• The Journal of Korean Institute of Communications and Information Sciences
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• 제31권9A호
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• pp.892-899
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• 2006

In this paper, we propose an automatic switching technology between the ad-hoc and the infrastructure modes without user intervention in the IEEE 802.11b wireless LAN. Also, we design our proposed technology and implemented on the Linux machine. For this operation, the area within an Access Point (AP) coverage is defined as a switching area, and a node without any transmission in this area is assumed to be able to relay frames between the AP and nodes in the shaded area that is outside the coverage and cannot reach the AP. By using the proposed technology, it is possible to provide the seamless Internet access service to nodes at the ad-hoc mode in the shaded area. In this paper, we explains the operation of the detection method of the switching area, presents the flowchart and implementation environment. To prove the operation of our technology, we obtain the results of captured packets transmitted between nodes and throughput results through ftp transmission experiment. Hence, we can see that our proposed scheme can be improve the wireless access service in wireless and mobile networks.

• International Journal of Computer Science & Network Security
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• 제21권9호
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• pp.132-140
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• 2021

Under the mobile ad-hoc network system, the main reason for causing congestion is because of the limited availability of resources. On the other hand, the standardised TCP based congestion controlling mechanism is unable to control and handle the major properties associated with the shared system of wireless channels. It creates an effect on the design associated with suitable protocols along with protocol stacks through the process of determining the mechanisms of congestion on a complete basis. Moreover, when bringing a comparison with standard TCP systems the major environment associated with mobile ad hoc network is regraded to be more problematic on a complete basis. On the other hand, an agent-based mobile technique for congestion is designed and developed for the part of avoiding any mode of congestion under the ad-hoc network systems.

• Journal of Internet Computing and Services
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• 제4권4호
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• pp.15-25
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• 2003

Wireless ad-hoc networks are only composed with mobile devices. Unlike the traditional wired networks, those devices are mostly operated with battery power. Since the battery-operated power is limited, the efficient energy resource managements becomes an important issue in wireless ad-hoc networks and various studies that considered these characteristics are progressed. One of those studies is an energy efficient routing using coordinators. In this method. only devices elected as coordinator participate in data transmissions in ad-hoc networks, while other devices remain in sleep node. The overall energy consumption of a system can be reduced. In order to minimize energy consumption of a total network, previous results try to maximize the number of nodes in sleep mode. However, minimizing the number of coordinators does not ensure to increase the system lifetime. In this thesis, we propose an algorithm that can elect coordinators with considering the amount of necessary energy to transmit assigned data and a connectivity of nodes in the networks. The result of proposed coordinator election algorithm can increase the system lifetime of an Ad-hoc network from the results of existing coordinator election algorithms.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제38B권4호
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• pp.279-290
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• 2013

In this paper, we propose a transmission scheme of MAC protocol that enables secure voice communications by exploiting the wide spectrum and low signal strength characteristics of the ultra wide band technology. In addition, it also supports high level of terminal mobility by deploying mobile ad hoc network schemes. While most of existing UWB MAC protocols are operated as a synchronous mode, the proposed scheme operates in an asynchronous mode for supporting high mobility and sends voice packets without RTS/CTS control packets for efficient voice traffic transmission without retransmission. With simulation program, we prove that the proposed scheme satisfies the required voice quality and packet delivery time.

• Journal of the Institute of Convergence Signal Processing
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• 제12권2호
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• pp.119-127
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• 2011

The paper surveys various analytical models for IEEE 802.11 medium access control protocols and critically discusses recent issues developing in wireless mobile ad hoc networks and their MACs. The surveyed MAC protocols include the standard IEEE 802.11 MAC suites such as IEEE 802.11 DCF, IEEE 802.11 PCF, IEEE 802.11e EDCA, and IEEE 802.11 ad hoc mode; and also the newer, de facto MAC protocols. We study the analytic models of the standard MAC suites followed by the newer analytic models that have been published in recent years. Also, the paper tries to include most of current literatures discussing analytic modeling of MAC in conjunction to some critical issues such as contention among ad hoc nodes, hidden terminal problems, and real-time service support.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1685-1688
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• 2002

Application Routing Load Balancing (ARLB) is a novel load balancing mode that combines QoS routing and load balancing in per application to support QoS far real-time application based on wired network. Zone Routing Protocol (ZRP) is a recent hybrid proactive/reactive routing approach in an attempt to achieve scalability of ad-hoc network. This routing approach has the potential to be efficient in the generation of control traffic than traditional routing schemes. Up to now, without proper load balancing tools, the ZRP can actually guarantee QoS for delay-sensitive applications when congestion occurred in ad-hoc network. In this paper, we propose the ARLB to improve QoS fur delay-sensitive applications based on ZRP in ad-hoc network when congestion occurred and to be forwarding mechanism fur route coupling to support QoS for real-time applications. The critical point is that the routing metric of ARLB is originally designed for wired network environment. Therefore, we study and present an appropriate metric or cost computation routing of ARLB for recently proposed ZRP over ad-hoc network environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제16권5호
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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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• 제17권12호
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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 Korea Multimedia Society
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• 제21권8호
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• pp.897-908
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• 2018

In this paper, we propose a security framework for a cluster drones network using the MAVLink (Micro Air Vehicle Link) application protocol based on FANET (Flying Ad-hoc Network), which is composed of ad-hoc networks with multiple drones for IoT services such as remote sensing or disaster monitoring. Here, the drones belonging to the cluster construct a FANET network acting as WTRP (Wireless Token Ring Protocol) MAC protocol. Under this network environment, we propose an efficient algorithm applying the Lightweight Encryption Algorithm (LEA) to the CTR (Counter) operation mode of WPA2 (WiFi Protected Access 2) to encrypt the transmitted data through the MAVLink application. And we study how to apply LEA based on CBC (Cipher Block Chaining) operation mode used in WPA2 for message security tag generation. In addition, a modified Diffie-Hellman key exchange method is approached to generate a new key used for encryption and security tag generation. The proposed method and similar methods are compared and analyzed in terms of efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권6호
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• pp.3000-3022
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• 2019

Full-duplex (FD) technologies enable wireless nodes to simultaneously transmit and receive signal using the same frequency-band. The FD modes could improve their physical layer throughputs. However, in the wireless ad hoc networks, the FD communications also produce new interference risks. On the one hand, the interference ranges (IRs) of the nodes are enlarged when they work in the FD mode. On the other hand, for each FD pair, the FD communication may cause the potential hidden terminal problems to appear around the both sides. In this paper, to avoid the interference risks, we first model the IR of each node when it works in the FD mode, and then analyze the conditions to be satisfied among the transmission ranges (TRs), carrier-sensing ranges (CSRs), and IRs of the FD pair. Furthermore, in the media access control (MAC) layer, we propose a specific method and protocol for collision avoidance. Based on the modified Omnet++ simulator, we conduct the simulations to validate and evaluate the proposed FD MAC protocol, showing that it can reduce the collisions effectively. When the hidden terminal problem is serious, compared with the existing typical FD MAC protocol, our protocol can increase the system throughput by 80%~90%.