在分時多工下的長期演進技術，部分架構基於大量的下行需求而指定較多的下行子訊框。在這情況下，多個混合式自動重傳請求重傳回報應該要在同一個預先指定的上行子訊框做上傳。當大量機械式型態通訊的特定需求使用者進入分時多工下的長期演進系統時，會讓系統面臨相當大的挑戰。再者，基於分時多工的下一代長期演進系統將會支援載波聚合的技術，將會讓上下行資源不對稱的情況面臨更大的挑戰。為了能夠有效地減少上行控制訊息對上行資源所造成的負擔，時間軸綑綁機制利用聯集運算將多個混合式自動重傳請求重傳回報結合成單一個回報。 然而，時間軸綑綁機制會增加每個傳送區塊的傳送次數也同時降低整體系統的吞吐量。這篇論文提出以視窗為基礎之時間軸綑綁機制藉由策略地混合等待重傳的傳送區塊與新進入的傳送區塊來降低每個傳送區塊的重送次數並同時提升系統的吞吐量。這兩種不同的區塊是藉由滑動視窗來控制。數值分析被提出來證明模擬分析與數值分析的一致性。模擬結果顯示以視窗為基礎之時間軸綑綁機制可以改善基於分時多工長期演進技術與下一代分時多工長期演進技術的混合式自動重傳請求重傳回報的運作。換句話說，當有大量機械式型態通訊的使用者存在基於分時多工長期演進系統與下一代分時多工長期演進系統時，整體系統的吞吐量效能與每個傳送區塊之傳送次數可以被改善。 In Long Term Evolution (LTE) Time-division Duplexing (TDD), some configurations which assign more subframes for Downlink (DL) are designed for heavy DL traffic. In such case, multiple Hybrid Automatic Repeat reQuest (HARQ) ACK/NACKs for different DL subframes shall be transmitted in a given Uplink (UL) subframe. This situation will become worse while Machine Type Communication (MTC) User Equipments (UEs) come into the LTE network because the number of the MTC UEs is very large, and MTC UEs have several particular features. Furthermore, in LTE-Advanced (LTE-A) TDD, the system supports the Carrier Aggregation (CA) which also makes the asymmetry problem of DL and UL subframes even worse. Indeed, to efficiently reduce the UL overhead caused by control signallings, the time bundling is adopted to combine multiple HARQ ACK/NACKs into an ACK/NACK by AND operation. However, the time bundling increases the number of transmission times of each Transport Blocks (TBs) and also degrades the overall system throughput. This thesis proposes the Window-based Time Bundling (WBTB) to decrease the number of retransmission times and to increase the system throughput by strategically mixing the portion of TBs waiting for retransmission and the portion of newly coming TBs. These two kinds of portions are controlled by a so called moving window. The numerical analysis is also provided to prove that the simulation results match the results of the numerical analysis. The simulation results show that the WBTB can significantly improve the efficiency of HARQ feedback operation in LTE and LTE-A TDD. In other words, the overall throughput performance and the number of transmission times per TB are improved especially for a large number of MTC UEs existing in LTE and LTE-A TDD network.
