LTE 長期演化網路是第四代無線通訊技術之標準，對於網路資料的傳輸提供較高的系統頻寬。而我們了解到無線網路傳輸速率是受限於行動裝置的電池容量。另一方面，由於現在的智慧型手機提供行動性讓現代人擁有很好的行動自由度，因此如何延長行動裝置的電池壽命是目前最重要的議題之一。在LTE無線網路架構之下，使用”非連續性接收系統操作(DRX)”休眠機制來保存行動裝置的電池電力。在無線傳輸網路之中我們專注在基地台與行動裝置之間的下鏈傳輸。首先，提出一個修改型的DRX休眠機制，此機制允許遠端基地台能夠以下鏈傳輸封包的方式進接到兩個行動裝置。為了避免了兩個行動裝置接收封包時會彼此碰撞，所以我們在原本的DRX機制中增加一個等待狀態。第二，我們推導出相關的數學模型來描述共享相同通道的兩個行動裝置之LTE DRX機制。我們將此它描述成一個具有半馬可夫程序特性的系統，然後使用嵌入式馬可夫鏈推導出在狀態轉移時間點時系統的穩態機率分佈。一旦穩態機率分佈被找到，透過由我們自己所提出來的兩種近似方法來計算所感興趣的效能量度。例如:功率節能因子、功率消耗平均百分比、封包延遲。根據實施輕/重載的資料流量以及服務差異化，我們可以考慮到四種情況。第三，研究四種系統參數對效能量度的影響。例如，靜止計數器、短循環計數器、短循環、長循環。如果系統具有服務差異化，我們可以發現參數靜止計數器比其他參數還容易造成重大的影響。在大量的數值實驗之後，顯示出第一個近似方法優於第二個近似方法。最後但並非最不重要，解析結果是借透過模擬結果驗證的。電腦模擬是使用C語言來撰寫。在所有我們研究的情況中，解析結果和模擬結果是非常吻合的。

The fourth-generation (4G) wireless technologies, such as Long-Term Evolution (LTE), promise to provide high bandwidth for data transmission. On one hand, the data rate for wireless transmission is limited by battery capacity. On the other hand, people enjoy the freedom provided by the mobility of user equipment (UE). Therefore, how to extend the battery lifetime of UEs is one of the most significant issues. Accordingly, LTE wireless networks employ the power-saving operation called Discontinuous Reception Operation (DRX) to conserve UE battery. We focus on the downlink transmission in LTE networks under the DRX mechanism. First, we propose the Modified DRX mechanism to allow the RNC to initiate a downlink transmission shared by two UEs. To avoid the collision between two UEs, a new mode, defer mode, is added to the original DRX mechanism. Second, we develop the analytical model to describe the LTE DRX operation with two UEs sharing the same link. We characterize the system of interest as a semi-Markov process. We utilize the embedded Markov chain to derive the steady-state probability distribution of the system of interest at the state transition points. Once the steady state probability distribution is found, the performance measures of interest are computed via two proposed approximation methods. The performance measures of interest are the power saving factor, mean percentage power consumption, and wake-up delay. Based on whether the traffic load is light or heavy and whether the service differentiation is enforced, we consider four scenarios. Third, we study the effect of four system parameters, i.e., the inactivity timer, the DRX short cycle timer, the short cycle, and the long cycle, on performance measures. With service differentiation, the inactivity timer results in the most significant effect among the four system parameters. After extensive numerical experiments, approximation method 1 is shown to outperform approximation method 2. Last but not least, we verify the accuracy of the analytical results by the simulation program written in C. In most cases studied, the analytical results are reasonably close to the simulation results.

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