• Convergence Security Journal
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• v.14 no.2
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• pp.43-50
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• 2014

Recently, lot of researches for the multi-level protocol have been done to balance the sensor node energy consumption of WSN and improve the node efficiency to extend the life of the entire network. Especially in multi-hop protocol, a variety of models have been proposed to improve energy efficiency and apply it to WSN protocol. In this paper, we analyze LEACH algorithm and propose new method based on center of local clustering routing algorithm in wireless sensor networks. We also perform NS-2 simulation to show the performance of our model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.203-209
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• 2004

In OBS networks, the burst dropping due to contention significantly affects the performance of TCP, but existing drop policies have not considered this problem and researches related to TCP have been mainly studied on burst assembling. We propose the drop policy considering retransmission of TCP to improve the performance of TCP in OBS networks. The proposed drop policy is the Retransmission Count-based DP that regards retransmission count of bursts as priority when it selects dropping burst. This paper evaluates the performance of RC-based DP model and general DP model using ns-2. The metrics of performance evaluation are TCP throughput, maximum sequence number of received TCP packets and drop rate of packet as simulation time increases.

• Journal of IKEEE
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• v.10 no.2 s.19
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• pp.123-127
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• 2006

An Ad-hoc network which is composed of mobile nodes only should be able to distribute the traffic load evenly to the network so that the network could utilize its resources effectively However, most of researches have been concentrated in channel establishment level, not in channel reestablishment level. In this paper, the existing AODV routing protocol has been modified and upgraded to disperse the traffic load more quickly A node which uses the modified AODV routing protocol proposed in this paper broadcasts a control message to adjacent nodes, which announces congestion around the node. In order to verify the performance improvement of the proposed protocol, simulation study has been carried out by using ns2 simulator.

• Convergence Security Journal
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• v.7 no.2
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• pp.39-47
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• 2007

The scheduling algorithms to provide quality of service (QoS) in broadband convergence network (BcN) are compared and analysed. The main QoS management methods such as traffic classification, traffic processing in the input queue and weighted queueing are first analysed, and then the major scheduling algorithms of round robin, priority and weighted round robin under recently considering for BcN to supply real time multimedia communications are analysed. The simulation results by NS-2 show that the scheduling algorithm with proper weights for each traffic class outperforms the priority algorithm.

• Journal of the Korea Society for Simulation
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• v.14 no.4
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• pp.77-86
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• 2005

[ $IP^2$ ] (IP-based IMT Network Platform) is a ubiquitous platform supporting mobility using two step If address IPha (IP host address) and IPra (IP routing address) - in a backbone network. MN (Mobile Node) in $IP^2$ maintains either Active or Dormant state, which is transferred to Active state through Paging process when communication is required. In this paper, we proposed a Paging method using proxy to resolve the problem of the conventional Paging method which transmits the Paging messages to all cells in LA (Location Area) resulting in the excessive use of network resources. Performanceevaluation of the proposed method using NS-2 showed that the usage of network resources becomes more efficient by reducing paging loads, especially under the condition of increased nodes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.584-587
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• 2012

MANET, which can be constructed with only terminal devices, has structural advantages of ease installation and operation, also has environmental change of rapid supply of smart phone, it's usage can be extended to application area likes as emergency communication, leasure, exploration and investigations. But, as one characteristic of MANET, no use of communicaton infrastructure caused disadvantage of weakness for information intrusion which is frequently occurred, nowadays. In this paper, the effects of IDS(Intrusion Detection System), one of defence tools for information intrusion, is analyzed for transmission performance. Blackhole attack is assumed as a type of intrusion, MANET defence with IDS from intrusions. Computer simulation based on NS-2 used for performance measurement. In this paper, performance measurement is done for application service to analyze application level effects of IDS. VoIP service is used as application service.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.10
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• pp.1903-1911
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• 2016

As interest in MANET is increasing nowadays, research upon an efficient MANET routing protocol is actively under way. A LQA(Link Qualty Aware)-AODV routing protocol to deal with frequent changes of topology and wireless link variations under tactical operating conditions is proposed in this paper. The suggested LQA-AODV takes into account the channel capacity of each hop during the route request process of the traditional AODV protocol. In detail, LQA-AODV adds a channel capacity cost value to the RREQ message format that occurs during the routing process of the existing AODV Routing Protocol causing the accumulated channel capacity cost values of each sections to be compared before establishing a route. To verify the performance of LQA-AODV, NS2.35 was utilized and the Link-Quality Model was applied in order to reflect the tactical wireless environment. The simulation compares and analyzes LQA-AODV and the existing AODV, showing a large improvement over the traditional AODV in regards to the Packet Delivery Ratio, and End-to-End Delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.189-197
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• 2016

Mobile ad-hoc networks (MANETs) experience frequent link disconnections due to non-uniform node distribution and mobility. Thus, end-to-end path establishment-based routing protocols cause frequent transmission failures in MANETs, resulting in heavy control messages for path reestablishment. While location-based MANET routing protocols, such as Greedy Perimeter Stateless Routing (GPSR), use location information to forward messages in a hop-by-hop routing fashion without an end-to-end path establishment procedure, such protocols encounter communication void problems when message forwarding to the next hop fails due to the absence of a relay node. Therefore, to solve this problem, this paper proposes a Delay Tolerant-GPSR (DT-GPSR) protocol, which combines Delay Tolerant Networking (DTN) technology with the GPSR protocol. The performance of DT-GPSR is compared with the performances of the original GPSR and PRoPHET routing protocols through simulation using NS-2. The simulation results confirm that DT-GPSR outperforms GPSR and PRoPHET in terms of the message delivery ratio and message delivery delay.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.386-391
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• 2019

This paper presents analysis results for the effect of the directional group delay of the antenna to implement a precision radio navigation system. The analysis was conducted through antenna simulation and test, and the test was performed in an anechoic chamber. The directional group delay of the antenna was calculated in phase-based analysis method. The results showed that a variation of up to 7.7ns in group delay occurred per antenna direction. The group delay variation from the analysis is 2.31 meters when converted into distance. It was tested using a real radio navigation system based on the time of arrival (TOA). The test verified the distance variation of 2.1 meters, and this value is similar to those obtained from the simulation and chamber test analysis.

• ETRI Journal
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• v.27 no.6
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• pp.798-801
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• 2005

This Letter proposes a scheme that supports a fast handover effectively in hierarchical mobile IPv6 networks (F-HMIPv6) by optimizing the associated data and control flows during the handover. By NS-2 simulation, we show that the proposed scheme can give better handover performance than a simple combination of existing schemes.