第五代巨量天線徑分多重接取蜂巢式系統中使用通用濾波多載波調變及其同步方法之研究

Abstract

在這篇論文中，我們研究了在第五代巨量天線徑分多重接取蜂巢式系統下行傳輸中使用通用濾波多載波調變及其同步方法。在我們的系統中，我們使用多載波調變技術去傳送用戶的資料。正交頻分多工是其中一種多載波調變，不過它有一個缺點是有很高的頻帶外功率。通用濾波多載波作為一種新興的多載波調變技術，比起正交頻分多工它可以很有效的壓制頻帶外功率。另外，多載波傳輸會對時間和頻率的同步非常敏感。在我們系統的上行傳輸中，領航序列可以用來執行同步。不過在下行傳輸中，因為沒有傳送領航序列，所以我們只能根據接收訊號的統計特性來進行同步估計。在一般的正交頻分多工系統中會使用循環前綴，而循環前綴可以用來執行粗略同步。然而，我們提出了在通用濾波多載波系統中，沒有循環前綴的粗略同步方法。另外，為了可以正確解調訊號，我們還提出了細符元時間的估計方法。

In this thesis, we studied and investigated the synchronization procedure for universal filtered multi-carrier (UFMC) in our proposed 5G massive antenna multipath division multiple access (MDMA) cellular system of downlink transmission. In our system, we consider multicarrier modulation to transmitted traffic data. One of the multicarrier scheme is OFDM, which has the problem of high out-of-band power. UFMC is a novel multicarrier transmission scheme, and it can suppress out-of-band power effectively as compared to OFDM system. In addition, multicarrier schemes are sensitive to time-frequency synchronization. In uplink transmission, pilot sequence can be used for synchronization. However, in downlink transmission, there is no pilot sequence and blind synchronization is need. In CP-OFDM system, CP can be used to execute the coarse synchronization. For UFMC, we proposed the coarse synchronization method which does not require the CP. Also, a fine symbol timing estimation method is proposed to obtain accurate time synchronization to demodulate signal correctly.