為了提升無線感測網路 (Wireless Sensor Networks) 的壽命，利用具有能量效益的方法使能量花費達到最小並且滿足效能與延遲要求條件是非常重要的。在本篇論文中，我們首先研究具有能量效益的多輸入多輸出傳輸並且同時考慮傳輸與接收天線個數與星座大小對總能量花費的影響，接這利用多輸入多輸出帶來的特性與優點。我們將延伸我們的分析結果到合作式多輸入多輸出無線感測網路 (Cooperative MIMO WSNs) 中，在此合作式多輸入多輸出無線感測網路中，每顆感測器上裝置單根天線並且以合作式方式組成合作式多輸入多輸出無線感測網路架構。我們針對此多輸入多輸出無線感測網路架構，設計傳輸與接收天線個數與星座大小使其達到最佳化進而讓合作式多輸入多輸出無線感測網路能量花費達到最小。與先前合作式多輸入多輸出無線感測網路方法比較後，我們所提出的方法可以達到較高的能量效益並且擁有較小的關鍵距離。關鍵距離定義為在此距離以上合作式多輸入多輸出方法比傳統單輸入單輸出方法更具有能量效益。最後我們將之前分析具有能量效益合作式多輸入多輸出結果延伸到多跳躍無線感測網路架構中。藉由結合考慮跳躍次數與跳躍長度進一步提出新的具有能量效益多跳躍無線感測網路模型。數值分析結果證明我們所提出的模型不僅可以平衡整體能量花費並且顯著的節省總能量。

To prolong the lifetime of wireless sensor networks (WSNs), an energy-efficient method is required to minimize the energy consumption while meeting the throughput and delay requirements. In this thesis, we first analyze the energy efficiency of multiple-input multiple-output (MIMO) transmission with the consideration of both the number of antennas and the constellation size. Secondly, we extend our analysis results to a cooperative MIMO WSN where individual single-antenna sensor nodes are cooperating to form multiple-antenna transmission and reception. Furthermore, we optimize the number of antennas and the constellation size for transmission/reception such that the energy consumption is minimized for the cooperative MIMO WSN. As compared to previous cooperative MIMO schemes for WSNs, the proposed one achieves a higher energy efficiency and has a smaller critical distance above which a cooperative MIMO approach outperforms a single-input single-output (SISO) approach. In the end, the previous analysis results of energy-efficient cooperative MIMO are extended to multi-hop WSN scenarios. By jointly considering the number of hops and hop length, a new energy-efficient multi-hop model is proposed. Numerical results show that the proposed model can not only balance the energy consumption but also save energy significantly.

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