• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.9
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• pp.741-749
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• 2012

Ad Hoc Self-Organizing TDMA (ASO-TDMA) has been proposed as a specification to support the multi-hop data communication service for ships over VHF band. It allows for organizing a multi-hop ad-hoc network in a distributed manner by sharing the radio resources among the ships navigating along the route. In this paper, Markov chain analysis is given to provide the average throughput performance for ASO-TDMA protocol Furthermore, the analytical results are verified with computer simulation, which shows that there exists the optimal transmission rate to maximize the average throughput as the subframe size and the number of ships are varying in each hop region.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.906-912
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• 2012

A ship ad-hoc network (SANET) can provide ships with diverse multimedia services by replacing expensive satellite communications. While ITU-R M. 1842-1, standards for maritime VHF band digital communications, can be used as the specifications of physical layer for SANETs, no standards are specified for higher layers of SANETs. In this paper, we propose a ship ad-hoc communication (SAC) protocol for SANETs, based on medium access control (MAC) and routing protocols for terrestrial ad-hoc networks. SAC protocol is a cross-layer protocol which combines MAC and routing into one algorithm and considers maritime environments, including the existence of neighboring ships, the possibility of routing to a destination, and changing the communication mode in case of VHF channel failure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.2
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• pp.179-192
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• 2019

Additional frequencies are allocated in maritime digital data exchange to alleviate overload of the VHF data link. The shipborne ad-hoc network (SANET) for this frequencies was subsequently proposed, which provides various IP-based services to ships on behalf of satellite communications. In SANET, a ship should determine its own IP address to achieve IP connectivity to the shore. Accordingly, this paper proposes a SANET configuration (SANETconf) protocol as an IP configuration protocol. SANETconf propagates non-overlapping IP addresses across the network from the shore to ships. A ship obtains its IP address by exchanging Request and Response messages with its neighbors. Therefore, SANETconf eliminates the process of DAD and managing the movement of ships. Extensive simulations were performed to verify the applicability of SANETconf. Based on results, 85% of the ships can determine their own IP address within one frame. Also, SANETconf has a high resource efficiency by using 0.024 percent of resources for IP configuration.

• The Magazine of Kiice
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• v.12 no.2
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• pp.25-29
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• 2011

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.5
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• pp.775-784
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• 2008

It is not easy to access very high speed Internet services at sea due to some technical and economical problems. In order to realize the very high speed Internet services at sea like on land, new communication network models based on MANET should be adopted. In this paper, a new MANET model at sea is provided, which considered the ocean environments, and the characteristics and movement of vessels. On the basis of the fact that most vessels navigate on the predetermined courses, which are the shortest paths between source and destination ports in most cases, a type of location oriented routing protocol is proposed in this paper. The Hybrid Course-Based Routing Protocol(HCBR) makes use of the static information such as courses and positions of ports to proactively find the shortest paths not only among ports but also the cross points of courses. HCBR also makes use of the locational information of vessels obtained via GPS and AIS systems to reactively discover the shortest route by which data packets are delivered between them. We have simulated the comparison of the performance of HCBR with those of LAR scheme 1 and scheme2, the most typical protocols using geographical information. The simulation results show that HCBR guarantees the route discovery even without using any control packet. They also show that HCBR is more reliable(40%) and is able to obtain more optimal routes(10%) than LAR scheme1 and scheme2 protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.6
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• pp.681-688
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• 2016

Several VHF bands for the use in analog communications has been changed to those for the use in new maritime digital communications by WRC-12. ITU-R M. 1842-1 has been also standardized, recommending the characteristics of maritime digital communication systems. In addition, a Shipborne Ad-hoc Network (SANET) has been introduced by IMO in order to provide ships, which cannot be connected to a shore directly, with maritime digital data exchange services with the help of ad-hoc communication. In this paper, several functionalities of the SANET, including channel access, route determination to a shore, and data exchange, are verified via sea trials. It is expected that the SANET can be applicable to collecting and analyzing maritime information, facilitating the entry and departure of vessels, and the communication infrastructure of e-navigation.

• Journal of KIISE:Information Networking
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• v.35 no.6
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• pp.521-528
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• 2008

Such conventional maritime communication technologies as radio have short some comings in their transmission quality. It can be overcome by wireless channels provided by satellites such as INMARSAT, which nevertheless suffer from the high costs. In this paper, we propose a novel technology resolving the above problems, featuring in the establishment of maritime communication networks with multi-hop structures. The inter vessel and ship-to- shore networks previously modeled after MANET are remodeled by SANET (Ship Ad Hoc Networks) in the present work. Fan-shaped Search Zone Routing (FSR) protocol also is presented, which utilizes not only static geographical information including the locations of ports and the navigations of courses but also the unique characteristics of ships in terms of mobile nodes. The FSR finds the fan-shaped search zone on which the shortest path is located. The performance of LAR protocol is compared with that of FSR in several ways. First, FSR does not make use of a type of control packets as beaconing data, resulting in a full utilization of the bandwidth of the wireless channels. Second, the delivery rate by the FSR is 100% for the fan-shaped search zone includes at least one route between source and destination nodes on its border line, where as that of LAR has been turned out to be 64%. Third, the optimality of routes searched by the FSR is on a 97% level. Of all, the FSR shows a better performance than LAR by about 50%.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1269-1277
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• 2008

Ships at sea cannot exchange data among them easily so far. Basically voice-oriented communication systems are the main methods, some of them utilize the HF radio systems at lower bit rates, and for higher bit rates, the Inmarsat or VSAT are adopted. None of them are used widely because of lower qualities and higher costs. There exist many technical and economical limits to have the Internet service just like on land such as the WWW service. In order to achieve the improved transmission rates of the maritime communication networks at farther sea, MANET(Mobile Ad Hoc Network) is one of the most practical models. In this paper, a new routing protocol named EZR (Expansive Search Zone Routing Protocol) is proposed, which is based on SANET (Ship Ad Hoc Network) model that has some different features from MANET and VANET (Vehicular Ad Hoc Network). The search zone for the shortest path is firstly found by EZR. If no path is searched in the zone, the zone is expanded according to the rule of EZR. The zone-expanding and path-searching procedures are repeated until the path is found out. The performance of EZR is evaluated and compared with LAR protocol which is one of the most typical routing protocols based on geographical information. The simulated results show that EZR is much better than LAR at sea environments in terms of routing success rate, route optimality, and a single index of performance combined the previous two metrics.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.477-479
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• 2012

최근 선박의 사고가 증가하고 해양 환경오염 문제가 대두되면서 운항 중인 선박을 대상으로 하는 다양한 안전운항 솔루션에 대한 필요성이 요구되고 있다. 안전운항 솔루션은 일반적으로 육상과 선박을 연결하는 광대역 무선 데이터 통신기술, 해상 데이터를 처리할 수 있는 메타데이터 기술, 안전운항을 지원하는 서비스의 요소 기술로 구성된다. 본 논문에서는 광대역 애드혹 통신망을 기반으로 하는 선박의 안전 입출항 지원 서비스의 항목을 정의하고, 이를 구현하기 위한 서버 및 클라이언트 시스템에 대하여 기술한다. 본 연구의 안전 입출항 지원 서비스는 교통정보, 환경정보, 충돌회피지원정보로 구성되며, 선박에 탑재된 클라이언트에서 육상에 설치된 서버 시스템으로 서비스를 요청하고 정보를 제공 받도록 설계하였다. 이렇게 설계된 시스템은 테스트 플랫폼을 통해 서비스의 구현 가능성을 검토하며, 실해역(여수항)에서의 시험을 통해 그 실효성을 검증할 예정이다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.06a
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• pp.343-345
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• 2013

해양사고가 증가하고 이에 따른 피해가 늘어남에 따라 선박의 안전항해에 대한 관심이 높아지고 있으며, 해양사고에 대한 규제 및 사고 방지를 위한 기술 개발이 활발하게 진행되고 있다. 선박의 안전 입출항 지원 서비스는 일반적으로 육상과 선박을 연결하는 광대역 무선 데이터 통신기술, 해상 데이터를 처리할 수 있는 메타데이터 기술, 안전운항을 지원하는 서비스의 요소 기술로 구성된다. 본 논문에서는 광대역 애드혹 통신망을 기반으로 하는 안전 입출항 지원 시스템 및 서비스를 정의하고, 이를 시험하기 위한 시뮬레이터 시스템에 대하여 기술한다. 안전 입출항 지원 시스템은 선박에 탑재된 클라이언트에서 육상에 설치된 서버 시스템으로 서비스를 요청하고 해당 정보를 제공 받도록 설계 되었으며, 선박운항 시뮬레이터를 기반으로 하는 테스트 플랫폼을 이용하여 서비스의 구현 가능성을 검토하며, 향후 실 해역 실험을 통해 그 실효성을 검증할 예정이다.