發(fā)布時間：2018-11-07 16:24

【摘要】：移動通信經(jīng)過三十年的快速發(fā)展,逐漸演化成為社會發(fā)展必不可少的工具。面對著新興移動業(yè)務的流量需求,第五代移動通信系統(tǒng)應運而生。在憧憬著萬物互聯(lián)的新時代的同時,未來5G技術(shù)也面臨著新的發(fā)展和挑戰(zhàn)。多址接入技術(shù)是無線通信物理層最核心技術(shù)之一,傳統(tǒng)的正交多址接入技術(shù)已經(jīng)不能滿足5G中大容量,海量接入等需求,稀疏多址碼接入技術(shù)(SCMA)應5G需求設計產(chǎn)生。SCMA使用稀疏碼本實現(xiàn)過載,有效的提高了頻譜利用率,且可以通過設計良好的多維星座圖和SCMA用戶碼本來提高系統(tǒng)性能。在接收端通過消息傳遞算法(MPA)進行譯碼,對譯碼算法進行改進也可降低多用戶檢測算法的復雜度。本文首先對SCMA的基本架構(gòu)和基礎原理進行了研究,介紹了SCMA的系統(tǒng)模型和編碼原理,其中重點研究了三種SCMA碼本設計方法,包括基于方形QAM星座圖碼本設計、基于星形QAM星座圖碼本設計以及基于星座旋轉(zhuǎn)交織碼本設計方式,并對不同生成碼本在相同仿真條件下進行性能仿真和比較。接下來研究了SCMA譯碼算法,由于傳統(tǒng)的消息檢測算法涉及到大量的非線性指數(shù)運算,在其基礎上提出了低復雜度的Max-Log-MPA譯碼算法,在1/2Turbo碼率下僅有0.5dB左右的性能損失。本設計還在基于Turbo迭代聯(lián)合譯碼下,提出了基于MPA(Max-Log-MPA)與Turbo的聯(lián)合迭代多用戶譯碼算法,并完成了其性能仿真。最后在基于本文理論基礎上,在FPGA上完成了基于Max-Log-MPA檢測的SCMA譯碼的系統(tǒng)驗證與硬件實現(xiàn),硬件實測結(jié)果與軟件性能仿真結(jié)果一致,且在SCMA譯碼模塊工作在240MHz時鐘頻率下,譯碼模塊的吞吐率可以達到720Mbps。
[Abstract]:After three decades of rapid development, mobile communication has gradually evolved into an indispensable tool for social development. Facing the traffic demand of the new mobile service, the fifth generation mobile communication system emerges as the times require. At the same time, 5 G technology is facing new development and challenge. Multiple access technology is one of the core technologies in the physical layer of wireless communication. The traditional orthogonal multiple access technology can no longer meet the needs of large capacity and mass access in 5G. Sparse multiple access code (SCMA) technology should be designed for 5G requirement. SCMA uses sparse codebook to realize overload, which can effectively improve spectrum efficiency and improve system performance by designing good multi-dimensional constellation diagram and SCMA user code. The improved decoding algorithm can also reduce the complexity of the multiuser detection algorithm by decoding through the message passing algorithm (MPA) at the receiving end. In this paper, the basic structure and principle of SCMA are studied, and the system model and coding principle of SCMA are introduced. Three design methods of SCMA codebook are studied, including the design of codebook based on square QAM constellation. Based on star QAM constellation codebook design and constellation rotation interleaved codebook design method, the performance of different generated codebooks under the same simulation conditions is simulated and compared. Then the SCMA decoding algorithm is studied. Because the traditional message detection algorithm involves a large number of nonlinear exponential operations, a low complexity Max-Log-MPA decoding algorithm is proposed. Under 1/2Turbo code rate, only the performance loss of 0.5dB can be achieved. Based on Turbo iterative joint decoding, a joint iterative multiuser decoding algorithm based on MPA (Max-Log-MPA) and Turbo is proposed, and its performance simulation is completed. Finally, based on the theory of this paper, the system verification and hardware implementation of SCMA decoding based on Max-Log-MPA detection are completed on FPGA. The measured results of hardware are consistent with the simulation results of software performance. The throughput of the decoding module can reach 720Mbps when the SCMA decoding module works at the 240MHz clock frequency.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN929.5

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本文編號：2316901