單載波頻域均衡(SC-FDE)系統近年來受到越來越多關注，因為其有著與正交分頻多工(Orthogonal Frequency Division Multiplexing,OFDM)相近的效能也有著相似的模塊，SC-FDE不僅能有效的對抗多路徑衰減，且SC-FDE的峰均值功率比較OFDM低，是寬頻無線通訊系統物理層的主要技術之一，並且SC-FDE的發射機價格比OFDM來的低，因為OFDM在傳送端設計較複雜。離散傅立葉變換擴展正交分頻多工(Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing,DFT-S-OFDM)就是一種結合SC-FDE與OFDM優點的技術。
本篇論文主要是應用Wi-Fi6 IEEE 802.11ax的前導序列規格與DFT-S-OFDM系統做結合並加入波束成型在軟體定義無線電上做傳收。利用IEEE 802.11ax的前導序列做符元時間同步、載波頻率同步、通道估計，任何一項估計對於DFT-S-OFDM都很重要。波束成型則是需要知道先知道訊號到達的角度(Angle of Arrival,\ AOA)，以找到訊號能量最強的部份，接著用NLMS演算法計算權重並更新且以此權重來優化訊號。本文的另一大特色則是將以上系統應用在軟體定義無線電(SDR)上以達到實做的目的。 ;Single-Carrier Frequency Domain Equalization (SC-FDE) system has received more and more attention in recent years, because it has similar performance and similar modules to Orthogonal Frequency Division Multiplexing(OFDM), SC-FDE can not only effectively combat multi-path fading , but also the peak-average power of SC-FDE is lower than that of OFDM. Besides,the complexity requirement of the SC-FDE transmitter is lower than that of OFDM.Discrete Fourier Transform Spread Orthogonal Frequency Division Multiplexing(DFT-S-OFDM) is a technology combining the advantage of SC-FDE and OFDM.
This thesis mainly considers the Wi-Fi6 IEEE 802.11ax preamble sequence specification to combine the DFT-S-OFDM system and add the beamforming technique to design a transceiver on the Software-Defined Radio(SDR) platform.The preamble sequence of IEEE 802.11ax is used for symbol time synchronization、carrier frequency synchronization and channel estimation.Beamforming needs to know the angle of arrival(AOA)\\of the signal to find the part with the strongest signal energy,and then uses the NLMS algorithm to calculate and update the antenna weights for optimizing the received SNR.Another feature of this work is that the above system is realized with SDR for the purpose of demonstrating feasibility.
