• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.12
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• pp.1186-1194
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• 2012

In order to resolve the energy efficiency in wireless sensor networks, a multihop transmission technique is utilized. However, multihop transmission in wireless sensor networks (WSN) has pros and cons. It reduces total energy consumption, while it may cause a severe decrease in network lifetime. To solve this problem, we suggest the so called strike and bargaining algorithm (SBA). The routing path is determined by wages of nodes. Each node negotiates its wage with their neighbor nodes and determine a reasonable value to reach a optimally balanced point. By analysis and simulations, we show SBA can achieve a near optimal solution.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.156-160
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• 2007

본 연구는 무선 메쉬 네트워크에서 균형적 네트워크 부하분산 휴리스틱을 제안한다. 다수의 무선 라우터가 다중홉으로 구성되어있는 무선 메쉬 네트워크는 유선망과 연결되어 있는 gateway 역할을 하는 무선 라우터 쪽으로 과부하가 걸리기 쉽다. 이 같은 상황은 추가적으로 발생하는 서비스 요구사항을 충족시켜줄 수 얼을 확률이 높아 전체 네트워크 성능저하를 야기 시킨다. 본 연구는 다수의 도메인으로 구성된 무선 메쉬 네트워크에서 gateway 무선 라우터로 몰리는 네트워크 부하의 균형을 달성하는 부하분산(Load Balancing) 기법을 소개하고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.304-306
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• 2005

이동 애드혹 네트워크(Mobile Ad Hoc Network: MANET)는 유선 인프라 없이 구축된 무선 네트워크로 멀티 홉 통신을 수행할 수 있다. 인터넷 노드와 통신하고자 하는 MANET 노드에게 인터넷 연결을 가능하게 하는 방법이 요구되며 인터넷 연결은 인터넷과 MANET을 중계하는 인터넷 게이트웨이를 통해 지원된다. 게이트웨이들 간의 부하를 잘 분배한다면 네트워크 성능 향상을 얻을 수 있으므로, MANET 내에 여러 개의 인터넷 게이트웨이가 존재할 경우 이들 간의 부하균등화는 중요한 이슈이다. 본 연구에서는 부하균등화 기법을 제어 메시지의 플러딩 방법과 인터넷 게이트웨이를 선택하는 주체에 따라 4가지로 분류하며, 부하균등화 문제를 해결하기 위한 새로운 메트릭(metric)을 제안한다. 시뮬레이션을 통하여 홉 수와 라우팅 엔트리의 수를 메트릭으로 이용하는 새로운 기법의 성능이 기존 기법에 비하여 향상되었음을 보인다.

• Journal of Korea Society of Industrial Information Systems
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• v.10 no.2
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• pp.13-20
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• 2005

An ad hoc wireless networks forms temporary network without the aid of fixed networks or centralized administration with a collection of wireless mobile hosts. In this case, it is necessary for one mobile host to enlist the aid of other hosts in forwarding a packet to its destination. This paper presents an efficient cluster-based routing protocol scheme for ad hoc networks. The cluster is used for path setup and data delivery. Our cluster-based routing algorithm is designed for the improvement of the load balance. Our simulation results show the improved performance for low mobility networks comparing with the previous works.

• Journal of Digital Convergence
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• v.10 no.9
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• pp.289-295
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• 2012

Routing technique of wireless sensor network that is presented to improve effectiveness of consumption in energy at the previous study is existing in various ways, however for routing, its own location data and nodes' location data close to with 1-hop distance should be kept. And it uses multi-hop transmission method that transmits data to BS node via several nodes. This technique makes electronic consumption of sensor node and entire network's energy consumption so that it makes effective energy management problem. Therefore, this paper suggests location based 1-hop routing technique of BS node that satisfies distance $d{\pm}{\alpha}$ with source node using RSSI and radio wave range of sensor node.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.3
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• pp.440-448
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• 2021

This paper presents problems of network technology in smart grid and implements a blockchain-based LoRa multi-hop network to solve them. Since some smart grid applications are operated in harsh environments, it is difficult to establish communication infrastructure. We propose a LoRa network with multi-hop using the Flooding routing protocol. Smart grid environment composes an independent network using various power grid protocols depending on the application. Since this has a problem that an independent infrastructure must be established for each network, a single gateway device supports multiple power grid protocols to implement a method for network integration. Lastly, the author applied Hyperledger-based blockchain to the LoRa network to ensure the integrity of data in a smart grid environment, and strengthened security by physically distributing it. After constructing the three suggestions on the actual test bed, we confirmed that the network operates normally through experiments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.163-168
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• 2010

In this paper, we propose novel two-way relaying scheme in which number of two users transmit the signal to number of two destination. The scheme is difference with conventional multi-hop two-way relay scheme in which number of two users exchange the each signal. In the conventional scheme, each user have to perform back-propagating self-interference method to remove the own signal from received signal. It occurred to increase the complexity for signal processing at the user. To overcome the problem, we apply the Pre-cancellation which can reduce the process of back-propagating self-interference to our proposal network Simulation result show that proposal scheme outperform the convention multi-hop two-way relay scheme. Also we analysis the trad-off between performance and complexity accordance with using Pre-cancellation method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11B
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• pp.1030-1037
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• 2008

This paper presents an algorithm for the path-finding problem in unknown environments with cooperative and commutative multi-robots. To verify the algorithm, we investigate the problem of escaping through the exit of a randomly generated maze by muti-robots. For the purpose, we adopt the so called frontier cells and cell utility functions, which were used in the exploration problem for the multi-robots. For the wireless communications among the mobile robots, we modify and utilize the so called the random basket routing, a kind of hop-by-hop opportunistic routing. A mobile robot, once it finds the exit, will choose its next action, either escape immediately or stay-and-relay the exit information for the others, where the robot takes one action based on a given probability. We investigate the optimal probability that minimizes the average escaping time (out of the maze to the exit) of a mobile robot.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7A
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• pp.646-653
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• 2010

This paper provides a unified framework for the joint optimal subchannel and power allocation in multi-hop relay network, where each node in the network has multiple parallel subchannels such as in OFDM or MIMO system. When there are multiple parallel subchannels between nodes, the relay node decides how to match the subchannel at the first hop with the one at the second hop aside from determining the power allocation. Joint optimal design of subchannel matching and power allocation is, in general, known to be very difficult to solve due to the combinatorial nature involved in subchannel matching. Despite this difficulty, we use a simple rearrangement inequality and show that seemingly difficult problems can be efficiently solved. This includes several existing solution methods as special cases. We also provide various design examples to show the effectiveness of the proposed framework.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.455-462
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• 2009

In this paper, we propose a buffer management scheme for decreasing the packet loss due to buffer overflow and improving the packet fairness between nodes in IEEE 802.11 based multi-hop mesh networks. In the proposed scheme, each mesh router that is an intermediate node receives fairly packet sent from neighboring mesh routers and mobile nodes, and it improves the reception ratio of multi-hop traffic of neighboring mesh routers. Therefore, the proposed scheme can reduce transmission delay and energy consumption. In order to improving the packet loss and the packet fairness, the proposed scheme uses the modified RTS/CTS under the IEEE 802.11 MAC protocol and reduces the packet loss by recognizing the packet size to send to the destination in advance. By using the simulation, we evaluated the proposed scheme in terms of the packet loss ratio and the number of received packet in each mesh router, and compare it to a traditional scheme.