Isam Ishaq

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.

Facilitating Sensor Deployment, Discovery and Resource Access Using Embedded Web Services

Smart embedded objects such as sensors and actuators will become an important part of the Internet of Things. With recent technologies, it has now become possible to deploy a sensor network and interconnect it with IPv6 Internet. However, several manual configuration steps are still needed to integrate a sensor network within an existing networking environment. In this paper we describe a novel self-organization solution to facilitate the deployment of sensor networks and enable the discovery, end-to-end connectivity and service usage of these newly deployed sensor nodes. The proposed approach makes use of embedded web service technology, i.e. the IETF Constrained Application Protocol (CoAP). Automatic hierarchical discovery of CoAP servers is one of the key features, resulting in a brows able hierarchy of CoAP servers, up to the level of the sensor resources, which can be accessed both over CoAP and HTTP and through the use of either DNS names or IPv6 addresses. To demonstrate the feasibility of our approach we have implemented the solution and deployed it on a test setup, which is publicly accessible to everyone.

Internet of Things Virtual Networks: Bringing Network Virtualization to Resource-Constrained Devices

Networks of smart resource-constrained objects, such as sensors and actuators, can support a wide range of application domains. In most cases these networks were proprietary and stand-alone. More recently, many efforts have been undertaken to connect these networks to the Internet using standard protocols. Current solutions that integrate smart resource-constrained objects into the Internet are mostly gateway-based. In these solutions, security, firewalling, protocol translations and intelligence are implemented by gateways at the border of the Internet and the resource-constrained networks. In this paper, we introduce a complementary approach to facilitate the realization of what is called the Internet of Things. 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 IoTVN. 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. A first implementation demonstrating the key concepts of this approach is described. It illustrates the feasibility of integrating resource-constrained devices into virtual networks, but also reveals open challenges.

Flexible unicast-based group communication for CoAP-enabled devices.

Smart embedded objects will become an important part of what is called the Internet of Things. Applications often require concurrent interactions with several of these objects and their resources. Existing solutions have several limitations in terms of reliability, flexibility and manageability of such groups of objects. To overcome these limitations we propose an intermediately level of intelligence to easily manipulate a group of resources across multiple smart objects, building upon the Constrained Application Protocol (CoAP). We describe the design of our solution to create and manipulate a group of CoAP resources using a single client request. Furthermore we introduce the concept of profiles for the created groups. The use of profiles allows the client to specify in more detail how the group should behave. We have implemented our solution and demonstrate that it covers the complete group life-cycle, i.e., creation, validation, flexible usage and deletion. Finally, we quantitatively analyze the performance of our solution and compare it against multicast-based CoAP group communication. The results show that our solution improves reliability and flexibility with a trade-off in increased communication overhead.

Observing CoAP groups efficiently

It is envisioned that by the year 2020 the Internet will contain more than 50 billion devices, among which the majority of them will have constraints in terms of memory, processing power or energy. As a consequence, they are often unable to run current standard Internet protocols, requiring special, optimized protocols. A number of these protocols, covering the different layers of the protocol stack, have been developed and standardized lately. At the application level, the Constrained Application Protocol (CoAP) is proposed by the IETF as an HTTP replacement that is suitable for constrained devices. CoAP is a very light-weight base protocol that can be extended with optional specifications to satisfy specific use case needs. Two important optional specifications are observe, allowing monitoring of a CoAP resource over a period of time, and group communication, supporting interactions with multiple CoAP devices at once. Currently, these two optional specifications do not work together, i.e., it is not possible to gain the benefits of both of them at the same time. In this paper we present an alternative and novel approach to CoAP group communication that works well with the CoAP observe extension. In addition, it enables to perform operations on the observed results, bringing intelligence closer to the data sources.

Experimental Evaluation of Unicast and Multicast CoAP Group Communication

The Internet of Things (IoT) is expanding rapidly to new domains in which embedded devices play a key role and gradually outnumber traditionally-connected devices. These devices are often constrained in their resources and are thus unable to run standard Internet protocols. The Constrained Application Protocol (CoAP) is a new alternative standard protocol that implements the same principals as the Hypertext Transfer Protocol (HTTP), but is tailored towards constrained devices. In many IoT application domains, devices need to be addressed in groups in addition to being addressable individually. Two main approaches are currently being proposed in the IoT community for CoAP-based group communication. The main difference between the two approaches lies in the underlying communication type: multicast versus unicast. In this article, we experimentally evaluate those two approaches using two wireless sensor testbeds and under different test conditions. We highlight the pros and cons of each of them and propose combining these approaches in a hybrid solution to better suit certain use case requirements. Additionally, we provide a solution for multicast-based group membership management using CoAP.

Enabling the web of things: facilitating deployment, discovery and resource access to IoT objects using embedded web services

Today, the IETF Constrained Application Protocol CoAP is being standardised. CoAP takes the internet of things to the next level: it enables the implementation of RESTful web services on embedded devices, thus enabling the construction of an easily accessible web of things. However, before tiny objects can make themselves available through embedded web services, several manual configuration steps are still needed to integrate a sensor network within an existing networking environment. In this paper, we describe a novel self-organisation solution to facilitate the deployment of constrained networks and enable the discovery, end-to-end connectivity and service usage of these newly deployed sensor nodes. By using embedded web service technology, the need of other protocols on these resource constrained devices is avoided. It allows automatic hierarchical discovery of CoAP servers, resulting in a browsable hierarchy of CoAP servers, which can be accessed both over CoAP and hypertext transfer protocol.

Group Communication in Constrained Environments Using CoAP-based Entities

The Constrained Application Protocol (CoAP) is a new Internet protocol that is currently being standardized. CoAP allows access to the drastically increasing number of smart objects and their sensing resources from virtually anywhere. It is a light-weight protocol designed to cope with the restrictions imposed by the limited resources (CPU, memory, power,...) of many smart objects. Depending on the application, information from individual objects might not be sufficient, reliable, or useful. An application may need to aggregate and/or compare data from a group of objects in order to obtain accurate results. Although multicast may be used to transmit the same request to several objects, multicast communication with smart objects has some disadvantages. Programming individual requests is another solution but lacks flexibility and opportunities for reusability. In this paper we propose a novel CoAP-based approach for communication with a group of resources across multiple smart objects. This approach organizes the group of resources that should be accessed into a new CoAP resource, called an entity, and nicely integrates several important aspects of entity management: creation, validation, usage and manipulation. In order to demonstrate the feasibility of this approach we present an implementation and experimental validation.

Leveraging upon standards to build the Internet of Things

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 were 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. Long time, most efforts were focusing on the networking layer. More recently, the IETF CoRE working group started working on an embedded counterpart of HTTP, allowing the integration of constrained devices into existing service networks. In this paper, we will briefly review the history of integrating constrained devices into the Internet, with a prime focus on the IETF standardization work in the ROLL and CoRE working groups. This is further complemented with some research results that illustrate how these novel technologies can be extended or used to tackle other problems.

Building embedded applications via REST services for the internet of things

As embedded networks are evolving to open systems, its becoming possible to create new applications on top of these existing embedded systems. However, developing new applications can be difficult due to the large diversity of protocols that exist today. In this paper, the authors demonstrate how employing the CoAP protocol can enable rapid application development by re-using well-known principles from the Web development world. Furthermore, we also demonstrate how a number of extensions to CoAP help to lower the barrier for developing applications even further.