• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.251-253
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• 2012

본 논문은 무선 센서 망의 실시간 데이터의 전달 확률 향상을 위한 기회적 실시간 데이터 전달 프로토콜을 제안한다. 기존에 재전송 기법은 데이터 전달 확률 향상을 위한 방법으로 잘 알려져 있으나, 이 기법은 딜레이를 발생시키기 때문에 실시간 데이터 전달에 적용하기는 적절치 않다. 이 문제를 해결하기 위해서 본 논문은 무선 망의 브로드캐스팅 방법과 순차적 기회 제공 방법을 동시에 사용한다. 하나의 센서 노드의 1-홉 내에는 실시간 요구사항을 만족하는 다수의 노드가 존재한다. 제안 방안에서는 실시간 요구사항을 만족하는 노드들에게 브로드캐스팅으로 데이터를 전달하고, 이 그룹에 속한 노드들에게 순차적으로 데이터를 중계할 기회를 제공한다. 제안 방안은 데이터를 빨리 처리할 수 있는 노드에게 먼저 기회를 제공하여 좀 더 많은 노드들이 데이터를 전송할 수 있는 기회를 갖게 함으로써 데이터 전달 확률을 높인다.

• Journal of Communications and Networks
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• v.10 no.2
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• pp.213-220
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• 2008

This paper analyzes a broadcasting technique for wireless multi-hop sensor networks that uses a form of cooperative diversity called opportunistic large arrays (OLAs). We propose a method for autonomous scheduling of the nodes, which limits the nodes that relay and saves as much as 32% of the transmit energy compared to other broadcast approaches, without requiring global positioning system (GPS), individual node addressing, or inter-node interaction. This energy-saving is a result of cross-layer interaction, in the sense that the medium access control (MAC) and routing functions are partially executed in the physical (PHY) layer. Our proposed method is called OLA with a transmission threshold (OLA-T), where a node compares its received power to a threshold to decide if it should forward. We also investigate OLA with variable threshold (OLA-VT), which optimizes the thresholds as a function of level. OLA-T and OLA-VT are compared with OLA broadcasting without a transmission threshold, each in their minimum energy configuration, using an analytical method under the orthogonal and continuum assumptions. The trade-off between the number of OLA levels (or hops) required to achieve successful network broadcast and transmission energy saved is investigated. The results based on the analytical assumptions are confirmed with Monte Carlo simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9A
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• pp.853-866
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• 2008

In this paper, a multi-hop relaying transmission scheme is analyzed regarding its feasibility and potentiality in the IEEE 802.22-based cognitive radio (CR) environment. Shortly, basic design issues are addressed such as relay station (RS) deployment and a frame structure of physical channel to escape inter-hop interference. This paper mainly develops a radio resource management scheme based on spectrum sensing results aggregated from CR secondary nodes and improves the opportunistic spectrum sharing efficiency. In particular, a decision rule about a channel availability is made using a distributed sensing method. Subsequently, spectrum allocation and routing path decision procedures are proposed to establish a link from source to destination with a hop-by-hop manner. Simulation results show that the proposed multi-hop relaying scheme is substantially profitable in CR environments if the number of hops and RS deployment are designed in such a way that the spectrum sharing gain is larger than spectrum division loss which is inherently induced in multi-hop relaying systems.