditional telephony networks with the benefits of Internet services. This paper will evaluate how good the current wireless access network technologies are for usage in combination with IMS services. Based upon a reference implementation of IMS core elements, the Open IMS Core, measurements were carried out on signaling to give an indication as to what networks will be most applicable for usage, particularly for a vehicular environment.

IMS Signaling over Current Wireless Networks: Experiments Using the Open IMS Core

The IP Multimedia Subsystem (IMS) as defined by the 3GPP emerges as blueprint for a central architecture to provide Next Generation Network (NGN) services. As an overlay architecture for IP based access networks, it provides standardized interfaces to services which will merge the advantages of traditional telephony networks with the benefits of Internet services.

The Open IMS Core[1] project of the Fraunhofer Institute FOKUS which is described in this article started in 2006 as an Open Source initiative targeted at all parties interested in the research development of NGN services and IMS testbeds. The Open IMS Core consists of Call Session Control Functions and a Home Subscriber Server and aims to fill the void in the Open Source software landscape with flexible solutions that have proved their conformance and performance in several national and international R&D projects.

This article highlights the challenges in the development of the components and provides insights on major implementation details as well as for their performance. Examples of the usage of the Open IMS Core will illustrate how IMS Open Source software helps not only rapid, but also efficient, flexible and powerful design, development and testing of NGN components and services.

Development of an open source IMS core for emerging IMS testbeds, the academia and beyond

The challenging and ever increasing requirements of future applications demand new concepts for better control and management of network resources. The Third Generation Partnership Project (3GPP) introduced in their latest specifications the Evolved Packet Core (EPC) architecture for transparently unifying the parameters of different technologies, like the UMTS, WLAN, non-3GPP access technologies and a future Evolved Radio Access Network, called Long Term Evolution (LTE), with the use of multiple application platforms such as IP Multimedia Subsystem (IMS) and the Internet. This paper describes a testbed implementation of the Evolved Packet Core named OpenEPC which provides a reference implementation of 3GPP’s EPC developed by the Fraunhofer Institute FOKUS. OpenEPC is a set of software components offering advanced IP mobility schemes, policy-based QoS control, and integration with different application platforms in converging network environments. This initiative, in addition to fostering research and development, enables academic and industry researchers to rapidly realize state-of-the-art NGMN infrastructures and application testbeds.

/pdf/openepc-a-technical-infrastructure-for-early-prototyping-of-4v9y2zg01l.pdf

Dragos Vingarzan

Papers

Cloudified IP Multimedia Subsystem (IMS) for Network Function Virtualization (NFV)-based architectures

Design and implementation of an open IMS core

IMS Signaling over Current Wireless Networks: Experiments Using the Open IMS Core

Development of an open source IMS core for emerging IMS testbeds, the academia and beyond

OpenEPC: A Technical Infrastructure for Early Prototyping of NGMN Testbeds