非正交多重接取系統中之混合式自動重傳請求

Hybrid-ARQ in Non-orthogonal Multiple Access System

吳晉廷(Chin-Ting Wu)

指導教授 ： 蘇炫榮

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201603668

摘要

具有連續干擾消除器（SIC）的非正交多址（NOMA）是用於進一步LTE增強的有希望的下行鏈路多址方案。本文研究了NOMA與SIC的系統級性能。自適應調製和編碼方案（AMC）和混合自動重傳請求（HARQ）是鏈路自適應的兩個不可或缺的部分，並且在現代無線通信系統中也起著非常重要的作用。 AMC可以根據信道條件來調整調製和編碼方案（MCS）以最大化系統吞吐量，並且HARQ可以通過重傳解碼失敗的數據來提高系統可靠性和信道編碼增益。然而，在NOMA系統中，HARQ比在OMA中具有更多的困難。在本文中，我們調查比例公平（PF）設計在重傳和新的HARQ設計下行鏈路NOMA系統。提到了用戶配對和傳輸功率分配對NOMA性能的影響。另外，由於沒有實現具有固定閾值的AMC作為實際系統設計，我們提出了一種根據每個傳輸輪中的HARQ確認（ACK）反饋信息來自適應地調整AMC閾值的方法。

關鍵字

非正交多址 ； 干擾消除 ； 比例公平排程 ； 混合自動重傳請求 ； 自適應調製和編碼方案 ； 閾值調整

並列摘要

Non-orthogonal multiple access (NOMA) with a successive interference canceller (SIC) is a promising downlink multiple access scheme for further LTE enhancement. This paper investigates the system-level performance of NOMA with SIC. Adaptive modulation and coding scheme (AMC) and hybrid automatic repeat request (HARQ) are two indispensable parts of link adaptation, and also play very important roles in modern wireless communication system. AMC can adjust modulation and coding schemes (MCS) according to channel condition to maximize system throughput and HARQ can improve system reliability and channel coding gain by retransmitting data packet which decoded unsuccessfully. However, in NOMA system, HARQ has more difficulties than in OMA. In this paper, we investigate proportional fairness (PF) design in retransmission and new HARQ design for downlink NOMA system. The impacts of user pairing and transmission power allocation on NOMA performance are mentioned. In addition, without implementing AMC with fixed threshold as practical system design, we propose a method to adaptively adjust the AMC thresholds according to the HARQ acknowledge (ACK) feedback information in each transmission round.

並列關鍵字

NOMA ； interference cancellation ； PF scheduling ； HARQ ； AMC ； threshold adjustment

參考文獻

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