• KIPS Transactions on Computer and Communication Systems
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• v.7 no.9
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• pp.227-234
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• 2018

Guaranteeing the end-to-end delay deadline is an important issue for quality of service (QoS) of delay sensitive systems, such as real-time system, networked control system (NCS), and cyber-physical system (CPS). Most routing algorithms typically use the mean end-to-end delay as a performance metric and select a routing path that minimizes it to improve average performance. However, minimum mean delay is an insufficient routing metric to reflect the characteristics of the unpredictable wireless channel condition because it only represents average value. In this paper, we proposes a deadline-aware routing algorithm that maximizes the probability of packet arrival within a pre-specified deadline for CPS by considering the delay distribution rather than the mean delay. The proposed routing algorithm constructs the end-to-end delay distribution in a given network topology under the assumption of the single hop delay follows an exponential distribution. The simulation results show that the proposed routing algorithm can enhance QoS and improve networked control performance in CPS by providing a routing path which maximizes the probability of meeting the deadline.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.41-46
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• 2011

Mobile Ad-Hoc networks (MANET) has been getting the spotlight in the area of the wireless networks because of its flexibility and salability, and developing of many applications with it. As a consequence, MANETs are required to process not only simple data traffics, but also multimedia traffics, which has some constraints on the performances. However, unlike wired-networks, the wireless networks have frequent route-disconnections due to some reasons such as channel errors and mobility. Such frequent link disconnections makes the delivery of multimedia traffics difficult. Even though there many researches on multimedia transmissions on various environments, the performances of multimedia transmissions over fading channel and mobility even using various routing protocols have not been evaluated. Therefore, this paper extensively simulates the MPEG-4 video transmission over fading channel environment with node's mobility. In addition, the performances with two routing protocols such as AODV and DSR are compared. Finally, the simulation results shows that DSR protocol has the better performances to deliver MPEG-4 traffic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3A
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• pp.290-296
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• 2007

We propose new routing scheme, Cooperative Diversity-based Routing (CDR) which utilizes the cooperative space diversity for power saving and performance enhancement of wireless ad-hoc networks. The improved performance is compared with Multi-hop Relay Routing (NRR) by analytical methods. When the required outage probability is $1\times10^{-3}$ at the destination node in ad-hoc networks with 7 nodes, we noticed that each node can save power consumption by 15.5 dB in average, by using our proposed CDR compared to MRR.

• Journal of Aerospace System Engineering
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• v.11 no.6
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• pp.1-9
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• 2017

The ICS, Intercom is the equipment which mixes and distributes the audio signal from other LRUs and plays the Voice Messages. Henceforth, it is of immense contributory importance to the pilots. Especially, the audio routing, which controls On/Off mode of each audio channel, is significant in executing a pilots' mission. But the audio routing process is quite complicated as it has the interface combination of many control signals. Underthecondition, the exceptional handling becomes difficult, which decreases maintainability and productivity. In the present work, to prevent such a situation, the author suggests amethodology,whichwillhavealower impact when the software is changed and provides high maintainability and productivity for audio routing processing.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.249-258
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• 2013

In multi-hop ad hoc networks, multi-interface multi-channel architecture is being noticing as methodology to improve the effective bandwidth and end-to-end throughput, But since existing routing metrics designed for networks based on single-interface exactly can not reflects the nature of networks based on multi-interface multi-channel, we are not expected the effect of throughput improvement. there had been proposal of MCR that discover high throughput by using metrics such as channel diversity and interface switching cost. however, MCR have an problem that is degraded it's performance in congested networks, because it not reflects the impact of traffic load. in this paper, we propose MAMCR metric, which select high throughput paths under congested conditions by combination MCR with channel access time metric, and conform it's the effect of performance improvement by ns-2 simulation.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.268-270
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• 2001

현재 ad hoc의 연구 방향은 무천 기반의 패킷 라우팅에 관련된 것이 대부뿐 이러 네트워크 토폴로지 생성에 대한 연구는 거의 진행된 것이 없다. 현재 대부분의 ad hoc 네트워크는 대표적인 싱글 채널 방식인 broadcast 기반의 무선 미디어 방식을 물리적 계층을 사용하며, 이를 기반으로 이동 노드의 무선 범위 제한을 극복하기 위한 형태로 네트워크 토폴로지를 형성한다. 블루투스(B1uetooth)는 frequency hopping(FH) 방식을 사용하므로 연결 설정 과정에서 동기화 과정이 반드시 요구되며, ad hoc 네트워크을 형성을 위해 다중 채널을 사용한다. 따라서 블루투스와 같이 다중 채널을 물리적 계층으로 사용하는 네트워크에서는 싱글 채널 방식과 달리 명시적으로 토폴로지를 형성하기 위한 메커니즘이 요구된다. 본 논문에서는 다중 채널과 블루투스가 탑재된 노드의 이질적 특성을 고려한 스캐터넷(Scatternet) 구성 메커니즘을 제안한다. 본 메커니즘은 칵 노드의 전력 상태와 이동성 정보를 바탕으로 스캐터넷의 마스터와 브리지 노드틀 선택 함으로서 효율적인 네트워크 토플로지를 구성한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.885-888
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• 2008

무선 센서 네트워크 라우팅 프로토콜에서의 경로탐색에서 중복 브로드캐스트 메시지에 의한 비용이 증가되고, 많은 노드들이 동시에 통신을 시도하기 때문에 많은 충돌이 발생한다. 이러한 문제를 해결하기 위해 본 논문에서는 Directed Diffusion 라우팅 방법에 지향성 안테나를 도입하여 채널 이용율을 높여 통신에서의 충돌을 줄이고 네트워크 구성 및 유지 시 사용될 flooding의 범위와 노드간의 통신시 불필요한 방향으로의 통신을 최소화하여 중복되는 브로드캐스트 메시지 수를 줄일 수 있는 라우팅 방법을 제안한다.

• Journal of Advanced Navigation Technology
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• v.18 no.3
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• pp.236-241
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• 2014

In a mobile ad hoc networks, multi-hop transmission is used to transfer data from source node to destination node and the routing protocol is the one of the important technical issues. The links between nodes can be unstable due to the changes of node location and channel conditions, and it can induce link error. To solve this problem, multipath routing was proposed. Multipath routing can reduce the data congestion and increase data throughput. In the multipath routing, however, each path can be interfered by the other path, and it can aggravate network performance. In this paper, we propose the multipath routing technique in the multi-rate MANET. The proposed multipath routing can avoid interference without the knowledge of node location. Simulation results show that the proposed multipath routing can reduce transmission delay and error.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2422-2429
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• 2013

WMN is considered as a core methodology to provide mobile wireless network service with multi-hop routing feature. It has a merit that can be easily deployed by utilization of protocols for MANET. However, it has differences in supporting multiple networks and channels, network architecture, and so on. Especially, in case of routing protocols, to apply them intactly to WMN can be a cause of low performance because of do not moving mesh routers. AODV seems like suitable for WMN among the various routing protocols for MANET. However, it has a defect in scalability. In this paper, an enhanced AODV routing method for WMN was proposed. The proposed method was designed to be suitable to the architecture of WMN by use of layering and localizing the broadcasting domain.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.6
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• pp.1077-1082
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• 2009

Wireless Mesh Network(WMN) is wireless backbone networks technique which has ease of network configuration and cost of advantage. Recently, WNM released a new product, but most of existing research and technology analysis the performance through the simulation. This paper build the wireless mesh network testbed for actual situation. Testbed supports multi-channel multi-interface using bridge, the Wireless Distribution System and dynamic location-based routing protocol. This routing protocol strongly design against wireless interference using metric for link channel change and real distance. Then, the address of mesh clients assigned by the centralized address management server. Mesh clients is designed and implemented to manage network through Simple Network Management Protocol.