Abstract—This is the survey paper on the interoperability issues and countermeasures. Internet of things is an emerging technology where machines are embedded with sensors, that allow them to relate with each other with little to know human involvement. IoT architecture comprises of three layers namely perception layer, network layer and application layer. There are interoperability issues at network layer , so there is a need to enforce principles and countermeasures at network layer. With growing need for IoT everywhere , future of IoT is secured only if the interoperability issues of IoT are mitigated. This study explores different used in IoT devices and security issues at each layer and their countermeasures.
Keywords— Internet of Things , IoT , Interoperability.
I. INTRODUCTION
Internet of Things (IoT) concept proposes a surge in amount of human-unattended devices able to discover each other, establish a connection and share information among heterogeneous devices without any human interference. IoT has deep impact of production and life[1]. In near future , IoT has fundamental impact on human life with its applications and services. IoT should have three characteristics such comprehensive perception , reliable transmission & intelligent processing .
The term Iot was coined by British entrepreneur Kevin Ashton in 1999 while working at Auto-ID Labs [2]. “Things” in the IoT sense, can be referred as plethora of devices such as automobiles with built-in sensors, DNA analysis devices for environmental monitoring, biochips , heart monitoring implants, field operation devices. Iot will revolutionize the way in which individuals and organizations interact with physical world and as well among themselves.
The most demanding requirement for realization of many IoT visions is interoperability. The two major problems faced by IoT devices is security and interoperability. As a response to increasing concerns over interoperability, many companies agreed to enable interoperability by open source development.
“Internet of Things” refers to a variety of information sensing equipment and systems, such as sensor networks, RFID reading device, bar code , global positioning systems and other short-range wireless ad hoc networks based on things-things communication model (M2M), through combining a variety of access network and the Internet to form a huge intelligence network[3]. IoT is implemented using different technologies such as RFID ( Radio Frequency based Identification ), Wireless sensor networks ,communication technology , embedded technology.
The rest of the paper is organized as follows . section II about the literature review. In Section III the layers of IoT and architecture are elaborated . Section IV elaborates different approaches to achieve interoperability . In section V comparison of different approaches is stated. In section VI recommendations are stated . Finally the paper is concluded in section VII.
II. LITERATURE REVIEW
Interoperability in IoT has become a major concern now. Different companies manufacture their own IoT devices, and communication among different IoT devices was not possible because different companies used different protocols. Later, light weighted protocols were used for these low powered devices. Researchers came up with an approach to solve this issue by introducing a semantic gateway [4].This gateway translates different protocols into a single stream to access over internet. Different nodes connected to gateway and gateway is connected to internet.
Researchers also proposed layered and distributed architectures called “Distributed internet like Architecture for Things “,[10] that have interoperability characteristics. They used detailed description of their layer architecture to show how it can tackle interoperability , scalability and heterogeneity.
Researchers have proposed a concept of “Social Network service of things” (SNSoT )[]. It is a platform ,where SNS plays a major role in connecting the devices with the help of internet. The data produced by different devices which is called as updates of the devices and the circulation of data relies on the social relationship among other devices.
Later, different companies agreed to formed a consortium and agreed to build a open source framework. This open source framework is being utilized by different companies to build an IoT device . Consortiums such as Allseen alliance , where different companies agreed to work on open source framework. Alljoyn is open source framework which makes devices to communicate with each other[5]. With this open source framework , all the developers who want to contribute to the interoperability issue can work on the open source software. If the interoperability issue is mitigated, then IoT is going to have a huge scope in future because , every device will be communicating with each other.
III. ARCHITECTURE OF IoT
IoT devices comprises of three layers ,namely perception layer, network layer and application layer[6].
Perception Layer: This is the bottom layer of the architecture mainly responsible for the connectivity with the other devices. Almost all the IoT devices have Ardiuno or Rasberry pie as their chipset. Ardiuno devices have Ethernet for connectivity where as Rasberry pie have wifi for their connectivity. Each of these devices have a unique identifier which are used to identify each other . The technology used here is RFID (Radio Frequency Identification ).
Network Layer : This layer is the interconnection between the perception layer and application layer . This layer includes communication channels, network management , network intelligence. In order to communicate with the other devices , all devices should follow some set of protocols . Previously there weren`t any standard protocols but MQTT[7] and constrained application protocol (CoAP)[8] were commonly used protocols. Unlike TCP\IP protocols the protocols are different . These protocols are designed for IoT devices by taking their low power batteries into consideration. The data received from sensors or any other device is processed and sent through the gateway wirelessly.
Application Layer: This layer is service oriented layer[9]. This layer is responsible for the services of the user.
IV.APPROACHES FOR INTEROPERABILTIY
A) Semantic Technology: The semantic technology in IoT was an early adoption. Most of them were developed by research groups, individuals. Previously, IoT had provision of end-to-end message delivery and lacks accessibility to semantic data. Organizations such as IETF, which considers CoAP standards, and XMPP are working on standardizing sensor data models as steps toward semantic data annotation [13]. The sensor data is utilized with the help of standard mechanism to provide interoperability. Semantic Web community has proposed standard ontologies for sensor observation, description, discovery and services via O&M, SensorML, SOS and SSN , which is integrated and provided to semantic web enabled messaging interface. , a third party service can convert heterogeneous sensor observations to higher level abstractions [14].
Fig 1 Semantic IoT Architecture
In Semantic IoT architecture the raw data from the sensors is sent to the semantic gateway which has enough computational resources. In the proposed semantic IoT architecture, the gateway acts as the center of data communication between the physical-world and the Cloud. This architecture can be categorized as a Semantic Service Oriented Architecture (SSOA) for IoT systems as it fulfills technical requirements such as service-oriented archi-tecture, standard based design, and semantic-based computing leveraging application agents to autonomously interpret sensor data and interact mutually [15], [16].The devices can get connected to each other with wired or wireless connection. A node acts as the endpoint and connects to the gateway using CoAP , XMPP or MQTT protocol. Due to the lower processing capabilities of the devices or nodes, they can be only utilized as clients. The CoAP protocol provides data in JSON or XML format while the MQTT only support XML. The data transferred from the nodes to the gateway is in raw format without any semantic annotations.
B) Distributed Architecture: In this approach the functionalities of IoT is grouped into three layers namely –i) Virtual Object Layer (VOL), ii)Composite Virtual Object Layer (CVOL) , iii) Service Layer (SL). These three layer architecture and their main functionalities are put together as stack , called IoT Daemon.
Fig 2 Layered Architecture for IoT
i)Virtual Object Layer: This layer plays a vital role in bridging the physical and cyber world. This layer is responsible for the digital representation of physical objects.
ii)Composite Virtual Layer: This layer is responsible for the co-ordination and communication of different physical objects that are needed to engage to accomplish the task.
iii)Service Layer: This layer handles the creation and management of services. It handles the service requests of users and initiates the services on it’s own in order to enable automatic service creation. This layer , on receiving the service request splits the request into smaller subtask .
C) Web Based Application Framework: The main barrier of IoT is proliferation of incompatible standards and protocols used by device manufacturers, which makes the data integration and co-ordiantion of appliances from different vendors a very complex process.
To address the heterogeneity of different IoT devices , researchers have focused on a web infrastructure as a platform , through which different devices can interact with each other[11]
Fig 3 Application Framework
Figure 3 depicts the architecture of web based application framework. It`s a layered model and it is composed of three significant layers: Device Layer, which is responsible for the management and control of devices, Control Layer, which is the central processing unit of the system and Presentation Layer, which generates a dynamic representation of the available devices and their services to the Web, enabling the uniform interaction with them over a RESTful interface
D)SNSoT : As we know from the name, SNS plays a major role in this framework. This framework is suitable for the collection and circulation of data among devices. . The procedure to build a social network among different devices is as follows. Firstly, all the devices register itself to the platform. Secondly, these devices post their status to the platform. Application developers search the Things (devices, users, applications, etc) that are suitable for the application and create the friend relationship among the chosen Things. The relationship is dependent on the flow of data among the devices. After an establishment of a relationship , the postings from Things are forwarded to the friends of the owner of postings. Real time processing is achieved with this framework[12].
Fig 4 Architecture of SNSIoT
E)Open Source Framework: AllJoyn is an open source software framework that makes it easy for devices and apps to discover and communicate with each other. Developers can write applications for interoperability regardless of transport layer, manufacturer, and without the need for Internet access. The software has been and will continue to be openly available for developers to download, and runs on popular platforms such as Linux and Linux-based Android, iOS, and Windows, including many other lightweight real-time operating systems.[17]
V COMPARATIVE ANALYSIS
There isn`t much to compare the different approaches stated above because, all these approaches have a common goal of achieving interoperability. Some approaches like semantic technology , Distributed architecture lack standardization. Approaches like Open source framework and SNSIoT need more professional developers because there is so much to understand . Different approaches require different tools to develop .
VI RECOMMENDATIONS
As we live in a world where open source software’s have taken a boom since android was introduced. I would recommend open Source framework because through this approach all the ideas of the developers can be implemented and on a single platform and the best can be chosen among them. By this approach Interoperability will be achieved in all IoT devices.
VII CONCLUSION
Interoperability is the major challenge in securing the future of Internet of Things. The open source framework is the intelligent approach to achieve interoperability in IoT. Developers can their hands on this open source framework and contribute to the framework. It`s like Android , which can be developed by developers in any way they want. The advantage of Open Source Framework is , all the manufactures will be working on the same framework and it will be easy for the devices to communicate with each other.
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