Jae-Doo Huh

Guaranteeing Real-Time Services for Industrial Wireless Sensor Networks With IEEE 802.15.4

Industrial applications of wireless sensor networks require timeliness in exchanging messages among nodes. Although IEEE 802.15.4 provides a superframe structure for real-time communication, a real-time message-scheduling algorithm is still required to schedule a large number of real-time messages to meet their timing constraints. We propose a distance-constrained real-time offline message-scheduling algorithm which generates the standard specific parameters such as beacon order, superframe order, and guaranteed-time-slot information and allocates each periodic real-time message to superframe slots for a given message set. The proposed scheduling algorithm is evaluated and analyzed extensively through simulations. In addition, a guaranteed time service is implemented in a typical industrial sensor node platform with a well-known IEEE 802.15.4-compliant transceiver CC2420 and ATmega128L to verify the feasibility of the guaranteed time service with the schedule generated by the proposed scheduling algorithm. Through experiments, we prove that the real system runs accurately according to the schedule calculated by the proposed algorithm.

Scheduling support for guaranteed time services in IEEE 802.15.4 low rate WPAN

We propose a real-time message scheduling algorithm which is applied to schedule periodic real-time messages in IEEE 802.15.4 for LR-WPAN (low rate wireless personal area network). The standard allows GTSs (guaranteed time slots) in the optional use of a superframe structure in a beacon-enabled network to be used to exchange real-time messages. To utilize these features of the standard efficiently, a proper message scheduling algorithm is needed. The proposed offline message scheduling algorithm which is based on a distance constrained scheduler generates the standard specific parameters including BO, SO, and GTS information to schedule the given message set. The algorithm is evaluated by simulation and the guaranteed time service using the schedule is implemented and evaluated on CC2420DB which is a prototyping platform including an IEEE 802.15.4 compliant transceiver of Chipcon AS.

Sensor Information Management Mechanism for Context-aware Service in Ubiquitous Home

Recently, sensor network technologies are being applied to more places such as the intelligent home, offices and universities. It is considered a main component of ubiquitous computing. This work focuses on sensor networks, the main infrastructure for context-aware service in ubiquitous home network. The context-aware services will trigger intelligent and automatic services according to the context information based on the sensor platform context in the future home. This service requires accurate sensing information about the environment or user, (which is gathered via information exchange among sensors without human intervention) and management of this information. Hence, if the intelligent service develops configuration and control problems related to some sensed information. Such problem causes interaction issues which require an optimal solution. This papers proposed model, implements a location tracking system, sensor information management (SIM) model, and mechanism, which can gather optimal information through the interaction within sensed information. Finally, context-aware services such as location tracking service and appliance control service presently adopt SIM mechanism. The SIM model implements a framework which comprise of foundation for intelligent physical agents (FIPA) based on intelligent agent platform, a sensor platform, an environment sensor node, and an ultra-sonic based active bat location sensor node.

Rate Adaptation Scheme for Slot Reservation in WiMedia MAC

The rate adaptation technique is an effective way to reliably transmit data in wireless networks. In this paper, we propose a novel rate adaptation scheme using not only range measurement operation (RMO) for measuring distance, but also average receive signal strength indication (RSSI) values for recognizing further obstacles. A decided data rate based on an estimated channel condition is used for both reliable data transmission and slot reservation in distributed reservation protocol (DRP) of WiMedia MAC. Last, we show the throughput measurement of our scheme working on WiMedia MAC.

Link Adaptation Strategy on Transmission Rate and Power Control in IEEE 802.11 WLANs

Link Adaptation techniques, such as rate adaptation and power control, aim at reliable data transmission through maintaining link quality. In order to do that, we measure the performance of IEEE 802.11 Wireless LAN (WLAN) in real environments that produce unexpected interference from neighbor access points or electronic devices. In this paper, we propose a novel strategy for the link adaptation technique in WLAN MAC. The new strategy provides two decisions to estimate the link condition and to manage both the transmission rate and power. Finally, we show reliable transmission through the throughput measurement using the MAC we designed.

Context-aware based mobile service for ubiquitous home

In this paper, context-aware based home services are described and developed for ubiquitous home, which consists of many sensors, digital appliances and a home server. The context-aware services provide residents with the intelligent services according to their situation, location, time and so on. For these services, information is collected by the sensors and is analyzed for the context by context-aware engine in a home server. Then services are performed by many kinds of digital appliances in a ubiquitous home. In this paper, we design and simulate the software architecture to provide the context-aware based mobile service. Using our scheme, our lives can be more convenient and comfortable in the future ubiquitous home

Context-Aware Services Platform Supporting Mobile Agents For Ubiquitous Home Network

A context-aware services platform supporting mobile agents consists of sensor nodes and a sensor coordinator. Sensor nodes collect environmental information and transmit the collected information to the sensor coordinator through wireless sensor networks. The sensor coordinator passes the information to the context-aware service module, and the mobile agent. The context-aware service module or the mobile agent performs services suitable for a users situation based on the environmental information and a service actuation message is delivered to an actuation node through the sensor coordinator. In this paper, we present a context-aware services platform structure employed in our project, and describe context-aware services platform interfaces with a context-aware service module and mobile agents

Simulation and Implementation of Voice-Over-IEEE 802.15.4 LR-WPAN

The IEEE 802.15.4 LR-WPAN specifies low cost, low energy, low rate transmission of 20~250 kbps and mostly within 10 meters of diameter. Its specification of PHY and MAC layers can be used as the lower layers of ZigBee technology. As many applications for short range, wireless networking environment have been developed, the need for voice transmission over the IEEE 802.15.4 LR-WPAN has been also increased. This paper studies the possibility and effectiveness of voice transmission over the IEEE 802.15.4 LR-WPAN by intensive simulations using ns-2 simulator, and shows several use cases as its applications by their implementations.

Design and implementation of baby-care service based on context-awareness for digital home

In this paper, we design and implement baby-care service based on context-awareness in digital home, where sensors are widespread for collecting raw data and a home server exists for triggering automatic services according to the babys situation. We describe a scenario and techniques, design and implement system architecture and service flows for this service. Using our scheme, we can take care of baby safer and more easily in the future digital home

Design of Information Management Model for Sensor Based Context-Aware Service in Ubiquitous Home

Recently, sensor network technologies are being applied to more places such as the intelligent home, offices and universities. It is considered a main component of ubiquitous computing. This work focuses on sensor networks, the main infrastructure for context-aware service in ubiquitous home network. The context-aware services will trigger intelligent and automatic services according to the context information based on the sensor platform context in the future home. This service requires accurate sensing information about the environment or user, which is gathered via information exchange among sensors without human intervention and management of this information. Hence, if the intelligent service develops configuration and control problems related to some sensed information. Such problem causes interaction issues which require an optimal solution. This papers proposed model, implements a location tracking system, sensor information management (SIM) model, and mechanism, which can gather optimal information through the interaction within sensed information. Finally, context-aware services such as location tracking service and appliance control service presently adopt SIM mechanism. The SIM model implements a framework which comprise of foundation for intelligent physical agents (FIPA) based on intelligent agent platform, a sensor platform, an environment sensor node, and an ultra-sonic based active bat location sensor node.