• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1535-1541
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• 2009

In this paper, we suggest an efficient path searching algorithm that reduces the hop count when each node sends a data in ZigBee networks. As the hop count reduces, the network traffic is also reduces and leads to less energy consumption. This enables the sensor network live longer with limited node power. The proposed path searching algorithm consists of two sub-algorithms. One for upstream process and the other for downstream process. When a node selects its proper routing path, the node not only uses the information of the parent and child node, but it also uses the neighbor nodes for each node. In the simulation, we changed various network environment factors such as network parameters, number of nodes, and number of neighbor nodes and observed their performances. We compare the performance to the previous ZigBee Tree routing algorithm with separate two algorithms, the upstream and the downstream, and then compare the performance when all two algorithms are applied.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.114-121
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• 2008

Multi-path routing has been studied widely in wired networks. Multi-path routing is known to increase end-to-end throughput and provide load balancing in wired networks. However, its advantage is not obvious in wireless multi-hop network because the traffic along the multiple paths may interfere with adjacent paths. In the paper, we introduce a new multi-path routing scheme, Cluster-Based Multi-Path Routing for multi-hop wireless networks. The main idea of the proposed routing scheme is to extend the hop-by-hop multi-path to a cluster-by-cluster multi-path. In cluster network, each cluster can work independently from other clusters and hence reduce interference. The purpose of the proposed scheme is to find a less interfering path for wireless multi-hop networks. We also showed the throughput improvement of the proposed scheme through simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6B
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• pp.443-452
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• 2012

In Mobile Ad-hoc Networks, previous routing protocols classified into proactive and reactive approach respectively have pros and cons under the use of applications and environment. Moreover, to integrate their advantages in case by case, hybrid approach is consistently researched, and Zone Routing Protocol (ZRP) was motivating many recent hybrid protocols. ZRP uses proactive routing to the node located within the zone defined by the specific number of hops, while it uses reactive routing to other nodes. However, in ZRP, because proactive routing is applied only within the zone defined by the number of hops, the zone is formed regardless of whether real data communication occurred frequently or not. In this paper, we propose a new hybrid routing scheme which employs the zone method but forms customized zone considering traffic load and number of hops, by a new decision method named Dynamic Zone Decision (DZD). Additionally, we analyze the performance of the proposed scheme, comparing with the previous proactive, reactive, and hybrid routings.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.7
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• pp.993-1000
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• 2002

In this paper, we design the CORBA-based Mobile Agent Model (CMAM) which has the capability of the efficient work processing in distributed environment through sensing network traffic and searching the optimal path for migration nodes of mobile agent. In case existing mobile agent model is given various works from user, the network overhead and traffic are increased by increasing of execution module size. Also, if it happens a large quantity of traffics due to migration of nodes according to appointment of the passive host(below node) routing schedule by user, it needs much cost for node search time by traffic. Therefore, in this paper, we design a new mobile agent m()del that assures the reliability of agent's migration through dynamic act on the specific situation according to appointment of the active routing schedule and can minimize agent's work processing time through optimal path search. The proposed model assigns routing schedule of the migration nodes actively using an extended MAFFinder. Also, for decreasing overhead of network by agent's size, it separates the existing mobile agent object by mobile agent including only agent calling module and push agent with work executing module based on distributed object type of CORBA. Also, it reduces the required time for round works of mobile agent through the optimal path search of migration nodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8A
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• pp.830-836
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• 2006

One of the seminal operation parameters of AODV is the node-to-node travel time of data, which is currently set to fixed value of 40 ms in the RFC3561 and widely used to compute other parameters such as the expected round-trip time of the connection setup message, etc. We have naturally thought the network performance could be improved by dynamically varying the node-to-node travel time with respect to the traffic condition in the networt rather than using the fixed value, which motivates this work. To this end, we apply the idea of using timestamp; every node places the current time in the message before sending it out, and the receiver node computes the node travel time based on the moving average algorithm by considering not only the current value but also the previous ones in an accumulated and exponentially decreasing fashion with time. We evaluate the performance of the proposed scheme in respect of the number of RREQ messages generated, throughput, and delay as a function of traffic load and node mobility, and compare the result with the original AODV scheme. The results show that the proposed scheme presents noticeable performance improvements, expecially under the condition of high node mobility and high traffic load.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.339-350
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• 2010

Despite lots of efforts to obtain an accurate picture of structure at the level of individual ASes, there is a few application works using the AS-level Internet topology. In this paper, we show that the power-law fits the number of down-stream customer ASes very well and also present the distributions of AS links with the "public view" from UCLA IRL laboratory. Moreover, we obtain the distributions of source-destination pairs of routing hops for two sites in Korea and the United States, and then we propose a new method to decide the randomness of Internet traffic using the obtained distributions and the BGP valley-free routing policy. The randomness of traffic must be a portent of outbreak of the distributed denial-of-service attacks.

• The KIPS Transactions:PartC
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• v.9C no.5
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• pp.647-654
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• 2002

Ad-hoc networks consist of a set of mobile hosts that communicate using wireless links, without the use of other supporting communication facilities (such as base stations, etc.). Therefore, the topology of an Ad-hoc network frequently changes due to the movement of mobile host, which nay lead to sudden packet loss. Recently, the large amount of research has focused on the routing protocols needed in such an environment. In this paper, TCP Reno, Sack, and Tahoe versions are analysed using DSR protocol which is the representative On-Demand routing protocol in Ad-hoc wireless network. As the result of this simulation, we know that TCP Reno relatively has higher throughput than that of Sack and Tahoe, and TCP Reno has more stable performance than that of TCP Tahoe and Sack, regardless of the speed of mobile node and the size of topology.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.4
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• pp.572-580
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• 2021

In order to reduce transmission delay and increase reliability in networks, mainly high-performance and high-power network equipment is used to guarantee network quality. In this paper, we propose an optimization algorithm to minimize the energy consumed when transmitting traffic in networks with a bundle link composed of multiple physical cables. The proposed optimization algorithm is a meta-heuristic method, which uses tabu search algorithm. In addition, it is designed to minimize transmission energy by minimizing the cables on the paths of the source and destination nodes for each traffic. In the proposed optimization algorithm, performance evaluation was performed in terms of the number of cables used in the transmission and the link utilization for all traffic on networks, and the performance evaluation result confirmed the superior performance than the previously proposed method.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.117-124
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• 2006

In this paper, we propose the optimal migration path searching method including path adjustment and reassignment techniques for an efficient migration of mobile agent which has an autonomous ability for some task processing. In traditional agent system, if the various and large quantify of task processing were required from the users, it could be derive excessive network traffic and overload due to increasing the size of agent. And also, if an agent migrates from node to node according to routing schedules specified by the user at which the most of network traffic occurs, it could not actively cope with particular situations such as communication loss and node obstacles and required much cost for node traversal Therefore. this paper presents the migration method of agent which can try to adjust and reassign path to the destination automatically through the optimal path search using by network traffic perception in stead of the passive routing schedule by the user. An optimal migration path searching and adjustment methods ensure the migration reliability on distributed nodes and reduce the traversal task processing time of mobile agent by avoiding network traffic paths and node obstacles.

• The KIPS Transactions:PartC
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• v.12C no.4 s.100
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• pp.535-542
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• 2005

This paper proposes an on-demand ad hoc routing protocol, Node Density Based Routing (NDBR), which enhances the routing performance applying a new method to establish alternate patlis. It is important to reserve alternate paths for the route from source to destination in mobile ad hoc networks that are susceptible to failure due to the movement or the power exhaustion of mobile nodes. NDBR aims to establish a route that contains more alternate paths toward the destination by involving intermediate nodes with relatively more adjacent nodes in a possible route, and introduces a new routing criterion called 'node density.' This approach can localize the effects of route failures, and reduce control traffic overhead and route reconfiguration time by enhancing the reachability to the destination node without source-initiated route re-discoveries at route failures. This paper describes the route setup procedure using node density and the route re-configuration procedures employing alternate path information at the intermediate nodes. We show the performance of our routing schemes through a series of simulations using the Network Simulator 2 (ns-2).