由於物連網時代的來到，無線感測器系統更有靈活性，能在多種環境中應用，不管是在家內或室外（住宅、商業或工業），都能夠使設備的佈線架構更自由和方便管理。同時能源的使用也是無線感測器系統設計最重要的考慮因素之一。感測器的電池通常功率和容量都很小，所以充電成了主要問題，如果不是不可能的話。因此，人們一直考慮使用可再生能源來充電感測器，例如太陽能、風力、與熱能。我們著重於太陽能。為了更接近現實生活的情況，我們研究了時變能量採集，即日照水準是時變的。具體來說，不同的日照水準由不同的能量到達狀態表示，能量到達速率取決於能量到達狀態。為了區分封包的緊迫性或重要性，我們假設有兩類封包：高優先和低優先。為了提高服務品質，每一類封包的能量需求可能是不同的。此外，為了強調每個封包可能有不同的不耐煩，我們假設在佇列中等待的每個封包可能變得不耐煩，且在沒有完成服務的情況下離開系統。總而言之，我們研究了具有時變可再生能源採集、不耐煩、異質能量需求和優先權的無線感測器系統的效能。具體來說，我們研究四種情境：(1)只有一個感測器節點，每個封包的能量需求是相同的；（2）只有一個感測器節點，每個封包的能量需求可能不同；（3）有三個連接的感測器節點，每個封包的能量需求是相同的；（4）有三個連接的感測器節點，每個封包的能量需求可能不同。在這四種情境下，我們都假定能量到達速率取決於能量到達狀態。
首先，我們推導所需情境的解析模型。我們採用疊代演算法來尋找穩態機率分佈和感興趣的效性能指標。第二，我們研究了各種系統參數對不同模型的感興趣效能指標的影響。第三，我們比較了高優先和低優先封包的效能。最後，我們通過模擬和分析結果來驗證我們結果的準確性。

With the advent of the Internet of Things (IoT) era, wireless sensor systems have become more flexible and can be used in a variety of environments, whether inside or outside the home (residential, commercial, or industrial), allowing for more freedom and ease of management in the wiring structure of the devices. Energy use is one of the most important considerations in WSN design. The batteries in the sensors are usually of low power and capacity, making charging a major issue, if not impossible. Therefore, renewable energy has been considered for charging the sensor battery, e.g., solar energy, wind power, and thermal energy. We focus on the solar energy. To get closer to the real-life situations, we study the time-varying energy harvesting, i.e., the sunshine levels are time-varing. Specifically, different sunshine levels are represented by different energy arrival states and the energy arrival rate depends on the energy arrival state. To distinguish the urgency or importance of a packet, we assume that there are two classes of packets: high priority and low priority. To improve the quality of service, the energy requirement of each class of packets may be different. Furthermore, to emphasize that each packet may have different impatience, we assume that each packet waiting in the queue may become impatient and leave the system without completing its service. To summarize, we study the performance of WSN with time-varying renewable energy harvesting, impatience, heterogeneous energy requirements, and priority. Specifically, there are four scenarios we studied: (1) there is only one sensor node and the energy requirement of each packet is identical, (2) there is only one sensor node and the energy requirement of each packet may be different, (3) there are three connected sensor nodes and the energy requirement of each packet is identical, (4) there are three connected sensor nodes and the energy requirement of each packet may be different. In all four scenarios, it is assumed that the energy arrival rate depends on the energy arrival state. First, we derived the analytical models of the desired scenarios. An iterative algorithm is adopted to find the steady-state probability distribution and the performance measures of interest. Second, we study the effect of the various system parameters on the performance measures of interest for different models. Third, we compare the performances of HP and LP packets. Lastly, the simulation and the analytical results are obtained to verify the accuracy of our results

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