無線感測網路是由 Sink node與許多Sensor nodes所組成。Sensor nodes將其所感測的資料透過multi-hop方式回傳給Sink node。在資料回傳的過程中，越接近Sink node的Sensor nodes將因代傳較多的資料而使電量較快耗盡，整個WSNs因電量耗費不均而造成網路分割。本論文擬提出一有效的網路佈建、拓樸建構及排程協定，以達到延長感測網路的生命週期、降低資料傳送delay time、平衡各個Sensor nodes電量的消耗以及避免資料傳送時發生碰撞等目的。首先，我們以Mesh-base Topology為討論範圍，將Sensor Nodes建立一Balance 的虛擬樹狀結構。之後，我們分別研發了distance-based 及density-based 的擺放技術，使各Sensor Node能達到耗電平衡的目的。當各Sensor Nodes的擺放位置確定後，本論文再針對各Sensor Node進行MAC Scheduling，使其傳送資料時能避免衝撞，並且在最短時間內回傳給Sink Node。最後，我們將上述技術延伸其應用範圍至Random Deployed 的WSNs，由於在此環境下Sensor Node的擺設位置及密度均不規則，我們整合distance-based及density-based兩種技術，使原先在Mesh-based WSNs 所開發的技術能應用在Random Deployed WSNs，並使各Sensor Node的耗電平衡以達到延長網路生命期之目的。實驗顯示，本論文所研發的協定能使各Sensor Node的耗電平衡以達到延長網路生命期之目的。 Wireless sensor networks (WSNs) comprise a sink node and a large number of sensor nodes. In the application of environmental monitoring, sensor nodes that are deployed far away from the sink node transmit the gathered information to the sink node in a multi-hop manner. Therefore, sensor nodes nearby the sink node tend to exhaust their energy earlier than other nodes due to their heavy traffic for packet forwarding. The unbalanced power consumption among sensor nodes may cause network partitioned. This paper proposes efficient node placement, topology control, and MAC scheduling protocols to prolong the sensor network lifetime, reduce the packet transmission delay, and avoid collision. Firstly, a virtual tree topology is constructed based on mesh-based WSNs. Then two node-placement techniques, namely distance-based and density-based deployments are proposed to balance the power consumption of sensor nodes. Finally, a collision-free MAC scheduling protocol is proposed to prevent the packet transmissions from collision. In addition, extension of the proposed protocols are made from the mesh-based WSN to the random deployed WSN, making the mechanisms developed for Mesh-based WSNs can be applied to random deployed WSNs. Simulation results reveal that the developed protocols can efficiently balance each sensor node’s power consumption and prolong the network lifetime in both mesh-based and random deployed WSNs.
