稀疏碼多重存取(Sparse Code Multiple Access, SCMA)為一種非正交多重存取技術(NOMA)，相對正交多重存取技術能提高頻譜效率並提供更多接取資源。雖然目前3GPP第五代行動通訊標準並未採納SCMA技術，但為了滿足大規模機器型通訊(mMTC)及物聯網(IoT)應用需求，仍有眾多文獻研討SCMA相關技術。行動通訊系統之上行鏈路採用免授權(Grant-Free)機制，可大量減少排程的延遲，以達到第五代行動通訊需要高可靠低延遲通訊(uRLLC)應用的需求，也有許多專家學者將免授權上行鏈路採用稀疏碼多重存取系統技術視為未來行動通訊標準選項之一。
本論文即針對基於SCMA的免授權上行鏈路，在已知用戶活動性和通道資訊下，探討其系統設計，尤其一般SCMA接收端採用訊息傳遞演算法(Message Passing Algorithm, MPA)作為多用戶解碼處理技術，系統模擬顯示用戶的多寡對MPA解碼處理效能有顯著影響，因此論文提出整合基於功率域及SCMA之非正交多重存取，其中包含連續干擾消除(Sucessive Interference Cancellation, SIC)解碼技術，以提高多用戶資訊解碼之正確率。

Although not been accepted explicitly by 3GPP current standard, non-orthogonal multiple access (NOMA) technique a promising candidate to improve the spectrum efficiency and provide more access resources for mMTC applications. To support the needed of the scenario in 5G, ultra-reliable and low latency communications (uRLLC) and massive machine type communications (mMTC), uplink grant-free transmission based on SCMA has been proposed. Recently, hybrid power domain sparse code (or joint power and code domain) non-orthogonal multiple access (called PD-SCMA or PSMA) was proposed to further improve the spectrum efficiency. This thesis explore the partial system design for the uplink grant-free multiple access, based on hybrid power domain sparse code non-orthogonal multiple access (PD-SCMA or PSMA), to support low latency (for uRLLC) and provide more access resources (for mMTC or IoT) on uplink. The whole system design includes successive interference cancellation (SIC), multi-user data decoding, power control strategy, and channel coding based on correct codebook (CB) detection, perfect channel state information (CSI).

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