• 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.

• International Journal of Computer Science & Network Security
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• v.22 no.9
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• pp.376-388
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• 2022

The expansion of new applications and business models is being significantly fueled by the development of Fifth Generation (5G) networks, which are becoming more widely accessible. The creation of the newest intelligent vehicular networks and applications is made possible by the use of Vehicular Ad hoc Networks (VANETs) and Software Defined Networking (SDN). Researchers have been concentrating on the integration of SDN and VANET in recent years, and they have examined a variety of issues connected to the architecture, the advantages of software-defined VANET services, and the new features that can be added to them. However, the overall architecture's security and robustness are still in doubt and have received little attention. Furthermore, new security threats and vulnerabilities are brought about by the deployment and integration of novel entities and a number of architectural components. In this study, we comprehensively examine the good and negative effects of the most recent SDN-enabled vehicular network topologies, focusing on security and privacy. We examine various security flaws and attacks based on the existing SDVN architecture. Finally, a thorough discussion of the unresolved concerns and potential future study directions is provided.

• International Journal of Computer Science & Network Security
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• v.22 no.9
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• pp.231-243
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• 2022

The expansion of new applications and business models is being significantly fueled by the development of Fifth Generation (5G) networks, which are becoming more widely accessible. The creation of the newest intelligent vehicular net- works and applications is made possible by the use of Vehicular Ad hoc Networks (VANETs) and Software Defined Networking (SDN). Researchers have been concentrating on the integration of SDN and VANET in recent years, and they have examined a variety of issues connected to the architecture, the advantages of software defined VANET services, and the new features that can be added to them. However, the overall architecture's security and robustness are still in doubt and have received little attention. Furthermore, new security threats and vulnerabilities are brought about by the deployment and integration of novel entities and several architectural components. In this study, we comprehensively examine the good and negative effects of the most recent SDN-enabled vehicular network topologies, focusing on security and privacy. We examine various security flaws and attacks based on the existing SDVN architecture. Finally, a thorough discussion of the unresolved concerns and potential future study directions is provided.

• Journal of KIISE:Information Networking
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• v.35 no.5
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• pp.409-414
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• 2008

In mobile ad hoc networks, most of on demand routing protocols such as DSR and AODV do not deal with traffic load during the route discovery procedure. To solve the congestion and achieve load balancing, many protocols have been proposed. However, the existing load balancing schemes has only considered avoiding the congested route in the route discovery procedure or finding an alternative route path during a communication session. To mitigate this problem, we have proposed a new scheme which considers the packet bursting mechanism in congested nodes. The proposed packet bursting scheme, which is originally introduced in IEEE 802.11e QoS specification, is to transmit multiple packets right after channel acquisition. Thus, congested nodes can forward buffered packets promptly and minimize bottleneck situation. Each node begins to transmit packets in normal mode whenever its congested status is dissolved. We also propose two threshold values to define exact overloaded status adaptively; one is interface queue length and the other is buffer occupancy time. Through an experimental simulation study, we have compared and contrasted our protocol with normal on demand routing protocols and showed that the proposed scheme is more efficient and effective especially when network traffic is heavily loaded.

• Journal of KIISE:Information Networking
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• v.35 no.6
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• pp.521-528
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• 2008

Such conventional maritime communication technologies as radio have short some comings in their transmission quality. It can be overcome by wireless channels provided by satellites such as INMARSAT, which nevertheless suffer from the high costs. In this paper, we propose a novel technology resolving the above problems, featuring in the establishment of maritime communication networks with multi-hop structures. The inter vessel and ship-to- shore networks previously modeled after MANET are remodeled by SANET (Ship Ad Hoc Networks) in the present work. Fan-shaped Search Zone Routing (FSR) protocol also is presented, which utilizes not only static geographical information including the locations of ports and the navigations of courses but also the unique characteristics of ships in terms of mobile nodes. The FSR finds the fan-shaped search zone on which the shortest path is located. The performance of LAR protocol is compared with that of FSR in several ways. First, FSR does not make use of a type of control packets as beaconing data, resulting in a full utilization of the bandwidth of the wireless channels. Second, the delivery rate by the FSR is 100% for the fan-shaped search zone includes at least one route between source and destination nodes on its border line, where as that of LAR has been turned out to be 64%. Third, the optimality of routes searched by the FSR is on a 97% level. Of all, the FSR shows a better performance than LAR by about 50%.

• Journal of KIISE:Information Networking
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• v.31 no.6
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• pp.643-658
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• 2004

Mobile ad hoc networks(MANET) have recently attrarted a lot of attention in the research community as well as in industry. Although the previous research mainly focused on the various problems of MANET in data link and network layers, we consider, in this paper, how to efficiently support applications such as service discovery on top of MANET. Peer-to-Peer(P2P) overlay network can be adopted to service discovery mechanism because P2P and MANET share certain similarities, primarily the fact that both arc instances of self-organizing decentralized systems. Especially, distributed hash table(DHT) systems used for r2r overlay network can be effective in reducing the communication overhead in service discovery. However, since overlay network is independent of physical network topology and existing topology-aware mechanisms are based on the wired network, they are inefficient in MANET. We propose a proximity-based overlay network routing to overcome the inefficiency of routing in overlay network. In the proximity-based overlay network routing, each node collects information of physically close nodes by using one hop broadcast and routes messages to the logically closest node to destination. In a detailed ns-2 simulation study, we show that the proximity-based overlay network routing reduces the number of physical hops comparable to the flooding-based mechanism with low communication overhead. We also find that the proposed scheme works well in the mobile environment.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.532-543
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• 2004

Mobile Ad hoc NETworks (MANET) consist of mobile nodes which are usually powered by battery Approaches for minimizing power consumption have been proposed for all network layers and devices. IEEE 802.11 DCF (Distributed Coordination Function), a well-known medium access control protocol for MANETS, also defines a power save mode operation. The nodes in power save mode periodically repeat the awake state and the doze state in synchronized fashion. When all nodes are in the awake state, the exchange the announcements for the subsequent message transmission with neighbors. The nodes that send or receive the announcements stay awake for data transmission, and others go into the dole state. The previous works for enhancing the power save mode operation have focused on shortening the duration of the awake state. We observed that the longer sleeping period results in seriously long delivery latency and the consequent unnecessary power consumption as well, because the packets can move forward only one hop for a fixed interval. In this paper, we propose an improved protocol for the power save mode of IEEE 802.11 DCF, which allows the flooding packets to be forwarded several hops in a transmission period. Our approach does not reduce the duration of compulsory awake period, but maximizes its utilization. Each node propagates the announcements for next flooding to nodes of several hops away, thus the packets can travel multiple hops during one interval. Simulation results of comparison between our scheme and the standard show a reduction in flooding delay maximum 80%, and the unicasting latency with accompanying flooding flows near 50%, with slight increase of energy consumption.

• Journal of KIISE:Information Networking
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• v.37 no.6
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• pp.420-430
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• 2010

Due to increasing demand for improving road safety and optimizing road traffic, Vehicular Ad-Hoc Networks (VANET) have been subject to extensive attentions from all aspects of commercial industry and academic community. Security and user privacy are fundamental issues for all possible promising applications in VANET. Most of the existing security proposals for secure VANET concentrate authentication with privacy preservation in vehicle-to-vehicle (V2V) and vehicle-to-roadside infrastructure (V2I) communications and require huge storage and network capacity for management of revocation list. Motivated by the fact, we propose a new scheme with security and privacy preservation which combines V2V and V2I communication. With our proposed scheme, the communication and computational delay for authentication and overhead for management of revocation list can be significantly reduced due to mutual authentication between a vehicle and a Roadside Unit (RSU) requires only two messages, and the RSU issues the anonymous certificate for the vehicle on behalf of the Trust Authority (TA). We demonstrate that the proposed protocol cannot only guarantee the requirements of security and privacy but can also provide efficiency of authentication and management of revocation list.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.631-640
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• 2003

Because of multi-hop wireless communication, P2P applications in ad hoc networks suffer poor performance. We Propose neighbor caching strategy to overcome this shortcoming and show it is more efficient than self caching that nodes store data in theirs own cache individually. A node can extend its caching storage instantaneously with neighbor caching by borrowing the storage from idle neighbors, so overcome multi-hop wireless communications with data source long distance away from itself. We also present the ranking based prediction that selects the most appropriate neighbor which data can be stored in. The node that uses the ranking based prediction can select the neighbor that has high possibility to keep data for a long time and avoid caching the low ranked data. Therefore the ranking based prediction improves the throughput of neighbor caching. In the simulation results, we observe that neighbor caching has better performance, as large as network size, as long as idle time, and as small as cache size. We also show the ranking based prediction is an adaptive algorithm that adjusts times of data movement into the neighbor, so makes neighbor caching flexible according to the idleness of nodes

• Journal of KIISE:Information Networking
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• v.33 no.1
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• pp.38-48
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• 2006

For extending of hot-spot of WLAN, (2) proposes internetworking scheme between wireless LAN (WLAN) and mobile ad-hoc network (MANET), which employ the same layer-2 protocol with different mode. Compared to internetworking schemes between UMTS (Universal Mobile Telecommunications Systems) and WLAN (3-4), the scheme from (2) has relatively low overhead and latencies because WLAN and MANET are physically and logically similar to each other. However, the mode switching algorithm proposed in r2] for internetworking between WLAN and MANET only considers signal strength and determines handoff, and mobile nodes following a zigzag course in pollution area may perform handoff at short intervals. Furthermore, (2) employs mobile IPv6 (MIPv6) at base, which brings still high delay on handoff and overhead due to signal message exchange. In this paper, we present optimized internetworking scheme between WLAN and MANET, modified from (2). To settle ping-pong handoff from (2), we propose adaptive mode switching algorithm. HMIPv6 is employed for IP connectivity and mobility service in WLAN, which solves some shortcomings, such as high handoff overhead and vulnerable security. For routing in MANET, OLSR is employed, which is a proactive Protocol and has optimally reduced signal broadcasting overhead. OLSR operates with current P protocol compatibly with no change or modification. The proposed internetworking scheme based on adaptive mode switching algorithm shows better performance than scheme from (2).