省電方法是無線感測網路(wireless sensor network, WSN) 的一個重要的挑戰。大多數的省電方法是利用媒介存取控制 (Media Access Control, MAC) 通訊協定或利用喚醒無線電 (wake-up radio, WUR) 。 由於MAC 通訊協定無法消除閒置聆聽 (idle listening) 的現象，且大部份的研究文獻著重低功率 (low power) WUR的硬體方式來解決閒置聆聽的問題和改善WUR的感應(sensitivity)度，但是目前研究文獻只有達成低感應(low sensitivity) 度和短通訊距離(short radio range) ，造成WUR 在WSN的應用不廣泛，並且大部份的WUR研究文獻未用軟體方式來增強感應度和通訊距離，所以本文將提出一個事件驅動 (event-driven) WUR的電路設計和以軟體方式的展頻碼(spreading code)演算法，用以解決閒置聆聽，增強感應度和通訊距離，以使省電的WUR能被廣泛應用。另一個省電方法是如何提高WUR的成功傳輸率 (throughput) ，由於目前的研究文獻著重在硬體電路設計，卻忽略用軟體方式改善傳輸率 (throughput) ，所本文將提出一個以軟體方式的區塊正交碼 (block orthogonal code) 演算法，以增強WUR的成功傳輸率，並且達成省電效果。
大部份的研究文獻著重在低功率WUR設計，但却減少無線電範圍 (radio range)，造成增加WSN的部署密度 (deployment density)。本文利用低資料傳輸率 (low data rate) 和前向錯誤糾正 (forward error correction, FEC) 技術，設計一個916.5 MHz 的高感應 (high sensitivity) WUR，此WUR在資料傳輸率 370 bit / s, 可增強感應能力到 −122 dBm，符碼錯誤率 (symbol error rate, SER) 10−2，可達成編碼增益 (coding gain) 13 dB，並且達成4倍資料無線電 (data radio) 的通訊範圍，使得WUR更適合WSN的應用。此WUR設計可以從任何的IEEE 802.15.4發射器 (transmitter) 穩定地接收喚醒信號 (wake-up signal) ，並且在訊號雜訊比 (Signal-to-Noise Ratio, SNR) 4 dB之下，達成低封包錯誤率 (packet error rate, PER) 0.0159。再者，此WUR設計將節點識別代碼 (node ID) 嵌入喚醒信號，以避免喚醒其他不希望喚醒的節點 (node)。
為了增強WUR 的傳輸率 (throughput)，本文提出區塊正交碼演算法，以降阺 SER，因此增強在WSN中WUR 的傳輸率。目前利用開關調制鍵控 (On-Off Keying, OOK) 調變的WUR研究文獻著重在低功率積體電路 (integrated circuit) 設計。但是它們並未考慮到錯誤更正碼 (error correction coding) 技術，因此增加錯誤率 (error rate) , 並且減少節點的生命週期 (lifetime) 。本文開發一個系統模型 (system model)，以評估區塊正交碼的傳輸率。本文實現系統模型的模擬，而且展現出區塊正交碼顯著地改善WUR的傳輸率。與8B10B編碼方式的OOK調變相比，區塊正交碼在不需要額外的硬體或能量消耗的情況下，對於WUR的傳輸率上，可以達到10 倍的改善效果。

Energy efficiency is an important challenge for resource constrained wireless sensor networks. Most research use Media Access Control (MAC) and wake-up radio (WUR) to achieve energy efficiency. As MAC can’t eliminate the idle listening and currently proposed WURs focus on low power hardware design with low sensitivity and short radio range, it means current WURs will increase the deployment density and installation and maintenance cost, and won’t be suitable to wireless sensor networks. This thesis proposes an event-driven WUR design and a spreading code algorithm in order to eliminate the idle listening, improve sensitivity, and enhance the radio range. Our design decreases the deployment density and installation and maintenance cost, and is more suitable to wireless sensor networks. The other method to achieve energy efficiency is improving the throughput of WUR. As improving the throughput is achieved by reducing the symbol error rate, which can reduce wake-up signal’s retransmissions, and avoid waking up high power data radios, and therefore increase the node lifetime. As current proposed WURs focus on hardware design and don’t take software design into account, and therefore reduce the throughput. This will increase symbol error rate, retransmissions, and effectively reduce the node lifetime. This thesis proposes a block orthogonal code algorithm in order to improve the throughput and power consumption.
Most of the published wake-up radios propose low energy design at the expense of reduced radio range, which means that they require an increased deployment density of sensor networks. In this thesis, we introduce a design of a high sensitivity 916.5 MHz wake-up radio using low data rate and forward error correction (FEC). It improves the sensitivity, up to − 122 dBm at a data rate 370 bit / s. It achieves up to 13 dB of coding gain with symbol error rate (SER) 10−2, and up to 4 times the range of the data radio, rendering it more suitable to sensor networks. Our design can receive wake-up signal reliably from any IEEE 802.15.4 transmitter and achieves a low packet error rate (PER) 0.0159 at SNR 4 dB. Furthermore, our design encodes the node ID into a wake-up signal to avoid waking up the undesired nodes.
In terms of improving the throughput of wake-up radios, we propose the use of a block orthogonal code to reduce the symbol error rate, and therefore improve the throughput of wake-up radios used in sensor networks. Currently proposed wake-up radios that use, for example, on-off keying modulation focus on integrated circuit design for low power operation. They do not take error correction coding into account and therefore increase the error rates and reduce the node lifetime. We develop a system model to evaluate the throughput of our proposed scheme. We implement a simulation of this model and show that our approach significantly improves the throughput of these radios. When compared with on-off keying modulation using 8B10B encoding we can achieve up to a factor of 10 improvement in the radio’s throughput without any additional hardware or energy consumption.

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