Experimental Evaluation of Unicast and Multicast CoAP Group Communication

The proliferation of the Internet of Things (IoT) has introduced significant challenges in protocol selection for resource-constrained devices operating in smart healthcare, industrial automation, and agricultural monitoring. While lightweight protocols like Message Queuing Telemetry Transport (MQTT) and Constrained Application Protocol (CoAP) are designed for low-power Wide Area Networks, the ubiquity of Hypertext Transfer Protocol (HTTP) persists despite its substantial overhead. This research provides a multi-dimensional performance evaluation of MQTT, CoAP, and HTTP using the NS-3 discrete-event simulator. The study uniquely benchmarks these protocols across nine performance metrics, including Average Latency, Network Jitter, CPU Energy Usage, and Network Footprint, under varying iteration loads (50 and 500) to simulate both nominal and high-stress IoT environments. Our empirical analysis demonstrates that while CoAP provides the highest throughput and lowest resource consumption, MQTT offers superior reliability in persistent monitoring scenarios. Notably, the evaluation reveals a critical scalability threshold for HTTP, where high-stress iterations lead to a complete communication collapse (0% PDR) due to TCP-induced network saturation. By correlating system-level impact (CPU usage) with network-level stability (Jitter), this paper proposes an application-specific decision framework. The findings serve as a technical roadmap for optimizing next-generation IoT deployments based on specific latency and energy requirements.

Purpose – The purpose of this paper is to study lightweight security scheme for Internet of Things (IoT) applications using Constrained Application Protocol (CoAP). Resource-constrained characteristics of IoT systems have ushered in compelling requirements for lightweight application protocol and security suites. CoAP has already been established as the candidate protocol for IoT systems. However, low overhead security scheme for CoAP is still an open problem. Existing security solutions like Datagram Transport Layer Security (DTLS) is not suitable, particularly due to its expensive handshaking, public key infrastructure (PKI)-based authentication and lengthy ciphersuite agreement process. Design/methodology/approach – This paper proposes a lightweight security scheme in CoAP using Advanced Encryption Standard (AES) 128 symmetric key algorithm. The paper presents an object security (payload embedded)-based robust authentication mechanism with integrated key management. The paper introduces few unique modifications to CoAP header to optimize security operation and minimize communication cost. Findings – It is resilient to number of security attacks like replay attack, meet-in-the-middle attack and secure under chosen plaintext attack. This scheme is generic in nature, applicable for gamut of IoT applications. The paper proves efficacy of our proposed scheme for vehicle tracking application in emulated laboratory setup. Specifically, it compares with DTLS-enabled CoAP to establish the lightweight feature of our proposed solution. Research limitations/implications – This paper mainly focuses on implementing in-vehicle tracking systems as an IoT application and used CoAP as the application protocol. Practical implications – Such a lightweight security scheme would provide immense benefit in IoT systems so that resource constraint-sensing devices and nodes can be made secure. This would impact IoT eco systems to a large extent. Originality/value – Such kind of security suite that provides both robustness and lightweight feature is hitherto not known to the authors, particularly in CoAP for IoT applications.

Service discovery is one of the key requirements to realize the vision of the Internet of Things (IoT). Constrained application protocol (CoAP) is a well-accepted model that utilizes both centralized and distributed service discovery methods for lightweight and constrained IoT networks. Since CoAP is in its early stage of adoption for the IoT networks, it is important to select an efficient method for the service discovery requirement. In this paper, we implement both centralized and distributed models of the CoAP based service discovery techniques. We have used Contiki OS and Cooja simulator to build the experimental setup for our prototype systems. Our detailed empirical analysis finds the gaps in general CoAP based service discovery techniques to recommend further improvement scopes.

Electrical substations are crucial elements of Smart Grids (SGs), where they are mainly responsible for voltage transformations. However, due to the integration of distributed energy resources in the grid, substations now have to provide additional grid management capabilities which in turn require supervision and automation solutions for large low-voltage grids. A recurring challenge in such deployments are siloed systems that are due to noninteroperable communication protocols across substations: although most substations’ communication is based on the International Electrotechnical Commission (IEC) 61850 standard, deployed legacy protocols lag behind modern communication technologies in terms of performance, hindering the full transition to lightweight protocols. This paper demonstrates that IEC 61850 can be fully mapped to the Constrained Application Protocol (CoAP) in combination with the Concise Binary Object Representation (CBOR) format while improving system performance compared to existing alternatives [e.g., WS-SOAP and Hypertext Transfer Protocol (HTTP)]. On average, CoAP+CBOR needs 44% and 18% of the message size and 71% and 85% of the time compared to systems based on HTTP and WS-* Web services, respectively—this is especially relevant for resource-constrained devices and networks in electrical grids. In addition, CoAP is based on the REpresentational State Transfer (REST) architectural style, which supports system integration and interoperability through uniform identification and interaction. This approach fosters the standard-compliant integration of legacy platforms with modern substations as well as current IoT systems in neighboring domains, such as building management and infrastructure automation systems.

With the rapid expansion of Internet of Things (IoT), Constrained Application Protocol (CoAP) is developed to enable those devices with small memory, constrained computing power and limited ability to communicate with other nodes in the network. Meanwhile, group communication is very useful for managing and controlling a set of homogeneous devices in many IoT scenarios. Thus, many scholars are devoted to expanding CoAP to enable group communication. Furthermore, because CoAP is widely applicated in transportation, health care, industrial and many other areas, the security and consistency of data is of great importance. In this paper, we adopt Communicating Sequential Processes (CSP) to model group communication CoAP, and we use model checker Process Analysis Toolkit (PAT) to verify six properties of our model, including deadlock freedom, divergence freedom, data reachability, data leakage, client faking and entity manager faking. The verification results show that the original architecture has the security risk of data leakage. So we enhance it by adding message authentication code in the process. In the light of the new verification results, it can be found that we succeed in eliminating the possibility of data leakage.KeywordsGroup communicationCoAPCSPModelingVerification

The Internet of Things (IoT) is a framework of interconnected computing devices mechanical and digital machines, internationally identifiable physical objects (or things) or people that are have unique identity and the ability to transfer data over a network without human-to-human or human-to-computer interaction., their combination with the Internet, and their representation in the digital world. The accessibility and availability of cheap components of IoT devices enables a extensive range of applications and provide smart environments. These devices perform actuating and sensing tasks and identified through unique addresses. The IoT devices are connected to the Internet and expected to use the Constrained Application Protocol (CoAP) at the application layer as a main web transfer protocol. Message Queuing Telemetry Transport (MQTT) does not enforce the use of a particular security approach for its applications, but instead leaves that to the application designer. Therefore, IoT solutions can be based on application context and specific security requirements. MQTT is a Client Server publish/subscribe messaging transport protocol. It is lightweight, open, uncomplicated, and designed to make implementation more easier. These characteristics of MQTT make it perfect for use in most of the situations, including communication in Machine to Machine (M2M) and Internet of Things (IoT). In IOT there is major use of Wireless Sensor Networks (WSN) which connects virtual world to physical world. In this paper focus is given to application layer of IOT. In application layer two important protocols are MQTT and CoAP. Security mechanism is proposed in the paper for these protocols.

Recently, IETF (Internet Engineering Task Force) presented CoAP (Constrained Application Protocol) for the communication between sensor and actuator nodes in a constrained environment such as small amount of memory and low power. IETF CoAP protocol can convert easily, and can use to monitor or control infrastructure utilities through low-power sensor and actuator networks in IoT (Internet of Things) and M2M (Machine-to-Machine) environment. IETF CoAP protocol provides the special requirements of this constrained environment, especially considering energy, automation, and other IoT applications. In this paper, we design and implement a node registration and discovering based CoAP in IoT environment. The node is a CoAP node which is designed for working in constrained environment. For node registration in IoT, we used CoRE RD (Resource Directory) functionalities to register CoAP node’s information which works in IoT environment.

The Internet of Medical Things (IoMT) is a collection of medical equipment and software that can help patients get better care. The purpose of this study is to improve the security of data collected through remote health monitoring of patients utilizing Constrained Application Protocol (CoAP). Asymmetric cryptography techniques may be used to assure the security of such sensor networks. For communication between different IoMT devices and a remote server, the safe CoAP is compatible with the Datagram Transport Layer Security (DTLS) protocol for creating a secure session using existing algorithms such as Lightweight Establishment of Secure Session. The DTLS layer of CoAP, in contrast, has shortcomings in key control, session establishment, and multicast message exchange. As a consequence, for IoMT communication, the creation of an efficient protocol for safe CoAP session establishment is needed. Thus, to solve the existing problems related to key management and multicast security in CoAP, we have proposed an efficient and secure communication technique to establish a secure session key between IoMT devices and distant servers using lightweight Energy-Efficient and Secure CoAP Elliptic Curve Cryptography (E2SCEC2). The advantage of using E2SCEC2 over other identification methods such as Rivest-Shamir-Adleman (RSA) is its compact key size, which allows it to use a smaller key size. This article also compares these algorithms on parameters such as time spent generating keys, signature generation, and verification of E2SCEC2 and RSA algorithms, as well as energy consumption and radio duty cycle, to see if they are compatible in constrained environments.

Observing CoAP groups efficiently

The Internet of Things (IoT) is playing a key role in consumer and business environments. Due to the sensitivity of the information IoT devices collect and share, and the potential impact a data breach can have in people’s lives, securing communication and access to data in IoT has become a critical feature. Multiple application layer protocols are used nowadays in IoT, with the Constrained Application Protocol (CoAP) and the Message Queue Telemetry Transport (MQTT) being two of the most widely popular. In this paper, we propose a solution to increase the security of both CoAP and MQTT based on the distributed Usage Control (UCON) framework. The inclusion of UCON provides dynamic access control to the data shared using these protocols. This occurs by monitoring mutable attributes related to the local protocol nodes and also by sharing data values between remote nodes via the distributed instances of UCON. We present the architecture and the workflow of our approach together with a real implementation for performance evaluation purposes.

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 selforganisation 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.

GraphQL can be used for reducing delays and energy consumption in duty cycled wireless sensor networks (DC-WSNs) in Internet of Things (IoTs) deployments. The authors evaluate GraphQL for DC-WSN based IoTs and Web of Things applications over Constrained Application Protocol (CoAP) and Hyper Text Transfer Protocol (HTTP), respectively.

The Internet of Things (IoT) primary objective is to make a hyper-connected world for various application domains. However, IoT suffers from a lack of interoperability leading to a substantial threat to the predicted economic value. Schema.org provides semantic interoperability to structure heterogeneous data on the Web. An extension of this vocabulary for the IoT domain (iot.schema.org) is an ongoing research effort to address semantic interoperability for the Web of Things (WoT). To design this vocabulary, a central challenge is to identify the main topics (concepts and properties) automatically from existing knowledge in IoT applications. We designed KE4WoT (Knowledge Extraction for the Web of Things) to automatically identify the most important topics from literature ontologies of 3 different IoT application domains - smart home, smart city and smart weather - based on our corpus consisting of 4500 full-text conference and journal articles to utilize domain-specific knowledge encoded within IoT publications. Despite the importance of automatically identifying the relevant topics for iot.schema.org, up to know there is no study dealing with this issue. To evaluate the extracted topics, we compare the descriptiveness of these topics for the 10 most popular ontologies in the 3 domains with empirical evaluations of 23 domain experts. The results illustrate that the identified main topics of IoT ontologies can be used to sufficiently describe existing ontologies as keywords.

Internet of Things (IoT) is a massive network based on tiny devices connected internally and to the internet. Each connected device is uniquely identified in this network through a dedicated IP address and can share the information with other devices. In contrast to its alternatives, IoT consumes less power and resources; however, this makes its devices more vulnerable to different types of attacks as they cannot execute heavy security protocols. Moreover, traditionally used heavy protocols for web-based communication, such as the Hyper Text Transport Protocol (HTTP) are quite costly to be executed on IoT devices, and thus specially designed lightweight protocols, such as the Constrained Application Protocol (CoAP) are employed for this purpose. However, while the CoAP remains widely-used, it is also susceptible to attacks, such as the Distributed Denial-of-Service (DDoS) attack, which aims to overwhelm the resources of the target and make them unavailable to legitimate users. While protocols, such as the Datagram Transport Layer Security (DTLS) and Lightweight and the Secure Protocol for Wireless Sensor Network (LSPWSN) can help in securing CoAP against DDoS attacks, they also have their limitations. DTLS is not designed for constrained devices and is considered as a heavy protocol. LSPWSN, on the other hand, operates on the network layer, in contrast to CoAP which operates on the application layer. This paper presents a machine learning model, using the CIDAD dataset (created on 11 July 2022), that can detect the DDoS attacks against CoAP with an accuracy of 98%.

Constrained Application Protocol (CoAP) is a communication protocol at application layer in the Internet of things (IoT). It employs NSTART parameter to maintain outstanding parallel connections toward individual destinations for data transfer. In the existing implementation of CoAP, the value for NSTART is defined statically. Where the higher values of this parameter up to a threshold give better throughput in moderate traffic, the lower values for the same control the congestion in overload situations. In overload situations, higher values of NSTART result in increased overhead and thereby perform poorly in terms of throughput. The static nature of the parameter and its relevant performance issues demand to manage NSTART dynamically in CoAP. In this work, we propose an algorithm to adjust the value of NSTART dynamically based on the congestion in the network. The proposed approach is an attempt to make the client free from managing NSTART dynamically. For the proof of concept, we implement and run simulations on Cooja mote at IoT/FIT-Lab testbed and Californium CoAP client. The results show 15% improvement in throughput, 15% reduction in average exchange duration, and 48% reduction in average number of retries (average taken of three scenarios) by proposed approach in comparison with the best case of CoCoA (NSTART = 4).