在本篇論文中，使用 LTE 中的下行系統，論文的重點是 MAC 層與實體層間的下行共享通道(Downlink Shared Channel, DL-SCH)編碼以及 MAC 層中的混合式自動重送請求(Hybrid Automatic Repeat request ,HARQ)機制，其中也使用到複雜的 turbo code 編碼。本篇論文參考了 IR Type II HARQ (Incremental Redundancy Type II HARQ)的理念，提出了調適性速率匹配(Adaptive Rate Matching)，而其目的並不是 IR Type II HARQ 的重傳方法，而是希望透過訓練的方式來調整碼率，使得系統能夠適應不同的通道環境，並且依照通道環境的好壞來調整出適當的碼率，在調整完碼率後，整個 LTE 系統的運算將可以節省相當多。而本篇論文也 採用 OFDM、beamforming 等技術，模擬時使用了不同的環境，而從模擬的結果發現，調適性速率匹配可以依照不同的環境需求來提升碼率，節省傳輸位元，且不會因為碼率的提升而影響解碼成功率，在解碼失敗需要使用 HARQ 機制的情況也很少。 This thesis focuses on LTE downlink systems with shared channel coding between medium access control layer (MAC) and physical layer, using turbo coding, and hybrid automatic repeat request (HARQ). It made reference to Incremental redundancy type II HARQ (IR Type II HARQ), and proposed adaptive rate matching, Its purpose is not IR Type II HARQ retransmission method, We want to adjust the way through the training code rate, allows the system to adapt to different channel environments. After adjust code rate, LTE systems can save computing time. And we also use OFDM, beamforming technology and simulation in different environments. The simulation results showed that adaptive rate matching can enhance the code rate according to different environments, saving transmission bits, and will not affect the decoding success rate, need to use very few number of HARQ.
