• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.7
• /
• pp.1465-1470
• /
• 2011

In this paper, we propose a new MAC protocol, namely DM-MMAC (Doze Mode Multi-Channel MAC) for ad hoe wireless networks which can utilize multiple channels effectively, thereby enhancing the network throughput considerably. Basically, the IEEE 802.11 specification allows for the use of multiple channels available at the physical layer, but its MAC protocol is designed only for a single channel with the fatal drawback, so called multi-channel hidden terminal problem in multi-channel environments. In this vein, several multi-channel MAC protocols have been proposed, but most of them demonstrate the performance problem that its throughput drastically decreases as the number of mobile hosts residing in a given network increases with small number of available channels. In this work, we tried to improve the performance of multi-channel MAC protocols in terms of network throughput as well as power saving effects by simplifying the channel assignment and channel capturing procedures and reducing the possibility of collisions between mobile hosts.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.6
• /
• pp.85-91
• /
• 2014

Nowadays, Dynamic lighting control and management skills are studied and used. If the system which is to manage multiple intelligent spot applied ubiquitous service technology is built with decision making and used in the complex intelligent space like a apartment then will improve energy efficiency and provide comfortability in optimal conditions. To solve this problem distributed autonomous control middleware and energy management system which process data gathering by zigbee mesh network and search proper services to save energy by the existing state of things is necessary. In paper we designed DDLEMS (Distributed Dynamic Lighting Energy Management System) that is to service duplex communication embedded by software based home server platform to provide mobile services in the smart place and support decision making about energy saving to the best use of wireless censor node and controled network, energy display devices.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.11A
• /
• pp.1164-1172
• /
• 2007

To solve scalability problem in the ZigBee Network, this paper presents a new mesh routing protocol for ZigBee, called ZigBee Cluster Label (ZiCL). ZiCL divides the ZigBee network into one or more logical clusters and then assigns a unique Cluster Label to each cluster so that it discovers a route of a destination node based on Cluster Label. When a node collects new Cluster Label information of a destination node according to discovery based on Cluster Label, ZiCL encourages nodes with the same Cluster Label to share the information. Consequen tly, it contributes on reducing numerical potential route discoveries and improving network performances such as routing overhead, end-to-end delay, and packet delivery ratio. Simulation results using NS-2 show ZiCL performs well.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.37 no.1A
• /
• pp.17-24
• /
• 2012

In this paper, we described a received signal model in terms of the starting point of FFT window and derive a post-detection SINR for the receiver with MMSE filter and the corresponding filter coefficients in order to mitigate the effects of interferences caused by time and frequency selective fading channels and time difference of arrival (TDoA) in OFDMA-based Mesh Networks. In addition, we proposed an MMSE Bidirectional Successive Detection (BSD) technique which can suppress the effects of interferences among multi-nodes without any redundant FFT operations. It was shown by simulation that the proposed interference suppression technique has not an error floor at higher average SNR than 30dB in terms of 64QAM uncoded BER contrary to the conventional techniques.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.13 no.5
• /
• pp.77-83
• /
• 2013

Nowadays, the limitation of Lighting control and management skills is the excessive cost of equipments, the operational difficulties and wasting energy. To solve this problem is in need of communication and management S/W that is worked out complexly well as a information system of smart lighting energy, which is loaded wireless network facility. This paper made a study od the energy saving technology through energy monitoring and we developed LEIS(Lighting Energy Information Sysem) to converge this one. LEIS is monitoring and control lighting energy data that is collelcted from sensors by Zigbee mesh network and shows lighting use information by visualization to users. It is consists of lighting energy information data base based on LEM(Lighting Energy Metering) information and LEIS Web application, provide function scenario to manage energy optimization through LEIS.

• Journal of Broadcast Engineering
• /
• v.13 no.2
• /
• pp.261-273
• /
• 2008

Multimedia service whose use is rapidly increasing supports effective services to convert and transmit multimedia data based on network speed, noise circumstance, terminal computation, and type of contents for satisfying QoS. For supporting information protection of multimedia service, it offers middle level of singular security service or security mechanism which is based on policy of service provider, depending on present terminal computation and type of contents. It can support security mechanism for more effective multimedia service, if we study security of application layer and network layer for supporting multimedia service. In this paper, we propose Multimedia security framework reflected on quantitative analysis of the WLAN(Wireless Local Area Network) mesh network security using the utility function in the level of the sorority, violation and addictive compensation model.

• Journal of the Korean Geotechnical Society
• /
• v.34 no.9
• /
• pp.19-32
• /
• 2018

In this study, the applicability and practicality of landslides monitoring by using wireless sensor network (WSN) was analysed. WSN system consists of a sensor node for collecting and transmitting data using IEEE 802.14e standard, a gateway for collecting data and transmitting the data to the monitoring server. In the topology of the sensor network, a highly flexible and reliable mesh type was adopted, and three testbeds were chosen in each location of Seoul metropolitan area. Soil moisture sensors, tensiometers, inclinometers, and a rain gauge were installed at each testbed and sensor node to monitor the landslide. For the estimation of the optimal network topology between sensor nodes, the susceptibility assessment of landslides, forest density and viewshed analysis of terrain were conducted. As a result, the network connection works quite well and measured value of the volumetric water content and matric suction simulates well the general trend of the soil water characteristic curve by the laboratory test. As such, it is noted that WSN system, which is the reliable technique, can be applied to the landslide monitoring.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.8
• /
• pp.918-931
• /
• 2013

The conventional object tracking techniques using PTZ camera detects object movements by analyzing acquired image. However, this technique requires expensive hardware devices to perform a complex image processing. And it is occasionally hard to detect object movements, if an acquired image is low quality or image acquisition is impossible. In this paper, we proposes a smart security CCTV system applying to wireless sensor network technique based on IEEE 802.15.4 standard to overcome the problems of conventional object tracking technique, which enables to track suspicious objects by detecting object movements and GPS data in sensor node. This system enables an efficient control of PTZ camera to observe a wide area, decreasing image processing complexity. Also, wireless sensor network is implemented using mesh networks to increase the efficiency of installing sensor node.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.21 no.4
• /
• pp.157-166
• /
• 2022

The most commonly used wireless communication technologies in IoT technology include ZigBee, WiFi, Bluetooth, and Z-Wave. In particular, Z-Wave is currently one of the preferred wireless communication technologies, with a global market share of 60 % of these technologies. In this research, a temperature and humidity sensor module using a Z-wave protocol was designed and manufactured by referring to the data sheet. Subsequently, the Z-Wave protocol was analyzed during the operation of the sensor module, and the firmware of the controller module was mounted and implemented. In addition, a program for monitoring the temperature and humidity information from the sensor module was developed and validated. Finally, the performance of the sensor module was validated through master distance and low power tests on it and its reception data success rate.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.9
• /
• pp.1250-1256
• /
• 2018

Recently, wireless networks are becoming an important infrastructure for the critical large-scale applications such as cyber-physical systems and next generation industrial automations. However, the fundamental performance uncertainty of wireless networks may incur the serious instability problem of the overall systems. This paper proposes the proactive network optimizer to guarantee the application demands without any real-time link monitoring information of the networks. In particularly, the proposed proactive optimizer is the cross-layer approach to jointly optimize the routing path and traffic distribution in order to guarantee the performance demand within a maximum k number of link faults. Through the simulations, the proposed proactive network optimizer provides better robustness than the traditional existing reactive networks. Furthermore, the proactive network does not expose to the major weakness of the reactive networks such as the performance degradation due to the erroneous link monitoring information and the network reconfiguration cost.