• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.6
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• pp.122-130
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• 2008

In many applications of wireless sensor networks, sensed data can be classified either normal or urgent data according to its time criticalness. Normal data such as periodic monitoring is loss and delay tolerant, but urgent data such as fire alarm is time critical and should be transferred to a sink with reliable. In this paper, by exploiting these data characteristics, we propose a novel energy-efficient data-aware routing protocol for wireless sensor networks, which provides a high reliability for urgent data and energy efficiency for normal data. In the proposed scheme, in order to enhance network survivability and reliability for urgent data, each sensor node forwards only urgent data when its residual battery level is below than a threshold. Also, the proposed scheme uses different data delivery mechanisms depending on the data type. The normal data is delivered to the sink using a single-path-based data forwarding mechanism to improve the energy-efficiency. Meanwhile, the urgent data is transmitted to the sink using a directional flooding mechanism to guarantee high reliability. Simulation results demonstrate that the proposed scheme could significantly improve the network lifetime, along with high reliability for urgent data delivery.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.46-48
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• 2006

현재 컴퓨터에서 사용되는 수의 체계는 컴퓨터의 메모리구조에서 사용하기 가장 알맞은 2진법과16진법이며 여러 프로그램들에서 효율적으로 사용되어 왔다. 그러나 어떠한 수의 체계든지 프로그램의 성질에 따라 예외적으로 드러나는 비효율적인 특성을 가지고 있다. 본 논문에서, 우리는 라우팅 관점에서의 2진법과 16진법의 예외적인 부분을 이용한 새로운 라우팅 어드레스의 표기법을 제안하며, 제안된 어드레스의 표기법을 이용한 라우팅 테이블과 라우팅 어드레스맵을 구성, 최소한의 메모리를 사용하여 센서네트워크 상에서 효율적인 Ad-Hoc 양방향 라우팅 방식을 구현하였다.

• Journal of KIISE:Information Networking
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• v.35 no.3
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• pp.215-226
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• 2008

As sensor networks are used in various and dynamic applications, the function of sink-to-sensors reliable multicasting such as for task reprogramming is newly required. NAK-based error recovery schemes have been proposed for energy efficient reliable multicasting. However, these schemes have incompleteness problems such as the last packet loss. This paper introduces an ACK-based error recovery scheme, RM2I(Reliable Multicast with Implicit ACK and Indirect Recovery). It utilizes wireless multicast advantage in which a packet may be delivered to all of its omni-directional neighbor nodes. When a sender overhears a packet which its receiver forwards to the next nodes, it may interpret it as an ACK from the receiver. We call it an Implicit ACK. In Indirect Recovery, when a node receives a packet from neighbor nodes which are not its direct upstream node, it saves and utilizes it for error recovery. Using NS-2 simulator, we have analyzed their effects. We have also compared RM2I with the NAK-based error recovery scheme. In results, RM2I shows comparable performances to the ideal NAK-based scheme, except where Implicit ACK and Indirect Recovery do not occur at the edges of the networks.