• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.1191-1194
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• 2007

이동 애드혹 네트워크 (MANET)는 기지국과 같은 인프라 없이 구성된 무선 네트워크로 멀티 홉 무선통신을 수행할 수 있다. MANET에서 경로 끊김이 발생하는 이유는 일반적으로 경로를 설정하고 있는 노드들의 이동이나 hidden terminal 과 같은 무선 채널 충돌 때문이다. 무선 채널 충돌처럼 노드들의 위상과 상관없이 패킷들의 충돌 때문에 경로 끊김이 발생하는 현상은 불필요한 경로 재설정이 유발된다. 그리고 이에 따른 제어 메시지의 과도한 생성은 전체 네트워크의 오버헤드를 증가시켜 성능 감소로 이어진다. 특히 일반적으로 MANET에서 사용하는 reactive 방식의 라우팅 프로토콜을 사용하는 네트워크에서는 더 많은 성능 감소가 일어나게 된다. 본 논문에서는 MANET의 이러한 불필요한 경로 재설정을 방지하여 자원을 보다 효율적으로 사용할 수 있는 노드 이동 감지 기법을 제안한다. 이 기법은 HELLO 메시지와 이웃 노드 테이블을 이용하여 무선 채널 충돌과 같은 현상을 예측하고 효율적으로 대처할 수 있게 한다. 성능 분석 결과, 본 논문에서 제안한 노드 이동 감지 기법이 기존 방법들에 비해 패킷 전송률과 라우팅 오버헤드 측면에서 우수한 성능 결과를 보였다.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.3
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• pp.55-70
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• 2016

The most critical research issue in MANET environment is on supporting reliable communication between various devices. Various Multi-Hop Routing Protocol studies have proceeded. However, some problems you might have found when you use the existing link state routing technique are that it increases Control Message Overhead and it is unstable when node moves in CR circumstance which has transformation of using channel and MIMC circumstance which uses a number of interfaces. This essay offers a technique which is based on On-Demand Hello and the other technique which used Broadcast Interface of optimization as a solution to decrease Control Message Overhead. Also it proposes Quick Route Restoration technique which is utilized by GPS and MPR Selection technique which consider mobility as a solution of stable communication when node moves. Those offered Routing Protocol and OPNET based simulator result will be expected to be an excellent comparison in related research fields.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3A
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• pp.287-295
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• 2010

In wireless sensor networks(WSNs), the studies that support sink mobility without global position information exploit a Backbone-based Virtual Infrastructure (BVI) which considers one-hop clusters and a backbone-based tree. Since the clusters of a sink and a source node are connected via flooding into the infrastructure, it causes high routing cost. Although the network could reduce the number of clusters via multi-level clusters, if the source nodes exist at nearest clusters from the cluster attached by the sink and they are in different branches of the tree, the data should be delivered via detour paths on the tree. Therefore, to reduce the number of clusters, we propose a novel multi-hop cluster based communication protocol supporting sink mobility without global position information. We exploit a rendezvous cluster head for sink location service and data dissemination but the proposed protocol effectively reduces data detour via comparing cluster hops from the source. Simulation shows that the proposed protocol is superior to the existing protocols in terms of the data delivery hop counts.

• The KIPS Transactions:PartC
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• v.15C no.4
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• pp.311-320
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• 2008

In general, routing algorithms that were applied to ad-hoc networks are not suitable for the environment with many nodes over several thousands. To solve this problem, hierarchical management to these nodes and clustering-based protocols for the stable maintenance of topology are used. In this paper, we propose the clustering-based modified LEACH protocol that can applied to an environment which moves around metal containers within communication nodes. In proposed protocol, we implemented a module for detecting the movement of nodes on the clustering-based LEACH protocol and improved the defect of LEACH in an environment with movable nodes. And we showed the possibility of the effective communication by adjusting the configuration method of multi-hop. We also compared the proposed protocol with LEACH in four points of view, which are a gradual network composition time, a reconfiguration time of a topology, a success ratio of communication on an containers environment, and routing overheads. And to conclude, we verified that the proposed protocol is better than original LEACH protocol in the metal containers environment within communication of nodes.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.257-264
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• 2012

In this paper, we propose a Route Stability-based Direction Guided Routing protocol(RSDGR) in mobile ad-hoc wireless networks. The main features and contributions of the proposed routing protocol are as follows. First, it can calculate link stability between two nodes as well as route stability of multi hop quantitatively by using nodes' mobility. And this protocol can establish the most stable path between a source node and a destination node. Second, according to the route stability between a source node and a destination node, it can control and optimize the direction guided region dynamically for route setup. Third, we suggest theoretical model for quantitative calculation of link stability between two nodes and route stability of multi hop path. The performance evaluation of the proposed routing protocol is performed by simulation using OPNET(Optimized Network Engineering Tool) and theoretical analysis. The results of performance evaluation show that the patterns of PDR are similar in simulation and analysis according to route stability. The faster mobile nodes' velocity and the smaller source node's direct guided reigion, the lower route stability and PDR and the higher delay and control overhead related to this.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.534-535
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• 2008

최근 유비쿼터스 기술이 급속도로 발전함에 따라 많은 application들이 다양한 환경에서 통신서비스를 요구하고 있다. 이를 지원하기 위하여 많은 무선 센서 네트워킹 기술들이 제안되었지만 제한된 대역쪽과 높은 에러율로 인하여 이동성을 지원하기에는 부족하였다. 특히, 경로를 획득하기 위한 Route Request (RREQ)의 잦은 브로드캐스트 과정은 오히려 혼잡 및 에너지 소모를 야기시키며 네트워크 성능을 저하시키는 문제점이 있다. 본 논문에서는 언제, 어디서나 다양한 토폴로지 환경에서 자가 구성이 가능하며, 이동성을 지원하는 Tree기반의 Self-Routing 기법을 제안한다. 기존의 센서 네트워크내 멀티홉 라우팅 프로토콜과는 달리, 라우터 혹은 싱크노드의 비컨 프레임내 Association 정보만을 이용하여 새로운 라우팅 테이블을 형성함으로써 컨트롤 패킷의 오버 헤드를 크게 줄일 수 있다. 성능 평가를 위하여 실제 모바일 로봇을 이용한 실험과 시뮬레이션을 동시에 하였으며, 기존의 기법보다 향상된 성능을 가짐을 보인다.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.879-884
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• 2024

Wireless sensor network technology is becoming increasingly important with the advancement of the Fourth Industrial Revolution. Consequently, various protocols such as LEACH, PEGASIS, and EEACP have been developed in an attempt to increase energy efficiency. However, the EEACP protocol still has room for improvement in terms of energy consumption during transmission. Particularly, inefficient paths associated with data reception settings may compromise the network's survivability. The proposed A-EEACP protocol optimizes data transmission direction around the sink node to reduce energy consumption and enhance the network's survivability.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.4
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• pp.118-129
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• 2008

This paper describes an IEEE 802.15.4-based hierarchical sensor network model for a VAWS(Vehicle Approach Warning System) which provides the drivers of vehicles approaching a sharp turn with the information about vehicles approaching the same turn from the opposite end. In the proposed network model, a tree-structured topology, that can prolong the lifetime of network is formed in a self-organizing manner by a topology control protocol. A simple but efficient routing protocol, that creates and maintains routing tables based on the network topology organized by the topology control protocol, transports data packets generated from the sensor nodes to the base station which then forwards it to a display processor. These protocols are designed as a network layer extension to the IEEE 802.15.4 MAC. In the simulation, which models a scenario with a sharp turn, it is shown that the proposed network model achieves a high-level performance in terms of both energy efficiency and throughput simultaneously.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.259-266
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• 2013

Since the wireless communications have a limited transmission, the devices just around a master node can exchange data. Though Bluetooth and Zigbee support ad hoc, they are not appropriate for real-time voice communications. In this paper, we present a TDMA-based relay protocol for several users to communicate simultaneously. The proposed protocol can relay data or voice to other nodes in real-time by the multi-hop transmission method using TDMA. And the proposed protocol improves the network performance by allocating different frequencies to the slaves depending on the routing path scheduled by the routing table. NS-2 simulation shows that the performance of the proposed protocol is good in terms of the transmission delay and pecket loss probability in the real-time voice transmission.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.6
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• pp.1089-1096
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• 2019

Recently, small-scale IoT services using a small amount of information through low-performance computing have been spread. It requires low cost, low-power, and long-distance communication technologies with wide communication radius, relatively low power consumption. This paper proposes a MAC layer and routing protocol that supports multi-hop transmission in small-scale IoT environment distributed over a large area based on LoRa communication and delivering a small amount of sensing data. The terminal node is mobile and the communication type provides bidirectional transmission between the terminal node and the network application server. By applying the proposed protocol, a production line monitoring system for smart factory was implemented. It was confirmed that the basic monitoring functions are normally performed.