• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.122-130
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• 2008

In many applications of wireless sensor networks, sensed data can be classified either normal or urgent data according to its time criticalness. Normal data such as periodic monitoring is loss and delay tolerant, but urgent data such as fire alarm is time critical and should be transferred to a sink with reliable. In this paper, by exploiting these data characteristics, we propose a novel energy-efficient data-aware routing protocol for wireless sensor networks, which provides a high reliability for urgent data and energy efficiency for normal data. In the proposed scheme, in order to enhance network survivability and reliability for urgent data, each sensor node forwards only urgent data when its residual battery level is below than a threshold. Also, the proposed scheme uses different data delivery mechanisms depending on the data type. The normal data is delivered to the sink using a single-path-based data forwarding mechanism to improve the energy-efficiency. Meanwhile, the urgent data is transmitted to the sink using a directional flooding mechanism to guarantee high reliability. Simulation results demonstrate that the proposed scheme could significantly improve the network lifetime, along with high reliability for urgent data delivery.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12B
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• pp.1749-1757
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• 2010

This paper considers the cost minimization problem to satisfy QoS (Quality of Service) requirements for a given network, in particular when communication resources to each link can be additionally assigned. For the purpose of quantifying QoS requirements such as data transfer delay and packet loss, we introduce the cost function considering both the link utilization factor and the additionally assigned resource. To minimize this cost function, we firstly formulate a Basic Capacity Planning (BCP) problem, a special case of Network Utility Maximization (NUM). We show that the solution of this BCP problem cannot be optimal via a counter example. In this paper, we suggest the cross-layer design of both additionally assigned resource and routing path, whose initial values are set to the result of BCP problem. This cross-layer design is based on a heuristic approach which presents an effective way to plan how much communication resources should be added to support the QoS requirements in future. By simulation study, we investigate the convergence of the cost function in a more general network topology as well as in a given simple topology.

• Journal of KIISE:Information Networking
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• v.35 no.5
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• pp.395-401
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• 2008

In order to determine path(s) satisfied with bandwidth-guaranteed in the Internet, routers should have information on network topology and link state. The information is stored in Link State Database (LSDB) located in each router and managed. If link states information is changed, routers inform their neighbor of link state information changed by sending Link State Update (LSU) messages. However, there is trade-off between reflection of actual link state information on LSDB and cost of sending LSU messages. To find a bandwidth-guaranteed path effectively, it is important to decide whether LSU messages are sent or not for the change of link sate. In this paper, we propose a threshold-based LSU algorithm using statistic to effectively decide for sending LSU messages and evaluates its performance by intensive simulations. Simulation results show that the performance of proposed scheme is superior to the existing LSU schemes.

• Journal of the Korea Computer Industry Society
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• v.3 no.9
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• pp.1235-1244
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• 2002

This paper proposes a group key management protocol for a secure of all the multicast user in PIM-SM multicast group communication. With prosed architect, subgroups for multicast secure group management will be divided by RP (Rendezvous-Point) unit and each RP has a subgroup manager. Each subgroup manager gives a secure key to it's own transmitter md the transmitter compress the data with it's own secure key from the subgroup manager. Before the transmitter send the data to receiver, the transmitter prepare to encrypt a user's service by sending a encryption key to the receiver though the secure channel, after choking the user's validity through the secure channel. As the transmitter sending a data after then, the architecture is designed that the receiver will decode the received data with the transmitter's group key. As a result, the transmitting time is shortened because there is no need to data translation by group key on data sending and the data transmition is possible without new key distribution at path change to SPT (Shortest Path Tree) of the router characteristic. Additionally, the whole architecture size is samller than the other multicast secure architecture by using the conventional PIM-SIM routing structure without any additional equipment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11B
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• pp.956-966
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• 2004

Nowadays, NGN(Next Generation Network) is evolving into network with packet based QoS.\ulcorner This paper presents the recovery method as a selecting way of more efficient path in MPLS network that reduces the service interruption time. In order to increase the efficiency of usage of recovering resource which is one of major functions of disorder recovering, it opens the state information of each Node both to fault detector and bandwidth broker so that it reduces message transmission time for recovery when functional disorder occurs. in addition, by effective management and adjustment of required bandwidth of entire network depending on the changes of traffic load, it improves the efficiency of bandwidth usage. and in MPLS network supporting priority selection function, it allocates domains depending on the traffic relating to priority order to the entire network so that\ulcorner it efficiently allocates proper resources to the restoring process between the entry and the end for the traffic of high priority and for low priority traffic, it restores path oかy inside disordered domain. by doing this, it reduces resetting time and unnecessary massage transmission.

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

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.113-115
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• 2015

In this paper, we proposed an algorithm based on movement prediction using rate of change of the attribute information of nodes what is called WRC(Weighted Rate Control) in delay tolerant networks(DTNs). Existing DTN routing algorithms based on movement prediction communicate by selecting relay nodes increasing connectivity with destination node. Thus, because the mobile nodes are in flux, the prediction algorithms that do not reflect the newest attribute information of node decrease reliability. In this paper, proposed algorithm approximate speed and direction of attribute information of node and analysis rate of change of attribute information of node. Then, it predict movement path of node using proposed weight. As the result, proposed algorithm show that network overhead and transmission delay time decreased by predicting movement path of node.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11B
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• pp.772-783
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• 2005

In this paper, we propose an effective multicasting protocol in wireless ad-hoc networks. Conventional wired and wireless network multicast protocols do not perform well in wireless ad hoc networks because they were designed without consideration of ad hoc environments such as node mobility, limited bandwidth, high error probability. To solve this problem, some multicasting protocols for ad hoc network have been proposed in the literature. However, these protocols can not provide high packet delivery ratio, low control packet overhead and low expended bandwidth at the same time. Therefore, in this paper, we propose RTMA that improves multicasting performance in wireless ad hoc networks. RTMA calculates its current region from its position information by using GPS in order to make tree among the multicast group nodes in the same region. The proposed region-based tree method is for high packet delivery ratio, low control packet overhead when many senders send data packets. RTMA makes a reliable tree by using speed information to fill a gap of the weak points of the tree structure. When searching the routing path, RTMA selects the reliable path excluding high speed nodes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11B
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• pp.792-803
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• 2005

Ultra wide band (UWB) technology will be applied in the high rare wireless personal area networks (WPANs) for its high rate, low power, and innate immunity to multipath fading. In this paper, a power aware multi-hop packet relay MAC protocol in UWB based WPANs is proposed and a power aware path status factor (PAPSF), which is derived from SINR and power resource condition of each device, is used to select a suitable relay node. Compared with relaying by piconet coordinator (PNC), which is easily chosen by other ad hoc routing protocol, the new scheme can achieve hi임or throughput, decrease the time required for transmitting high power signal and we can easily distribute the battery power consumption from PNC to other devices in the piconet to prevent the PNC device using up its battery too fast and finally avoid PNC handover too frequently.

• Journal of Korea Spatial Information System Society
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• v.10 no.1
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• pp.51-63
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• 2008

Previous studies for routing In USN (Ubiquitous Sensor Networks) appear to be unreliable due to the dependence on non-spatial data and the lack of map overlay analysis. Multiple spatial parameters and radio propagation modeling techniques were integrated to derive RSSI (Received Signal Strength Indicator) value between route nodes and produce a highly reliable path map. It was possible to identify area-wide patterns of USN route subject to many different Influences (e.g. the specific effects of radio blocking factors such as the visible area, road area, cell duplicated area, and building density), which cannot be acquired by traditional non-spatial modeling. The quantitative evidence concerning the USN route for individual cell as well as entire study area would be utilized as major tools to visualize paths in real-time and to select alternative path when failure or audition of route node occurs.