带限数字预失真系统关键技术研究
发布时间：2018-12-11 04:08
【摘要】：随着信息容量和数据传输速率的日益增长,现代无线通信系统大都采用了高阶的调制技术来充分利用有限的频谱资源,同时数据传输速率的增长使得信号的带宽大幅度增加。采用高阶调制体制技术的信号具有功率峰均比高的特点,这恶化了功放的高线性度和高效率的矛盾。功放的线性化技术是缓解这个矛盾的技术手段,其中,数字预失真技术以其线性化能力强,适应性强等特点成为了当前的研究热点。然而,随着信号带宽的增加,造成了反馈回路需要高采样率ADC的问题,增加了数字预失真技术的实现的成本和难度。针对上述问题,本文对宽带的数字预失真技术展开了研究。首先,由于在带限数字预失真系统中,传统的带限记忆多项式模型需要阶数非常高的带限滤波器来保证其精度,这造成了传统的带限记忆多项式模型复杂度高的问题,为此提出了一种低复杂度的带限记忆多项式模型,该模型可以降低所需的带限滤波器阶数,而且具有较高的性能。实验证明,与传统的带限记忆多项式模型相比,在同等性能条件下,模型系数数目和浮点运算数目分别下降了大约42%和65%。其次,针对带限数字预失真系统中的环路延时问题,采用自适应的算法求解小数时延,可提高算法估计的精度,并且采用自适应算法的估算算法,对于工程实现具有一定的参考价值。最后,由于带限数字预失真技术只能改善模拟滤波器带宽内的频谱,超出模拟滤波器的带宽外的频谱并不能得到改善,这部分信息将会干扰邻近信道,并且,带限预失真技术需采用带宽较窄的带限滤波器滤除掉受到模拟滤波器滚降等边缘不理想因素影响的频谱的局限性问题。为此,提出一种分频段的记忆多项式模型,实验证明该模型比传统的带限记忆多项式模型具有更低的复杂度,对信号的ACPR改善了19dBc,EVM改善了5.51%,同时对超出模拟滤波器的带宽外的频谱有一定的线性化能力。
[Abstract]:With the increasing of information capacity and data transmission rate, modern wireless communication systems mostly use high-order modulation technology to make full use of limited spectrum resources. At the same time, the increase of data transmission rate makes the signal bandwidth increase greatly. The signal with high order modulation system has the characteristics of high PAPR, which exacerbates the contradiction between high linearity and high efficiency of power amplifier. The linearization technology of power amplifier is the technical means to alleviate this contradiction. Among them, digital predistortion technology has become the focus of current research because of its strong linearization ability and strong adaptability. However, with the increase of signal bandwidth, the problem of high sampling rate ADC is caused by the feedback loop, which increases the cost and difficulty of digital predistortion technology. In order to solve the above problems, the digital predistortion technology of broadband is studied in this paper. First of all, in the band-limited digital predistortion system, the traditional band-limited memory polynomial model needs a very high order band-limited filter to ensure its accuracy, which leads to the high complexity of the traditional band-limited memory polynomial model. In this paper, a low complexity band-limited memory polynomial model is proposed, which can reduce the order of band-limited filter and has high performance. Experimental results show that compared with the traditional band-limited memory polynomial model, the number of coefficients and the number of floating-point operations are decreased by about 42% and 65% respectively under the same performance conditions. Secondly, for the loop delay problem in the band-limited digital predistortion system, adaptive algorithm is used to solve the fractional delay, which can improve the estimation accuracy of the algorithm, and the estimation algorithm of the adaptive algorithm is adopted. It has certain reference value for engineering realization. Finally, because band-limited digital predistortion technology can only improve the spectrum in the bandwidth of analog filter, the spectrum beyond the bandwidth of analog filter can not be improved. This information will interfere with adjacent channels, and, The bandlimited predistortion technique requires the use of bandlimited filters with narrow bandwidth to remove the limitation of the frequency spectrum affected by the undesired edge factors such as the roll down of the analog filter. For this reason, a memory polynomial model in frequency division band is proposed. The experimental results show that this model has lower complexity than the traditional band-limited memory polynomial model, and improves the ACPR of the signal by 5.51%. At the same time, there is a certain linearization ability for the spectrum beyond the bandwidth of the analog filter.
【学位授予单位】：中国工程物理研究院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN713
本文编号：2371837
[Abstract]:With the increasing of information capacity and data transmission rate, modern wireless communication systems mostly use high-order modulation technology to make full use of limited spectrum resources. At the same time, the increase of data transmission rate makes the signal bandwidth increase greatly. The signal with high order modulation system has the characteristics of high PAPR, which exacerbates the contradiction between high linearity and high efficiency of power amplifier. The linearization technology of power amplifier is the technical means to alleviate this contradiction. Among them, digital predistortion technology has become the focus of current research because of its strong linearization ability and strong adaptability. However, with the increase of signal bandwidth, the problem of high sampling rate ADC is caused by the feedback loop, which increases the cost and difficulty of digital predistortion technology. In order to solve the above problems, the digital predistortion technology of broadband is studied in this paper. First of all, in the band-limited digital predistortion system, the traditional band-limited memory polynomial model needs a very high order band-limited filter to ensure its accuracy, which leads to the high complexity of the traditional band-limited memory polynomial model. In this paper, a low complexity band-limited memory polynomial model is proposed, which can reduce the order of band-limited filter and has high performance. Experimental results show that compared with the traditional band-limited memory polynomial model, the number of coefficients and the number of floating-point operations are decreased by about 42% and 65% respectively under the same performance conditions. Secondly, for the loop delay problem in the band-limited digital predistortion system, adaptive algorithm is used to solve the fractional delay, which can improve the estimation accuracy of the algorithm, and the estimation algorithm of the adaptive algorithm is adopted. It has certain reference value for engineering realization. Finally, because band-limited digital predistortion technology can only improve the spectrum in the bandwidth of analog filter, the spectrum beyond the bandwidth of analog filter can not be improved. This information will interfere with adjacent channels, and, The bandlimited predistortion technique requires the use of bandlimited filters with narrow bandwidth to remove the limitation of the frequency spectrum affected by the undesired edge factors such as the roll down of the analog filter. For this reason, a memory polynomial model in frequency division band is proposed. The experimental results show that this model has lower complexity than the traditional band-limited memory polynomial model, and improves the ACPR of the signal by 5.51%. At the same time, there is a certain linearization ability for the spectrum beyond the bandwidth of the analog filter.
【学位授予单位】：中国工程物理研究院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN713
【参考文献】
相关博士学位论文 前1条
1 李明玉;宽带通信中功率放大器行为模型与预失真技术研究[D];电子科技大学;2010年
，本文编号：2371837
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