• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2A
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• pp.165-173
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• 2010

WMN(Wireless Mesh Network) is an wireless backbone network technology that is an easily configurable network in the low cost compared to the wireless LAN(Local Area Network). Most of the previous researches have evaluated their algorithms by the simulations rather than by the implementation. There exist some implementation papers, however, they have the limitations of the flexibility on the link establishment and the link quality utilization. Consequently, the benefit of the WMN - configuration flexibility is degraded and the performance deterioration occurs in the multi-hop wireless environment. In this paper, we introduce a Linux-based link layer Wireless Mesh Routing System - WBMR. The design and implementation of WBMR provides the dynamic link establishment and the effective multi-channel usage. We have modified the ntroof the original WLAN operation for the dynamic link establishment, and the Linux bridge for the link layer routing. The result of performance evaluation verifies that our WBMR supports fast self-configuration and increases data transmission throughput compared to the other researches of the wireless multi-hop environment.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.41-42
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• 2015

본 논문에서는 다수 1 차 사용자가 다수 존재하고 2 차 사용자들이 다중 홉 통신을 하는 스펙트럼 공유 방식 무선 인지 네트워크를 분석한다. 다수의 1 차 사용자로부터의 간섭신호를 고려하여 각 2 차 사용자에서의 수신 신호대간섭잡음비를 분석하고 이를 바탕으로 2 차 사용자 네트워크의 불능확률을 구한다. 모의실험을 통해 1 차 사용자의 수가 감소함에 따라 불능확률이 감소한다는 것을 확인하였다.

• The KIPS Transactions:PartC
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• v.14C no.7
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• pp.583-588
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• 2007

It is easy to implement a temporary network with a mobile ad-hoc network in which mobile nodes have without using a infrastructure network. They depend on their limited power. Recently, it is a hot issue to save the energy in a mobile ad-hoc network because a mobile nodes have a limited energy. Research of IEEE 802.11 PSM was proposed in a single hop ad-hoc assumption. If IEEE 802.11 PSM is applied to multi hop ad-hoc network, non-optimal paths will be generated by the mobile nodes which didn't receive a message of routing request. Non-optimal paths increase not only a network latency but also energy consumption of mobile nodes. Reconfiguring algorithm of non-optimal paths caused by the mobile nodes which didn't receive a message of routing request is proposed in this paper. A mobile node can overhear the data in his range. A wireless medium is shared by all mobile nodes using the same bandwidth. All mobile nodes lookout the non-optimal paths with these properties of a medium, if non-optimal path is generated, optimal reconfiguring will be accomplished by modifying routing table of itself or sending a request message of routing update to nearby nodes. By reconfiguring the non-optimal paths to optimized ones, network latency and energy consumption was decreased. It is confirmed to ignore the overhead caused by a algorithm presented in this paper through the result of the simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.977-985
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• 2012

Recently, many countries have been developing new protocols to improve the performance of tactical ad hoc networks for implementing NCW (Network Centric Warfare). Combat net radio (CNR) networks are the most important communication infra for the ground forces such as infantry of Army. U.S. Army had developed MIL-STD-188-220D that is the Interoperability Standard for DMTDs (Digital Messages Transfer Device Subsystems) for voice and data communication in CNR. MIL-STD-188-220D is a candidate for MAC protocol of TMMR which is next radio and has a few constraints to used in TMMR. NAD (Network Access Delay) defined in MIL-STD-188-220D needs time synchronization to avoid collision. However, it is difficult for time synchronization to fit in multi-hop environment. We suggest the enhanced DAP (Deterministic Adaptable Priority)-NAD to prevent conflicts and decrease delays in multi-hop CNR. Simulation results show that the proposed scheme improves the performance in multi-hop CNR networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.1
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• pp.57-62
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• 2014

The benefits of infrastructure support are shown by analyzing a throughput scaling law of an erasure network in which multiple relay stations (RSs) are regularly placed. Based on suitably modeling erasure probabilities under the assumed network, we show our achievable network throughput in the hybrid erasure network. More specifically, we use two types of physical models, a exponential decay model and a polynomial decay model. Then, we analyze our achievable throughput using two existing schemes including multi-hop transmissions with and without help of RSs. Our result indicates that for both physical models, the derived throughput scaling law depends on the number of nodes and the number of RSs.

• The Journal of the Korea Contents Association
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• v.8 no.1
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• pp.177-185
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• 2008

Research on media access control (MAC) scheme for Wireless Sensor Network (WSN) has been mainly focused on energy efficiency improvement, while interest on latency is relatively weak. However, end-to-end latency could be a critical limitation specifically in the multi-hop network such as wireless multimedia sensor networks. In this paper we propose a media access control scheme with distributed transmission power control to Improve end-to-end transmission latency as well as reduce power consumption in multi-hop wireless sensor networks. According to the simulation results, the proposed scheme is turned out to be an energy efficient scheme with improved end-to-end transmission latency.

• The KIPS Transactions:PartC
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• v.15C no.4
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• pp.289-296
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• 2008

In wireless mesh network, studies on routing protocols have been actively carried out recently, and hop count is used as a major routing metric in destination-sequenced distance-vector (DSDV) routing protocol, which is a representative proactive routing protocol. Although hop-by-hop multi-path (HMP) DSDV and enhanced HMP (EHMP) DSDV routing protocols perform routing by considering both hop count and residual bandwidth within one hop distance nodes, it has a shortcoming that routing is carried out via non-optimal path from the aspect of end-to-end routing. In order to overcome the shortcoming, a cost-aware multi-path (CAMP) DSDV routing protocol is proposed in this paper, which considers hop count and end-to-end minimum residual bandwidth. Simulation results based on NS-2 show that the proposed routing protocol performs better than DSDV, HMP DSDV, and EHMP DSDV protocols from the aspect of throughput and packet delivery ratio, by appropriately using hop count and end-to-end minimum residual bandwidth information and has the same number of management messages with HMP DSDV and EHMP DSDV protocols.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.12
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• pp.447-454
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• 2016

The research on multipath routing has been studied to solve the problem of frequent path breakages due to node and link failures and to enhance data delivery reliability in wireless sensor networks. In the multipath routing, mobile sinks such as soldiers in battle fields and rescuers in disaster areas bring about new challenge for handling their mobility. The sink mobility requests new multipath construction from sources to mobile sinks according to their movement path. Since mobile sinks have continuous mobility, the existing multipath can be exploited to efficiently reconstruct to new positions of mobile sinks. However, the previous protocols do not address this issue. Thus, we proposed an efficient multipath reconstruction protocol called LGMR for mobile sinks in wireless sensor networks. The LGMR address three multipath reconstruction methods based on movement types of mobile sinks: a single hop movement-based local multipath reconstruction, a multiple hop movement-based local multipath reconstruction, and a multiple hop movement-based global multipath reconstruction. Simulation results showed that the LGMR has better performance than the previous protocol in terms of energy consumption and data delivery delay.

• Electronics and Telecommunications Trends
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• v.32 no.4
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• pp.67-77
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• 2017

최근 이슈가 되고 있는 자율주행차(Autonomous vehicle 또는 Self-driving car)를 실현하기 위해서는, 다양한 환경에서도 차량에 대한 끊김 없는 연결을 제공하는 커넥티드카(Connected car) 기술이 필수적이다. 현재 커넥티드카를 구현하기 위한 차량 네트워크(Vehicular network) 기술은 교통시스템 인프라 기반의 단일홉(Single-hop) 무선통신 기술이 주를 이루고 있다. 이러한 단일홉 통신은 커버리지가 교통시스템 인프라가 구축된 지역으로 제한된다. 따라서 차량 네트워크가 현재보다 더욱 넓은 지역을 커버하기 위해서는 차량 자체가 이동형 라우터 역할을 수행하여 차량 간의 전달을 통해 정보를 원거리로 전달할 수 있는 다중홉(Multi-hop) 통신 도입이 필요하다. 다중홉 차량 네트워크는 차량의 높은 동적 특성으로 인해 다수의 도전적인 기술적 이슈들을 가진다. 본고에서는 이러한 기술 이슈 중 차량 네트워크의 높은 이동성으로 발생할 수 있는 종단 노드 간 비연결성을 해결할 수 있는 기술인 지연감내형 차량 네트워킹(Delay-tolerant vehicular networking) 기술에 대한 주요 연구 동향을 살펴보고자 한다. 이를 위해 먼저 지연감내형 차량 네트워킹의 기술적 배경 및 주요 관련 기술들을 분석하고 이를 기반으로 향후 연구개발이 필요한 기술 이슈들을 정리한다.

• Journal of Advanced Navigation Technology
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• v.20 no.3
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• pp.182-189
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• 2016

In this paper, we propose a buoy system based on multi-hop relay networks for ocean observation. The proposed system consists of various sensor modules, a gateway, wireless communication modules, and a remote monitoring site. The sensor modules are integrated with various communication interfaces and connected to the gateway of the proposed buoy system with an unified protocol based on controller area network (CAN)-bus. In order to communicate with the remote monitoring site and extend the coverage, the proposed system uses long-term evolution (LTE) router and XBee mesh network modules. The field test results show that the proposed system can extend the coverage using the proposed multi-hop relay network.