James Pope

The impact of packet fragmentation on Internet-of-Things enabled systems

The Internet of Things (IoT) refers to a collection of technologies designed to interconnect physical devices with the Internet. Due to device resource constraints IoT connectivity requires the redesign of several basic Internet protocols. This paper studies the impact of packet fragmentation at the data link level on the end-to-end performance of some of these redesigned protocols. Our results show that fragmentation can seriously degrade the performance of a typical IoT device to gateway communication modality. On the other hand, our results also show that with proper design of data broadcast mechanisms, gateway-to-device communication can be maintained at high performance levels. These results can be used as a guide for IoT network engineers.

SPHERE in a Box: Practical and Scalable EurValve Activity Monitoring Smart Home Kit

Non-invasive, environmental monitoring is being successfully utilised to improve health care outcomes for patients while allowing them to more safely and comfortably live in their homes instead of health care facilities. This promises to reduce costs and ease the health care burden for many countries globally. However, these systems are still in early stages of research and only highly skilled researchers and engineers can successfully deploy them. The difficulty in deploying these systems prevents their mass use and potential cost savings motivating research interest in smart homes in a box (SHiB). In this paper we present the EurValve Activity Monitoring Kit, a minimalist activity monitoring system that can be deployed in a home by the patient and still obtain valuable lifestyle and activity level information for medical clinicians. We describe the design of the system and how it is being used in the H2020 EurValve Project. The initial results show that the system is easily deployed and yet still effective for non-invasive sensing for activity classification and localisation.

Efficient one-to-many broadcasting for resource-constrained wireless networks

Efficient one-to-many broadcasting is an essential function in dense or large-scale wireless systems managed by a sink or gateway. This paper describes HASTE, a novel heuristic designed for broadcast tree production. Minimizing maximum hop count reduces worst case broadcast latency, while maximizing the number of leaf nodes reduces the number of transmitted messages. The algorithm is designed to be used with current wireless routing protocols that have the capability to push tree configurations into the network. We evaluated HASTE against an approximation algorithm and found that it consistently produces trees with lower latencies and fewer transmissions. HASTE was also evaluated using a packet simulator and a novel approach using Bloom filters was proposed to include tree configuration information in packets. The results show that the HASTE generated spanning tree can be efficiently pushed into the network achieving high packet delivery rates with minimal overhead in packet transmissions.

CREST: An epoch-oriented routing control plane for Low-Power and Lossy Networks

There has been much recent interest in deploying IP-enabled routing and management protocols within Low-Power and Lossy Networks (LLN). For instance, the Routing Protocol for LLNs (RPL) forms a directed acyclic graph from which a routing tree can be selected. RPL is designed to dynamically modify routes in response to varying network conditions. However, many performance-sensitive LLN applications require stable routing trees with fixed homogeneous or heterogeneous transmission rates over defined time intervals. For these applications we introduce the CREST: Coordinated Routing for Epoch-based Stable Tree framework. CREST provides a LLN and IP-friendly routing control plane for supporting this application class. CREST is designed to supplement, rather than replace, LLN routing protocols such as RPL or CTP. We describe our implementation of CREST in the Contiki operating system. We also present a performance analysis for a utility maximization application using the framework comparing epoch-based protocols to an RPL approach. Our results show that the epoch-based protocols consistently deliver higher utility levels.

Managing Internet protocol routing for Low Power Lossy Networks

Protocols such as 6LoWPAN will soon directly connect the Internet to the rapidly growing number of deployed Low Power and Lossy Networks (L2Ns). The outcome will enable many novel applications, including new types of Cyber-Physical Systems, the “Internet-of-Thing”, the Smart Grid, etc. Due to resource constraints the performance of a L2N routing protocol is quite sensitive to changes in protocol parameters such as route maintenance and packet retransmission timers. However, the lack of network management tools makes it quite difficult to efficiently set these parameters or even to effectively compare different protocols across multiple metrics of reliability, energy consumption, throughput and delay. Our paper addresses this issue. We discuss the most important parameters that must be managed within an Internet-friendly L2N. We propose a novel management heuristic called ROLL-POWER, designed to simplify the monitoring of L2N performance, independent of the routing protocol type. Through extensive simulation we evaluate our claims about the importance of correct parameter setting and the efficiency of the ROLL-POWER metric. Our results show that this simple metric can be used by a network manager both to tune protocol parameters for L2Ns and as a simple and direct method of comparing different protocols.

A Distributed Algorithm for Maximizing Linear Tree Density for One to Many Wireless Communication

Reliable and efficient broadcast functions are essential in large, dense, multi-hop low power wireless systems managed by a gateway. Previous approaches addressing this issue rely on centralized and/or solutions requiring complex implementations. This paper describes the {\em Deal} algorithm for minimizing transmissions and hop count while maintaining reliability in a distributed fashion. The algorithm is compatible with and easily integrated into current low power, lossy network protocols. We first present Deal as a centralized algorithm and evaluate using numerical simulations. We then derive a distributed algorithm appropriate for low power, lossy networks. We evaluate the distributed algorithm using a testbed with over 300 nodes. Our results demonstrate that Deal is reliable and energy efficient. The experiments show that Deal significantly reduces the required number of transmissions for network broadcast in large low power, lossy networks.

Energy efficient heart rate sensing using a painted electrode ECG wearable

Many countries are facing burdens on their health care systems due to ageing populations. A promising strategy to address the problem is to allow selected people to remain in their homes and be monitored using recent advances in wearable devices, saving in-hospital resources. With respect to heart monitoring, wearable devices to date have principally used optical techniques by shining light through the skin. However, these techniques are severely hampered by motion artifacts and are limited to heart rate detection. Further, these optical devices consume a large amount of power in order to receive a sufficient signal, resulting in the need for frequent battery recharging. To address these shortcomings we present a new wrist ECG wearable that is similar to the clinical approach for heart monitoring. Our device weighs less than 30 g, and is ultra low power, extending the battery lifetime to over a month to make the device more appropriate for in-home health care applications. The device uses two electrodes activated by the user to measure the voltage across the wrists. The electrodes are made from a flexible ink and can be painted on to the device casing, making it adaptable for different shapes and users. In this paper we show how the ECG sensor can be integrated into an existing IoT wearable and compare the devices accuracy against other common commercial devices.

Inter-cloud data persistence in DIL networks

Cloud computing garners wide use by the information technology industry. Multiple cloud instances can now be configured to synchronize persisted data. Communicating internally and between cloud instances generally requires a modern networking infrastructure. However, some networks are severely constrained by their environments with disruptions, intermittent connectivity, and limited bandwidth. These types of networks are known as DIL networks. Employing cloud technologies in these environments remains difficult. We analyze current cloud data persistence techniques operating in a simulated environment where intra-cloud communications use a reliable network and inter-cloud communications operate over an unreliable DIL network. The results suggest that cloud technologies can be used effectively for data persistence across a subset of DIL networks. However, improvements will be necessary to support more constrained environments.