• 한국정보과학회논문지:정보통신
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• 제32권2호
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• pp.261-277
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• 2005

센서 네트워크에서는 베이스 노드와 다수의 센서 노드들간의 데이타 중심 (Data-centric) 기반의 통신 모델을 사용한다는 특징을 활용하여, 오버헤드를 최소화 하면서 최저 전력 라우팅 경로를 찾고, 또한 전체 네트워크의 수명을 최대화 시킬 수 있는 PAD (Power Aware Data-centric routing protocol)를 제안한다. PAD는 최저전력 라우팅 경로와는 상관없는 통신 링크를 제거한 최저전력특징그래프(Minimum Energy Property Graph)를 찾은 후, 오버혜드를 최소화 하고 slow convergence와 라우팅 경로의 루프 문제를 해결한 Distributed Data-centric Bellman-Ford Algorithm을 사용하여 라우팅 경로를 결정한다. 특히 PAD가 제안한 최저전력특징그래프를 찾는 알고리듬은 기존의 방식에 비해서 훨씬 빠르며, 간단하여 구현이 용이하면서도 가장 적은 수의 에지를 가지는 그래프를 구한다. 이는 기존의 방식이 사용하던 path-loss 모델만을 이용한 기하학적 계산과 복잡한 알고리듬을 path-loss 모델로부터 독립시켜 전력소모를 예측할 수 있는 어떠한 방법이든지 사용 가능하게 하고 또한 최단거리 알고리듬을 사용한 결과이다. PAD는 모든 과정을 분산된 방식으로 수행하며, 또한 최소의 오버헤드만을 가지므로, 다양한 센서 네트워크 응용에서 사용할 수 있을 것으로 기대한다.

• 디지털산업정보학회논문지
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• 제5권4호
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• pp.117-126
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• 2009

The recent interest in sensor networks has led to a number of routing schemes that use the limited resources available at sensor nodes more efficiently. These schemes typically try to find the minimum energy path to optimize energy usage at a node. Some schemes, however, are prone to unbalance of the traffic and energy. To solve this problem, we propose a novel solution: a gradient-field approach which takes account of the minimum cost data delivery, energy consumption balancing, and traffic equalization. We also modify the backoff-based cost field setup algorithm to establish our gradient-field based sensor network and give the algorithm. Simulation results show that the overhead of routing establishment obtained by our algorithm is much less than the one obtained by Flooding. What's more, our approach guarantees the basic Quality of Service (QoS) without extra spending.

• 한국정보통신학회논문지
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• 제19권7호
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• pp.1561-1567
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• 2015

모바일 애드혹 네트워크의 노드는 일반적으로 에너지의 용량이 제한된 배터리를 사용한다. 경로의 안정성을 유지하기 위해 균형 잡힌 에너지 소비가 중요하다. 본 논문에서는 애드혹 네트워크에서 데이터 전송 경로의 안정성을 향상시키는 것을 목표로 한다. 이를 위해 데이터를 전송할 수 있는 최단 전송 경로 중에서 노드 에너지 잔량의 최소값이 가장 큰 경로를 선택하는 새로운 라우팅 프로토콜을 제안한다. 에너지 잔량의 최소값이 가장 큰 경로는 다른 경로보다 상대적으로 긴 수명을 갖게 되어 데이터 전송에 안정성을 향상 시킬 수 있다. NS-3 시뮬레이터를 사용하여 제안하는 라우팅 프로토콜이 AODV와 EA-AODV보다 수명이 긴 안정적인 경로를 제공하는 것을 확인한다.

• Journal of Communications and Networks
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• 제10권2호
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• pp.204-212
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• 2008

We study the routing problem in all-wireless networks based on cooperative transmissions. We model the minimum-energy cooperative path (MECP) problem and prove that this problem is NP-complete. We hence design an approximation algorithm called cooperative shortest path (CSP) algorithm that uses Dijkstra's algorithm as the basic building block and utilizes cooperative transmissions in the relaxation procedure. Compared with traditional non-cooperative shortest path algorithms, the CSP algorithm can achieve a higher energy saving and better balanced energy consumption among network nodes, especially when the network is in large scale. The nice features lead to a unique, scalable routing scheme that changes the high network density from the curse of congestion to the blessing of cooperative transmissions.

• 한국경영과학회지
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• 제35권2호
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• pp.53-69
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• 2010

This paper proposes an ant-based routing algorithm, Ant System-Routing in wireless Senor Networks(AS-RSN), for wireless sensor networks. Using a transition rule in Ant System, sensors can spread data traffic over the whole network to achieve energy balance, and consequently, maximize the lifetime of sensor networks. The transition rule advances one of the original Ant System by re-defining link cost which is a metric devised to consider energy-sufficiency as well as energy-efficiency. This metric gives rise to the design of the AS-RSN algorithm devised to balance the data traffic of sensor networks in a decentralized manner and consequently prolong the lifetime of the networks. Therefore, AS-RSN is scalable in the number of sensors and also robust to the variations in the dynamics of event generation. We demonstrate the effectiveness of the proposed algorithm by comparing three existing routing algorithms: Direct Communication Approach, Minimum Transmission Energy, and Self-Organized Routing and find that energy balance should be considered to extend lifetime of sensor network and increase robustness of sensor network for diverse event generation patterns.

• Journal of Information Processing Systems
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• 제6권3호
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• pp.295-306
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• 2010

Network lifetime is a critical issue in Wireless Sensor Networks (WSNs). In which, a large number of sensor nodes communicate together to perform a predetermined sensing task. In such networks, the network life time depends mainly on the lifetime of the sensor nodes constituting the network. Therefore, it is essential to balance the energy consumption among all sensor nodes to ensure the network connectivity. In this paper, we propose an energy-efficient data routing protocol for wireless sensor networks. Contrary to the protocol proposed in [6], that always selects the path with minimum hop count to the base station, our proposed routing protocol may choose a longer path that will provide better distribution of the energy consumption among the sensor nodes. Simulation results indicate clearly that compared to the routing protocol proposed in [6], our proposed protocol evenly distributes the energy consumption among the network nodes thus maximizing the network life time.

• 한국통신학회논문지
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• 제28권7A호
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• pp.451-466
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• 2003

Untethered nodes in mobile ad-hoc networks strongly depend on the efficient use of their batteries. In this paper, we propose a new metric, the drain rate, to forecast the lifetime of nodes according to current traffic conditions. This metric is combined with the value of the remaining battery capacity to determine which nodes can be part of an active route. We describe new route selection mechanisms for MANET routing protocols, which we call the Minimum Drain Rate (MDR) and the Conditional Minimum Drain Rate (CMDR). MDR extends nodal battery life and the duration of paths, while CMDR also minimizes the total transmission power consumed per packet. Using the ns-2 simulator and the dynamic source routing (DSR) protocol, we compare MDR and CMDR against prior proposals for power-aware routing and show that using the drain rate for power-aware route selection offers superior performance results.

• 한국산업정보학회논문지
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• 제15권1호
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• pp.1-14
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• 2010

최근 무선센서네트워크 환경에서는, 네트워크의 확장성 및 이동성을 제공하고 외부 인터넷망과 연동할 수 있는 기술이 큰 이슈가 되고 있다. 현재 IPv6 기반의 저전력 무선 센서네트워크 기술인 6LoWPAN (IPv6 over Low-power Wireless Personal Area Network) 기술이 IETF에서 표준화 되고 있다. 본 논문에서는 6LoWPAN 환경에서 사용하기 위한 라우팅 프로토콜서, LOAD를 기반으로 하여 Link Qualities 값에 따른 패킷 재전송률을 경로 비용으로 활용하여 경로를 결정함으로서 최소 패킷 재전송이 이루어지는 최소경로비용 라우팅 프로토콜(MCL; Minimum route Cost routing protocol for 6Lowpan)을 제안하였다. 제안한 기법은 LOAD와 AODV 비해 각각 평균적으로 약 13%, 약 16% 정도 에너지 소비가 적은 것으로 실험을 통해 확인하였고, 전체 네트워크의 에너지를 고르게 사용하여 에너지 효율성이 우수하고, 네트워크 라이프타임이 향상됨을 알 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.504-521
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• 2016

Recently, energy harvesting technology has been integrated into wireless sensor networks to ameliorate the nodes' energy limitation problem. In theory, the wireless sensor node equipped with an energy harvesting module can work permanently until hardware failures happen. However, due to the change of power supply, the traditional hierarchical network routing protocol can not be effectively adopted in energy harvesting wireless sensor networks. In this paper, we improve the Low-Energy Adaptive Clustering Hierarchy (LEACH) protocol to make it suitable for the energy harvesting wireless sensor networks. Specifically, the cluster heads are selected according to the estimation of nodes' harvested energy and consumed energy. Preference is given to the nodes with high harvested energy while taking the energy consumption rate into account. The utilization of harvested energy is mathematically formulated as a max-min optimization problem which maximizes the minimum energy conservation of each node. We have proved that maximizing the minimum energy conservation is an NP-hard problem theoretically. Thus, a polynomial time algorithm has been proposed to derive the near-optimal performance. Extensive simulation results show that our proposed routing scheme outperforms previous works in terms of energy conservation and balanced distribution.

• 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.