• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.11
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• pp.69-76
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• 2008

Safety-related messages are propagated in form of broadcasting among vehicles in vehicle safety communication. There is the broadcast storm problem in high density vehicle environments. To solve this problem, a distance-based broadcast scheme has been proposed. It causes a serious problem such as retransmission delay in low density vehicle environments since it requires additional defer time to rebroadcast messages. This paper proposes a distance and random-based broadcast scheme. The proposed scheme selects a random time from zero to the defer time that estimated depending on the distance between sending and receiving vehicles. Simulation results show that the proposed scheme requires shorter defer time and less rebroadcasting message than existing schemes.

• Journal of KIISE:Information Networking
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• v.34 no.6
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• pp.423-434
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• 2007

Vehicular ad-hoc network (VANET), a kind of mobile ad-hoc network (MANET), is a key technology for building intelligent transportation system (ITS). VANET is automatically and temporarily established through vehicle-to-vehicle communication without network infrastructure. It has the characteristics that frequent changes of network topology and node density are occurred and messages are disseminated through several relay nodes in the network. Due to frequent change of network topology and node density, however, VANET requires an effective relay node selection scheme to disseminate messages through the multi-hop broadcast. In this paper, we propose a contention window based multi-hop broadcast scheme for VANET. Each node has an optimized contention window and competes with each other for a relay node. The experimental results show that the proposed scheme has a better performance than the distance-based deterministic broadcast scheme in terms of message propagation delay and network traffic.

• The KIPS Transactions:PartC
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• v.14C no.7
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• pp.571-582
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• 2007

Vehicular ad-hoc networks is temporarily established through inter-vehicle communication without any additional infrastructure aids. It requires a immediate message propagation because it mainly deals with critical traffic information such as traffic accidents. The distance-based broadcast scheme is one of the representative broadcast schemes for vehicular ad-hoc network. In this scheme, a node to disseminate messages is selected based on a distance from a source node. However, a message propagation delay will be increased if the relay nodes are not placed at the border of transmission range of the source node. In particular, when the node density is low, the message propagation delay is getting longer. In this paper, we propose a time-window reservation based relay node selection scheme. A node receiving the alert message from the source node has its time-window and randomly selects its waiting time within the given time-window range. A proportional time period of the given time-window is reserved in order to reduce the message propagation delay. The experimental results show that the proposed scheme has shorter message propagation delay than the distance-based broadcast scheme irrespective of node density in VANET. In particular, when the node density is low, the proposed scheme shows about 26% shorter delay and about 46% better performance in terms of compound metric, which is a function of propagation latency and network traffic.

• Proceedings of the Korean Information Science Society Conference
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• 2010.06d
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• pp.258-261
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• 2010

VANET(Vehicular Ad hoc NETwork)에서 차량간(V2V) 무선 통신을 통해 긴급 메시지를 빠르고 정확하게 전송하기 위하여 거리와 밀도를 기반으로 최적의 전송 대기시간을 계산하고, 이를 기반으로 중계노드를 선정하여 전송지연을 줄이는 멀티홉 브로드캐스트 기법을 제안한다. 제안한 기법을 통하여 밀도가 낮은 환경에서도 전송 지연 없이 전체 네트워크에 전송할 수 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.355-356
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• 2014

기존의 MANET 환경에서 동작하는 계층화된 데이터 전송 프로토콜은 각 계층이 독립적인 기능을 수행하기 때문에 노드의 이동 상황에 따라 변하는 네트워크 환경을 잘 반영하지 못하고 있다. 본 논문에서는 라우팅 계층과 MAC 계층 간의 상호 작용을 통하여 MANET의 2-홉 거리에 있는 노드 수를 반영하여 더 우수한 성능을 나타내는 Cross-Layer 모델 기반의 브로트캐스트 기법을 제안한다. 본 논문에서 제안하는 Cross-Layer 모델은 IEEE 802.11 MAC 프로토콜을 수정하여 이동 노드 주위의 상태에 따라 브로드캐스트 패킷을 적응적으로 전송하도록 동작한다.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.75-84
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• 2010

As broadcasting in Mobile Ad hoc NETwork (MANET) is the process that a node sends a packet to all other nodes in the network. it is used for routing protocols such as Ad hoc On demand Distance Vector (AODV) to disseminate control information for establishing the routes. In this paper, we propose Probabilistic Broadcasting mechanism based on Distance Ratio between sender and receive node in MANETs. The proposed approach is based on the combination of probability and distance based approach. A mobile node receiving broadcast packets determines the probability of rebroadcasting considering distance ratio from sender. The distance ratio of a node is calculated by the distance from sender and the length of radio field strength. As a node with high distance ratio is located far away from sender, rebroadcast probability is set to high value. On contrary, the low rebroadcast probability is set for a node with low distance ratio which is close to sender. So it reduces packets transmission caused by the early die-out of rebroadcast packets. Compared with the simple flooding and fixed probabilistic flooding by simulation, our approach shows better performances results. Proposed algorithm can reduce the rebroadcast packet delivery more than 30% without scanting reachability, where as it shows up to 96% reachability compared with flooding.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1780-1792
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• 2016

In this paper, we propose an efficient counter-based broadcast scheme for high reachability and energy efficiency. To achieve this, we propose a method to calculate additional coverage when a node receives the same broadcast message from both nodes, in order to rebroadcast by a node who can cover an large area. We also propose a formula to determine random access delay (RAD) considering addition coverage, distance, density, and remaining battery information, and a formula to determine count threshold ($C_{th}$) considering density and remaining battery information. In addition, we evaluate the performance of the proposed broadcast scheme compared with the existing counter-based broadcast schemes through simulation.

• Journal of the Korea Society of Computer and Information
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• v.14 no.12
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• pp.109-117
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• 2009

In this paper, we propose an efficient service discovery scheme that combines peer-to-peer caching advertisement and node ID-based selective forwarding service requests. P2P caching advertisement quickly spreads available service information and reduces average response hop count since service information store in neighbor node cache. In addition, node ID-based service requests can minimize network transmission delay and can reduce network load since do not broadcast to all neighbor node. Proposed scheme does not require a central lookup server or registry and not rely on flooding that create a number of transmission messages. Simulation results show that proposed scheme improved network loads and response times since reduce a lot of messages and reduce average response hop counts using adaptive selective nodes among neighbor nodes compared to traditional flooding-based protocol.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.3
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• pp.93-103
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• 2000

This paper describes Internet multicast routing protocols over MPLS (Multiprotocol Label Switching) networks. Internet multicast routing protocols are divided into 3 categories in terms of tree types and tree characteristics: a shortest path tree, a shared tree and hybrid tree types. MPLS should support various multicast mechanisms because of extremely different IP multicast architectures, such as uni-/bi-directional link, Flooding/prune tree maintenance mechanism, the existence of different tree types with the same group, etc. There are so many problems over MPLS multicast that the solutions can't be easily figured out. In this paper, we make a few assumptions on which the solutions of IP multicast routing protocols over MPLS networks are given. A broadcasting label is defined for the shortest path tree types. Cell interleaving problems of the shared tree types is solved by using block-based transmission mechanism. Finally, the existing hybrid-type multicast routing protocol is reasonably modified to support MPLS multicast.

• The KIPS Transactions:PartC
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• v.10C no.1
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• pp.77-86
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• 2003

This paper describes the new method for Internet multicast routing protocols using MPLS (Multiprotocol Label Switching) networks. Internet multicast routing protocols are divided into three categories in terms if tree types and tree characteristics : a shortest path tree a shared tree and hybrid tree types. MPLS should support various multicast mechanisms because of extremely different IP multicast architectures, such as uni-/bi-directional link, Flooding/prune tree maintenance mechanism. the existence of different tree types with the same group, etc. There are so many problems over MPLS multicast that the solutions can't be easily figured out. In this Paper, we make a few assumptions on which the solutions of IP multicast routing protocols over MPLS networks are given. A broadcasting label is defined for the shortest path tree types. Cell interleaving problems of the shared tree types is solved by using block-based transmission mechanism. Finally, the existing hybrid-type multicast routing protocol is reasonably modified Shortest Path tree type to support MPLS multicast. It has been shown that these modifications give better performance (transmission delay) than the orignal method.