Doo Seop Eom

Flexible beacon scheduling scheme for interference mitigation in body sensor networks

This paper investigates the issue of interference mitigation in body sensor networks (BSNs). IEEE 802.15 Task Group 6 presented several schemes to reduce interference, but these are still not proper solutions for BSNs. We present a novel distributed TDMA-based flexible beacon scheduling scheme that reduces interference among the BSNs. A design goal of the scheme is to avoid the wakeup period of each BSN coinciding with other networks by employing carrier sensing before a beacon transmission. We analyze the flexible beacon scheduling scheme and investigate the proper back-off length when the channel is busy. We compare the performance of the proposed scheme with the schemes of IEEE 802.15 Task Group 6 using an OMNeT++ simulation. The simulation results show that the proposed scheme has a lower packet loss, energy consumption, and delivery-latency than the schemes of IEEE 802.15 Task Group 6.

The CoAP-based M2M gateway for distribution automation system using DNP3.0 in smart grid environment

As a power system develops rapidly into a smarter and more flexible state, so must the communication technologies that support it. Machine-to-machine (M2M) communication in a Smart Grid environment has been discussed by the European Telecommunications Standards Institute (ETSI). A power system is not easily replaceable, due to system replacement costs. THE M2M gateway is required in other to improve interoperability in the M2M environment. The Distributed Network Protocol 3.0 (DNP3.0) is the most important standard in SCADA systems for power. It has been used for device data collection/control in Substation Systems and Distribution Automation Systems. If the DNP3.0 data model is combined with a set of contemporary web protocols, it can result in a significant shift. We selected the Constrained Application Protocol (CoAP) based on RESTful as the M2M protocol. It is a specialized web transfer protocol for use with constrained nodes and constrained networks. We used the OPNET Modeler 17.1 to compare the performance of Simple Object Access Protocol (SOAP) to that of CoAP. In this paper, we propose a CoAP-based M2M Gateway for a Distribution Automation system using DNP3.0 in a Smart Grid Environment.

Dynamic transmission power control for wireless sensor network reprogramming

In wireless sensor networks, the necessity of reprogramming becomes more and more important due to the inaccessibility of the sensor nodes. Because reprogramming produces a large amount of data, it consumes a great deal of energy and causes frequent collisions. Many conventional studies regarding reprogramming attempt to reduce the energy consumption and collisions. However, they overlook transmission power control which is highly related to energy efficiency and the collision problem. In this paper, we present a novel reprogramming scheme that uses dynamic transmission power control. The protocol deals not only with the energy consumption of each sensor node but also the network load distribution. We prove that our protocol extends the lifetime of the sensor network through OMNeT++ simulation results.

An Intelligent Agent-Based Routing Scheme Supporting Multiple Mobile Sinks in WSNs

Mobile sink brings new challenges to densely deployed and large wireless sensor networks (WSNs). When the sink moves, frequent location updates from the sink can generate excessive power consumption of sensors. In this paper, we propose IAR, an Intelligent Agent-based Routing protocol that provides efficient data delivery to mobile sink. Proposed algorithm reduces signal overhead and improve degraded route called triangular routing problem. We have evaluated IAR performance through both mathematical analysis and simulation experiments. The results show that our scheme effectively supports sink mobility with low overhead and the improvement of triangular routing problem.

Performance Analysis of Binary Exponential Backoff MAC Protocol for Cognitive Radio in the IEEE 802.16e/m Network

We propose a distributed MAC protocol for cognitive radio when primary network is IEEE 802.16e/m WiMAX. Our proposed MAC protocol is Truncated Binary Exponential Backoff Algorithm where backoff stage of algorithm is doubled at each collision, and backoff counter is operated by frame basis and is freezed at a frame with no idle slots. We model our proposed MAC protocol as a 3-dimensional discrete-time Markov chain and obtain steady state probability of the Markov chain by using a censored Markov chain method. Based on this steady state probability, we obtain the throughput, packet loss probability and packet delay distribution of secondary users. Our numerical examples show that initial contention window size can be determined according to the number of secondary users in order to obtain higher throughput for secondary users, and the maximum backoff stage has a large impact on the secondary user’s packet loss probability.

A Design of Integrated Management System for Building Constructions Based on USNs

This paper designs an Integrated Management System for building constructions based on USNs, which consist of diverse sensors, actuators and RFID attached devices so that the system can monitor the status the construction environments via the USNs and analyze the status information of the construction sites. Through the designed system, we expect the construction management to be carried out efficiently and rapidly for managing and monitoring the resources of workers, materials and equipment. Finally, the system can reduce both the construction cost and its building period.