• 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.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권9호
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• pp.3138-3150
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• 2021

Multimedia services on the Internet are continuously increasing. Accordingly, the demand for a technology for efficiently delivering multimedia traffic is also constantly increasing. The multicast technique, that delivers the same content to several destinations, is constantly being developed. This technique delivers a content from a source to all destinations through the multicast tree. The multicast tree with low cost increases the utilization of network resources. However, the finding of the optimal multicast tree that has the minimum link costs is very difficult and its calculation complexity is the same as the complexity of the Steiner tree calculation which is NP-complete. Therefore, we need an effective way to obtain a multicast tree with low cost and less calculation time on SDN-based smart network platforms. In this paper, we propose a new multicast tree generation algorithm which produces a multicast tree using an agent trained by model-based meta reinforcement learning. Experiments verified that the proposed algorithm generated multicast trees in less time compared with existing approximation algorithms. It produced multicast trees with low cost in a dynamic network environment compared with the previous DQN-based algorithm.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.462-465
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• 2002

This paper presents a basic theory of information flow from single sending point to multiple receiving points, where new theories of algebraic system called "Hybrid Vector Space" and flow vector space play important roles. Based on the theory, a new algorithm for finding maximum homogenous information flow is proposed, where homogenous information flow means the flow of the same contents of information delivered to multiple clients at a time. Effective multi-routing algorithms fur tree-shape delivery rout search are presented.

• 한국정보통신학회논문지
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• 제20권11호
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• pp.2187-2192
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• 2016

무선 센서 네트워크의 생존시간을 증가시키기 위하여 중계노드에서의 데이터 병합을 고려한 데이터 중심 라우팅이 필요하다. 본 논문에서는 무선 센서 네트워크에서 센싱 정보의 수집 시간과 노드의 에너지 소비량 간의 트레이드 오프를 고려하여 에너지 소비를 최소화하면서도 빠른 시간 내에 센싱 정보를 수집하는 에너지 효율적인 데이터 중심 라우팅 알고리즘을 제안한다. 제안 하는 라우팅 방식은 먼저 전체 센서 노드 중에서 최대 거리가 최소화가 되도록 만드는 노드를 싱크 노드로 설정한다. 이후 빠른 정보 수집을 위하여 센서 노드와 싱크 노드 간 최대 거리의 증가를 최소화하면서 에너지 소비를 줄이기 위하여 노드간 연결 링크 비용을 최소화하는 방식으로 트리 구조를 확장해나간다. 시뮬레이션 결과, 제안하는 데이터 중심 라우팅 알고리즘은 짧은 정보 수집 시간과 낮은 에너지 소비량을 가지며, 이로 인하여 기존 라우팅 알고리즘 대비 높은 네트워크 에너지 효율을 달성한다.

• 한국정보통신학회논문지
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• 제11권6호
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• pp.1214-1221
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• 2007

Ad-hoc 망은 기반의 하부 구조 계층의 도움 없이 이동 노드와 클러스터(Cluster)들만으로 구성된 유연한 무선 통신망이다. 본 논문에서는 이동 노드의 다양한 상황 정보를 분석하여 효율적인 온톨로지(Ontology) 기반의 상황인식(Context-Aware) 기술을 적용한 네트워크의 변화에 대한 예측이 가능한 추론망을 연구 제안한다. 제안된 구조에서는 각 노드간의 거리 정보등 상황정보를 이용한 분석으로부터 망을 형성하기 위한 초기단계와 노드의 상태값을 비교하여 노드의 경로를 예측 유지 및 분석하는 단계로 구성된다. 제안하고자 하는 RODMRP(Resilient Ontology-based Dynamic Multicast Routing Protocol)의 추론망 구조는 이동 노드간의 변화된 환경에서 복원력이 뛰어난 트리 구조의 효율적인 packet를 제공한다.

• ETRI Journal
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• 제22권1호
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• pp.30-37
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• 2000

Existing tree construction mechanisms are classified into source-based trees and center-based trees. The source-based trees produce a source-rooted tree with a low delay. However, for the applications with multiple senders, the management overheads for routing tables and resource reservations are too high. The center-based trees are easy to implement and manage, but a priori configuration of candidate center nodes is required, and the optimization mature such as tree cost and delay is not considered. In this paper, we propose a new multicast tree building algorithm. The proposal algorithm basically builds a non-center based shared tree. In particular, any center node is not pre-configured. In the purposed algorithm, a multicast node among current tree nodes is suitably assigned to each incoming user: Such a node is selected in a fashion that tree cost and the maximum end-to-end delay on the tree are jointly minimized. The existing and proposed algorithms are compared by experiments. In the simulation results, it is shown that the proposed algorithm approximately provides the cost saving of 30% and the delay saving of 10%, compared to the existing approaches. In conclusion, we see that the cost and delay aspects for multicast trees can be improved at the cost of additional computations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권12호
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• pp.3219-3236
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• 2012

A tree routing structure is often adopted for many-to-one data gathering and aggregation in sensor networks. For real-time scenarios, considering lossy wireless links, it is an important issue how to construct a maximum-lifetime data gathering tree with delay constraint. In this work, we study the problem of lifetime-preserving and delay-constrained tree construction in unreliable sensor networks. We prove that the problem is NP-complete. A greedy approximation algorithm is proposed. We use expected transmissions count (ETX) as the link quality indicator, as well as a measure of delay. Our algorithm starts from an arbitrary least ETX tree, and iteratively adjusts the hierarchy of the tree to reduce the load on bottleneck nodes by pruning and grafting its sub-tree. The complexity of the proposed algorithm is $O(N^4)$. Finally, extensive simulations are carried out to verify our approach. Simulation results show that our algorithm provides longer lifetime in various situations compared to existing data gathering schemes.

• International Journal of Internet, Broadcasting and Communication
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• 제12권3호
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• pp.46-55
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• 2020

Ad Hoc network is a special wireless network, mainly because the nodes are no control center, the topology is flexible, and the networking could be established quickly, which results the transmission stability is lower than other types of networks. In order to guarantee the transmission of data packets in the network effectively, an improved Queue Ad Hoc On-demand Distance Vector Routing protocol (Q-AODV) for node detection by using blockchain technology is proposed. In the route search process. Firstly, according to the node's daily communication record the cluster is formed by the source node using the smart contract and gradually extends to the path detection. Then the best optional path nodes are chained in the form of Merkle tree. Finally, the best path is chosen on the blockchain. Simulation experiments show that the stability of Q-AODV protocol is higher than the AODV protocol or the Dynamic Source Routing (DSR) protocol.

• 한국콘텐츠학회논문지
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• 제4권1호
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• pp.100-104
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• 2004

무선 단말기를 이용하여 단순한 문자 및 음성 전송 뿐만 아니라 멀티미디어 트래픽을 전송하고자 하는 사용자가 증가하고 있다. 본 논문에서는 이동컴퓨팅 환경에서 QoS보장을 위한 멀티캐스트 라우팅 알고리즘을 제안한다. 시뮬레이션 결과, 새로운 알고리즘은 이동컴퓨팅 환경에서 가장 절약한 대역폭으로 지연이 비교적 작은 멀티캐스트 트리를 구성할 수 있음을 보였다.

• 한국통신학회논문지
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• 제22권12호
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• pp.2626-2634
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• 1997

The purpose of multicasting is to reduce the network costs for transmitting the same traffic to multiple destinations. In this paper, an efficient delay-bounded multicasting routing algorithm is proposed, which satistifies the network conditions of cost minimization and can adjust the dynamic events, such as 'leave and/or join ones' from the multicast group. Also, our algorithm is designed for various network requirements such as the efficiet dynamic group support, high-quality data distribution, and adaptability to variable situation. After the delay tolerance and the maximum group size are determined according to network state and requirements for delay and cost, the dynamic delay-bounded multicast tree is constructed using partial multicast routing. We evaluate the performance of the proposed algorithm by running simulations on randomly generated test networks using a Sun Sparc 20 workstation. We were able to obtain good simulation resutls, which means solutions that lies between the minimum cost solution and the minimum delay one.