New I/Q imbalance modeling and compensation in OFDM systems with frequency offset
New I/Q imbalance modeling and compensation in OFDM systems with frequency offset
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具有频率偏移的 OFDM 系统中的新 I/Q 不平衡建模和补偿
DOI：
10.1109/pimrc.2002.1047284
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
P. Champs
中科院分区：
文献类型：
--
作者：
S. Simoens;M. D. Courville;François Bourzeix;P. Champs
本文提出了一种新的模拟I/Q OFDM收发器正交不平衡模型和补偿方案。传统上，I/Q不平衡的影响是通过对称OFDM子载波对之间的串扰来建模的。我们表明，当载波频率偏移在I/Q不匹配源后进行补偿时，该模型是无效的。假设对基带频率偏移进行完美的数字补偿，则I/Q不平衡会在所有子载波之间产生干扰，而不仅仅是对称载波。当考虑模拟分量、多径传播和频率偏移时，完全矩阵分析必须利用伪循环矩阵对角化等数学结果。现有的模型恰好是这个更普遍的新结果的子情况。提出了一种适用于各种情况的补偿方案和接收机自动校准程序。结果表明，系统特定假设可以简化补偿的实现。这些假设在5ghz无线局域网收发器设计的框架中得到了验证，模拟组件的实际生产分布。
In this paper, a new model and compensation scheme of quadrature imbalance in analog I/Q OFDM transceivers is presented. Classically, the effect of I/Q imbalance is modeled by a crosstalk between pairs of symmetrical OFDM sub-carriers. We show that this model is not valid when the carrier frequency offset is compensated after the source of I/Q mismatch. Assuming a perfect digital compensation of the frequency offset in baseband, the I/Q imbalance generates interference between all sub-carriers and not only symmetrical ones. When analog components, multipath propagation and frequency offsets are taken into account, the complete matrix analysis has to make use of mathematical results such as the diagonalization of pseudo-circulant matrices. The existing models happen to be a sub-case of this new more general result. A new compensation scheme applying to every case is proposed as well as a receiver autocalibration procedure. It is shown that system-specific assumptions can simplify the implementation of the compensation. These assumptions are validated by simulation in the framework of a 5 GHz WLAN transceiver design with realistic production spread of the analog components.