Analysis of One-Tap Frequency Domain RLS Equalizer for OFDM Systems

• Main Authors: Chin-Chuan Chang, 張晉銓
• Other Authors: Yung-An Kao
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/07649441749373562802

碩士 === 長庚大學 === 電機工程研究所 === 93 === In this thesis, we explore the characteristics of one-tap frequency domain RLS equalizer for OFDM systems from a special viewpoint. By this one-tap equalizer, we compensated the channel effect and phase rotation of OFDM systems with the presence of CFO or SFO which caused by the local oscillator. The special viewpoint is that we regard the coefficient update equation of one-tap frequency domain RLS equalizer as one first order IIR filter equation. And we derived the frequency response of the one-tap frequency domain RLS equalizer from the RLS update equation. From the frequency response of the one-tap frequency domain RLS equalizer, the relation of magnitude and phase between its input signal and output signal are discussed in detail. Different forgetting factor value of the RLS update equation induces different frequency responses, and the relationships between input signal and output signal are changed by the different forgetting factor choice. From the results of computer simulation under IEEE802.11a, we can find that this method really solves the phase rotation caused by CFO and SFO, and the simulation has verified that our results of deriving are correct.