191 research outputs found
IETF standardization in the field of the Internet of Things (IoT): a survey
Smart embedded objects will become an important part of what is called the Internet of Things. However, the integration of embedded devices into the Internet introduces several challenges, since many of the existing Internet technologies and protocols were not designed for this class of devices. In the past few years, there have been many efforts to enable the extension of Internet technologies to constrained devices. Initially, this resulted in proprietary protocols and architectures. Later, the integration of constrained devices into the Internet was embraced by IETF, moving towards standardized IP-based protocols. In this paper, we will briefly review the history of integrating constrained devices into the Internet, followed by an extensive overview of IETF standardization work in the 6LoWPAN, ROLL and CoRE working groups. This is complemented with a broad overview of related research results that illustrate how this work can be extended or used to tackle other problems and with a discussion on open issues and challenges. As such the aim of this paper is twofold: apart from giving readers solid insights in IETF standardization work on the Internet of Things, it also aims to encourage readers to further explore the world of Internet-connected objects, pointing to future research opportunities
ICNLoWPAN -- Named-Data Networking for Low Power IoT Networks
Information Centric Networking is considered a promising communication
technology for the constrained IoT, but NDN was designed only for standard
network infrastructure.
In this paper, we design and evaluate an NDN convergence layer for low power
lossy links that (1) augments the NDN stateful forwarding with a highly
efficient name eliding, (2) devises stateless compression schemes for standard
NDN use cases, (3) adapts NDN packets to the small MTU size of IEEE 802.15.4,
and (4) generates compatibility with 6LoWPAN so that IPv6 and NDN can coexist
on the same LoWPAN links. Our findings indicate that stateful compression can
reduce the size of NDN data packets by more than 70% in realistic examples. Our
experiments show that for common use cases ICNLoWPAN saves 33% of transmission
resources over NDN, and about 20% over 6LoWPAN
Flexible Multimodal Sub-Gigahertz Communication for Heterogeneous Internet of Things Applications
To realize low-power and low-cost wireless communication over long distances, several wireless standards using sub-1 GHz frequencies have recently been proposed, each with their own strengths and weaknesses in terms of coverage, energy consumption, and throughput. However, none of them are currently flexible enough to satisfy the requirements of future dynamic and heterogeneous IoT applications. To alleviate this, a novel architecture that uses a multimodal device for flexibly employing a variety of heterogeneous sub-1 GHz wireless networks is proposed. It greatly increases network flexibility, resilience, and performance. A device design is presented together with an abstraction layer that combines the different networks into a single flexible virtual network substrate. The article elaborates on the qualitative advantages of this approach. Measurement-based simulation results show advantages in terms of energy efficiency, with significant reduction in energy use compared to a single-technology solution in a representative IoT track and trace scenario. Finally, the article identifies several open research challenges that need to be resolved to fully realize this vision of flexible multimodal communication for demanding IoT applications
An eco-friendly hybrid urban computing network combining community-based wireless LAN access and wireless sensor networking
Computer-enhanced smart environments, distributed environmental monitoring, wireless communication, energy conservation and sustainable technologies, ubiquitous access to Internet-located data and services, user mobility and innovation as a tool for service differentiation are all significant contemporary research subjects and societal developments. This position paper presents the design of a hybrid municipal network infrastructure that, to a lesser or greater degree, incorporates aspects from each of these topics by integrating a community-based Wi-Fi access network with Wireless Sensor Network (WSN) functionality. The former component provides free wireless Internet connectivity by harvesting the Internet subscriptions of city inhabitants. To minimize session interruptions for mobile clients, this subsystem incorporates technology that achieves (near-)seamless handover between Wi-Fi access points. The WSN component on the other hand renders it feasible to sense physical properties and to realize the Internet of Things (IoT) paradigm. This in turn scaffolds the development of value-added end-user applications that are consumable through the community-powered access network. The WSN subsystem invests substantially in ecological considerations by means of a green distributed reasoning framework and sensor middleware that collaboratively aim to minimize the network's global energy consumption. Via the discussion of two illustrative applications that are currently being developed as part of a concrete smart city deployment, we offer a taste of the myriad of innovative digital services in an extensive spectrum of application domains that is unlocked by the proposed platform
Alternate marking-based network telemetry for industrial WSNs
For continuous, persistent and problem-free operation of Industrial Wireless Sensor Networks (IWSN), it is critical to have visibility and awareness into what is happening on the network at any one time. Especially, for the use cases with strong needs for deterministic and real-time network services with latency and reliability guarantees, it is vital to monitor network devices continuously to guarantee their functioning, detect and isolate relevant problems and verify if all system requirements are being met simultaneously. In this context, this article investigates a light-weight telemetry solution for IWSNs, which enables the collection of accurate and continuous flowbased telemetry information, while adding no overhead on the monitored packets. The proposed monitoring solution adopts the recent Alternate Marking Performance Monitoring (AMPM) concept and mainly targets measuring end-to-end and hopby-hop reliability and delay performance in critical application flows. Besides, the technical capabilities and characteristics of the proposed solution are evaluated via a real-life implementation and practical experiments, validating its suitability for IWSNs
IETF standardization in the field of the internet of things (IoT): a survey
Smart embedded objects will become an important part of what is called the Internet of Things. However, the integration of embedded devices into the Internet introduces several challenges, since many of the existing Internet technologies and protocols were not designed for this class of devices. In the past few years, there have been many efforts to enable the extension of Internet technologies to constrained devices. Initially, this resulted in proprietary protocols and architectures. Later, the integration of constrained devices into the Internet was embraced by IETF, moving towards standardized IP-based protocols. In this paper, we will briefly review the history of integrating constrained devices into the Internet, followed by an extensive overview of IETF standardization work in the 6LoWPAN, ROLL and CoRE working groups. This is complemented with a broad overview of related research results that illustrate how this work can be extended or used to tackle other problems and with a discussion on open issues and challenges. As such the aim of this paper is twofold: apart from giving readers solid insights in IETF standardization work on the Internet of Things, it also aims to encourage readers to further explore the world of Internet-connected objects, pointing to future research opportunities.The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no 258885 (SPITFIRE project), from the iMinds ICON projects GreenWeCan and O’CareCloudS, a FWO postdoc grant for Eli De Poorter and a VLIR PhD scholarship to Isam Ishaq
Discovery and Group Communication for Constrained Internet of Things Devices using the Constrained Application Protocol
The ubiquitous Internet is rapidly spreading to new domains. This expansion of
the Internet is comparable in scale to the spread of the Internet in the ’90s. The
resulting Internet is now commonly referred to as the Internet of Things (IoT) and
is expected to connect about 50 billion devices by the year 2020. This means that
in just five years from the time of writing this PhD the number of interconnected
devices will exceed the number of humans by sevenfold. It is further expected that
the majority of these IoT devices will be resource constrained embedded devices
such as sensors and actuators. Sensors collect information about the physical world
and inject this information into the virtual world. Next processing and reasoning
can occur and decisions can be taken to enact upon the physical world by injecting
feedback to actuators.
The integration of embedded devices into the Internet introduces new challenges,
since many of the existing Internet technologies and protocols were not
designed for this class of constrained devices. These devices are typically optimized
for low cost and power consumption and thus have very limited power,
memory, and processing resources and have long sleep periods. The networks
formed by these embedded devices are also constrained and have different characteristics
than those typical in todays Internet. These constrained networks have
high packet loss, low throughput, frequent topology changes and small useful payload
sizes. They are referred to as LLN. Therefore, it is in most cases unfeasible to
run standard Internet protocols on this class of constrained devices and/or LLNs.
New or adapted protocols that take into consideration the capabilities of the constrained
devices and the characteristics of LLNs, are required.
In the past few years, there were many efforts to enable the extension of the
Internet technologies to constrained devices. Initially, most of these efforts were
focusing on the networking layer. However, the expansion of the Internet in the
90s was not due to introducing new or better networking protocols. It was a result
of introducing the World Wide Web (WWW), which made it easy to integrate services
and applications. One of the essential technologies underpinning the WWW
was the Hypertext Transfer Protocol (HTTP). Today, HTTP has become a key
protocol in the realization of scalable web services building around the Representational
State Transfer (REST) paradigm. The REST architectural style enables
the realization of scalable and well-performing services using uniform and simple
interfaces. The availability of an embedded counterpart of HTTP and the REST
architecture could boost the uptake of the IoT.
Therefore, more recently, work started to allow the integration of constrained
devices in the Internet at the service level. The Internet Engineering Task Force
(IETF) Constrained RESTful Environments (CoRE) working group has realized
the REST architecture in a suitable form for the most constrained nodes and networks.
To that end the Constrained Application Protocol (CoAP) was introduced,
a specialized RESTful web transfer protocol for use with constrained networks and
nodes. CoAP realizes a subset of the REST mechanisms offered by HTTP, but is
optimized for Machine-to-Machine (M2M) applications.
This PhD research builds upon CoAP to enable a better integration of constrained
devices in the IoT and examines proposed CoAP solutions theoretically
and experimentally proposing alternatives when appropriate. The first part of this
PhD proposes a mechanism that facilitates the deployment of sensor networks
and enables the discovery, end-to-end connectivity and service usage of newly
deployed sensor nodes. The proposed approach makes use of CoAP and combines
it with Domain Name System (DNS) in order to enable the use of userfriendly
Fully Qualified Domain Names (FQDNs) for addressing sensor nodes. It
includes the automatic discovery of sensors and sensor gateways and the translation
of HTTP to CoAP, thus making the sensor resources globally discoverable and
accessible from any Internet-connected client using either IPv6 addresses or DNS
names both via HTTP or CoAP. As such, the proposed approach provides a feasible
and flexible solution to achieve hierarchical self-organization with a minimum
of pre-configuration. By doing so we minimize costly human interventions and
eliminate the need for introducing new protocols dedicated for the discovery and
organization of resources. This reduces both cost and the implementation footprint
on the constrained devices.
The second, larger, part of this PhD focuses on using CoAP to realize communication
with groups of resources. In many IoT application domains, sensors
or actuators need to be addressed as groups rather than individually, since individual
resources might not be sufficient or useful. A simple example is that all
lights in a room should go on or off as a result of the user toggling the light switch.
As not all IoT applications may need group communication, the CoRE working
group did not include it in the base CoAP specification. This way the base protocol
is kept as efficient and as simple as possible so it would run on even the most
constrained devices. Group communication and other features that might not be
needed by all devices are standardized in a set of optional separate extensions. We
first examined the proposed CoAP extension for group communication, which utilizes
Internet Protocol version 6 (IPv6) multicasts. We highlight its strengths and
weaknesses and propose our own complementary solution that uses unicast to realize
group communication. Our solution offers capabilities beyond simple group
communication. For example, we provide a validation mechanism that performs
several checks on the group members, to make sure that combining them together
is possible. We also allow the client to request that results of the individual members
are processed before they are sent to the client. For example, the client can
request to obtain only the maximum value of all individual members.
Another important optional extension to CoAP allows clients to continuously
observe resources by registering their interest in receiving notifications from CoAP
servers once there are changes to the values of the observed resources. By using
this publish/subscribe mechanism the client does not need to continuously poll the
resource to find out whether it has changed its value. This typically leads to more
efficient communication patterns that preserve valuable device and LLN resources.
Unfortunately CoAP observe does not work together with the CoAP group communication
extension, since the observe extension assumes unicast communication
while the group communication extension only support multicast communication.
In this PhD we propose to extend our own group communication solution to offer
group observation capabilities. By combining group observation with group
processing features, it becomes possible to notify the client only about certain
changes to the observed group (e.g., the maximum value of all group members has
changed).
Acknowledging that the use of multicast as well as unicast has strengths and
weaknesses we propose to extend our unicast based solution with certain multicast
features. By doing so we try to combine the strengths of both approaches to obtain
a better overall group communication that is flexible and that can be tailored
according to the use case needs.
Together, the proposed mechanisms represent a powerful and comprehensive
solution to the challenging problem of group communication with constrained devices.
We have evaluated the solutions proposed in this PhD extensively and in
a variety of forms. Where possible, we have derived theoretical models and have
conducted numerous simulations to validate them. We have also experimentally
evaluated those solutions and compared them with other proposed solutions using
a small demo box and later on two large scale wireless sensor testbeds and under
different test conditions. The first testbed is located in a large, shielded room,
which allows testing under controlled environments. The second testbed is located
inside an operational office building and thus allows testing under normal operation
conditions. Those tests revealed performance issues and some other problems.
We have provided some solutions and suggestions for tackling those problems.
Apart from the main contributions, two other relevant outcomes of this PhD are
described in the appendices. In the first appendix we review the most important
IETF standardization efforts related to the IoT and show that with the introduction
of CoAP a complete set of standard protocols has become available to cover the
complete networking stack and thus making the step from the IoT into the Web
of Things (WoT). Using only standard protocols makes it possible to integrate
devices from various vendors into one bigWoT accessible to humans and machines
alike.
In the second appendix, we provide an alternative solution for grouping constrained
devices by using virtualization techniques. Our approach focuses on the
objects, both resource-constrained and non-constrained, that need to cooperate
by integrating them into a secured virtual network, named an Internet of Things
Virtual Network or IoT-VN. Inside this IoT-VN full end-to-end communication
can take place through the use of protocols that take the limitations of the most
resource-constrained devices into account. We describe how this concept maps to
several generic use cases and, as such, can constitute a valid alternative approach
for supporting selected applications
Discovery and group communication for constrained Internet of Things devices using the Constrained Application Protocol
The ubiquitous Internet is rapidly spreading to new domains. This expansion of
the Internet is comparable in scale to the spread of the Internet in the ’90s. The
resulting Internet is now commonly referred to as the Internet of Things (IoT) and
is expected to connect about 50 billion devices by the year 2020. This means that
in just five years from the time of writing this PhD the number of interconnected
devices will exceed the number of humans by sevenfold. It is further expected that
the majority of these IoT devices will be resource constrained embedded devices
such as sensors and actuators. Sensors collect information about the physical world
and inject this information into the virtual world. Next processing and reasoning
can occur and decisions can be taken to enact upon the physical world by injecting
feedback to actuators.
The integration of embedded devices into the Internet introduces new challenges,
since many of the existing Internet technologies and protocols were not
designed for this class of constrained devices. These devices are typically optimized
for low cost and power consumption and thus have very limited power,
memory, and processing resources and have long sleep periods. The networks
formed by these embedded devices are also constrained and have different characteristics
than those typical in todays Internet. These constrained networks have
high packet loss, low throughput, frequent topology changes and small useful payload
sizes. They are referred to as LLN. Therefore, it is in most cases unfeasible to
run standard Internet protocols on this class of constrained devices and/or LLNs.
New or adapted protocols that take into consideration the capabilities of the constrained
devices and the characteristics of LLNs, are required.
In the past few years, there were many efforts to enable the extension of the
Internet technologies to constrained devices. Initially, most of these efforts were
focusing on the networking layer. However, the expansion of the Internet in the
90s was not due to introducing new or better networking protocols. It was a result
of introducing the World Wide Web (WWW), which made it easy to integrate services
and applications. One of the essential technologies underpinning the WWW
was the Hypertext Transfer Protocol (HTTP). Today, HTTP has become a key
protocol in the realization of scalable web services building around the Representational
State Transfer (REST) paradigm. The REST architectural style enables
the realization of scalable and well-performing services using uniform and simple
interfaces. The availability of an embedded counterpart of HTTP and the REST
architecture could boost the uptake of the IoT.
Therefore, more recently, work started to allow the integration of constrained
devices in the Internet at the service level. The Internet Engineering Task Force
(IETF) Constrained RESTful Environments (CoRE) working group has realized
the REST architecture in a suitable form for the most constrained nodes and networks.
To that end the Constrained Application Protocol (CoAP) was introduced,
a specialized RESTful web transfer protocol for use with constrained networks and
nodes. CoAP realizes a subset of the REST mechanisms offered by HTTP, but is
optimized for Machine-to-Machine (M2M) applications.
This PhD research builds upon CoAP to enable a better integration of constrained
devices in the IoT and examines proposed CoAP solutions theoretically
and experimentally proposing alternatives when appropriate. The first part of this
PhD proposes a mechanism that facilitates the deployment of sensor networks
and enables the discovery, end-to-end connectivity and service usage of newly
deployed sensor nodes. The proposed approach makes use of CoAP and combines
it with Domain Name System (DNS) in order to enable the use of userfriendly
Fully Qualified Domain Names (FQDNs) for addressing sensor nodes. It
includes the automatic discovery of sensors and sensor gateways and the translation
of HTTP to CoAP, thus making the sensor resources globally discoverable and
accessible from any Internet-connected client using either IPv6 addresses or DNS
names both via HTTP or CoAP. As such, the proposed approach provides a feasible
and flexible solution to achieve hierarchical self-organization with a minimum
of pre-configuration. By doing so we minimize costly human interventions and
eliminate the need for introducing new protocols dedicated for the discovery and
organization of resources. This reduces both cost and the implementation footprint
on the constrained devices.
The second, larger, part of this PhD focuses on using CoAP to realize communication
with groups of resources. In many IoT application domains, sensors
or actuators need to be addressed as groups rather than individually, since individual
resources might not be sufficient or useful. A simple example is that all
lights in a room should go on or off as a result of the user toggling the light switch.
As not all IoT applications may need group communication, the CoRE working
group did not include it in the base CoAP specification. This way the base protocol
is kept as efficient and as simple as possible so it would run on even the most
constrained devices. Group communication and other features that might not be
needed by all devices are standardized in a set of optional separate extensions. We
first examined the proposed CoAP extension for group communication, which utilizes
Internet Protocol version 6 (IPv6) multicasts. We highlight its strengths and
weaknesses and propose our own complementary solution that uses unicast to realize
group communication. Our solution offers capabilities beyond simple group
communication. For example, we provide a validation mechanism that performs
several checks on the group members, to make sure that combining them together
is possible. We also allow the client to request that results of the individual members
are processed before they are sent to the client. For example, the client can
request to obtain only the maximum value of all individual members.
Another important optional extension to CoAP allows clients to continuously
observe resources by registering their interest in receiving notifications from CoAP
servers once there are changes to the values of the observed resources. By using
this publish/subscribe mechanism the client does not need to continuously poll the
resource to find out whether it has changed its value. This typically leads to more
efficient communication patterns that preserve valuable device and LLN resources.
Unfortunately CoAP observe does not work together with the CoAP group communication
extension, since the observe extension assumes unicast communication
while the group communication extension only support multicast communication.
In this PhD we propose to extend our own group communication solution to offer
group observation capabilities. By combining group observation with group
processing features, it becomes possible to notify the client only about certain
changes to the observed group (e.g., the maximum value of all group members has
changed).
Acknowledging that the use of multicast as well as unicast has strengths and
weaknesses we propose to extend our unicast based solution with certain multicast
features. By doing so we try to combine the strengths of both approaches to obtain
a better overall group communication that is flexible and that can be tailored
according to the use case needs.
Together, the proposed mechanisms represent a powerful and comprehensive
solution to the challenging problem of group communication with constrained devices.
We have evaluated the solutions proposed in this PhD extensively and in
a variety of forms. Where possible, we have derived theoretical models and have
conducted numerous simulations to validate them. We have also experimentally
evaluated those solutions and compared them with other proposed solutions using
a small demo box and later on two large scale wireless sensor testbeds and under
different test conditions. The first testbed is located in a large, shielded room,
which allows testing under controlled environments. The second testbed is located
inside an operational office building and thus allows testing under normal operation
conditions. Those tests revealed performance issues and some other problems.
We have provided some solutions and suggestions for tackling those problems.
Apart from the main contributions, two other relevant outcomes of this PhD are
described in the appendices. In the first appendix we review the most important
IETF standardization efforts related to the IoT and show that with the introduction
of CoAP a complete set of standard protocols has become available to cover the
complete networking stack and thus making the step from the IoT into the Web
of Things (WoT). Using only standard protocols makes it possible to integrate
devices from various vendors into one bigWoT accessible to humans and machines
alike.
In the second appendix, we provide an alternative solution for grouping constrained
devices by using virtualization techniques. Our approach focuses on the
objects, both resource-constrained and non-constrained, that need to cooperate
by integrating them into a secured virtual network, named an Internet of Things
Virtual Network or IoT-VN. Inside this IoT-VN full end-to-end communication
can take place through the use of protocols that take the limitations of the most
resource-constrained devices into account. We describe how this concept maps to
several generic use cases and, as such, can constitute a valid alternative approach
for supporting selected applications
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