Reliable Detection of Unknown Cell-Edge Users via Canonical Correlation Analysis
Reliable Detection of Unknown Cell-Edge Users via Canonical Correlation Analysis
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DOI：
10.1109/twc.2020.2980511
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发表时间：
2020-03
影响因子：
10.4
通讯作者：
M. S. Ibrahim;N. Sidiropoulos
中科院分区：
文献类型：
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作者：
M. S. Ibrahim;N. Sidiropoulos
即使5G部署即将到来，为靠近小区之间边缘的用户提供可靠的服务仍然是蜂窝系统中的一个挑战。这些用户受到显著的信号衰减，这也降低了他们的上行链路信道估计。由于远近功率不平衡和信道估计误差，即使使用基站（BS）协作的联合检测也常常不能可靠地检测这样的用户。是否有可能绕过信道估计阶段，并设计一个检测器，可以可靠地检测小区边缘的用户信号在显着的远近不平衡？本文表明，也许令人惊讶的是，答案是肯定的-虽然不是通过传统的多用户检测。利用小区边缘用户信号较弱但对不同基站来说是共同的，而小区中心用户对于其服务基站来说是唯一的这一特点，本文建立了小区边缘用户检测与相关空时基带等效矩阵的典型相关分析（CCA）之间的良好联系。它证明了CCA识别这些矩阵的公共子空间，即使在显著的小区间和小区间干扰下。随后可以使用公知的代数信号处理技术来解开小区边缘用户信号的所得混合。有趣的是，所提出的方法甚至不要求来自不同基站的信号同步-也可以自动确定正确的同步。实验结果表明，所提出的方法实现了数量级的BER改善相比，“预言”多用户检测，假设完美的知识的小区中心的用户信道。
Providing reliable service to users close to the edge between cells remains a challenge in cellular systems, even as 5G deployment is around the corner. These users are subject to significant signal attenuation, which also degrades their uplink channel estimates. Even joint detection using base station (BS) cooperation often fails to reliably detect such users, due to near-far power imbalance, and channel estimation errors. Is it possible to bypass the channel estimation stage and design a detector that can reliably detect cell-edge user signals under significant near-far imbalance? This paper shows, perhaps surprisingly, that the answer is affirmative – albeit not via traditional multiuser detection. Exploiting that cell-edge user signals are weak but common to different base stations, while cell-center users are unique to their serving BS, this paper establishes an elegant connection between cell-edge user detection and canonical correlation analysis (CCA) of the associated space-time baseband-equivalent matrices. It proves that CCA identifies the common subspace of these matrices, even under significant intra-and inter-cell interference. The resulting mixture of cell-edge user signals can subsequently be unraveled using a well-known algebraic signal processing technique. Interestingly, the proposed approach does not even require that the signals from the different base stations are synchronized – the right synchronization can be automatically determined as well. Experimental results demonstrate that the proposed approach achieves order of magnitude BER improvements compared to ‘oracle’ multiuser detection that assumes perfect knowledge of the cell-center user channels.