Yoonmee Doh

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.

PLUS: Parameterized and Localized trUst management Scheme for sensor networks security

The wireless and resource-constraint nature of a sensor network makes it an ideal medium for attackers to do any kinds of vicious things. In this paper, we describe PLUS, a parameterized and localized trust management scheme for sensor networks security, where each sensor node maintains highly abstracted parameters, rates the trustworthiness of its interested neighbors to adopt appropriate cryptographic methods, identify the malicious nodes, and share the opinion locally. Results of a serious of simulation experiments show that the proposed scheme can maximize security as well as minimize energy consumption for sensor networks. And also, the secure routing proposed based on PLUS shows its benefit and feasibility

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.

PLUS: parameterised localised trust management-based security framework for sensor networks

Ubiquitous computing, regarded as the calm technology, opens up various novel applications. It relies on the use of tiny devices embedded in everyday objects and environments, intelligently collecting and delivering information and communicating without any fixed infrastructure. Sensor networks as a sufficient enabling technology can be used as room temperatures controller, as real-time traffic monitor and can provide security in office buildings, military surveillance, etc. However, the wireless and resource-constraint nature of a sensor network makes it an ideal medium for attackers to do any kind of vicious things. In this paper, we propose a Parameterised and Localised trUst management Security (PLUS) framework that incorporates well-managed parameters and localised trust model to achieve security for wireless sensor networks. In the framework, each sensor node maintains highly abstracted parameters, rates the trustworthiness of its interested neighbours to adopt appropriate cryptographic methods, identify the malicious nodes and share the estimation locally. And also, as an application of the framework, a secure routing protocol, called PLUS_R, was designed. Results of a series of simulation experiments show that with PLUS, network can maximise security as well as minimise energy consumption. Additionally, PLUS_R shows its benefit and feasibility with security-aware route and a reasonable communication overhead.

Power aware chain routing protocol for data gathering in sensor networks

To prolong the network lifetime, we propose an energy efficient chain-based routing scheme and a distributed algorithm for constructing the routing chain based on the minimum cost tree. The chain construction algorithm calculates the transmission cost based on optimal transmission power. Therefore, it does not require global knowledge of location information of notes and provides more accurate communication cost calculation among nodes under different practical deployment environments. The proposed power aware mechanism for leader node election in the chain ensures more uniform energy consumption among nodes. The simulation shows the new scheme provides more uniform energy consumption among nodes and better active network lifetime in different network settings as compared to previous chain-based protocols.

ANTS: an evolvable network of tiny sensors

As a promising technology that enables ubiquitous computing and leads IT industries of next generation, sensor networks (SN) are foreseen to expand and populate the globe in such a way as the present Internet does. In this scenario, new challenges appear with such massive deployment, as the constant interaction of nodes and networks will transform them in dynamic entities that will need to evolve with their environment. In this paper, we discuss the future of sensor networks defining the concept of evolvability and its application. We also describe ANTS, a complete new architecture for wireless sensor networks, as our implementation to solve the challenges imposed by this evolvable future.

An optimal and lightweight routing for minimum energy consumption in wireless sensor networks

There are many trials to provide an optimal route for minimum energy consumption in a wireless sensor network. Currently, however, the mechanisms to find minimum energy property graph (MEPG) do not properly take into account the efficiency in time and storage, the optimality in results, and the feasibility in real systems. In this paper, we propose an efficient and first optimal algorithm to find the MEPG, in which all minimum energy paths are included, not only significantly reducing its total number of edges, but also obtaining an optimal result in O(VlogV+E). We also develop power aware data-centric routing protocol characterized by minimum energy consumption and longer lifetime.

A multi-access asynchronous low-power MAC based on preamble sampling for WSNs

Asynchronous low-power MACs based on preamble sampling are considered some of the most promising low-power protocols for wireless sensor networks. Although many such protocols have been suggested, they suffer from the inefficiency of essential features such as a means for preamble collision avoidance. We suggest a multiple preamble transmission scheme rather than the previous exclusive method in which only one sender can transmit a series of preambles to prevent preamble collisions and other neighbors should wait until the sender finishes all preamble and data transmissions. In the proposed scheme, the preamble interval that was stationary in previous works becomes variable. Since the sampling duration must be longer than the preamble interval, we calculate its most appropriate value from an analysis of preamble interval based on the renewal theory. Our simulation and experiment demonstrate the correctness of the analysis and the performance improvement.

Multitiered and Distributed WSAN for Cooperative Indoors Environment Management

For the past decade, wireless sensor networks have focused primarily on data collection. As a result the network topology for these systems was usually heavily centralized. However, for these networks to form a full system, the introduction of proper actuation units and decision-making intelligence is inevitable. Such a new wireless sensor and actuator network system enables new architectural research issues that have not been previously studied. In this work, we introduce the DWSAN system architecture, which effectively combines both sensor and actuation hardware devices to a single network and manages this network so that the actuation decisions are made in a distributed manner and the topology of the network maintains a multitier architecture. Our intensive set of evaluations reveal that, compared to the centralized approach that has been used in most wireless sensor network systems until now, when actuation units are introduced to the system, the DWSAN architecture reduces the transmission load of the network and the actuation decision-making latency by close to twofold and threefold, respectively. Furthermore, we show that this benefit naturally leads to better scalability of the system, making it suitable for various sensing applications in different environments.

Nano-Fabricated Mesoporous Pt electrode on Silicon for CMOS Integrated Electrochemical Sensor Applications

Most of the biosensors are based on the enzymatic electrochemical analysis and are disposable due to the use of the enzymes that are living creatures. Thus, these are limited to the in-vivo and handheld continuous monitoring sensor system applications. In this paper, a nano-hole (mesoporous) arrayed Pt electrode is investigated for developing the non-disposable electrochemical sensors without using any enzymes, which are also integrated with silicon CMOS read out circuitry. In comparison of the mesoporous Pt electrode and the plane (non-treated) Pt electrode, the current responses of mesoporous Pt electrode and the plane Pt electrode are approximately 4.62 muA/mm2 and 9.91 nA/mm2 respectively in 10 mM glucose solution. The fabricated mesoporous Pt electrode was hardly influenced by the interrupt material as the ascorbic acid. This result shows the nano-fabricated mesoporous Pt electrode is promising for CMOS integrated non-disposable sensor applications