• Journal of Information Technology Applications and Management
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• 제10권2호
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• pp.61-71
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• 2003

Ad-hoc networks are characterized by multi-hop wireless links, frequently changing network topology and the need for efficient dynamic routing protocols. In an Ad-hoc network, each host assumes the role of a router and relays packets toward final destinations Because a packet is broadcast to all neighboring nodes, the optimality criteria of wireless network routing is different from that of wired network routing. tn this paper 1 point out the more important cost factor than the number of links in the Ad-hoc network. A class routing protocols called on-demand protocols has recently found attention because of their low routing overhead since it performs a blind flooding to look for a path. In this paper, 1 propose the method which reduces overhead by using the information of neighboring nodes and doing a selective flooding. Simulation results demonstrate better reduction of routing overheads with this scheme.

• 전자공학회논문지A
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• 제33A권4호
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• pp.142-151
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• 1996

This paper presents a new symmetrical routing architecture for FPGA and an efficient routing algorithm for the architecture. The routing architecture adopts the segmented wires and the improved switch modules. Segmetned wires construct routing channels which pass through the chip in vertical and horizontal directions. To maximize the utility of a track, a track in each switch module can be separated in two part using a programmable switch to route two different net. The proposed routing algorithm finds all assignable tracks for a given net and selects the best track from assignable tracks to minimize the number of programmable switches and the unused portion of the wire segments. In order to stabilize the perfomrance of the algorithm, the routing order is defined by weighted sum of the number of wire segment, the length of wire segmetn, and the number of pin. Experimental results show that routability is improved dramatically and the number of crossing switches are reduced about 40% compared with the previous works.

• 한국정보과학회논문지:정보통신
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• 제28권3호
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• pp.406-416
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• 2001

동적 메트릭을 사용하는 단일 경로 라우팅 방식이 폭주에 대처하는 방법은 폭주 영역을 피해 갈수 있도록 경로를 바꾸어주는 것이다. 그러나 이러한 라우트 변경은 라우팅 진동을 야기할 수 있고 폭주에 대응하여 실제적으로 네트워크 상에존재하는 다중의 경로들을 모두 동시에 이용할 수 없다는 한계점이 있다. 이에 본 논문에서는 라우팅 오버헤드 측면에서 매우 효율적이면서 라우팅 성능을 높일 수 있는 동적 로드 밸런싱을 수행하는 다중 경로 라우팅 방식인 MP-DLB를 제안하였다. MP-DLB 방식은 동적 로드 밸런싱을 수행하는 다중 경로 라우팅의 오버헤드를 줄이기 위해 인터넷 트래픽이 일부 hot 목적지로 집중되는 패턴을 보이는 인터넷 패킷배치 분석자료를 근거로 hot 목적지에 대해서만 다중 경로를 설정하고 이들 다중 경로에 대해서만 동적로드 밸런싱을 수행한다. 소수의 hot 목적지에 대해서만 다중 경로를 사용하도록 하는 것은 다중 경로 사용을 위한 오버헤드를 감소시키면서도 라우팅 성능에 주된 영향을 미치는 트래픽에 대한 라우팅을 효율적이고 안정되게 제공하는 효과가 있다. 제안하는 MP-DLB 방식의 성능을 검토하기 위하여 시뮬레이션을 실행한 결과 MP-DLB는 하나의 hot 목적지를 향하여 임의의 라우터에 집중되고 있는 여러 소스로부터의 트래픽을 다중 경로를 이용해 분산 전송함으로써 효과적으로 폭주를 경감시키고 라우팅성능을 높임을 볼수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권2호
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• pp.371-388
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• 2014

Cognitive Radio (CR) has been recently proposed as a promising technology to remedy the problems of spectrum scarcity and spectrum underutilization by enabling unlicensed users to opportunistically utilize temporally unused licensed spectrums in a cautious manner. In Cognitive Radio Ad Hoc Networks (CRAHNs), data routing is one of the most challenging tasks since the channel availability and node mobility are unpredictable. Moreover, the network performance is severely degraded due to large numbers of path failures. In this paper, we propose the Fault-Tolerant Cognitive Ad-hoc Routing Protocol (FTCARP) to provide fast and efficient route recovery in presence of path failures during data delivery in CRAHNs. The protocol exploits the joint path and spectrum diversity to offer reliable communication and efficient spectrum usage over the networks. In the proposed protocol, a backup path is utilized in case a failure occurs over a primary transmission route. Different cause of a path failure will be handled by different route recovery mechanism. The protocol performance is compared with that of the Dual Diversity Cognitive Ad-hoc Routing Protocol (D2CARP). The simulation results obviously prove that FTCARP outperforms D2CARP in terms of throughput, packet loss, end-to-end delay and jitter in the high path-failure rate CRAHNs.

• 디지털산업정보학회논문지
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• 제6권1호
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• pp.83-90
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• 2010

DTNs (Delay Tolerant Networks) refer to the networks that can support data transmission in the extreme networking situations such as continuous delay and no connectivity between ends. DTMNs (Delay Tolerant Networks) are a specific range of DTNs, and its chief considerations in the process of message delivery in the routing protocol are the transmission delay, improvement of reliability, and reduction of network loading. This article proposes a new LCN (Largest Common Neighbor) routing algorism to improve Spray and Wait routing protocol that prevents the generation of unnecessary packets in a network by letting mobile nodes limit the number of copies of their messages to all nodes to L. Since higher L is distributed to nodes with directivity to the destination node and the maximum number of common neighbor nodes among the mobile nodes based on the directivity information of each node and the maximum number of common neighbor nodes, more efficient node transmission can be realized. In order to verify this proposed algorism, DTN simulator was designed by using ONE simulator. According to the result of this simulation, the suggested algorism can reduce average delay and unnecessary message generation.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2007년도 춘계종합학술대회
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• pp.401-405
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• 2007

센서네트워크에서 효율적인 에너지사용에 관한 클러스터 기반 라우팅 프로토콜이 다양하게 연구되고 있다. 하지만 기존의 클러스터 기반의 라우팅 프로토콜은 클러스터 재구성에 있어 센서 노드들의 불균형적인 에너지 소비문제와 클러스터 헤더를 선정함에 있어 헤더 노드와 싱크 노드가 멀리 떨어져 있을 때 연결이 제대로 이루어지지 않는다는 문제점이 있다. 본 논문에서는 클러스터의 재분할과 헤더 노드의 멀티 홉 전송방식을 제시한다. 클러스터 재분할은 기존의 클러스터를 소규모의 클러스터로 재분할하는 방식이고, 멀티 홉 전송방식은 헤더 노드들 사이의 중계전송에 관한 방식이다. 시뮬레이션을 통하여 제시한 라우팅 기법이 균등한 에너지 소비와 에너지 효율성에 있어서 기존의 라우팅 기법보다 우수함을 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권4호
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• pp.1223-1247
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• 2012

The need for securing Wireless Sensor Networks (WSNs) is essential especially in mission critical fields such as military and medical applications. Security techniques that are used to secure any network depend on the security requirements that should be achieved to protect the network from different types of attacks. Furthermore, the characteristics of wireless networks should be taken into consideration when applying security techniques to these networks. In this paper, energy efficient Security Model for Tree-based Routing protocols (SMTR) is proposed. In SMTR, different attacks that could face any tree-based routing protocol in WSNs are studied to design a security reference model that achieves authentication and data integrity using either Message Authentication Code (MAC) or Digital Signature (DS) techniques. The SMTR communication and processing costs are mathematically analyzed. Moreover, SMTR evaluation is performed by firstly, evaluating several MAC and DS techniques by applying them to tree-based routing protocol and assess their efficiency in terms of their power requirements. Secondly, the results of this assessment are utilized to evaluate SMTR phases in terms of energy saving, packet delivery success ratio and network life time.

• Journal of Communications and Networks
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• 제12권1호
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• pp.67-73
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• 2010

Current on-demand ad-hoc routing protocols are not appropriate for wireless mesh networks (WMNs), because flooding-based route discovery is both redundant and expensive in terms of control message overhead. In this paper, we propose an efficient on-demand routing approach with directional flooding (DF), which is suitable for the WMNs with limited mobility. In the route discovery process to reach a gateway, our DF scheme can reduce the number of route request (RREQ) packets broadcast by using a restricted directional flooding technique. Simulation results show that ad hoc on-demand distance vector (AODV) with DF (AODV-DF) can significantly reduce routing overhead by RREQ packets and enhance overall performance compared with the original AODV.

• 한국컴퓨터정보학회논문지
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• 제8권1호
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• pp.114-119
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• 2003

온라인 게임서비스 향상을 목적으로 한 QoS 라우팅을 위하여 각각의 요구에 대한 제한조건을 충족시키는 것은 물론, 전체 네트워크 자원의 최적화에 대해서도 고려해야 할 필요가 있다. 본 논문에서는 온라인 게임을 위해 도메인으로 분할된 대규모 네트워크의 QoS 라우팅에서 transit traffic을 위한 경로를 선계산 방식으로 설정하고, 이들 경로들의 예약 가능성을 높이기 위해 자원 예약 측면에서 가장 좋은 K개의 경로들을 부하균등을 고려하여 설정하는 방안을 제안하였다. 그리고 동일한 자원 비용 산정 방식을 transit traffic과 intra traffic에 모두 적용하여 도메인간 라우팅과 도메인내 라우팅을 무리 없이 연계하면서 transit traffic을 우선으로 하는 방식을 제안하였다.

• Journal of Communications and Networks
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• 제13권1호
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• pp.17-25
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• 2011

A convergecast is a popular routing scheme in wireless sensor networks (WSNs) in which every sensor node periodically forwards measured data along configured routing paths to a base station (BS). Prolonging lifetimes in energy-limited WSNs is an important issue because the lifetime of a WSN influences on its quality and price. Low-energy adaptive clustering hierarchy (LEACH) was the first attempt at solving this lifetime problem in convergecast WSNs, and it was followed by other solutions including power efficient gathering in sensor information systems (PEGASIS) and power efficient data gathering and aggregation protocol (PEDAP). Our solution-chain routing with even energy consumption (CREEC)-solves this problem by achieving longer average lifetimes using two strategies: i) Maximizing the fairness of energy distribution at every sensor node and ii) running a feedback mechanism that utilizes a preliminary simulation of energy consumption to save energy for depleted Sensor nodes. Simulation results confirm that CREEC outperforms all previous solutions such as LEACH, PEGASIS, PEDAP, and PEDAP-power aware (PA) with respect to the first node death and the average lifetime. CREEC performs very well at all WSN sizes, BS distances and battery capacities with an increased convergecast delay.