可抗多用戶干擾之預編碼正交分頻多工存取上鏈系統

A MAI-Free Multiuser OFDMA Uplink System with Precoding Technique

張育誠(Yuh-Cherng Jang)

指導教授 ： 鄧俊宏

元智大學/電機通訊學院/通訊工程學系/碩士(2012年)

摘要

本篇論文針對即將來臨的4G時代提出適用於WiMAX及LTE的預編碼上鏈系統。吾人針對常見的載波頻率偏移(CFO)現象在同時有多個用戶存在的情形下遭遇到的多用戶干擾做出研究並應用於兩者。
　　首先本論文提及應用區塊對角化(Block Diagonalization)方法於各用戶，藉此消除多用戶干擾。並配合吾人所提出以QR分解為出發點的污紙編碼(Dirty Paper Code)運算出適當的預編碼矩陣，配合基地台的處理不但可以擁有比以往的DPC更好的錯誤率，更能降低峰對均值比(PAPR)。本論文更進一步針對新提出的QR-DPC以注水理論(Water Pouring)優化其錯誤率表現。
　　第二部份則推廣此預編碼方式至多天線收發架構。吾人首先著眼於一新的SIMO收發機架構，提出異於以通道容量為判斷標準的方法，以獲取更低的錯誤率。接著提出將此預編碼收發機推廣至 之架構，實際上此架構能推廣至任何 MxM 大小，其中M > 2，並符合LTE release 10規格對MIMO的設計。最後吾人提出一結合STBC與空間多工的MIMO抗多用戶干擾架構，以此架構達到高品質、高傳輸率的OFDMA上鏈系統。

關鍵字

預編碼 ； 正交分頻多工存取 ； 上鏈系統 ； 長期演進技術

並列摘要

In this thesis, we propose a precoding OFDMA uplink system for the upcoming 4G cellular system. WiMAX, which is one of the 4G candidates. We especially tackle the common CFO problem which brings the MAI under multiple users circumstance.
The main idea of this thesis is the proposed QR-DPC precoding method, which is based on QR decomposition. Assisted with block diagonolization (BD) algorithm, we successfully utilize the precoding technique to eliminate the annoying MAI. Thus the combination of BD and QR-DPC can significantly increase the BER performance as compared to conventional DPC. Moreover we can further enhance the performance of QR-DPC by using the famous Water Pouring algorithm.
The second part is to extend QR-DPC to MIMO structure. First, a new SIMO antenna selection scheme is proposed to attain better BER performance than the channel-capacity-based selection method. Next, we derive a QR-DPC structure, which can be extended to any MxM MIMO case with M > 2, and fits the LTE release 10 specification. Finally, we propose a combined STBC and (SM) MIMO structure with MAI precoding to achieve high rate and high quality transmission for OFDMA uplink system.

並列關鍵字

precoding ； OFDMA ； uplink system ； LTE

參考文獻

FDMA Based Radio Access. John Wiley & Sons, 2009.

[2] Jeffrey G. Andrews, Arunabha Ghosh, Rias Muhamed,

Fundamentals of WiMAX: understanding broadband wireless

network. Pearson Education Inc., 2007.

Telecommunications and information exchange between