• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.2
• /
• pp.49-56
• /
• 2011

One of the most important VANET applications is providing active safety by broadcasting emergency messages. In order to prevent broadcast storm of flooding-based broadcasting scheme in which any node receiving message will rebroadcast, the existing protocols use the different methods to limit the number of relay nodes. Nevertheless, the existing protocols have low delivery ratio with high traffic density and cause message overhead. Currently, the dramatic increase in the number of vehicles equipped with Global Positioning System (GPS) and onboard radar created new application scenarios that were not feasible before. Consequently, we proposed a broadcasting protocol that selects relay node by using GPS-based position information and detecting neighboring vehicles with the help of onboard radar to. Simulation results show that our proposed protocol has better performance than the existing schemes.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.4
• /
• pp.252-258
• /
• 2013

As WSN is energy constraint so energy efficiency of nodes is important. Because avoiding long distance communication, clustering operating in rounds is an efficient algorithm for prolonging the lifetime of WSN and its performance depends on duration of a round. A short round time leads to frequent re-clustering while a long round time increases energy consume of cluster heads more. So existing clustering schemes determine proper round time, based on the parameters of initial WSN. But it is not appropriate to apply the round time according to initial value throughout the whole network time because WSN is very dynamic networks nodes can be added or vanished. In this paper we propose a new algorithm which calculates the round time relying on the alive node number to adapt the dynamic WSN. Simulation results validate the proposed algorithm has better performance in terms of energy consumption of nodes and loss rate of data.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.11 no.3
• /
• pp.181-188
• /
• 2011

With the rapid proliferation of wireless networks and mobile computing applications, the landscape of the network security has greatly changed recently. Especially, Vehicular Ad Hoc Networks maintaining network topology with vehicle nodes of high mobility are self-organizing Peer-to-Peer networks that typically have short-lasting and unstable communication links. VANETs are formed with neither fixed infrastructure, centralized administration, nor dedicated routing equipment, and vehicle nodes are moving, joining and leaving the network with very high speed over time. So, VANET-security is very vulnerable for the intrusion of malicious and misbehaving nodes in the network, since VANETs are mostly open networks, allowing everyone connection without centralized control. In this paper, we propose a weighted intrusion detection method using rough set that can identify malicious behavior of vehicle node's activity and detect intrusions efficiently in VANETs. The performance of the proposed scheme is evaluated by a simulation study in terms of intrusion detection rate and false alarm rate for the threshold of deviation number ${\epsilon}$.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.40 no.12
• /
• pp.2392-2400
• /
• 2015

Zigbee, which was a representative standard technology for dealing low energy and mesh networks in large deployment area such as smart home, smart building, and massive sensor networks, has been developed and deployed for increasing communication area by using Ad hoc method. It has been originally developed based on IEEE 802.15.4 standard so every node needs 48bit unique address defined by IEEE. However, it is absolutely inefficient to assign an unique address to every communication node where it would be deployed through large-scale network area, e.g., smart lighting and massive sensor networks, because there could be variously multiple companies to deploy network infrastructure and they could have different policy to assign node ID. To prevent the problem, this paper proposes a method of dynamic PANID assignment in overall Personal Coordinators, and also proposes a method for addressing PANID conflict problem which could be derived from dynamic PANID assignment.

• Journal of KIISE
• /
• v.42 no.6
• /
• pp.791-800
• /
• 2015

In this paper, we propose the contribution-level-based opportunistic flooding in a wireless multihop network which achieves outstanding transmission efficiency and reliability. While the potential of the the predetermined relay node to fail in its receipt of broadcast packets is due to the inherent instability in wireless networks, our proposed flooding actually increases network reliability by applying the concept of opportunistic routing, whereby relay-node selection is dependent on the transmission result. Additionally, depending on the contribution level for the entire network, the proposed technique enhances transmission efficiency through priority adjustment and the removal of needless relay nodes. We use the NS-3 simulator to compare the proposed scheme with dominant pruning. The analysis results show the improved performance in both cases: by 35% compared with blind flooding from the perspective of the transmission efficiency, and by 20~70% compared to dominant pruning from the perspective of the reliability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.12
• /
• pp.3675-3681
• /
• 2009

One of the most important factors in the lifetime of WSN(Wireless Sensor Network) is the limited resources and static control problem of the sensor nodes. In order to achieve energy efficiency and network utilities, sensor nodes can be well organized into one cluster and selected head node and normal node by dynamic conditions. Various clustering algorithms have been proposed as an efficient way to organize method based on LEACH algorithm. In this paper, we propose an efficient clustering algorithm using information entropy theory based on LEACH algorithm, which is able to recognize environmental differences according to changes from data of sensor nodes. To measure and analyze the changes of clusters, we simply compute the entropy of sensor data and applied it to probability based clustering algorithm. In experiments, we simulate the proposed method and LEACH algorithm. We have shown that our data balanced and energy efficient scheme, has high energy efficiency and network lifetime in two conditions.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.3
• /
• pp.715-723
• /
• 2015

In this paper, we propose a context-awareness routing algorithm DDV (Dynamic Direction Vector)-hop algorithm in Mobile Ad Hoc Networks. The existing algorithm in MANET, it has a vulnerability that the dynamic network topology and the absence of network expandability of mobility of nodes. The proposed algorithm performs cluster formation using a range of direction and threshold of velocity for the base-station, we calculate the exchange of the cluster head node probability using the direction and velocity for maintaining cluster formation. The DDV algorithm forms a cluster based on the cluster head node. As a result of simulation, our scheme could maintain the proper number of cluster and cluster members regardless of topology changes.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.11B
• /
• pp.1363-1372
• /
• 2011

Flooding based routing protocols are usually used to disseminate information in wireless sensor networks. Those approaches, however, require message retransmissions to all nodes and induce huge collision rate and high energy consumption. In this paper, HoGoP (Hop based Gossiping Protocol) in which all nodes consider the number of hops from sink node to them, and decide own gossiping probabilities, is introduced. A node can decide its gossiping probability according to the required average reception percentage and the number of parent nodes which is counted with the difference between its hop and neighbors' ones. Therefore the decision of gossiping probability for network topology is adaptive and this approach achieves higher message reception percentage with low message retransmission than the flooding scheme. Through simulation, we compare the proposed protocol with some previous ones and evaluate its performance in terms of average reception percentage, average forwarding percentage, and forwarding efficiency. In addition, average reception percentage is analyzed according to the application requirement.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.12
• /
• pp.1261-1266
• /
• 2014

Smart shipyard, all of the business of shipyard by using a mobile application, and the rapid spread of smart equipment, the overload of infrastructure due to a variety of mobile services is expected. Because macrocell and femtecell to reduce the overloading of existing infrastructure, additional core network devices have a problem, in this paper, the efficiency of resources than the communication over the existing infrastructure smart shipyard network to improve, to apply the D2D communication technology that can reduce the load on the infrastructure. The proposed routing path plan in accordance with the transfer method and the traffic type of network configuration and D2D equipment navigation and data for applying a smart shipyard. Whether to execute the function to overload traffic in the core network can send to the optimized path was confirmed by using the state transition diagram. Smart shipyard, by applying D2D communication allow efficient traffic handling than conventional communication method.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.47 no.2
• /
• pp.1-10
• /
• 2010

Mapping virtual process topology to physical processor topology is one of the most important design issues in parallel programming. However, the mapping problem is complicated due to the topology irregularity and routing complexity. This paper proposes a new process mapping scheme called adjacency-based mapping (AM) for irregular cluster systems assuming that the two-dimensional mesh process topology is specified as an interprocess communication pattern. The cluster systems have been studied and developed for many years since they provide high interconnection flexibility, scalability, and expandability which are not attainable in traditional regular networks. The proposed AM tries to map neighboring processes in virtual process topology to adjacent processors in physical processor topology. Simulation study shows that the proposed AM results in better mapping quality and shorter interprocess latency compared to the conventional approaches.