以基頻預先補償實現 2.4GHz CCK 編碼調變之高線性發射機

The Design and Implementation of High Linearity Transmitter with Base-band Predistorter for 2.4GHz CCK Modulation

陳逸樺(Yi-Hua Chen)

指導教授 ： 楊正任

元智大學/工程學院/電機工程學系/碩士(2001年)

摘要

在無線通訊系統中，微波發射機的非線性現象，使得訊號非線性失真、增加錯誤率。特別是非線性互調雜波，在通帶外很難用濾波器濾除，容易造成訊號間干擾。本論文將利用查表內插法（Look Up Table of interpolation）的技術在基頻作訊號預先補償。並針對IEEE 802.11b無線區域網路卡2.4GHz之發射機部分，改善發射機非線性失真造成之錯誤率及抑制互調雜波。查表內插法為利用查表法建立發射機非線性模型，再以內插法來找出預先補償器的補償函數值，其補償函數值會接近理想的補償函數。本論文利用IEEE 802.11b無線區域網路卡的標準，進行理論的模擬及實際應用2.4GHz無線區域網路卡，進行發射機非線性特性的改善。藉由理論模擬及實際電路架構的驗證，查表內插法所設計的訊號預先補償器適合在實際電路架構中實現。並且可用相同的訊號預先補償器，解決同一類型的發射機非線性現象。並可找出適當的輸入功率，得到最大的輸出功率及最佳的通帶外頻譜抑制效果。

關鍵字

預先補償器

並列摘要

With the increasing importance of spectral efficiency in mobile communications, linearity of the transmitter has become a critical design issue for digital communication. The concern for linearity is primarily due to the stringent restriction on intermodulation products and out-of-band power emission requirements. Additionally, for bandwidth-efficient modulation the transmitter nonlinearity can produce substantial signal distortion and, hence, increased bit error rates. In this article, digital signal predistortion is applied to 2.4GHz WLAN system and is used to improve the signal distortion and intermodulation for CCK modulation. The technique of Look-up Table with interpolation will be used for data signal predistortion on the baseband. We simulate the predistorted algorithm that can compensate the nonlinearity of the WLAN transmitter. The in-band distortion and out-band suppression are also evaluated by theoretical analysis and experimental measurement in this research.

並列關鍵字

predistorter

參考文獻

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