Resilience in Smart City ICT Infrastructure
David Perez Abreu, Edmundo Monteiro, Marilia Curado
Department of Informatics Engineering, University of Coimbra,
Polo II, Pinhal de Marrocos, 3030-290, Coimbra - Portugal
Email: {dabreu, edmundo, marilia}@dei.uc.pt
Abstract—Today companies and governments are using Information and Communication Technologies (ICT) as tools to deploy
their services and make them accessible to citizens, leading to the
smart city paradigm. The Internet of Things (IoT) is enabling
smart cities by providing sensors, actuators, and in general
embedded communication devices to collect data that is processed
by applications and services using an ICT infrastructure.
Given the importance of the communication and information
services in today activities, in this research we present a survey
of efforts made to guarantee the flexibility, reliability, and
robustness of the services and ICT infrastructure in smart cities
and urban environments.
I. I NTRODUCTION
The huge growth of Information and Communication Technologies (ICT) infrastructure and also of mobile computing
over the last years, has been the major actor in the evolution
of cities to smart cities. Today it is possible for citizens to
use their smart devices and their associated software to stay
in communication between them using different technologies,
such as 3G ,4G, and WiFi, also to access the services available
in the cities using the cloud paradigm. Besides of these
types of communication, another type has emerged in the
environment of smart cities, the Machine-to-Machine (M2M)
communication. In this kind of communication often the endpoints are special devices, like sensors and actuators, that need
to exchange data to coordinate their operations. Specifically,
this type of communication is defined as Internet of Things
(IoT), which is not more than the interconnection of embedded
computing devices (sensors, surveillance cameras, smart TVs)
using the Internet infrastructure.
The convergence between devices and services in smart
cities is only possible with a good end-to-end network quality,
and with a cloud computing infrastructure capable to deliver
its services even in the worst scenarios. Nowadays, more
and more services have been deployed near to the citizens
to enhance their quality of live, for example, urban traffic
advisers, emergency health assistant, and evacuation routes in
case of natural disasters. These conveniences have made easier
day-to-day activities, making essential the access to these
services everytime and everywhere; for example, consider the
benefits for the citizens of a well organized urban traffic using
cameras and others sensors. In this scenario, citizens could
be more productive, since they will spend less time in traffic
jams, and more time doing work or personal activities.
The increase of dependency between citizens and services,
and the sophistication of these services in smart cities, have
made these environments more attractive to cyber-criminals
and more vulnerable in emergency situations. For these reasons the resilience of ICT infrastructures and services in smart
cities has to be taken into consideration to guarantee the user
expectation and also the possibility to increase the safety of
the citizen in hostile situations.
Given the importance of keeping alive the services deployed
in a smart city, and the necessity to include resilience in these
environments, in this research we present a survey of resilience
requirements, relevance solutions, and research directions in
smart cities ICT infrastructure.
This paper is organized as follows, Section II shows the
concept of resilience, first in a general way to advance to the
different types of resilience, and finishing with an approach
of resilience in ICT. Section III presents two scenarios where
resilience is important, the first one is related with services
in a smart city, while the second one is centered in urban
traffic. This section finishes with a list of possible infrastructure requirements for both environment scenarios. Section IV
displays a set of works related with the cases of study. In
Section V some open research issues are discussed. Finally,
Section VI concludes the paper.
II. R ESILIENCE C ONCEPTS
The term resilience has been included in different scientific
fields as a possible solution to manage unexpected behaviors
and challenging circumstances. According with Sterbenz et.
al. [?] the concept of resilience has came out recently in the
scientific field, and also the amount of articles that are related
with it has increased. Given the diversity of scientific fields
where the term resilience could appear, in the remainder of this
section a discussion about it is presented, making a special
emphasis in how resilience is used in the Information and
Communication Technology field.
The term resilience is used to indicate any system’s response
to alterations from inside or outside itself, according to Smith
et. al. [?]. The use of this term in many different disciplines
and fields of applications has led to multiple and sometimes
puzzling definitions. However, it is possible to mention that
independently of the field of study the fundamental idea
beyond resilience is to deal with the challenges or risks that
a system could not avoid. It involves the persistence over the
time even if is necessary to manage unpredictable behaviors
and/or environments, as Norris et. al. suggested [?]. In general,
resilience is an attribute often related to robustness, and
survivability from one side, and sustainability from other side.
This diversification of concepts was recompiled in the work
of Koslowski and Longstaff [?], where the authors proposed a
resilience classification that defines the term according with
the main expectations of a group of scientific fields. This
classification is presented below.
•
•
•
•
Resilience Type I - The capacity to reborn and recover.
Here resilience is described as a measure of flexibility in
case of disruption and the rapidity of the recovery to a desired state. According with this, resilience can be seen as
a system property or measure of stability. Usually fields
that are related with engineering and system designing
use this perspective of resilience.
Resilience Type II - The capability to maintain a desirable state. This type of resilience applies to systems
or disciplines with low complexity that want to define a
way to rollback to a previously agreed state in case of a
failure. The key of resilience Type II is to maintain the
system identity and its functions with the ability to stand
up to and recover within some parameters. This type of
resilience is commonly used in business, psychology and
social fields.
Resilience Type III - The capacity of the systems to withstand stress. Some disciplines are interested in building
solutions that work in pressure conditions, that need to
know all the time the distance between the actual and
the desired state of the system. This type of disciplines
consider resilience as a measure indicator of the distance
separating the current and the expected state. This type of
resilience is focused in defining a persistence threshold
that allows to determine the level of robustness of the
system. Environments that need to manage the transition
probability between the possible states are inside this
classification.
Resilience Type IV - The capability to adapt and thrive.
In social systems resilience is often conceptualized as a
skill that an individual or group can bring to a disturbance
that will allow it to reach a level of functionality that has
been determined to be correct. In this classification is
known the existence of multiple possible states, but also
explicitly call for a successful adaption before or after a
disturbance occurs.
Given that this work is related with computer science
and more specifically with Information and Communication
Technology, Section II-A presents how resilience is applied to
ICT environments.
A. Resilience in ICT
According to Koslowski and Longstaff [?], in computer
science resilience could be defined as an ”intrinsic system
attribute that is arising in every domain of system and software
development”. Despite this concept applies to all areas in
computer science, as specified by Sterbenz et al. [?], resilience
in ICT is the capacity of the network to give and maintain an
acceptable level of service when faults and difficulties occur
during its operation. This last concept classifies resilience in
networking as a Type I resilience according to Section II.
There are different disciplines that serve as the basis of
network resilience. Since these disciplines have developed
independently, there is no established self-consistent schema
and terminology. In the research of Sterbenz et al. [?], authors
propose an interoperability scheme between the disciplines
involved in resilience that is shown in Fig.1. At the highest
level, they divide the disciplines into two categories Challenge
Tolerance and Trustworthiness. On the left side are Challenge
Tolerance disciplines that deal with the design and engineering
of systems that continue to provide service in the face of
challenges. On the right side are Trustworthiness disciplines
that describe measurable properties of resilient systems. The
relationship between these two is Robustness, which formally
is the performance of a control system when perturbed, or in
our context, the trustworthiness of a system when challenged.
Fig. 1: Resilience Disciplines (source [?])
The first main subset of resilience disciplines tackle the
problem of how to design systems that support the challenges
that obstruct the expected service delivery. These challenges
can be subdivided into (1) component and system failures
for which fault tolerance and Survivability are concerned,
(2) disruptions of communication paths for which Disruption
Tolerance is concerned, and (3) challenges due to the injection of traffic into the network, for which Traffic Tolerance
is concerned. The second subset of disciplines are related
with Trustworthiness, that Avizienis et. al. [?] defined as the
assurance that a system will performance as expected, which
must be determined by measurable properties. In particular
these disciplines measure how the network deliver its services,
using concepts of (1) Dependability, (2) Security, and (3)
Performability.
Another concept that could be found in ICT environments
with resilience properties is known as self-healing networks.
Kephart and Chess [?] defined that a system is self-healing
when it has the capability to discover, diagnose, and react
to disruptions. Following this approach, a self-healing network must be capable to discover, diagnose, and react to
internal and external challenges, and that means that is a
network with a high level of resilience. The main idea of
adding self-healing features to a network is to maximize
the availability, survivability, maintainability, and reliability;
features that are essential nowadays because many services
use communications networks as mentioned Nunes et. al.
[?], when authors comment that communication networks and
specially Internet is considered today as part of our society’s
critical infrastructures.
The concept of resilience has been discussed in this section
and now the importance of this notion is clear in ICT field,
specifically in the infrastructure that supports the deployment
and access to services required for users. In the following
sections of this paper we discuss the importance of ICT
infrastructure resilience in smart city scenarios, that is why
for us resilience is the ability of a system or infrastructure
to provide and maintain an acceptable level of service when
internal or external challenges appear in its operation.
III. S MART C ITIES AND U RBAN T RAFFIC
Today half of the worlds population is living in urban
areas (according to Larios [?]), and cities are expanding
their infrastructures and services to be up to date. In the
past decades the European Union (EU) has developed many
projects with the intention of allowing a smooth transition of
their cities to the new paradigm of smart cities. The term smart
city, as defined by Giffinger [?], is presented to discuss the use
of modern technologies in everyday urban life. This not only
includes ICT, but also incorporates other aspects as modern
transport technologies and its logistic. An important logistic
related with transport is the urban traffic, that is defined by
the European Conference of Ministers of Transport [?] as a
”physical phenomenon related to the manner in which vehicles
impede each others’ progression as demand for limited road
space approaches full capacity”.
The European Union has improved its urban traffic policies,
and therefore the amount of fatalities by population has
decreased; however, as shown in Fig. 2, it is possible to
decrease even more the number of fatalities in some countries
(e.g. Portugal) where the average number of victims is above
the EU average. In order to achieve this goal it is necessary to
guarantee the availability of all services, particularly the ICT
services, provided in an smart city, and it is here where the
concept of resilience could be helpful. Moreover, in urban
emergencies provoked by conventional accidents (e.g. carcrash accidents) or natural disasters, a good infrastructure
with resilience properties will increase the probability to have
success in the rescue activities. In the next subsection we
present two urban scenarios that could be improved using
resilience; after that we will identify the infrastructure requirements where resilience techniques could be useful.
A. Scenario Description
Many cities of the EU are trying to evolve to the paradigm
of smart city as we previously mentioned, and in this migration
process ICTs have the important role to provide the infrastructure to deploy a huge amount of devices and services related
with health care, government, news, traffic, and others, that
improve the quality of life of the citizens. This infrastructure
is really broad, composed by different types of devices as sensors, actuators, cameras, smartphones, laptops, and computers,
that need to use diverse communication networks (e.g. cellular
networks, satellite connections, Internet) in order to provide
the final user services that frequently are running totally or
partially in datacenters and cloud environments.
The availability of the services in an smart city is very
important taking in consideration two points of view, the first
one is that these services make easier the day-to-day activities
to the citizen, and the second one is that these services are
extremely necessary in emergency situations. Fig. 3 shows
a general urban emergencies scenario, where different actors
(police, firemen, doctors) need to coordinate their activities
(e.g. making decisions) also they have to be communicated
(e.g. using cellular networks, Internet) to deal with the different situations that could occur. Same situation applies to
IoT where embedded devices, as sensors and actuators, need
to collect and send data to datacenters where they will be
processed by applications.
Resilience surely is required in the scenario described
before, but in a general way ICT resilience could help in
smart cities, in order to guarantee the proper function of the
infrastructure that supports all the necessary services in the
day-to-day activities or in emergency situations.
Fig. 3: Smart City Scenario (source [?])
Fig. 2: Traffic fatalities by population 2010-2013 (source [?])
An specific urban traffic scenario where ICT resilience could
be helpful is related with the traffic. Fig. 4 shows in the
left side some traffic issues related with proximity and in the
right side some examples associated with vision limitation. In
both cases, in smart cities, RoadSide Units (RSU) assist the
drivers via different services. Imaging these two situations,
(1) something is wrong in the road and it is necessary to
activate the breaks suddenly (left side of the Fig. 4), or (2)
the visibility of the driver in a corner is limited (right side
of the Fig. 4); in these two scenarios an RSU, like a camera,
could be helpful if the data is sent using a specific service and
is processed by the vehicles nearby to decide the actions to
take and avoid a possible accident. However, these situations
are possible only if the services are available all the time, and
to do that it is necessary to incorporate resilience features to
the ICT infrastructure.
Fig. 4: Urban Traffic Scenario (source [?])
B. Infrastructure Requirements
In highly dynamic environments, like the scenarios presented in Sub-Section III-A, where everything is a service and
service is everything, a good resilience on the ICT infrastructure level that guaranties the availability of the services, could
be the difference between a normal function or chaos. Below,
we explain the ICT infrastructure requirements that need to
be present in scenarios as the one described above in order to
maintain an acceptable level of ICT services.
• High Availability. The ICTs infrastructures must be available all the time (24/7) to provide the necessary resources
for the services that users need. To provided a good level
of availability it is mandatory to take into consideration
all the disciplines mentioned in Sub-Section II-A.
• Scalability. In smart cities and IoT environments, the
amount of devices and services is huge, and every day
more and more devices and services are developed, thus
the ICTs infrastructures need to have the capacity to
provide the requirements of the new devices and services
without decreasing the performance of the currently deployed devices and services.
• Flexibility. In complex scenarios, the amount of devices
involved in the ICT infrastructure is considerable, and in
these cases an infrastructure with capacities of autoconfiguration will improve the elasticity and management of
the services.
• Self-Healing. The capacity to deal with external and
internal faults in order to keep the level agreement of
the services is a desirable requirement for any ICT
infrastructure.
• End-to-End Communication. Many times the services that
users utilize are integrated by small devices and services
deployed everywhere, thus, a good ICT infrastructure
needs to guarantee the end-to-end communication, not
only between users but also inter devices and inter
services.
Good Performance. Services related with emergencies or
user experience need some commitment, in these cases
low-latency in the network or sometimes an specific level
of Quality of Service (QoS) is required.
• Heterogeneity. In smart cities the diversity of devices is
unimaginable, thus the ICT infrastructure has to deal with
this heterogeneity, in order to allow a good interaction
between them.
• Mobility. The capacity to offer users, devices, and services freedom of movement is a mandatory requirement
in all the ICT environments today.
• Security. The trust of the user in the services and also
in the communication technologies used in smart cities,
is a key requirement. An ICT infrastructure needs to be
capable to provide reliability, and confidentiality to users.
The importance of resilience in smart cities, IoT, and urban
traffic is enormous, given that it enhances the quality of the
services in these environments. In this section we presented
some specific scenarios where the concept of ICT resilience
is fundamental, and this discussion allowed us to identify the
basic resilience requirements that must be present in the smart
city ICT infrastructure.
•
IV. R ELATED W ORKS
Much research has been done in the field of smart cities
and urban traffic. In this section we present some of these
researches, specially those works that involve ICT infrastructures with the resilience requirements that were presented in
Sub-Section III-B.
A. Smart Cities and Urban Traffic
The research developed by Khan and Kiani [?] present a
cloud computing architecture with context-aware components
as an infrastructure for data storage and processing to support
all the smart city applications. In this solution, authors give
much importance to the high availability of the components
in the proposed architecture. In the same kind of ideas,
Hernandez and Larios [?] present a list of characteristics of
some services that need to be present in an smart city, and with
this information authors propose a strategy for service based
in a cloud infrastructure for the city of Guadalajara, Mexico.
In the infrastructure authors incorporated some resilience
requirements, as diversity and fault tolerance, because this city
often is affected by flooding and hurricanes.
A network architecture based on virtualized networks for
smart cities using Software Defined Networking (SDN) is
presented by Guerrero et. al. [?], in this work authors suggest
to use the approach of SDN to manage the heterogeneity of
network technologies, as well as the mobility and flexibility
requirements present in smart cities.
Another trending in smart cities is crowdsourcing. Chatzimilioudis et. al. [?] defined crowdsourcing as ”a distributed
problem-solving model in which a crowd of undefined size is
engaged to solve a complex problem through an open call”
(see Fig. 5). In this research authors present three applications
that optimized location-based search with smartphone following the paradigm of crowdsourcing; these applications are running in the smartphones, doing computations and generating
data. This data usually was generated from sensors, and will
be used as input in the crowdsourcing when the smartphone
is participating in it. An extra important characteristic of
these applications is that tasks (processing and sensing) are
transparent to users, because they usually run in background.
in the WSN architecture, authors consider the use of different
wireless communication technologies as IEEE 802.11p and
IEEE 802.15.4 to improve the flexibility and collect important
data for later analysis. The overall WSN roadside architecture
is shown in Fig. 6.
Fig. 6: WSN Roadside Architecture for Intelligent Transport
Systems (source [?])
Fig. 5: Crowdsourcing with Smartphones (source [?])
Asimakopoulou and Bessis [?] using the approach of crowdsourcing, described an scenario where a whole community in
a smart city contributes in an integrated disaster management,
at the same time each citizen receive personalized warnings,
evacuations routes and other messages according with the
situation. In this research authors pay particular attention to the
requirements of ICT infrastructure, in order to keep services
and communications alive in the scenario described.
Inside smart cities the urban traffic management represents
an important factor. Vehicular networks and more specifically
Vehicular Ad hoc NETworking (VANET) has emerged as an
ICT technology for safer, more efficient, and more comfortable
driving experience. Dietzel et. al. [?] propose a mechanism
to send information in a secure way after grouping the data,
this mechanism uses the technique of aggregation to mitigate
the bandwidth limitation in wireless communications and also
is capable to give responses when a fault occurs in the
network, providing resilience for the services and users. The
VIdeo Reactive Tracking-based UnicaSt protocol (VIRTUS)
developed by Rezende et. al. [?] is an effort to improve the
video streaming capabilities over VANETs using receivingbased solution, that uses vehicles current and future location
for a selection policy of relaying nodes. VIRTUS increases the
resilience of video service in urban traffic scenarios, besides
it fulfills video streaming requirement with a little increase in
the number of transmissions.
Bohli et. al. [?] propose a secure and resilient Wireless
Sensor Network (WSN) roadside architecture for a clever
transport system with supports of accident prevention and
post-accident investigation. In this proposal, vehicle generates
warning messages using On Board Units (OBUs), that are
delivered to nearby vehicles using a georouting approach. Also
B. Resilience in ICT Infrastructures
Several works in ICT resilience have been developed as part
of the objectives of the EU, an example is the project AMBER
[?], which aimed to coordinate the study of resilience measuring and benchmarking in computer systems. This project was
finished in 2010 and before it ended made contributions in
many topics as the state of the art on resilience assessment
methods, and a data repository to analyze and share field
data on computer failures and resilience evaluation experiment
results.
ResumeNet project [?] finished in 2011 and its main contribution was a framework to improve the resilience in Internet.
The general idea of this framework was to propose the defensive measures with the ability of modify them if an unexpected
condition occurred. In the context of ResumeNet, Sterbenz
et. al. [?] presented ResiliNets. ResiliNets is a well defined
resilience framework for network environments that follows
the approach D2 R2 + DR. The first active phase, D2 R2 :
Defend, Detect, Remediate, and Recover, is the inner control
loop and describes a set of activities that are undertaken in
order by a system to rapidly adapt to challenges and attacks
with the purpose of maintaining an acceptable level of service.
The second active phase DR: Diagnose, and Refine, is the
outer loop that enables longer-term evolution of the system in
order to enhance the approaches to the activities of phase one.
A graphical description of this approach is shown in Fig. 7.
Two more projects supported by the EU are DESEREC
[?] and HIDENETS [?]. The main interest of DESEREC is
to improve the dependability by the combination of three
technologies: modeling and simulation, incident detection, and
response. In the other hand, HIDENETS wants to provide
end-to-end mobility-aware resilience solutions addressing both
accidental and malicious faults, where the user perception of
trustworthiness is a key issue.
Fig. 7: ResiliNets Strategy (source [?])
Availability of services and infrastructure in ICT environments has been a trending research topic in recent years. Many
efforts have been done to improve network resilience, Menth
and Martin [?] proposed the use of multi-topology routing
for network adaptability against link and node failures. The
authors in this research describe the multi-topologies by an
n-dimensional vector of different link costs for all links in the
network, these vectors are the input to build the shortest-path
trees from any node to all other destinations. After building
the trees, the link costs are defined in such a way that the
routing topologies complement each other, this is that at least
one valid route remains in a single link or node failure scenario
for each pair of nodes in at least one routing topology. When
a fault occurs, packets are routed using the routing topology
built in the previous step.
Hansen et. al. [?] present Resilient Routing Layers (RRL)
for protected networks against large-scale disasters. RRL organizes the network topology in sub-topologies called routing
layers, by layer there are some nodes or areas that do not carry
transit traffic called safe nodes. These layers are constructed
so that all nodes are present in each layer, and so it exists a
path between all node pairs in each layer. Each node should
be safe in at least one layer to guarantee single node fault
tolerance. With this approach in the worst scenario it is still
possible routing packets into the network.
Another important technology that has demonstrated to have
features to improve resilience in ICT is SDN, and because
of this several researchers have utilized the SDN approach
to incorporate flexibility to network and cloud infrastructures.
Nguyen et. al. [?] affirm that nowadays Internet does not have
the necessary mechanisms to deal with unexpected disasters
such as earthquakes and tsunamis; specially the infrastructure
of the Wide Area Networks (WANs). With this in mind,
authors suggest to use SDN to improve the resilience level of
WANs, and because of this they constructed two evaluations
under a real large scale network topology to confirm the
feasibility of SDN-based resilient network towards fast disaster
recovery. The results showed that SDN could improve the
recovery of the network using an smart architecture.
The importance that companies grant to schemes to keep
their computing and network services running in disaster
recovery scenarios is discussed by Souza et. al [?]. Given
the importance of keeping alive all the service in ICT environments, authors pose a set of good guidelines to design a
data center network infrastructure to support a disaster-resilient
infrastructure as a service cloud. These guidelines describe
design requirements, the time to recover from disasters, and
also permit the identification of important challenges that
could be boosted.
A research that propose to develop the resilience in ICT infrastructures using SDN and replication methods was initiated
by Fonseca et. al. [?]. This research describes a mechanism
that provides an increase of resilience in SDN using a component organization. The authors used the possibility to obtain
regular updates in SDN to develop a new component called
CPRecovery. This component is based on the primary-backup
mechanism of SDN controllers, and with some modifications
allows to increase the resilience against several types of
failures in a centralized controlled network.
Given that nowadays the paradigm of cloud is present
almost everywhere, the importance to guarantee the security
and availability of the services and infrastructure has gained
the attention of many researchers. Nguyen et. al. [?] discuss
how cloud computing with mobility capacities could help the
day-to-day activities of the citizen in smart cities. In this
research authors present some advices to improve the quality
of services, deploy part of the services near of end user in
small clouds. Satyanarayanan et. al. [?] consider the use of
cloudlets in situations in which access to the cloud can not
be assumed, for example, natural disasters or in developing
countries. In these situations, authors suggest using cloudlets
as a proxy for the cloud, making the cloudlet transparent
during normal operations but taking over the essential cloud
functions during failure conditions.
Many efforts have been done to offer resilience in ICT
infrastructure for smart cities, some of them are related with
VANETs or WSNs, and more recent with IoT and SDN. These
researches have opened a niche to try to unify paradigms as
IoT, SDN, and cloud computing to enhance the resilience in
ICT in levels without precedent.
V. O PEN I SSUES AND R ESEARCH O PPORTUNITIES
After finishing the research about resilience and ICT infrastructure in smart cities presented in the past sections,
it is important to recognize the effort made to enhance the
availability and reliability of the services offered in an smart
city, however, there is still room for improvement, specially
taking in consideration the growth of the number of devices in
cities and their communication. Considering this, it is possible
to point out some issues to be addressed in future researches,
these open issues are mentioned below.
•
Real-time detection. In order to improve the robustness of
the services in smart cities it is necessary to have strong
mechanisms to detect faults and attacks, this issue is vital
to take the future actions of healing or configuration in
systems.
•
•
•
•
•
Cloud services near the users. Develop a strategy to bring
the services and data closer to users in smart cities.
The cloud computing paradigm opens a huge gamma of
improvements to citizens, some of these improvements
could be better quality of experience, lower latency, and
lower energy consumption of communication devices.
Smart service. The possibility to orchestrate services in
a general way, moving them near to end users and also
splitting the work between thin services (in the edge of
the cloud) and full services (inside powerful datacenters)
is an interesting approach that could improve the general
performance in smart cities. This specific approach could
be considered as a subset of cloud services near the users
described in the previous item.
Discovery services. The possibility to develop new discovery services that take in consideration the cloud
paradigm to build crowdsourcing to collaborate with
cloud services on the fly, or merely have the possibility to
incorporate specific requirements, like processing power,
to an specific service in the ambit of smart city would
enhance the response time of these services.
Management of services. In smart cities where there is
a big amount of devices (sensors, actuators) connected,
the term IoT has to be taken into consideration. Often
in this case, the control of devices and their services is
distributed. Mechanisms to deal with the management of
services in an environment like this taking in consideration the inherent requirements for smart city is still an
open issue.
Deal with density. In smart cities the paradigm of Internet
of Things represents a strong ally to offer a new kind
of services, such as electronic health, smart homes, and
intelligent traffic control. However, this creates a dense
environment that requires an ICT infrastructure capable of dealing with millions of communication devices,
with mechanism of autoconfiguration and self-healing.
Specific algorithms and applications that provide these
kind of features inside the ICT infrastructure need to be
improved.
There is the possibility to use a combination of these
approaches, finding a harmony among them and trying to
avoid their weak points while highlighting the strong ones.
A good proposal could be to combine the paradigms of SDN
and cloudlet to enhance the availability and flexibility of the
services in smart cities and IoT environments.
VI. C ONCLUSION
In this research we discussed the necessity of including
resilience in smart cities ICT infrastructures and urban traffic
scenarios, given the important role that ICT services and infrastructure have in day-to-day activities. Besides of presenting
a detailed definition of resilience, also some specific infrastructure requirements that must be taken into consideration to
incorporate resilience in smart cities have been exposed in this
research.
Several works were identified related with smart cities and
urban traffic scenarios, most of which were based on the use
of VANETs and WSNs, while new proposals are beginning
to use cloud, cloudlets, and SDN as a possible underlying
infrastructure that could enhance the resilience in smart cities,
urban scenarios, and IoT.
As future work we plan to further investigate mechanisms
and possible solutions that involve cloud, cloudlets, and SDN
to improve the level of resilience in smart cities and the IoT,
and propose some works that contribute with the flexibility
and robustness of the services provided in this kind of environments.
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