• Journal of Advanced Navigation Technology
• /
• v.14 no.2
• /
• pp.253-259
• /
• 2010

Wireless mesh network is flexible network like Ad hoc network or bluetooth together based on base station. But, wireless mesh network shows high packet loss and when TCP was created, however as it was design based on wired link, wireless link made more transmission error than wired link. It is existent problem of TCP congestion control algorithm that TCP unfairness and congestion collapse over wireless mesh network. When TCP operation occurs with the packet loss where is not the congestion loss, it brings the performance degradation which is serious. In this paper, in order to improve efficient TCP congestion control algorithm in wireless mesh network, we proposed that TCP can adaptively regulate the congestion window in wireless link.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2003.11b
• /
• pp.991-994
• /
• 2003

본 논문에서는 이동 컴퓨팅 시스템 간 분산응용 프로그래밍을 위한 Smart Message(SM) 메커니즘을 이용하여, 애드혹 네트워크와 유선망과의 유동적 연결 방법을 제안한다. 네트워크연동 아키텍처에 응용되는 기술들은 애드혹 네트워크, Mobile-IP, Smart Message 아키텍처 등이 있다. 애드혹 네트워크는 라우팅 장비 없이 각각의 무선 노드들로써 구성되는 네트워크로서 각 노드들은 각기 라우팅 기능과 호스트 기능을 수행한다. Mobile-IP는 무선노드들이 유선망과의 연결을 위한 IP의 확장 프로토콜이다. 본 논문은 애드혹 네트워크 내의 일부 이동 노드가 유선망의 에이전트에 접속 할 수 없을 시에, 해당 유선망의 에이전트에 접속할 수 있는 애드혹 네트워크에 소속된 노드를 대표 노드로 지정하여, 그 대표노드를 통해 유선망에 접속하는 방안을 제시한다. 애드혹 네트워크상의 분산 애플리케이션 개발을 위한 프로그래밍 아키텍처인 SM은 본 논문에서 제안하고자 하는 유연한 라우팅을 구현하기 위해 응용된다. 또한 대표노드를 통한 간접적 접속 방안의 장단점을 전송오버헤드, 네트워킹 비용 등의 관점에서 분석하고, 최적의 유무선 네트워크 연동에 관련된 프로토타입 구현을 위한 방향을 제시한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.9 no.3
• /
• pp.165-171
• /
• 2009

With rapid growth of Mobile Ad-Hoc network(MANET) and P2P service technologies, many attempts for integration of MANET and P2P service and development of such applications are actively introduced recently. The implementation of stable P2P service, however, is very difficult challenge because of the high mobility of mobile users in MANET. In this paper, we propose an efficient mobile P2P service, which shares and manages multimedia data files efficiently in mobile environment, uses distributed caches to store files considering their popularities in order to achieve high performance. The performance of proposed P2P service is evaluated by an analytic model and compared with those of existing DHT based P2P service in peer-to-peer network.

• Journal of KIISE:Information Networking
• /
• v.35 no.5
• /
• pp.409-414
• /
• 2008

In mobile ad hoc networks, most of on demand routing protocols such as DSR and AODV do not deal with traffic load during the route discovery procedure. To solve the congestion and achieve load balancing, many protocols have been proposed. However, the existing load balancing schemes has only considered avoiding the congested route in the route discovery procedure or finding an alternative route path during a communication session. To mitigate this problem, we have proposed a new scheme which considers the packet bursting mechanism in congested nodes. The proposed packet bursting scheme, which is originally introduced in IEEE 802.11e QoS specification, is to transmit multiple packets right after channel acquisition. Thus, congested nodes can forward buffered packets promptly and minimize bottleneck situation. Each node begins to transmit packets in normal mode whenever its congested status is dissolved. We also propose two threshold values to define exact overloaded status adaptively; one is interface queue length and the other is buffer occupancy time. Through an experimental simulation study, we have compared and contrasted our protocol with normal on demand routing protocols and showed that the proposed scheme is more efficient and effective especially when network traffic is heavily loaded.

• Journal of Korea Spatial Information System Society
• /
• v.10 no.3
• /
• pp.45-54
• /
• 2008

This paper designs and Implements a connectivity analyzer for the hybrid vehicular network based on the real-life movement history data achieved from the Taxi telematics system currently in operation, aiming at providing a useful guideline and information to build a telematics network. The simulator traces the location of each vehicle, sets the vehicle type, either gateway or normal, decides whether it can be connected to a mobile gateway, keeps track of status of the vehicle, and calculates the duration of disconnected state. With this analysis considering the transmission range and gateway ratio, we can decide the cost-effective number of mobile gateways having both cellular and ad-hoc network interfaces, and buffer space requirement based on the measured disconnection time and message generation ratio.

• Journal of the Korea Society of Computer and Information
• /
• v.14 no.10
• /
• pp.123-131
• /
• 2009

In this paper, we design ZigBee RF based framework for mobile web service on collected data by sensor node and transmitting data to data base by sensor network and remote sensing server through wireless connection. The proposed system is an integrated platform of sensor network for the sensor management and providing SOA based sensor web access. This paper combines SOA technology with sensor network. composes sensor node as web view, and provides high capability. extensiveness, reliability, and usability to the user who accesses to sensor web. The mobile message conversion module, SOAP message processing module. WSDL message generator, and mobile web service module is embodied for improving the capacity of the framework. The capacity evaluation of local wireless communication system which is proposed in this paper is analyzed through NS-2 simulation.

• Journal of the Korea Society of Computer and Information
• /
• v.12 no.1 s.45
• /
• pp.33-42
• /
• 2007

Mobile ad-hoc network(MANET) can increase independence and flexibility of network because it consists of mobile node without the aid of fixed infrastructure. But, Because of unrestriction for the participation and breakaway of node, it has the difficulty in management and stability which is a basic function of network operation. Therefore, to solve those problems, we suggest a distributed weighted clustering algorithm from a manageable and stable point of view. The suggested algorithm uses distributed weighted clustering algorithm when it initially forms the cluster and uses a concept which is distributed gateway and sub-cluster head to reduce the re-clustering to the minimum which occurs mobile nodes after forming the cluster. For performance evaluation, We compare DCA and WCA with the suggested algorithm on the basis of initial overhead, resubscriber rate and a number of cluster.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.14 no.4
• /
• pp.141-147
• /
• 2014

With the rapid development of major functions in a smartphone, many applications interacting with a smartphone are introduced and mobile applications converged with various related technologies are announced and rapidly disseminated recently. In this paper, we propose the design of a smart mobile application operated with devices like sensors in order to utilize various functions of the smartphone effectively. The mobile application proposed in this paper uses the bluetooth module of the smartphone, composes the wireless ad hoc network with various sensors around us, and collects bionic context information of the user in real time. The smart application designed and implemented in this paper is the sensor based healthy diet application that can fulfill healthy diet program by reflecting the user's sensed bionic context data in real time.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.10 no.4
• /
• pp.207-212
• /
• 2015

Wi-Fi Direct allows battery powered mobile devices to form a wireless ad hoc network. Since one member of the network called Group Owner (GO) takes the role of managing the network, the network lifetime is mainly affected by the energy efficiency of GO. Hence, Wi-Fi Direct defines power saving schemes that allow GO to save the energy by turning off its radio interface during the periods called absence periods. However, the Wi-Fi Direct specification does not specify how to set parameters (denoted by PS parameters) determining the schedule of the absence periods. In this paper, we therefore propose a novel traffic-aware power saving scheme for Wi-Fi Direct networks. In particular, the proposed scheme estimates the application-level traffic load and adaptively tunes the PS parameters according to the estimated value.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.5 no.4
• /
• pp.684-702
• /
• 2011

This paper proposes a TDMA-based multichannel medium access control (MAC) protocol for QoS provisioning in mobile ad hoc networks (MANETs) that enables nodes to transmit their packets in distributed channels. The IEEE 802.11 standard supports multichannel operation at the physical (PHY) layer but its MAC protocol is designed only for a single channel. The single channel MAC protocol does not work well in multichannel environment because of the multichannel hidden terminal problem. Our proposed protocol enables nodes to utilize multiple channels by switching channels dynamically, thus increasing network throughput. Although each node of this protocol is equipped with only a single transceiver but it solves the multichannel hidden terminal problem using temporal synchronization. The proposed energy efficient multichannel MAC (EM-MAC) protocol takes the advantage of both multiple channels and TDMA, and achieves aggressive power savings by allowing nodes that are not involved in communications to go into power saving "sleep mode". We consider the problem of providing QoS guarantee to nodes as well as to maintain the most efficient use of scarce bandwidth resources. Our scheme improves network throughput and lifetime significantly, especially when the network is highly congested. The simulation results show that our proposed scheme successfully exploits multiple channels and significantly improves network performance by providing QoS guarantee in MANETs.