• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.111-118
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• 2008

In this paper a novel medium access control mechanism is investigated as a means to support real-time services. The primary goal is to provide constant-bit-rate voice call services to pairs of autonomous mobile nodes operating in ad hoc networks. Here, a time-slot reservation based MAC is considered to provide real-time voice calls and a new MAC called the time-slot reservation coordination function(TRCF) is presented. In addition to this isochronous type MAC protocol development, the proposed protocol is modeled using a Markov chain in order to predict its behavior. The performance of TRCF is analytically derived and the performance measures such as average wait time taken for a call connection and throughput are obtained.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.815-818
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• 2015

AODV routing protocol, one of the most studied routing protocols for the Mobile Ad hoc Network (MANET), uses the number of hops as the metric to choose a path from a source node to a destination node. If the path is deteriorated, it will cause many problems to the communication. In order to improve the performance of the network, we propose AuM-AODV routing protocol that contains an auxiliary metric besides the number of hops. Nodes using AuM-AODV use control packets such as Route Request (RREQ), Route Reply (RREP), and HELLO to exchange information about network topology like AODV routing protocol. AuM-AODV routing protocol is implemented in NS-3 for performance evaluation. We use three performance metrics, that is to say, throughput, packet delivery ratio, and average end-to-end delay. According to numerical results, the new AuM-AODV routing protocol has better performance over three performance metrics than AODV routing protocol.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.5
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• pp.121-127
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• 2009

Wireless devices can communicate between each other without existing infrastructure in mobile Ad-hod network. Ad hoc networks can be used under difficult conditions, where it is difficult to construct infrastructures, such as shadowing areas, disaster areas, war area, and so on. In order to support to considerable and various wireless services, more spectrum resources are needed. However, efficient utilization of the frequency resource is difficult because of spectrum scarcity and the conventional frequency regulation. Ad-hoc networks employing cognitive radio (CR) system that guarantee high spectrum utilization provide effective way to increase the network capacity. In this paper, we simulate and compare the performance of conventional single and cooperative spectrum sensing with CR system using ad-hoc networks. And we demonstrate performance improvement by analyzing the system performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1A
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• pp.24-35
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• 2008

We propose a tree-based integrated network of infrastructure network and mobile ad hoc network to effectively support Mobile IP for mobile ad hoc networks and also proposed a network management protocol for formation and management of the integrated network and a tree-based routing protocol suitable for the integrated network. The integrated network has fixed gateways(IGs) that connect two hybrid networks and the mobile nodes in the network form a small sized trees based on the mobile nodes that are in the communication distance with a IG. A new node joins an arbitrary tree and is registered with its HA and FA along tree path. In addition, the proposed protocol establishes a route efficiently by using the tree information managed in every node. We examined the effectiveness of the tree-based integrated network for some possible network deployment scenarios and compared our routing protocol against the Mobile IP supported AODV protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.6A
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• pp.632-641
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• 2007

Since the mobile node acts as the router, the Mobile Ad Hoc network requires the security methods that are different from that of network of the wire environment. Also, since the total network can't be included in the transmission area of the mobile node, when one node sends the message to the other node, we need the middle node. But if the middle node is the unreliable malicious node, we can't guarantee the secure message transmission. Also, because all nodes configuring the network are the mobile nodes, they use the restricted battery capacity and the restricted resources. Therefore, because we have trouble performing the encryption that many resources are required when we sending the message, it is vulnerable to the security than the network of the wire environment. Last, because the network topology continues to change by the mobility of nodes configuring the network, we need the security measure that matches the network characteristics. We suggest the routing attack detection for performance enhancement of AODV protocol in Mobile Ad Hoc networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6B
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• pp.728-737
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• 2011

For the real time monitoring and tracking of shipping container which is one of the core objects for global logistics, Wireless Ad-Hoc Network technology might be needed in stacking environments such as ports, yards and ships. In this paper, we propose a container network routing protocol suitable for port or yard stacking environments which include some constraints such as shadow area problem from metal material, frequent movement of container, etc. With this protocol in which a mesh network algorithm is applied, every container data packet can be delivered to the sink node reliably even with frequent join/leave of container nodes. As soon as a node on path gets malfunction, alternative backup path is supported with notice to neighbor node, which makes constant total optimal path. We also verified that the performance of proposed protocol is better than AODV, one of previous major MANet(Mobile Ad-Hoc Network) protocol with a function for alternative path, which says the proposed protocol is better for frequent join/leave and variable link quality.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.6A
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• pp.600-610
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• 2010

In this paper, a multicast mechanism is proposed for intermittently disconnected networks where the nodes move forward in formation or within a limited area. The proposed scheme extends the well-known tree-based multicast routing mechanism called MAODV by modifying the tree construction and data delivery scheme. Especially, an algorithm is introduced which determines the flooding hop count k estimating the degree of the movement of children in the tree. The performance evaluation was done by the simulation and the proposed scheme was compared with MAODV and two multicast routing schemes for DTN (Disruption Tolerant Network) including the Epidemic routing and ST-multicast. The evaluation results show that our scheme improves the original MAODV from the aspect of tree reconstruction events and message delivery ratio. Compared with the Epidemic routing scheme, our scheme achieves 85% message delivery ratio with less than 50% message delivery overhead.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.60-65
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• 2011

Wireless devices can communicate between each other without existing infrastructure in mobile Ad-hod network. Ad hoc networks can be used under difficult conditions, where it is difficult to construct infrastructures, such as shadowing areas, disaster areas, war area, and so on. In order to support to considerable and various wireless services, more spectrum resources are needed. However, efficient utilization of the frequency resource is difficult because of spectrum scarcity and the conventional frequency regulation. Ad-hoc networks employing cognitive radio (CR) system that guarantee high spectrum utilization provide effective way to increase the network capacity. In this paper, to improve detection performance of the energy detection which is widely used in CR based ad-hoc network, we propose multiple antenna system for CR based ad-hoc networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2826-2834
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• 2013

In mobile ad hoc networks (MANET), power-saving technology of mobile nodes is divided into transmit power control (TPC), power-saving mode (PSM), and routing. TPC and PSM are operated in physical layer but the routing is managed in network layer, so the design of a joint algorithm is needed to provide better performance. Therefore, in this paper, we propose a joint power-saving and routing algorithm for maximizing the network lifetime while satisfying the end-to-end data rate in ad hoc networks. The proposed algorithm first applies the TPC or PSM to reduce the power consumption of mobile nodes and then performs the routing by considering the decided node lifetime in order to maximize the path lifetime. Simulation results show that the proposed algorithm maximize the lifetime while satisfying the required rate according to the number of mobile nodes and the level of interference.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1214-1221
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• 2007

Ad-hoc network is soft wireless communication network that is consisted of mobile node and clusters without helping of infrastructure. We propose a new ad hoc multicast routing protocol for based on the ontology scheme called inference network. Ontology knowledge-based is one of the structure of context-aware. Proposed structure is consisted of context awareness parameters as like distance between each nodes. The proposed architecture performs two types of routing discovery. One is Flooding Discovery Routing(FDR) for comparing analysis step and Local Discovery Routing(LDR) to compose path of node forecast(preservation) step from node's state value. The inference network structure of proposed RODMRP(Resilient Ontology-based Dynamic Multicast Routing Protocol) adopts a tree structure to enhance an efficient packet in various environment between mobile node. We will have developed an algorithm that will desist multi-hierarchy Layered networks to simulate a desired system.