補償OFDM系統I/Q不平衡與時變通道效應之可適性演算法

Adaptive Algorithms for Compensating I/Q Imbalance and Time-Varying Channel Effect in OFDM System

李馨如(Hsin-Ju Li)

指導教授 ： 黃正光

元智大學/工程學院/通訊工程學系/碩士(2005年)

摘要

無資料

關鍵字

I/Q不平衡

並列摘要

The implementation of OFDM-based physical layers suffers the effect of In-phase and Quadrature-phase (I/Q) imbalances in the receiver end. The I/Q imbalances can severely limit the achievable operating SNR, the constellation sizes and data rates. In this thesis, the effect of I/Q imbalances in OFDM systems is studied and algorithms for compensating the imbalances are proposed. The algorithms include least-squares, LMS, and NLMS equalization schemes. Computer simulations show that LS and NLMS algorithms have better performance. Also, we discuss the I/Q imbalances under a time-varying channel with high Doppler shift (1000 Hz). The decision-directed equalizer and two scattered pilot tone arrangements are exploited for channel estimations Different interpolation algorithms are also discussed. For a given pilot density, we have a BER level of to . We have compared the performances for all schemes with QPSK and 16-QAM as modulation schemes. The results are given by computer simulations.

參考文獻

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