• Journal of Korea Society of Industrial Information Systems
• /
• v.9 no.2
• /
• pp.65-73
• /
• 2004

By the progress of communication and hardware technology, It is possible to organize wireless sensor nodes using the tiny sensor in recently. It is a critical aspect to minimize energy consumption for long-term lively sensor because wireless sensor nodes are associated with the available resources. The wireless sensor network is restricted in communication, exhaustion of power, and computation but it is very similar an Ad-Hoc network. Each sensor node products a few data and application layer of each sensor has slow transmitting feature. Unlike Ad-hoc, which is usually source or sink, base station of the each senor nodes works as sink and the other nodes except sink node works as source. Generally, wireless sensor network keep staying fixed state and observing circumstances continuously after setting up. It doesnt fit for the wireless sensor networks under functioning of existing ad-hoc networks because original Ad-Hoc network routing protocol couldnt operate for wireless sensor network features. This thesis propose the effective routing protocol way in the filed of the expanded routing protocol based on tree with considering on the characteristic of wireless sensor networks pattern.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.10a
• /
• pp.121-124
• /
• 2001

Dynamic Source Route(DSR) protocol is a simple and efficient routing protocol designed specially for use of the multi-hop Ad Hoc Network. DSR allows the network to be completely self-organized and self-configured without the need for any existing infrastructure or administration. DSR protocol consists of the two mechanisms of Router discovery and Router Maintenance, works entirely On-demand in all aspects. In this paper, we will present the performance of DSR protocol on the multi-hop wireless Ad Hoc Networks, illustrate it with simulation, and then analysis the algorism of DSR.

• Journal of the Korea Society for Simulation
• /
• v.13 no.2
• /
• pp.53-63
• /
• 2004

In ad hoc networks, the link survivability is firstly considered if a routing between two mobile nodes takes place through wireless environments, because all of mobile nodes participating in a connection dynamically move to anywhere. Also, mobile nodes have multi-role to implement a communication without a static system supported by wired networks. Hence, it is difficult that all mobile nodes continuously provide a reliable connection when the nodes operate each role for the connection. Therefore, it is desired to maximize the lifetime of a route as long as possible for the reliable communication. In this paper, we propose a proactive link management scheme that can provide the continuous route supported by the link handover. It consider the wireless link quality and the power lifetime of a node so that the link handover is implemented for the link survivability without disconnecting the route on the communication.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.2B
• /
• pp.69-75
• /
• 2008

We propose new routing scheme, Cooperative Diversity-based Routing (CDR)which utilize the cooperative space diversity for power saving and for performance enhancement of wireless ad-hoc networks. The end-to-end performance of the proposed routing, CDR, is analyzed based on the Haenggi's link model. The improved performance is compared with Multi-hop Relay Routing (MRR) by analytical methods. When the required outage probability is $1{\times}10^{-3}$ at the destination node in ad-hoc networks with 7 nodes, we noticed that each node can save power consumption by 21.5 dB in average, by using our proposed CDR compared to MRR.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.2A
• /
• pp.107-112
• /
• 2009

Spectral efficiency of current two-phase cooperative communications protocols is low since in the second time the relay forwards the same signal received from the source to the destination, the source keeps silent in this time. In this paper, we propose a novel cooperative communications protocol where the signal needed to transmit to the destination is sent in both phases, the source and the relay also transmit different signal to the destination thus no loss of spectral efficiency. This protocol performs signal selection based on log-likelihood ratio (LLR) at relay and maximum likelihood (ML) detection at destination. While existing protocols pay for a worse performance than direct transmission in the low SNR regime which is of special interest in ad hoc networks, ours is better over the whole range of SNR. In addition, the proposal takes advantages of bandwidth efficiency, long delay and interference among many terminals in ad hoc network. Simulation results show that the proposed protocol can significantly save total energy for wireless ad hoc networks.

• Proceedings of the KSRS Conference
• /
• 2002.10a
• /
• pp.844-849
• /
• 2002

A provision of spatial information is expected to make a market explosion in various fields. A distribution of spatial data on wireless mobile environments indicates a huge expansion of mobile technology as well as a spread of geospatial applications. For high quality spatial information, 4S technology project integrating 4 kinds of spatial systems is currently being executed with the goal of nationwide integration of spatial data and spatial information systems. In terms of network environments, a mobile ad hoc network where mobile terminals communicate with each other without any infrastructures has been standardized for the next generation mobile wireless network. With respect to the future technologies for spatial information, it is necessary to design 4S applications on mobile ad hoc networks. This paper addresses the issue, which is proposing design points for distributing 4S spatial data on mobile ad hoc networks and ad hoc styled 4S applications.

• Korean Journal of Remote Sensing
• /
• v.19 no.1
• /
• pp.81-89
• /
• 2003

A provision of spatial information is expected to make a market explosion in various fields. A distribution of spatial data on wireless mobile environments indicates a huge expansion of mobile technology as well as a spread of geospatial applications. For high-qualified spatial information, the 4S technology Project that is integrating four kinds of spatial systems is currently being executed with the goal of nationwide integration of spatial data and spatial information systems. In terms of network environments, a mobile ad hoc network where mobile terminals communicate with each other without any infrastructures has been standardized for the next generation mobile wireless network. With respect to the future technologies for spatial information, it is necessary to design 4S applications on mobile ad hoc networks. This paper addresses the issue, which is proposing design concepts for distributing 4S spatial data on mobile ad hoc networks and for ad hoc styled 4S applications.

• Journal of Satellite, Information and Communications
• /
• v.6 no.1
• /
• pp.75-79
• /
• 2011

Wireless devices can communicate between each other without existing infrastructure in mobile Ad-hod network. Ad hoc networks can be used under difficult conditions, where it is difficult to construct infrastructures, such as shadowing areas, disaster areas, war area, and so on. In order to support to considerable and various wireless services, more spectrum resources are needed. However, efficient utilization of the frequency resource is difficult because of spectrum scarcity and the conventional frequency regulation. Ad-hoc networks employing cognitive radio (CR) system that guarantee high spectrum utilization provide effective way to increase the network capacity. In this paper, we simulate and compare the performance of conventional single and cooperative spectrum sensing with CR system using ad-hoc networks in additive white Gaussian noise (AWGN) and Rayleigh channel model. And we demonstrate performance improvement by analyzing the system performance.

• Journal of Communications and Networks
• /
• v.11 no.2
• /
• pp.187-195
• /
• 2009

The application of mathematical analysis to the study of wireless ad hoc networks has met with limited success due to the complexity of mobility, traffic models and the dynamic topology. A scenario based universal mobile telecommunications system (UMTS) time division duplex (TDD) opportunistic cellular system with an ad hoc behaviour that operates over UMTS frequency division duplex (FDD) licensed cellular network is considered. In this paper, we present a new routing metric which overall improves system performance in terms of interference and routing which operate in an ad hoc network in an opportunistic manner. Therefore we develop a simulation tool that addresses the goal of analysis and assessment of UMTS TDD opportunistic radio system with ad hoc behavior in coexistence with a UMTS FDD primary cellular networks.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.8A
• /
• pp.639-648
• /
• 2005

A wireless ad-hoc network is a temporal network formed by a collection of wireless mobile nodes without the aid of any existing network infrastructure or centralized ad-ministration. Numerous routing protocols have been developed for changing messages among the nodes in a wireless ad-hoc network. Some multi-path routing protocols have also been proposed to support load balancing and QoS for wireless ad-hoc networks. In this paper, we propose not only an efficient routing algorithm for wireless ad-hoc net-worts but also a protocol that can improve data transmission rate and reduce end-to-end delay. In our protocol, each mobile node need not broadcast routing messages periodically and the mobile node that wants to send data packets initiates route request and route establishment procedure. By simulation, we showed that faster route recovery is possible by maintaining multiple routing paths in each node, and the route maintenance overhead can be reduced by limiting the number of multiple routing paths.