應用於無線多輸入多輸出基頻處理器之頻率相依的IQ不平衡效應之研究

Abstract

直接降頻的接收器(DCR)架構目前在工業和學術界已經成為一個趨勢，因為它擁有體積小，便宜和消耗更少動力的優勢。但是，這種架構會一起伴隨著一些射頻(RF)的不完美效應，像是直流電(DC)偏移，頻率偏移，以及I/Q不平衡效應等等…在這篇論文中，主要是研究頻率相依的I/Q不平衡效應。 為了使無線接收器上的類比I/Q處理器得到令人滿意的效能，實部和虛部的匹配變得至關重要。 此論文提出一個新穎的基頻處理方法來估計和補償在MIMO-OFDM系統下，頻率相依的I/Q不平衡效應。 提出的方法只要使用一次的估算，就能夠估計並且補償非理想效應，它可以容忍的範圍包含了震幅誤差2dB， 相位誤差20 度，以及實部的低通濾波器是 [1 0.1 ]，虛部的低通濾波器是 [0.1 1 ] 的情況。

A direct-conversion receiver (DCR) architecture becomes a trend in industry and academic world nowadays because it is small, cheap and less power-consuming. This kind of architecture, however, accompanies with some radio frequency (RF) imperfections such as the direct current (DC) offset, frequency offset, inphase/quadrature (I/Q) imbalance, and etc. In this thesis, it focuses on the topic of the RF impairment of frequency dependent I/Q imbalance. To achieve satisfactory performance in analog I/Q (inphase/quadrature) processing based wireless receivers, the matching of amplitudes and phases of the I and Q branches becomes vital. In this thesis, a novel baseband I/Q estimation and compensation technique is proposed to overcome the frequency dependent I/Q imbalance in MIMO-OFDM systems. The proposed method uses a one-shot algorithm which is able to estimate and compensate the non-ideal effect up to gain error 2 dB, phase error 20 degree, and the low pass filter of the real part is [1 0.1], the low pass filter of the image part is [0.1 1].