無線感應器網路(wireless sensor network)是由一群感應器透過無線媒體(wireless medium)，藉以達成分散式的感應工作。感應器主要是在特定的感應範圍內用來監測某些物體所產生的變化，並且藉由無線感應器網路回傳給使用者得知這些觀察結果，經由這種模式，使用者可以在遠端透過存取某個感應器得知一些有意義而且有用的資訊。
每個感應器具有有限的記憶體以及計算能力，並且他們的運作受到能源的限制，一但感應器的能源用盡，則該感應器即無法運作，因此能源的考量在無線感應器網路中非常重要。
在本篇論文中，我們考慮感應器是以六角形網的形狀所排列，並使用TDMA的方式傳送資料，探討有效率的方向性擴散(directed diffusion)問題。我們在探討方向性擴散的問題時，會考慮到收送兩端可能的情況，例如：一點對全區域(sink-to-all)的傳播、一點對一區域(sink-to-region)的傳播、一點對多區域(sink-to -multi-regions)的傳播等傳播方式。如何在無線感應器網路上建構出能夠共用並且節省能源的時槽分配，即為本篇論文中最重要的研究核心。我們的目的是希望利用找出的時槽分配提昇方向性擴散的效能。

In this thesis, we present a new energy-efficient directed diffusion
protocol by using a proposed diagonal-based hexagonal-mesh scheme for a
wireless sensor network. The wireless sensor network is more reasonable to
carefully build a fixed-topological wireless network environment than the
conventional MANET due to the low mobility. Therefore, all sensor nodes are
arranged into a fixed-topological wireless network structure, namely the
hexagonal-mesh, while the MAC protocol is adopted the periodic
active-and-sleep model. Wireless sensor networks use battery-operated
computing and sensing devices. The directed diffusion is mainly operated on
the diagonal-paths of the hexagonal-mesh under the energy-efficient
consideration. To achieve the energy-efficient purpose, our diagonal-based
directed diffusion scheme has the following main contributions; (1) a
periodic active-and-sleep MAC protocol on TDMA channel model is designed, (2)
a periodic backbone-path-exchange scheme is periodically performed on the
diagonal-mesh to consider the per-node fairness problem, (3) three kinds of
directed diffusion communication applications are developed based on the
diagonal-based scheme. Finally, performance analysis result is finally
demonstrated to illustrate the energy-efficient achievement of our proposed
scheme.

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