This paper presents a multi-layer distributed performance management model for Internet of Things (IoT) as a service for caregivers. Performance monitoring and control of IoT devices and services are vital functions for e-health systems. Cloud-based IoT systems with centralized data centers further underline the need for distributed management. The main contribution of this paper is a model and prototype implementation that combines low-complexity policy-based and conventional network management with cloud computing paradigm, lightweight IoT protocols, and their data models. A case study on monitoring of heart activity demonstrates interworking between OMA Lightweight M2M protocol, Bluetooth low energy GATT services, and Azure IoT hub cloud platform to enable distributed policy-based performance management.

One of the major challenges in 6LoWPAN is to provide continuous services while mobile nodes' movements with minimizing network inaccessible time caused due to handoffs. Even though MIPv6, HMIPv6, and PMIPv6 are commonly accepted standards to address this in IP networks, they cannot inherently avoid the degradation in communication quality during handoff, since they are not designed with consideration of constrained node networks like 6LoWPAN. In this paper, we propose a new fast mobility management protocol for 6LoWPAN, named intra-MARIO. To minimize handoff delay and enhance service availability, intra-MARIO introduces three important components, which are a fast rejoin scheme for handoff management with an adaptive polling based movement detection and multi-hop pointer forwarding schemes for location management. To justify the effectiveness, we have conducted extensive simulations by comparing intra-MARIO with prior schemes like a basic mobility management scheme and a PMIPv6-based protocol. We then implement intra-MARIO on top of our 6LoWPAN platform (SNAIL) and evaluate the performance of intra-MARIO. The results highlight that intra-MARIO reduces overall handoff delay with low power consumption and minimizes packet losses during handoffs, compared to prior mobility protocols.

This paper proposes an interesting yet practical use case of CoAP, an important application protocol in realizing the Internet of Things (IoT) vision. Originally, CoAP protocol is designed to communicate between embedded devices, however its applications can spread well over the Internet by exposing the devices' capabilities to the Web as Web resources. Thus, we claim that CoAP protocol could also be used in web-based application to leverage CoAP-based resources. Unfortunately, the design of CoAP protocol, for example, bind to UDP socket to reduce the package size or bidirectional communication to cope with duty-cycle power scheme, prevents it from being supported on conventional web browsers. Additionally, translation of CoAP into HTTP protocol via HTTP/CoAP proxy as recommended by IETF is not the best solution since many CoAP features are limited. Instead, new bidirectional web protocol such as HTML5 Web Socket would help to preserve the protocol's characteristics. We propose a solution called SCoAP that facilitates true CoAP communication in conventional web browsers by applying HTML5 Web Socket protocol. Experiment results have shown significant advantages of SCoAP solution over standard HTTP/CoAP proxy in term of network traffic and computational demand.

Tree based hierarchical routing is widely used in 6LoWPAN due to advantages of low control overhead and low memory resources. However, it generates a triangular detour path considering point-to-point (P2P) traffic. Reactive routing provides a reasonable P2P path by conducting flooding-based route discovery, but the flooding increases packet interference due to huge control overhead. Multipath routing can improve the reliability by preparing for the alternative path. Nevertheless, it needs an extra table for storing the alternative path and it is not appropriate to diverse traffic patterns. In this paper, we propose a traffic-aware multipath routing (TAMR). By managing an overlaid topology comprised of two different topologies without additional overhead, TAMR can dynamically choose a proper routing protocol according to traffic patterns and it can improve network reliability. Besides, TAMR is suitable for 6LoWPAN, because it does not need to store global routing state and generates low control overhead. In order to evaluate the performance, we have conducted the simulation by comparing with representative routing protocols in 6LoWPAN. The results show the overall performance of TAMR surpasses others in terms of hop count, packet delivery ratio, number of control packets, and memory usage.

One of the important challenges in the Internet of Things (IoT) is how to acquire the physical context of things. IP-based wireless sensor networks (IP-WSNs) could be a promising approach to collecting the physical context of things and to integrating WSNs to the Internet. However, realizing IP-WSNs in IoT exposes two major challenges. One is how to embed the Internet Protocol (IP) in resource-constrained sensor nodes. The other is how to achieve real-world deployment of WSNs and its integration with the Internet on the fly and on the cheap. In this paper, we present the SNAIL (Sensor Networks for All-IP World) project and introduce a new type of IP-WSN gateway, which supports dual wireless access points for WiFi and IP-WSN, enabling deployment of SNAIL nodes in an easy and rapid manner as for the solution. To show the proof-of-concept, we implement a new SNAIL platform from tiny sensor nodes to a gateway.

Recently, a pointer forwarding scheme (PFS) was proposed to reduce location update overhead in wireless mesh networks. Using the PFS, location update is replaced with a simple forwarding pointer setup between two neighboring MRs until the forwarding chain K is less than or equal to the configurable parameter Kmaxfor each MC. However, in PFS, if the two MRs are not one hop neighbors, the PFS fails to set up a forwarding pointer, and a location update event must be triggered, increasing location update overhead. To improve PFS, we present a novel location update scheme called a multi-hop pointer forwarding scheme (MPFS). The MPFS allows forwarding pointers to be constructed over multi-hop at once even if MRs are not one hop neighbor with each other. The key to achieving this lies in the logical tree distance constructed during network formation. The tree distance is used to relay forwarding pointer packets over multi-hop links without additional control overhead and to estimate hop distance between two MRs. By doing so, the MPFS improves the probability of success in forwarding pointer setup while ensuring K ≤ Kmax, resulting in lowering the location update overhead. To evaluate our scheme we implement both the PFS and the MPFS in ns-2 and compare them. As a result, we show that the MPFS significantly reduces the number of location update events, resulting in reduction of location update delay and signaling overhead, and packet losses during location updates.

Tree-based routing protocols in low-rate wireless mesh networks usually have the detour problem in return for the no route discovery overhead. In this paper, we propose a novel algorithm, named Incremental Path Reduction (IPR), which incrementally shortens inefficient detoured path as more data packets are delivered. In IPR, data packets are delivered along the tree route in use by using 1-hop broadcast, enabling neighbor nodes to learn about the data packets' hop count. Using the hop counts, each node estimates their residual hop count to destination. As a result, each forwarder selects next hop node that has small residual hop count. In this way, IPR incrementally shortens the detoured route as more data packets are delivered. To verify our algorithm, we applied IPR to the representative tree routing protocols, and evaluated the path stretch and packet delivery ratio as well as control packet overhead. Simulation results show that IPR significantly enhances the overall routing metrics for any types of tree-based routing protocols.

To realize the Internet of Things (IoT), an important step would be to allow things and information about them to be accessible in an easy way and a platform-independent manner. As World Wide Web (WWW, Web) shows explosive growth over the last decade, the web is the most popular and familiar user interface to acquire knowledge about everyday life. In this respect, web browsing through standard protocols like HTTP over TCP could be a promising approach to access things and to collect things' information. In future, IP-based wireless sensor networks (IP-WSNs) are expected to be integrated into the IoT. However, due to the characteristics of IP-WSN such as resource limited and low data-rate, the challenges that we confronted are 1) how to make clients access IP-WSNs as if they use regular web browsers with rich presentation and acceptable response time and 2) how to embed the standard web in such resource-constrained sensor nodes. In this paper, to address these challenges, we introduce a new browsing architecture, which enables the exploration of the IP-WSNs through a conventional web browser and the navigation with rich user interfaces. We also design lightweight web protocols, lwHTTP and lwTCP, with header compression in order for HTTP and TCP to run on the resource-constrained IP-WSNs. To show the feasibility, we implement the proposed architecture in SNAIL (Sensor Networks for an All-IP world), our IP-WSN platform, and we evaluate the performance of proposed browsing architecture.

Mobility management is one of the most important research issues in 6LoWPAN, which is a standardizing IP-based Wireless Sensor Networks(IP-WSN) protocol. Since the IP-WSN application domain is expanded to real-time applications such as healthcare and surveillance systems, a fast and seamless handover becomes an important criterion for mobility support in 6LoWPAN. Unfortunately, since existing mobility protocols for 6LoWPAN have not solved how to reduce handover delay, we propose a new fast and seamless mobility protocol to support inter-PAN handover in 6LoWPAN, named inter-MARIO. In our protocol, a partner node, which serves as an access point for a mobile node, preconfigures the future handover of the mobile node by sending mobile node's information to candidate neighbor PANs and providing neighbor PAN information like channel information to the mobile node. Also, the preconfigured information enables the foreign agent to send a surrogate binding update message to a home agent instead of the mobile node. By the preconfiguration and surrogate binding update, inter-MARIO decreases channel scan delay and binding message exchange delay, which are elements of handover delay. Additionally, we define a compression method for binding messages, which achieves more compression than existing methods, by reducing redundant fields. We compare signaling cost and binding message exchange delay with existing mobility protocols analytically and we evaluate handover delay by simulation. Analysis and simulation results indicate that our approach has promising fast, seamless, and lightweight properties.