Abstract
The accuracy of channel state information (CSI) available at a base station (BS) has a direct impact on the performance of precoding in wideband multi-user multiple input, multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems and depends on many factors, including: the delay between estimation and beamforming at the BS (also called the CSI delay), Doppler spread, the channel estimation method used, the average transmit power of pilot symbols, and the average number of pilot symbols that must be estimated per channel parameter. In this paper, the coefficient of CSI error needed to adapt to fading channels is modeled as a function of Doppler spread, CSI delay, and signal-to-noise ratio (SNR). In terms of the Gaussian-Markov CSI error model, an adaptive robust maximum signal-to-leakage-and-noise ratio (Max- SLNR) precoder is designed to track the statistical parameters of CSI error. The Doppler spread and SNR can be obtained through real-time estimation based on orthogonal pilot patterns. Simulation results show that, compared to non-adaptive robust and non-robust precoders of Max-SLNR, the proposed adaptive robust Max- SLNR precoder performs much better in terms of bit error rate (BER). Moreover, as either the average number of training symbols per channel parameter or the average transmit power increases, the BER performance of the proposed precoder approaches that of a precoder with ideal CSI.
摘要
在宽带多用户MIMO-OFDM系统中,基站获得的信道状态信息会受到延时、多普勒扩展、信道估计方法、导频符号发射功率及每信道参数必须估计的导频符号数目的影响,基站获得的信道状态信息的精确性会直接影响预编码算法的性能。本文中,我们将信道状态信息误差模型系数建模为与多普勒扩展,时延和信噪比有关的函数。基于高斯马尔科夫信道状态信息误差模型提出了一个自适应稳健的最大化信泄噪比的预编码算法来实时跟踪信道状态信息估计误差的统计特性的变化。通过基于正交导频模式的实时估计可以获得多普勒扩展和信噪比,从而实时估计误差模型系数。仿真表明:提出的自适应稳健的Max-SLNR预编码算法误码率性能明显优于非自适应和非稳健的算法,稳健性强;随着导频符号数目或发射功率的增加,提出的预编码算法的误码率性能会逐步逼近完美信道状态信息下的性能
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Shu, F., Tong, J., You, X. et al. Adaptive robust Max-SLNR precoder for MU-MIMO-OFDM systems with imperfect CSI. Sci. China Inf. Sci. 59, 062302 (2016). https://doi.org/10.1007/s11432-015-5390-y
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DOI: https://doi.org/10.1007/s11432-015-5390-y