• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.16-27
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• 2014

In this paper, we propose an efficient grid based routing scheme using the location information in order to reduce the routing cost in mobile ad-hoc networks. In our proposed scheme, all nodes can be a candidate to forward messages to the specified destination node and reduce the management cost of head nodes because they do not exist. The intermediate nodes determine the next hop relaying messages on the basis of location relations between a node and a grid zone. The proposed scheme explores the routing path considering the direction of a node using the coordinate of a grid zone and neighbor node information. It also maintains the routing path considering connectivities among the nodes. In order to show the superiority of the proposed routing scheme, we compare it with the existing grid based routing scheme in terms of the overhead of message, the success rate of transmission.

• The Journal of the Korea Contents Association
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• v.6 no.1
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• pp.72-79
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• 2006

Recently, a MMORPG(Massively Multi-play Online Role Playing Game) has built distribute server by Seamless world. This paper proposes an efficient collision detection method. DLS is used to dynamically adjust spatial subdivisions in each the boundary regions of distribute server We use an index table to effectively utilize the relationships between in the nodes and can perform the collision detection efficiently by reconstructing nodes of the tree. Also, we maintain the information for the boundary region to efficiently detect the collections and adjust the boundary regions between distributed servers by using DLS. As the DLS uses pointers, the information for each server is not needed and the boundary regions between the distributed servers are efficiently searched. Using node index points, the construction table can be made to find between ray and neighborhood node, In addition, processes for Network traffic reduce because a copy of the boundary regions is not needed when a object moves with realtime.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4A
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• pp.369-379
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• 2011

During the routing process between nodes on the CR(Cognitive Radio) network conducting for efficient use of limited frequency resources, spectrum handover process due to the appearance of the PU occupies most of the routing latency, and also decreases the reliability of the path. In this paper, a cooperative routing protocol in a multi-channel environment is proposed. The source node broadcasts a message with available channel lists and probability of PU appearance during its route guidance. The intermediate nodes re-transmit the message, received from the source node, and update and maintain the information, status table of the path. The destination node determines the optimal path and sends a reply message to the selected path after it receives the messages from the intermediate nodes. The average probability of the PU appearance and the average time of the PU appearance are updated while transferring data. During data transmission the channel with the lowest probability of appearance of the PU is selected dynamically and if a PU appears on the current channel partial repairment is performed. It is examined that reliability of the selected path considerably is improved and the routing cost is reduced significantly compared to traditional routing methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.730-742
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• 2014

In the case of On-demand routing protocol in cognitive radio ad-hoc networks, broadcasting of control packets may occur common control channel overload and packet collisions during the routing procedure. This situation is to increase the overhead of path finding and also limited to find the accurate and reliable path. Since reliable channel and path finding is restricted, path life time is shorten and path reliability is reduced. In this paper, we propose a new routing algorithm that reduces control channel overhead and increases path life time by considering the probability of appearance of primary user and channel status of neighbor nodes. Each node performs periodic local sensing to detect primary user signal and to derive primary user activity patterns. The probability of primary appearance on the current channel and the channel status can be obtained based on the periodic sensing. In addition, each node identifies the quality of the channel by message exchange through a common channel with neighbor nodes, then determines Link_Levels with neighbor nodes. In the proposed method, the Link Level condition reduces the number of control messages that are generated during the route discovery process. The proposed method can improve path life time by choosing a path through Path_Reliability in which stability and quality are weighted depending on the location. Through simulation, we show that our proposed algorithm reduces packet collisions and increases path life time in comparison with the traditional algorithm.

• Journal of Korea Multimedia Society
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• v.4 no.5
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• pp.390-395
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• 2001

In this paper, we propose a fast warping prediction using bit-pattern for motion estimation. Because of the spatial dependency between motion vectors of neighboring node points carrying motion information, the optimization of motion search requires an iterative search. The computational load stemming from the iterative search is one of the major obstacles for practical usage of warping prediction. The motion estimation in the proposed algorithm measures whether the motion content of the area is or not, using bit-pattern. Warping prediction using the motion content of the area make the procedure of motion estimation efficient by eliminating an unnecessary searching. Experimental results show that the proposed algorithm can reduce more 75% iterative search while maintaining performances as close as the conventional warping prediction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.9
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• pp.751-764
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• 2013

In cognitive radio ad-hoc networks, common control channel overload and packet collisions are occured due to indiscriminate broadcasting of control packets. So that the path reliability is reduced and control channel is easily saturated. In this paper, we propose a new routing algorithm considering the probability of appearance of primary user and channel status of neighbor nodes. When the source node needs to transmit a data packet to the destination, it performs route discovery process by exchanging control messages using a control channel in ADOV CR Ad-hoc networks. If any intermediate node doesn't have common data channel with previous node to transmit data, it doesn't rebroadcast control packet. And if it has common data channels with previous node, each node determines channel contribution factor with the number of common channels. Based on the channel contribution factor, each node performs different back-off broadcasting. In addition, each node controls control packet flooding by applying to proposed advanced mode using such as number of available channels and channel stability. With the proposed method, the number of control packets to find the data transmission path and the probability of collision among control packets can be decreased. While the path reliability can be increased. Through simulation, we show that our proposed algorithm reduces packet collisions in comparison with the traditional algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.9B
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• pp.947-954
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• 2009

In mobile ad hoc networks, service discovery to search for an available service is an important issue. In this paper, we propose an efficient service discovery protocol that is combined a dht-based service discovery scheme and a P2P caching-based information spreading scheme. Proposed scheme store key information in hashed zone and search services using it's information. To search quickly a service, it use its physical neighbors information which collected by 1-hop hello message between a node and its physical neighbors. We do not use a central look up server and do not rely on flooding. Hence, it uniquely balanced all node's load in mobile ad hoc networks and reduced the number of messages exchanged, network load and response time. The simulation results show that our protocol outperforms DHT-based and flooding protocols.

• Journal of the Korea Society for Simulation
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• v.19 no.2
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• pp.119-125
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• 2010

In ad-hoc networks, dynamically reconfigurable and temporary wireless networks, all mobile devices cooperatively maintain network connectivity with no assistance of base stations while they have limited amounts of energy that is used in different rates depending on the power level. Since every node has to perform the functions of a router, if some nodes die early due to lack of energy, it will not be possible for other nodes to communicate with each other and network lifetime will be shortened. Consequently, it is very important to develop a technique to efficiently consume the limited amounts of energy resources so that the network lifetime is maximized. In this paper, geographical localized routing is proposed to help making smarter routing decision using only local information and reduce the routing overhead. The proposed localized routing algorithm selects energy-aware neighbors considering the transmission energy and error rate over the wireless link, and the residual energy of the node, which enables nodes to achieve balanced energy-consumption and the network lifetime to prolong.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.23-28
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• 2008

In this paper, we propose location-aided cooperative routing protocol (LACARP) for supporting power saving and stable route lifetime in mobile ad-hoc wireless sensor networks. The main ideas and features of the proposed routing protocol are as follows. First, the definition of the area of route search using location-based information to support power saving transmission. Second, the expect zone-based establishment of routing route within the area of route search. Third, the cooperative-aided transmission method. In the operation of data transmission over the established rout the datas are transmitted via both the established route and cooperative route aided by neighbor nodes. The performance evaluation using OPNET(Optimized Network Engineering Tool) shows the LACARP can improve the packet delivery ratio and power saving transmission efficiently.

• The KIPS Transactions:PartC
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• v.14C no.5
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• pp.425-430
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• 2007

Without the aid of stationary infrastructure, maintaining routing information for all nodes is inefficient in the Mobile Ad hoc Networks(MANET). It is more efficient when every time routing information is necessary that the source node broadcasts a query message to neighbour nodes. The source node using Ad hoc On-Demand distance Vector(AODV), which is one of the routing protocols of MANET, uses the Expanding Ring Search(ERS) algorithm which finds a destination node efficiently. In order to reduce the congestion of the network, ERS algorithm does not broadcast Route REQuest(RREQ) messages in the whole network. When the timer expires, if source node does not receive Route REPly(RREP) messages from the destination node, it gradually increases TTL value and broadcasts RREQ messages. Existing AODV cost a great deal to find a destination node because it uses a fixed NODE_TRAVERSAL_TIME value. Without the message which is added in existing AODV protocols, this paper measures delay time among the neighbours' nodes by making use of HELLO messages. We propose Adaptive ERS(AERS) algorithm that makes NET_TRAVERSAL_TIME optimum which apply to the measured delay time to NODE_TRAVERSAL_TIME. AERS suppresses the unnecessary messages, making NET_TRAVERSAL_TIME optimum in this paper. So we will be able to improve a network performance. We prove the effectiveness of the proposed method through simulation.