Impacts of practical channel impairments on the downlink spectral efficiency of large-scale distributed antenna systems
Impacts of practical channel impairments on the downlink spectral efficiency of large-scale distributed antenna systems
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DOI：
10.1007/s11432-018-9413-6
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发表时间：
2018-12
期刊：
影响因子：
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通讯作者：
Jiamin Li;Dongming Wang;Pengcheng Zhu;X. You
中科院分区：
文献类型：
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作者：
Jiamin Li;Dongming Wang;Pengcheng Zhu;X. You
信道损伤是大规模天线系统性能的主要限制因素。在本文中，我们分析了实际的信道损伤所造成的导频污染，多普勒频移，和相位噪声的大规模分布式天线系统（L-DAS）与最大比传输（MRT）和迫零（ZF）波束成形，其中考虑每用户功率归一化的下行链路频谱效率的影响。使用一个联合信道模型，允许这些信道损伤的同时影响的研究，我们推导出准确和易于处理的封闭形式近似的遍历可实现的下行链路速率，从而使频谱效率分析的L-DAS和有效的评估的影响的信道损伤。结果表明，信道损伤降低了下行链路的频谱效率，并对ZF波束成形有显着的影响。同时给出了L-DAS系统的渐近用户速率极限，并由此分析了L-DAS系统在信道损伤情况下的渐近性能。分析结果表明，MRT和ZF波束形成达到相同的渐近性能极限，即使在信道损伤。研究还发现，在基站侧使用大规模天线阵列可以减弱信道损伤的影响。
Channel impairments are major limiting factors in the performance of large-scale antenna systems. In this paper, we analyze the impacts of practical channel impairments caused by pilot contamination, Doppler shift, and phase noise on the downlink spectral efficiency of large-scale distributed antenna systems (L-DASs) with maximum ratio transmission (MRT) and zero-forcing (ZF) beamforming, in which per user power normalization is considered. Using a joint channel model that allows study of the simultaneous impacts of these channel impairments, we derive accurate and tractable closed-form approximations for the ergodic achievable downlink rate, thereby enabling spectral efficiency analysis of L-DASs and an efficient evaluation of the impacts of the channel impairments. It is shown that channel impairments reduce the downlink spectral efficiency and have a significant impact on ZF beamforming. The asymptotic user rate limit is also determined, from which we analyze the asymptotic performance of L-DASs with channel impairments. The analytical results show that MRT and ZF beamforming achieve the same asymptotic performance limit even with channel impairments. It is also found that the use of a large-scale antenna array at the base station sides can weaken the impacts of channel impairments.