Kee-Young Shin

A nano operating system for wireless sensor networks

In recent years, the availability of cheap and small micro sensor node and low power wireless communication give a contribution of enhanced developments of wireless sensor network application in real society. Furthermore, middlewares and operating systems for convenience on development of sensor network application are essentially needed. In this paper, we introduce a sensor network operation system, Nano-Qplus platform, which is flexible, dynamic, and easy manageable for sensor network application programmer. Furthermore, for the purpose of performance evaluation, we compare Nano-Qplus to other sensor network operating systems related to memory read/write time and task creation latency. The results of performance analysis shows that Nano-Qplus offers enhanced advantages that other sensor network operating systems, so we can notice Nano-Qplus is easily applied to real sensor network application

Embedded sensor networked operating system

Recently, the availability of cheap and small micro sensor node and low power wireless communication give a contribution of enhanced developments of wireless sensor network application in real society. Furthermore, middlewares and operating systems for convenience on development of sensor network application are essentially needed. In this paper, we introduce a sensor network operation system, Nano-Qplus platform, which is flexible, dynamic, and easy manageable for sensor network application programmers. Furthermore, for the purpose of performance evaluation, we compare Nano-Qplus to other sensor network operating systems related to memory read/write time and task creation latency. The results of performance analysis shows that Nano-Qplus offers enhanced advantages that other sensor network operating systems, so we can notice Nano-Qplus is easily applied to real sensor network applications

NanoMon: A Flexible Sensor Network Monitoring Software

In this paper, we present a sensor network monitoring software, named NanoMon, which has a highly flexible architecture and is able to support various user requirements arising in their individual wireless sensor network applications in an adaptive manner. With NanoMon, users can specify their own sensor types and custom GUI components by using a simply describable configuration file; and it can be automatically integrated to NanoMon GUI framework to support user-specific sensor network applications. NanoMon employs a widely used database, MySQL, to manage sensing data and node information of several types of sensor network applications and also to provide sensor data history and conditional sensor data look up functions. NanoMon provides well defined packet form at and transmission procedure to communicate with various sensor network platforms with no dependency on any specific WSN platforms; and it can publish sensing data received from sensor networks to other external monitoring devices via Internet using well defined XML packet format and transmission procedure. For platform independency, NanoMon is implemented in Java language.

CRIT: A Hierarchical Chained-Ripple Time Synchronization in Wireless Sensor Networks

Time synchronization in wireless sensor networks (WSN) is important for accurate time stamping of events and fine-tuned coordination of duty cycles to minimize power consumption. This paper presents a novel chained-ripple time synchronization (CRIT) protocol that is fast, flexible, and high-precise in WSN. CRIT adopts hierarchical and multi-hop time synchronization architecture with supporting the energy-saving problem in WSN. The algorithm works in two phases. In the first phase, a horizontal structure between missionary nodes (MN) is established in the network by piggy-back neighbor time synchronization (PBNT) algorithm. In the second phase, a vertical structure between a MN and sensor nodes (SN) is set up in each sensor group (SG) by distributed depth first search (DDFS) algorithm. By applying these two phases repeatedly, all nodes in WSN efficiently synchronizes to each other. For the purpose of performance evaluation, we first study the error sources of CRIT. In addition, we simulate CRIT in terms of synchronization errors of two phases and clock offset using network simulator (NS-2). The simulation results show that CRIT provides very accurate time synchronization and it can be easily expanded to real WSN

CAS/sup 2/: context awareness service system based on wireless sensor networks

In recent years, the appearance of ubiquitous computing provides a fair opportunity to access diverse information and service at anyplace, anytime for users. Furthermore, those services need system architecture and context-aware and, furthermore, location-aware technologies are essential. In this paper, we suggest that a system architecture (CAS2) for handling context information based on wireless sensor network (WSN) that can provide diverse and convenient services to user with only minimum actions by collecting context information of the user in real-time. CAS also provides optimized services to each user based on the context information

NACA: A New Adaptive CSMA/CA Algorithm of IEEE 802.15.4 in Beacon-enabled Networks

In this paper, we propose a new adaptive CSMA/CA algorithm (NACA) that aims to reduce redundant transmission of IEEE 802.15.4 LR-WPAN. In wireless sensor networks (WSN), energy consumption is one of the most important issues. Furthermore, it makes the network life-time longer by reducing retransmission. To achieve this goal, we improve the carrier sensing features in MAC layer of IEEE 802.15.4. When the network is busy, the MAC detects it and adaptively chooses the parameters of CSMA/CA mechanism to minimize collisions and redundancy of retransmission packet based on the NACA. We evaluated the proposed scheme with original 802.15.4 MAC on the ns-2 simulator. The results show that our scheme outperforms the original by about 15% in case of retransmission.

A flexible, high-precise time synchronization for multi-hop sensor networks

In recent years, time synchronization in wireless sensor networks (WSN) is important for accurate time stamping of events and fine-tuned coordination of duty cycles to minimize power consumption. This paper presents an on-demand hierarchical mesh-based time synchronization (OHMTS) that is flexible, multi-hop based and high-precise in WSN. OHMTS adopts hierarchical and multi-hop mesh-based network architecture with supporting energy-saving problem for WSN. For the purpose of performance evaluation, we first study the error sources of OHMTS and then we evaluate the performance of OHMTS with respect to synchronization delay error using network simulator (NS-2). The simulation results show that OHMTS provides fine-tuned clock offset mechanism and can be easily applied to real WSN platform

Enhanced Time-Sync Protocol for Embedded Sensor Networks

Time synchronization for embedded sensor networks (ESN) is important for accurate time stamping of events and fine-tuned coordination of duty cycles to minimize power consumption. This paper presents a novel chained-ripple time synchronization (CRIT) protocol that is fast, flexible, and high-precise in ESN. CRIT adopts hierarchical and multi-hop time synchronization architecture with supporting energy-saving problem in ESN. The algorithm works in two phases. In the first phase, a horizontal structure between missionary nodes (MN) is established in the network by piggy-back neighbor time synchronization (PBNT) algorithm. In the second phase, a vertical structure between a MN and sensor nodes (SN) is set up in each sensor group (SG) by distributed depth first search (DDFS) algorithm. By applying these two phases repeatedly, all nodes in ESN efficiently synchronize to each other. For the purpose of performance evaluation, we first study the error sources of CRIT. In addition, we simulate CRIT in terms of synchronization errors of two phases and clock offset using network simulator (NS-2). The simulation results show that CRIT provides very accurate time synchronization and it can be easily expanded to real ESN

Wireless sensor networks: a scalable time synchronization

This paper presents a novel Chained-RIpple Time Synchronization (CRIT) protocol that is scalable, flexible, and high-precise in Wireless Sensor Networks (WSN). CRIT adopts hierarchical and multi-hop time synchronization architecture with contributing energy-saving effects in WSN. The algorithm works in two phases. In the first phase, a horizontal structure between Missionary Nodes (MN) is established in the network by Piggy-Back Neighbor Time Synchronization (PBNT) algorithm. In the second phase, a vertical structure between a MN and Sensor Nodes (SN) is set up in each sensor group (SG) by Distributed Depth First Search (DDFS) algorithm. By applying these two phases repeatedly, all nodes in WSN efficiently synchronize to each other. For the purpose of performance evaluation, we first study the error sources of CRIT. In addition, we simulate CRIT in terms of synchronization errors of two phases using network simulator.

A Design and Implementation of Wireless Sensor Network Security on Nano-Qplus Platform

The sensor network features characteristics such as nodes being densely distributed, large quantities of nodes being scattered around, necessity of frequently changing the network topology as well as utilizing broadcasting system for communication. It also reflects a wireless network environment where batteries and computing powers are limited that it would be difficult to even make a decision on whether surrounding nodes are in credible conditions. Not only the numbers of nodes through which sensor nodes communicate exceed one, but additional research on password key control is required. It would be used on mutual authentication between nodes as well as authentication and enciphering by using limited sensor resources within the sensor network, which is based on the mesh structure. This paper makes statements on encryption algorithm, key management, security protocol, authentication and essential security elements of secure routing. It will be acting as basis of developing security mechanism, which will provide confidentiality of the MAC class level, authentication and integrity on a sensor network environment referred as the nano-Qplus platform.