TRANSACTIONS ON EMERGING TELECOMMUNICATIONS TECHNOLOGIES
Trans. Emerging Tel. Tech. (2016)
Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/ett.3077

SPECIAL ISSUE ARTICLE

The emergence of operator-neutral small cells as a
strong case for cloud computing at the mobile edge
I. Giannoulakis1*, E. Kafetzakis2 , I. Trajkovska3 , P S. Khodashenas4 , I. Chochliouros5 ,
.
C. Costa6 , I. Neokosmidis7 and P Bliznakov8
.
1 National Centre for Scientific Research “Demokritos” Patr. Gregoriou & Neapoleos 15310, Agia Paraskevi, Greece
,
2 ORION Innovations, Ameinokleous 43, 11744, Athens, Greece
3 ICCLab, Zurich University of Applied Sciences, Winterthur, Switzerland
4 i2CAT Foundation, C/Gran Capita, 2, 08034 Barcelona, Spain
5 OTE Group SA, Pelika & Spartis 1, 15122, Amarousion, Greece
6 CREATE-NET, Via alla Cascata, 56/D, 38123 Trento, Italy
7 Incites, 130, Route d’ Arlon, L-8008, Strassen, Luxemburg
8 Virtual Open Systems, Rue Lakanal 17 38000 Grenoble, France
,

ABSTRACT
Small cells have emerged as a useful tool for supporting increased network capacity through network densification, but they
can also be used to support edge cloud computing services. In this paper, we provide a preview of an innovative concept
that tackles the consolidation of multi-tenancy in such type communications infrastructures, as well as the placement of
network intelligence and applications in the network edge. After surveing the challenges and the enabling technologies,
we present the envisaged architecture to manage and control the Cloud-Enabled Small Cell infrastructure. Also, at the
operation level, we explain the potential advantages of adopting the proposed solutions on the long-term evolution access
networks. Copyright © 2016 John Wiley & Sons, Ltd.
*Correspondence
I. Giannoulakis, Institute of Informatics & Telecommunciations, National Centre for Scientific Research "Demokritos", Patr. Gregoriou
& Neapoleos 15310, Agia Paraskevi, Greece.
E-mail: giannoul@iit.demokritos.gr
Received 31 March 2016; Accepted 18 June 2016

1. INTRODUCTION
The fifth generation of mobile networks (5G) demands key
features beyond what the current 4G can offer, such as
significantly higher wireless capacity, reduced energy consumption per service and reliable connectivity with very
low latency [1]. However, to deliver a viable solution meeting all 5G requirements, a substantial change on the mobile
network paradigm is inevitable.
Traditionally, to provide coverage in one point of presence, actual installation of physical infrastructure, for
example, small cell (SC), is needed. Despite the fact that
mounting equipment in one place may not be possible (e.g.
dense areas), such an ownership increases operators capital
expenditure (CAPEX) and significantly hampers business
agility, particularly when considering the high degree of
cell densification needed to deal with the 5G requirements.
Moreover, the static nature of physical ownership makes
it difficult (impossible in some cases) to handle scenarios
Copyright © 2016 John Wiley & Sons, Ltd.

with dynamic capacity requirements. For example, a flash
crowd event at a venue (e.g., stadium and urban area)
cannot be well served without over-provisioning of the
underlying physical infrastructure. It can be easily translated to more operators expenses (CAPEX and operational
expenditure), which in turn increases the service cost for
the end users. To address this issue, the idea of multitenancy has been initiated in 3GPP [2], and it is expected
to play a vital role in 5G networks. In a multi-tenant scenario, a third party owns the underlying infrastructure and
provides access to the actors of the telecom scene like
network operators, service providers, Over-the-top players
and so on. Such a sharing increases service dynamicity and
reduces the overall cost and the energy consumption.
Furthermore, although nowadays, new stakeholders
enter the network value chain at an increasing pace,
network equipment deployed at the edge and access
networks are specialised devices with hard-wired functionalities. Any adaptation to the ever increasing and

I. Giannoulakis et al.

Figure 1. SESAME concept.

heterogonous market requirements means a huge investment to change/deploy hardware. Thanks to the advent of
cloud computing, software defined networking (SDN) and
network function virtualisation (NFV), the idea of having
general-purpose computing and storage assets at the edge
of mobile networks has emerged. It is a substantial change
on the architecture of current mobile access nodes (cloudradio access network (C-RAN) approach), from being
only a wireless head to cloud-enabled device equipped
with, for example, novel processor architectures, graphics
processing units, digital signal processors and/or fieldprogrammable gate arrays. In this line, new industry initiatives have already introduced the concept of mobile-edge
computing [3] and the related key market drivers [4]
implementations.
The resulting solution will allow several operators/
service providers to engage in new sharing models of both
access capacity and edge computing capabilities, that is,
promoting the concept of small cells as a service based on
the conceptual model of network slicing—the logical partitioning of the localised network infrastructure in one point
of presence.
In this paper, we review the implementation of CloudEnabled Small Cells (CESCs), able to support edge cloud
computing in a multi-tenant, multi-service ecosystem. To
this end, the solution proposed by H2020 5GPPP SESAME
project, (e.g. Figure 1), is reviewed from different aspects.
More specific, Section 2 provides a review of 5G communication challenges. High level architecture as well as
multi-tenancy features are explained in Section 3. Enabling
technologies are detailed in Section 4, while Section 5
deals with the possible small cell virtualization and function splits. Section 6 focuses on the orchestrator and
service function chaining (SFC) mechanisms. Finally, the
paper is concluded by Section 7, which provides a technoeconomic discussion on the impact of SESAME solution.

2. CHALLENGES FOR 5G
COMMUNICATIONS
Today, communication networks are essential means for all
areas and sectors of our modern societies and economies
and do constitute critical pillars to assure further evolu-

tion and growth. According to the recent market trends
and to the actual European policy measures, it is assessed
that the communication network and the wider modern services/facilities environment of the year 2020 will be enormously richer and much more complex than that of today.
In fact, within the forthcoming years, it is expected that the
underlying (usually heterogeneous) network infrastructure
will be able of connecting everything according to a multiplicity of application-specific requirements (thus including users, things, processes, computing centres, content,
knowledge, information and goods), in a purely flexible,
mobile and powerful way. The number of smart terminals,
machines and things (with sensors and actuators) attached
to current networks is growing exponentially, and soon,
it will be possible to connect and operate a multiplicity of equipment (including smart home gadgets, vehicles,
drones and even robots); this extends our abilities far
beyond our current experience of tablet and smartphone
connectivity.
Such innovative features necessitate and imply for the
proper establishment and the operation of a relevant novel
infrastructure, able to provide network features and performance characteristics to assure growth. Market actors
(such as network operators and service providers, content providers, manufacturers, SMEs and end-users) are
strongly involved in this kind of evolutionary process; this
is expected to redefine existing value chains and to reform
roles and/or relationships between the players, while creating new opportunities. The simultaneous gradual inclusion of modern features (such as of virtualisation and
of software-based network functionalities) in communications networks supports the expected transitional process
via further strengthening flexibility and reactivity.
The actual European vision towards assessing, understanding and then realising the wide multiplicity of challenges is to take place via a dedicated public–private
partnership (PPP) programme, able to provide solutions,
architectures, technologies and standards for the ubiquitous 5G communication infrastructures of the next decade.
More specifically, according to the related European programme of reference [5], the following high level key performance indicators (KPIs) have been proposed to frame
the research activities until 2020 and are briefly listed
as follows: (i) provision of 1000 times higher wireless
area capacity and of more varied service capabilities, if
compared with those of 2010; (ii) saving up to 90% of
energy per service provided. (The main focus in that direction should be in mobile communication networks, where
the dominating energy consumption comes from the radio
access network.); (iii) reduction of the average service creation time cycle from 90 hours to 90 minutes; (iv) creation
of a sufficiently secure, reliable and dependable Internet
with a zero perceived downtime for services provision; (v)
facilitating future very dense deployments of wireless communication links to connect over 7 trillion wireless devices
serving over 7 billion people, thus realising the option of
connecting everything or everyone at any time at any place;
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I. Giannoulakis et al.

and (vi) enabling advanced user controlled privacy, so that
to guarantee a protection level of the facilities offered.
It is expected that the development of the forthcoming 5G systems will be based on an ecosystem of a tight
cooperation between industry, SMEs and the research community to develop innovative solutions and to guarantee
the acceptance and exploitation of such solutions in global
standards and markets, in order to ensure interoperability,
economies of scale with affordable cost for system deployment and the end users. The new 5G systems will open
new opportunities for efficient services in the business,
administrative and private domain.

3. HIGH LEVEL FRAMEWORK
The key innovations proposed in the SESAME architecture focus on the novel concepts of virtualising small cell
networks by leveraging the paradigms of a multi-operator
(multi-tenancy), enabling framework coupled with an
edge-based, virtualised execution environment. The overall, high-level view of the SESAME system is proposed in
Figure 2.
To that end, the proposed CESC offers computing, storage and radio resources. Through virtualization, the CESC
cluster can be seen as a cloud of resources, which can be
sliced to enable multi-tenancy. Therefore, the CESC cluster becomes a neutral host for mobile small cell network
operators (SCNOs) or virtual SCNO (VSCNO) that want
to share IT and network resources at the edge of the mobile
network. In addition, cloud-based computation resources
are provided through a virtualised execution platform. This
execution platform is used to support the required Virtualized Network Functions (VNFs) that implement the

different features/capabilities of the Small Cells (and eventually of the core network) and the cognitive management
and self-x operations, as well as the computing support for
the mobile edge applications of the end users.
The CESC clustering enables the achievement of a
micro-scale virtualised execution infrastructure in the form
of a distributed data centre, denominated light data centre (light DC), enhancing the virtualisation capabilities and
process power at the network edge. Network services (NSs)
are supported by VNFs hosted in the light DC (constituted by one or more CESC), leveraging on SDN and NFV
functionalities that allow achieving an adequate level of
flexibility and scalability at the cloud infrastructure edge.
More specifically, VNFs are executed as Virtual Machines
(VMs) inside the light DC, which is provided with a hypervisor [based on kernel virtual machine (KVM)] specifically
extended to support carrier grade computing and networking performance.
Over the provided virtualised execution environment
(light DC), it is possible to chain different VNFs to meet
a requested NS by a tenant (i.e. mobile network operator).
Note that, in the context of SESAME, an NS is understood
as a collection of VNFs that jointly supports data transmission between user equipment and operators evolved packet
core (EPC), with the possibility to involve one or several service VNFs in the data path. Therefore, each NS is
deployed as a chain of small cell VNFs and Service VNFs.
Finally, the CESC manager (CESCM) is the central
service management and orchestration (MANO) component in the overall architecture figure. Generally speaking, it integrates all the necessary network management
elements, traditionally suggested in 3GPP, and the novel
recommended functional blocks of NFV MANO [37]. A

Figure 2. SESAME overall architecture.
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I. Giannoulakis et al.

single instance of CESCM is able to operate over several
CESC clusters, each constituting a light DC, through the
use of a dedicated virtual infrastructure managers (VIMs)
per cluster.

4. ENABLING TECHNOLOGIES
SESAME allows new stakeholders to dynamically enter
the network value chain by targeting to the development
and demonstration of an innovative architecture, capable
of providing small cell coverage to multiple operators, as
a service. For this purpose, the logical partitioning of a
long-term evolution (LTE) small cell network to multiple isolated slices as well as their provisioning to several
tenants is envisioned. In our case, the consolidation of
multi-tenancy and network sharing in LTE infrastructures
will be allowed by utilising the multi-operator core network protocol, appropriately adjusted for the purposes of a
small cell network.
In the context of distributed computing on the mobile
network edge, small form factor compute nodes, high cores
density and low power consumption are essential parameters for consideration. Virtualization is the main technique
to assure multi-tenancy and service isolation. Supporting
native virtualization extensions, advanced RISC machinebased SoCs fully satisfy those constraints. On the other
hand, existing VIMs, such as OpenStack and hypervisors such as the Linux KVM are already adopted by the
industry as de facto a standard. The convergence point of
these technologies is the KVM port to the advanced RISC
machine platform.
Likewise, an accelerated network between VNFs is crucial for the near native performance of the NFVI. A virtual
switch (vSwitch) is the key component to ensure interconnection between VNFs and their communication with the
outside world. In fact, virtual switches outperform their
hardware counterparts in some scenarios, such as VM-toVM communication. They are also more flexible when it
comes to extending their functionalities. Indeed, virtual
switches can benefit from different hardware accelerators
available on the host, for example, cryptochips and embedded hardware bridges. The effect is significant host CPU
offloading, allowing to increase VM density.
In the scope of the SESAME project, we implement
an accelerated user-space vSwitch solution based on the
SnabbSwitch[6] network framework and open data plane.
The virtual switch takes advantage of the LuaJIT (Lua
Just-In-Time) compiler dynamic optimisations of the code
during execution. Open data plane, on the other hand,
provides application program interface for accessing a
big number of hardware and software devices such as
NICs and hardware accelerators. The fact that the vSwitch
runs entirely in user space implies there is no performance penalty, otherwise related to context switching. The
vSwitch manages VM-to-VM connections, VM-to-NIC
attachments and commutation between multiple VMs. On
the host side, VMs expose their NIC as a vhost-user socket,
which makes network acceleration possible via zero-copy

memory mechanisms. At a higher level, the vSwitch is also
responsible for ensuring SFC, by responding to OpenFlow
rules, provided by an SDN controller.
Furthermore, the emerging concept of NFV and the
expanding offers of VNF coming from both the cloud and
telco world have brought the idea of offering service composition including the VNFs, as a business use case for the
network operators in SESAME. As described in the project
architecture, the role of the SESAME Orchestrator (in particular the VNF Orchestrator—located within the CESCM)
is to manage the deployment of VNFs and NSs, over the
virtualized infrastructure offered by the VIM. Based on
the service and the VNFs requirements, the VIM role is to
allocate optimally the resources (compute, storage and networking) so as to deploy the service and the VNFs in the
shared physical infrastructure.
Depending on the set of available services and VNFs,
certain types or templates of VMs will need to be created that will facilitate the service creation and chaining,
by allowing their easy and quick configurability and connectivity. These templates are called descriptors and hold
detailed information of hardware resources (i.e. storage,
switching and computation), VNF descriptors, NS templates and NFV instances. The stored information is used
for a wide range of purposes including service graph indication to map incoming edge service requests, identifying
the service deployment plan and its interconnection with
already existing services.

5. SMALL CELL VIRTUALIZATION
AND FUNCTIONAL SPLITS
In LTE, the evolved universal terrestrial radio access network protocol stack present in the eNodeB and user equipment is composed of the Physical (PHY), medium access
control (MAC), radio link control, packet data convergence protocol (PDCP) and radio resource control layers.
In macrocell installations, an eNodeB and its functionalities are split between two main components: the remote
radio head, which amplifies and converts baseband signals to radio frequency signals and the baseband unit
(BBU) located in an equipment closet. Remote radio head
and BBU are connected through an optical fibre to support the Common Public Radio Interface specificationgb
constraints [7].
The emerging trend in small cell virtualization prescribes that BBU functions are virtualised and run in virtual
machines (VMs) migrated in a datacentre made of Commercial off-the-shelf hardware [8]. During their lifecycle,
VNFs can be listed, created, queried, updated, deleted,
rebooted and resised. Not all the baseband processing functions can be efficiently realised in software, and for this
reason, purpose-built hardware can be used still. More in
general, the functional split divides a small cell into two
main blocks: the physical small cell (PSC) and the virtual
small cell (VSC) connected by a fronthaul link. The BBU
is then connected to an operator’s EPC through the backhaul. Depending on the split tight latency constraints for
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I. Giannoulakis et al.

the coordination between VSC and PSC can be hard to
achieve in practice. This is one of the hurdles behind RAN
virtualisation even in the context of the ETSI NFV MANO
framework [9].
The small cell forum recently published its work on
RAN virtualisation [10], in which multiple splitting points
between VSC and PSC are evaluated in terms of latency
and data rate constraints. Through splitting the RAN functionality in two parts, one executed locally and one executed remotely, it is possible to offer a centralisation gain,
while posing challenges on the requirements of the transport network [11]. Also, splitting enables multiple PSCs
being controlled by one VSC, which is a suitable configuration for RAN sharing. Depending on the chosen split, the
link requirements are reduced or increased, and a different
degree of centralisation is achieved. In case the splitting
is performed at the lowest possible PHY level, the latency
requirement can be as low as 250 s. This imposes to
select more challenging and costly technologies such as
optical fibre and E-band radio. When the functional split is
performed at the higher layers, bandwidth and latency constraint are relaxed, while RAN protocol stack dependencies
and requirements become more relevant.
Many factors determine the required latency and data
rate of each functional split, and several options exit for
splitting the RAN [10]. In overall, split may be realised: (i)
at the lower PHY, (ii) at the upper PHY, (iii) at the lower
MAC, (iv) at the upper MAC, (v) at the radio link control,
(vi) at the PDCP and (vii) above the PDCP. As mentioned previously, with a split at the lower MAC or below,
ensuring time critical coordination between VSC and
PSC becomes challenging because scheduling of physical
resource blocks (PRBs) occurs every 1 ms in LTE. Therefore, solutions looking to different separations between
VSC and PSC are of great importance to enable a cloud
environment, which can trade-off costs and complexity but
still leveraging on the advantages of NFV.

6. NETWORK FUNCTION
VIRTUALISATION ORCHESTRATION
AND SERVICE FUNCTION
CHAINING
As mentioned previously, the idea of NFV is to migrate
network functions, such as gateways, proxies, firewalls
and transcoders traditionally deployed over specialised
hardware (i.e. middle-boxes) to software-based applications, virtual network functions (VNF), implemented
and executed over standard high volume servers—in
our case light DC. It provides various benefits, including the following: (i) efficient management of hardware resources, (ii) rapid introduction of new functions and services to the market, (iii) ease of upgrades
and maintenance, (iv) exploitation of existing virtualization and cloud management technologies for VNF
deployment, (v) reduction in CAPEX and operational
expenditure , (vi) enabling a more diverse ecosystem and
(viii) encouraging openness within the ecosystem.
Trans. Emerging Tel. Tech. (2016) © 2016 John Wiley & Sons, Ltd.
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Network function virtualisation orchestrator (NFVO)
in the heart of CESCM is an essential component for
deployment, operation and management/orchestration of
NSs, especially under the specific 5G reliability and performance requirements. Carrying out such a responsibility means solving a multifold problem with challenging
issues. Among them, service chaining and service mapping
over the disturbed (network of connected CESCs) and heterogonous (CESCs are enriched with different hardware
accelerators, and IT resources) light DC environment are
two fundamental issues to address [12].
A service chaining procedure tries to logically combine
different requested NSs, considering their interdependencies. It means that upon receiving an NS request, NFVO
has the freedom to chain the functions in the best possible
way to fit the requirements of VSCNO while optimising
light DC resource utilisation. Such an optimal resource
allocation may include VNF sharing and reuse among one
VSCNO running NSs. After the service chaining, the second challenge is to find the best placement for VNFs,
considering (i) the distributed and heterogeneous nature of
light DC, (ii) requirements of the requested NS and (iii) its
possible impact on the other running NSs. The mentioned
problems can be modelled with NP-hard optimisation
problems, such as location-routing problems [13] and virtual network embedding [14]. Similar to a generic resource
allocation problem, a solution can be either based on a
complex and time-consuming integer liner programming
formulation or less accurate, light computational heuristic
algorithms. Note that depending on the agreed SLAs and
SCNO business plan, different optimisation objectives (e.g.
minimising energy consumption and maximising resource
utilisation.) may be selected.
6.1. Software defined networking and
traffic steering
To enforce a traffic steering and service chaining, several solutions have beefn introduced in the academia and
among the open source community. Beginning from the
open daylight (ODL) proper chaining solution [15] and few
implementations offered form NEC and Ericsson, several
standardisation groups are also involved in such use case
scenarios, one being the OPNFV group [16]. Overall, the
techniques that deal with enforcing traffic steering on a
network level can be divided as: ’packet based‘ and ‘flow
based’. The first requires that the packet carry the ID of
the chain as encoded information in the header field. This
can be performed by a simple packet tagging or rewrite
mechanisms [17] or by introducing new dedicated protocols, such as the NS header [18] introduced by Cisco and
leveraged in the ODL community to support their ODL
SFC integral project. The problem of rewriting and tagging is that it alters the original datagrams, and this can
potentially cause a problem for VNFs that require the
datagrams in their original structure in order to enforce a
decision on the traffic steering, such as the case of virtual
deep packet inspection. A typical burden of introducing

I. Giannoulakis et al.

new headers on the top of the already existing protocols
as we mentioned previously is the undesired overhead and
complexity agglomerated, as in the case of the additional
service header that is introduced in order to enforce endto-end traffic as an overlay connection above the service
chain path.
The benefit of SDN in the case of service chain is that
employing the open flow (OF) principles, the routing can
be steered over a specific networking path by programmatically applying OF based rules (flows) on the SDN
controller or the virtual switch inside the VM hosting the
VNF. This involves traffic steering based on flow programming rules by applying actions on the OF ports of the
switches, in order to gear the desired route of the packets
in the chain. This routing logic in this case is simplified
as opposed to the novel header approach, as it leaves the
packets untacked and agnostic of the existing chain. Furthermore, it avoids undesired overheads on the top of the
IP headers (e.g. OpenStack tenant isolation [19]). To have
a deterministic routing in the chain, a field can be reserved
that follows the sequence of the VNF traffic by keeping
track of the hops in the chain (the number of interfaces)—
the VLAN ID being a suitable candidate as the chain
routing does not follow the Ethernet routing.
To support the discussed implementations, a fully SDN
enabled network is a prerequisite. This would place the
SDN controller as absolute entity in charge of the chain
rules over the entire network graph. Considering traffic steering within the Sesame project inside the 5G-PPP
ecosystem, requires deeper understanding of the NFV concepts and consolidating the requirements to establish the
desired functionality in environment that is not fully prepared to support it. Many efforts have been spent today in
creating virtual EPC building blocks. Some virtualization
has taken place on the radio access front-haul side as well,
for example, OpenAirInterface [20]. SFC concepts based
on SDN can be applied in LTE environment to enforce
packets among a logical network graph and achieve certain
service functionality among the virtualized components
such as Business Support Systems (BSS), Home Subscriber Server (HSS) and RAN [21]. The SDN controller
role has been investigated in the literature along with some
experimental implementations in the industry sector [17,
22–25]. However, bridging the gap between VNF development in a mix cloud and telco ecosystem while offering the
ground for a networking solution and traffic steering based
on SDN is yet a virgin area and main targeted use case in
the SESAME framework.
6.2. Composition and service
function chaining
From a single data centre point of view, the SDN controller
is a component placed on the on the VIM. The service
orchestrator in Sesame will use the northbound interfaces
of the SDN controller application in order to request a composition of NSs. As a primary functionality in the case of
service chain, the Orchestrator schedules the deployment

of the virtual infrastructure, the scheduling of the VNFs
and the NS. The dataplane steering and rule enforcement
policy are kept within the SDN controller application logic
and enforced over the network that hosts the light DC specific NFVs. If the routing involves multiple light DCs, then
the SFC approach may alter depending on the placement of
the controller within the given architecture. This has to be
in accordance with the networking protocols applied in the
scenario, for example, multiprotocol label switching and
Border Gateway Protocol (BGP) as used today for intra
data-centre routing. If SFC is established on GPRS Tunneling Protocol (GTP) tagged traffic that enters the light DC,
then a component/function that removes the GTP header
and extracts and reconstructs the IP packets is required
as intermediator between the ingress/egress ports of thegb
light DC.
In order to compose and chain services/functions, those
need to be described as external dependencies. How this
is to be described is a piece of work currently underway; however, there are two identified candidates: TOSCA
[26] and NFV-GD [27]. With these inputs the NFVO can
carry out the composition through orchestration lifecycle.
Therefore, the composition of a service/function should
also maintain the lifecycle as an individual atomic service/function. A composed service aggregates/combines
services together with orchestration logic. Both atomic and
composed services can be used to create further composed
services. Included in this process can be the complementary process of SFC allowing the chaining of VNFs
and services.

7. TECHNO-ECONOMIC IMPACT
AND CONCLUSIONS
Business perspectives of the proposed solution are also
under investigation. This is of high importance because
new players are expected to enter the market while old
interactions, demand models and pricing schemes that
seem insufficient and thus must be modified. Furthermore,
in a multi-tenancy and highly heterogeneous environment
privacy issues are also significant.
A s a next step, revenue flows should be identified. This
will be also useful for the techno-economic analysis that
will assess the proposed solutions. Towards this direction,
the pricing schemes used in SESAME ecosystem (between
providers as well as between providers and end-users) need
be defined. This is necessary because the softwarization of
network along with the as a service concept urge the transition from old-traditional to new pricing schemes. In this
case, pricing of pure infrastructure, that is, pay a one-time/
up-front fee and receive ongoing connectivity at no incremental cost, is currently of no means. This model should be
modified in order to take into account other aspects such as
memory or CPU (percentage or number of cores) usage by
VMs in a server and/or the time that a function or a service
is used.
Of course, it should be mentioned that in a 5G environment characterised by multi-tenancy, heterogeneity and
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I. Giannoulakis et al.

resource sharing regulatory issues are of high importance
and thus should be investigated. This is further enhanced
by edge caching functionalities giving the ability to collect and process high volumes of date as well as by the
transformation of end users from pure consumers to mixed
content consumers and producers. National regulation in
terms of privacy, data protection and resource sharing was
introduced 20 to 30 years ago, and it is thus outdated. The
growth of a digital ecosystem based on dramatic changes
to technology and global linked in many countries was not
predicted by policy makers or regulators.
Undoubtedtly, the coming wave of 5G innovations will
have a concrete exploitation and socio-economic impact by
2020, through the deployment of the so-called 5G infrastructure. However, 5G will be much more that the next
step beyond 4G, as it is expected to be the core functional system of our modern digital society and economy,
thus generating a truly converged and tremendously dense
communication infrastructure, integrating IT systems (e.g.
processing and storage) with plentiful network resources.
So the challenge for 5G is to become a sort of universal,
highly flexible and ultra-low latency virtualized infrastructure, capable of serving immense numbers of smart things
with significant processing and storage capabilities that
may be increased via relevant cloud-based applications.

ACKNOWLEDGEMENT
The research leading to these results has been supported by
the EU funded H2020 5G-PPP project SESAME under the
grant agreement no 671596.

REFERENCES
1. 5G infrastructure public private partnership (PPP): The
next generation of communication networks will be
Made in EU. Digital agenda for Europe. Technical
Report, European Commission, February 2014.
2. Network sharing; architecture and functional description. Technical Report. 3GPP TS 23.251 v12.0.03. 12
2013.
3. Mobile-edge computing: introductory technical white
paper. Technical Report, ETSI, 2014.
4. Son I, Lee D, Lee JN, Chang YB. Market perception on cloud computing initiatives in organizations: an
extended resource-based view. Information & Management 2014; 51(6): 653–669.
5. European program of reference (Available from: http://ec.
.
europa.eu/research/index.cfm/) [Accessed on 03-2016].
6. Paolino M, Nikolaev N, Fanguede J, Raho D. Snabbswitch user space virtual switch benchmark and performance optimization for nfv. In 2015 IEEE Conference on Network Function Virtualization and Software
Defined Network (NFV-SDN), San Francisco, 2015;
86–92.
Trans. Emerging Tel. Tech. (2016) © 2016 John Wiley & Sons, Ltd.
DOI: 10.1002/ett

7. Specification I. Common public radio interface (cpri);
interface specification v6.0, 2013.
8. Chen C. C-ran: the road towards green radio access
network. In Proceedings of ICST Workshop on C-RAN,
Kunming, China, 2012.
9. ETSI G. 001, network functions virtualization (nfv): use
cases, 2010.
10. Scf 159.06.02, small cell virtualization: functional splits
and use cases, 2016.
11. Maeder A, Lalam M, De Domenico A, Pateromichelakis
E, Wubben D, Bartelt J, Fritzsche R, Rost P. Towards a
flexible functional split for cloud-ran networks. In 2014
European Conference on Networks and Communications
(euCNC), Bologna, 2014; 1–5.
12. Mehraghdam S, Keller M, Karl H. Specifying and placing chains of virtual network functions. In 3rd IEEE
International Conference on Cloud Networking (CloudNet), Luxembourg, 2014; 7–13.
13. Prodhon C, Prins C. A survey of recent research on
location-routing problems. European Journal of Operational Research 2014; 238(1): 1–17.
14. Fischer A, Botero JF, Beck MT, de Meer H, Hesselbach X. Virtual network embedding: a survey. IEEE
Communications Surveys & Tutorials 2013; 15 (4):
1888–1906.
15. OpenDaylight SFC. (Available from: https://github.com/
opendaylight/sfc) [Accessed on 03-2016].
16. OPFNV service function chaining. (Available from:
https://wiki.opnfv.org/display/sfc/
Service+Function+Chaining+Home) [Accessed on
03-2016].
17. Akyildiz IF, Wang P, Lin S. Softair: a software defined
networking architecture for 5G wireless systems. Computer Networks 2015; 85: 1–18.
18. Network service header. (Available from: https://
datatracker.ietf.org/doc/draft-ietf-sfc-nsh/) [Accessed
on 03-2016].
19. Overlay encapsulation in OpenStack DC network.
(Available
from:
https://gist.github.com/djoreilly/
db9c2d32a473c6643551) [Accessed: 03-2016].
20. Nikaein N, Marina MK, Manickam S, Dawson A, Knopp
R, Bonnet C. Openairinterface: a flexible platform for
5G research. SIGCOMM Comput. Commun. Rev. 2014;
44(5): 33–38.
21. Riggio R, Yahiya IGB, Rasheed T, Latre S. Orchestrating virtual network functions with scylla. In Proceedings
of the 2015 ACM Conference on Special Interest Group
on Data Communication (SIGCOMM ’15), London,
United Kingdom, 2015; 375–376.
22. Basta A, Kellerer W, Hoffmann M, Hoffmann K,
Schmidt ED. A virtual sdn-enabled lte epc architecture:
a case study for s-/p-gateways functions. In IEEE SDN

I. Giannoulakis et al.

for Future Networks and Services (SDN4FNS), Trento,
2013; 1–7.
23. Malik A, Qadir J, Ahmad B, Yau K A, Ullah U. Qos in
IEEE 802.11-based wireless networks. A contemporary
review. J. Network and Computer Applications 2015; 55:
24–46.
24. Chourasia S. SDN based evolved packet core architecture for efficient user mobility support. In 1st IEEE Conference on Network Softwarization (NetSoft), London,
2015; 1–5.
25. He J, Song W. Smart routing: fine-grained stall management of video streams in mobile core networks.
Computer Networks 2015; 85: 51–62.

26. OASIS. Topology and orchestration specification for
cloud Applications (TOSCA). (Available from: https://
www.oasis-open.org/committees/tc_home.php?wg_
abbrev=tosca) [Accessed on 03-2016].
27. NFV-MAN. Network functions virtualisation (nfv);
management and orchestration. (Available from: http://
www.etsi.org/deliver/etsi_gs/NFV-MAN/001_099/001/
01.01.01_60/gs_nfv-man001v010101p.pdf) [Accessed
on 03-2016].

Trans. Emerging Tel. Tech. (2016) © 2016 John Wiley & Sons, Ltd.
DOI: 10.1002/ett

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