Kun Mean Hou

A Real-Time Continuous Cardiac Arrhythmias Detection System: RECAD

Cardiac arrhythmia is a class of serious heart diseases that threatens many people. Current arrhythmias diagnostic techniques seem to be partially efficient due to the application limitations either in time or in space. The paper presents a real-time continuous arrhythmias detection system (RECAD) platform based on the wireless sensor network technology. This system provides long-term real-time surveillance thanks to the low-resource and low power consumptions of ambulatory wireless ECG sensor (AWES). Moreover, the AWES is compact and friendly use, so it enables patients to lead a normal life every where (indoors or outdoors). RECAD platform contains four sub-systems: AWES, local access server, remote access server and remote surveillance server. Each subsystem is configurable to run in multiple operation modes according to different application scenarios. A lossless signal compression algorithm is adopted to reduce network traffics and a dedicated application layer protocol is provided to guarantee a real-time reliable on-line ECG analysis. This system is evaluated on about twenty patients at the hospital Gabriel Montpied of Clermont-Ferrand and the real-time results are similar to the HP telemetry system

MIROS: A Hybrid Real-Time Energy-Efficient Operating System for the Resource-Constrained Wireless Sensor Nodes

Operating system (OS) technology is significant for the proliferation of the wireless sensor network (WSN). With an outstanding OS; the constrained WSN resources (processor; memory and energy) can be utilized efficiently. Moreover; the user application development can be served soundly. In this article; a new hybrid; real-time; memory-efficient; energy-efficient; user-friendly and fault-tolerant WSN OS MIROS is designed and implemented. MIROS implements the hybrid scheduler and the dynamic memory allocator. Real-time scheduling can thus be achieved with low memory consumption. In addition; it implements a mid-layer software EMIDE (Efficient Mid-layer Software for User-Friendly Application Development Environment) to decouple the WSN application from the low-level system. The application programming process can consequently be simplified and the application reprogramming performance improved. Moreover; it combines both the software and the multi-core hardware techniques to conserve the energy resources; improve the node reliability; as well as achieve a new debugging method. To evaluate the performance of MIROS; it is compared with the other WSN OSes (TinyOS; Contiki; SOS; openWSN and mantisOS) from different OS concerns. The final evaluation results prove that MIROS is suitable to be used even on the tight resource-constrained WSN nodes. It can support the real-time WSN applications. Furthermore; it is energy efficient; user friendly and fault tolerant.

Application of Modified RPL Under VANET-WSN Communication Architecture

This paper focuses on the routing protocol for driving safety that vehicle collects state message from roadside sensors in VANET-WSN. Routing Protocol for Low Power and Lossy Networks (RPL), a tree-based routing protocol, adapts naturally to our routing requirement. But RPL is designed for static wireless sensor network, so we need to modify RPL to fit in with high dynamic topology of VANET-WSN. For the first time, we utilize Geographical Information (GI) as the metric for RPL (GI-RPL), which lets RPL in a timely fashion. We also propose some strategies for tuning RPL in VANET-WSN. To demonstrate the performance of GI-RPL, we set up a simulation by using Cooja and compare with another modified RPL. The result of simulation shows that GI-RPL has high Package Delivery Ratio (PDR), reasonable overhead and low delay.

Enhanced Superframe Structure of the IEEE802. 15. 4 Standard for Real-time Data Transmission in Star Network

The IEEE 802.15.4 standard is one of the main communication protocols proposed for wireless sensor networks, IoT ‘Internet of Things’ and WoT ‘Web of Things’. This protocol provides a flexible MAC layer designed to meet a variety of applications. Since WSN is application-specific, it’s very difficult to provide a generic solution for all types of applications and topologies. In this work we focus on delay sensitive applications in star networks. This topology is used in wireless sensor networks for monitoring and control applications. The IEEE 802.15.4 standard provides some quality of service features for real-time data transmission. We identified some limitations of this standard and we proposed an improvement to provide a lower end-to-end delay with respect to energy consumption constraint by optimizing MAC layer. The experimentations are done using the NS-2 simulator. The results show the improvements expected by our approach among the IEEE 802.15.4 MAC standard.

A New Approach for Wireless Sensor Network Management: LiveNCM

The Wireless Sensor Networks (WSN), with their constant evolution, need more and more practical and effective WSN Management Tools (WMT) for large-scale deployment. Due to the resource constraints of wireless sensor node, it is impossible to implement the full classical SNMP standard in WSN applications. Therefore, it is important to develop new WMT providing a subset of functionalities of SNMP standard dedicated to WSN by taking into account the resource constraints of wireless sensor node. In this paper, we propose a new WMT named LiveNCM: LiveNode Non-invasive Context-aware, and modular Management. LiveNCM is based on a configurable modular architecture enables to fit to an application and to provide traditional administration functionalities similar to the SNMP ones. In addition, LiveNCM introduces the concept of noninvasive context-aware to diagnose the wireless sensor node state to reduce the network traffic then the energy consumption. This reduction is obtained by estimating some data with linear models like polygonal ones or interpreting data message exchanges. To validate the proposed concept, the LiveNode platform is used to implement and test energy consumption with LiveNCM protocol.

Cooperative Inter-Vehicle Communication Protocol Dedicated to Intelligent Transport Systems

MANET marks the new age of the modern communication and it is a key technology to solve many applications such as telemedicine, environment monitoring, intelligent transport system (inter-vehicle communication) etc. In this paper a new MANET protocol dedicated to intelligent transport system: CIVIC (communication inter vehicule intelligente et cooperative) is described. CIVIC is a context aware routing protocol taking into account the location of each mobile node, road traffic, geographic environment (road map) etc. Moreover, CIVIC is implemented to support infrastructure and ad-hoc network, hybrid MANET protocol, and multi- support wireless access mediums. In this paper, we introduce the different worldwide leading research projects dedicated to inter- vehicle communication, the key features of CIVIC, the implementation of CIVIC on LiveNode sensor and the application project MobiPlus.

SDREAM: A Super-Small Distributed REAL-Time Microkernel Dedicated to Wireless Sensors

Traditional embedded operation systems are resource consuming multitask, thus they are not adapted for smart wireless sensors. This paper presents a super‐small distributed real‐time microkernel (SDREAM) dedicated to wireless sensors. SDREAM is a tuple‐based message‐driven real‐time kernel. It adopts a meta language: Kernel Modeling Language to define and describe the system primitives in abstract manner. The IPC and processes synchronization are based on the LINDA concept: the tuple model implemented by two light primitives (SND: OUT & RCV: IN). In SDREAM, tasks are classified into two categories: periodic and priority. The periodic task has the highest priority level and is responsible for capturing sensor signals or actuating control signals; the priority task has various priority levels and is suitable for time‐constraints applications. A two‐level task scheduling policy scheme, named priority‐based pre‐emptive scheduling, is used for task scheduling. SDREAM is simple and efficient. It has a flexible hardware abstraction capability that enables it to be rapidly ported into different WSN platforms and other tiny embedded devices. Currently, it has been ported and evaluated in several hardware platforms. The performance results show SDREAM requires tiny resource and is suitable and efficient for hard real‐time multitask WSN applications.

A Scalable Context-Aware Objective Function (SCAOF) of Routing Protocol for Agricultural Low-Power and Lossy Networks (RPAL).

In recent years, IoT (Internet of Things) technologies have seen great advances, particularly, the IPv6 Routing Protocol for Low-power and Lossy Networks (RPL), which provides a powerful and flexible routing framework that can be applied in a variety of application scenarios. In this context, as an important role of IoT, Wireless Sensor Networks (WSNs) can utilize RPL to design efficient routing protocols for a specific application to increase the ubiquity of networks with resource-constrained WSN nodes that are low-cost and easy to deploy. In this article, our work starts with the description of Agricultural Low-power and Lossy Networks (A-LLNs) complying with the LLN framework, and to clarify the requirements of this application-oriented routing solution. After a brief review of existing optimization techniques for RPL, our contribution is dedicated to a Scalable Context-Aware Objective Function (SCAOF) that can adapt RPL to the environmental monitoring of A-LLNs, through combining energy-aware, reliability-aware, robustness-aware and resource-aware contexts according to the composite routing metrics approach. The correct behavior of this enhanced RPL version (RPAL) was verified by performance evaluations on both simulation and field tests. The obtained experimental results confirm that SCAOF can deliver the desired advantages on network lifetime extension, and high reliability and efficiency in different simulation scenarios and hardware testbeds.

Abnormal ECG signal detection based on compressed sampling in Wearable ECG sensor

Nowadays to diagnose cardiac arrhythmias Holter device is used to record 1 or 2 ECG leads during 24 or 48h. Power consumption limitations determine that the amount of data needs to be diminished without damaging the quality of information. To get a solution, we introduce a novel method based on Compressed Sensing (CS) technique to the Wearable ECG sensor (WES). The main principle underlying this framework is to sample analog signals at sub-Nyquist rate at the analog-digital converters (ADCs) and to classify directly compressed measurement into normal and abnormal state. Those compressed measurements which imply a risk of cardiac anomaly will be stored in a multimedia flash memory card or be transferred to the terminal of the network for a cardiologist to make an off-line diagnosis of cardiac arrhythmias using the reconstructed signals from the compressed measurements. In this paper we propose a scheme to directly classify compressed ECG samples into normal or abnormal states, thus avoiding reconstruction of the entire signal to perform this task. Our algorithm takes advantage of estimating parameters directly from the compressed measurements; thereby eliminating the reconstruct stage and reducing the computational complexity in WES. Direct cardiac arrhythmia detection based on CS reduces 34% energy consumption and 90% storage in WES for the reconstructed performance of 41dB.

Cooperative Inter-vehicle Communication Protocol With Low Cost Differential GPS

This paper describes a cooperative MANET protocol dedicated to intelligent transport systems, named CIVIC (Communication Inter Vehicule Intelligente et Cooperative). The CIVIC protocol is an auto-configuration inter-vehicle communication protocol, which supports adhoc and infrastructure networks, contains reactive and proactive routing components, and adapts different wireless standards. It is a context-aware protocol reacting to vehicle status, road traffic, and geographic environment. It supports location-based communication. To improve the accuracy of GPS, it integrates a localization solution called LCD-GPS (Low Cost Differential GPS). It has been implemented and experimented on the LiveNode sensor developed by our lab. At the end of this paper, an application project MobiPlus is introduced.