Toward a Realistic Assessment of Multiple Antenna HCNs: Residual Additive Transceiver Hardware Impairments and Channel Aging
Toward a Realistic Assessment of Multiple Antenna HCNs: Residual Additive Transceiver Hardware Impairments and Channel Aging
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DOI：
10.1109/tvt.2017.2710188
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发表时间：
2017-06
影响因子：
6.8
通讯作者：
Anastasios K. Papazafeiropoulos;T. Ratnarajah
中科院分区：
文献类型：
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作者：
Anastasios K. Papazafeiropoulos;T. Ratnarajah
鉴于广播信道的关键依赖的准确性，在发射机（CSIT）的信道状态信息，我们开发了一个通用的下行链路模型与迫零预编码，应用在现实的异构蜂窝系统与多天线基站（BS）。具体而言，我们考虑到不完美的CSIT由于导频污染，信道老化，由于用户的相对运动，以及不可避免的残留添加剂收发器硬件损伤（RATHIs）。假设基站是泊松分布，主要的贡献集中在推导的覆盖概率的上限和可达到的用户速率为这个一般模型。我们发现，覆盖概率和用户速率都依赖于不完美的CSIT和RATHIs。更具体地说，我们量化了由于这些影响而导致的网络性能损失。我们描述了上行链路RATHI具有相等的影响，但是下行链路发送BS失真具有比用户的接收硬件损害更大的影响。因此，发送BS硬件应该比用户的接收硬件具有更好的质量。此外，我们还根据信道的时变特性来估计覆盖概率和用户速率。结果表明，它们都随着用户移动性的增加而减小，但在归一化多普勒频移的特定值之后，它们又增加。实际上，遵循Jakes自相关函数的时间变化反映了这种对覆盖概率和用户速率的影响。最后，我们考虑空分多址（SDMA），单用户波束成形（SU-BF），和基线单输入单输出传输。这些方案之间的比较表明，通过SU-BF的覆盖优于SDMA的覆盖。
Given the critical dependence of broadcast channels by the accuracy of channel state information at the transmitter (CSIT), we develop a general downlink model with zero-forcing precoding, applied in realistic heterogeneous cellular systems with multiple-antenna base stations (BSs). Specifically, we take into consideration imperfect CSIT due to pilot contamination, channel aging due to users relative movement, and unavoidable residual additive transceiver hardware impairments (RATHIs). Assuming that the BSs are Poisson distributed, the main contributions focus on the derivations of the upper bound of the coverage probability and the achievable user rate for this general model. We show that both the coverage probability and the user rate are dependent on the imperfect CSIT and RATHIs. More concretely, we quantify the resultant performance loss of the network due to these effects. We depict that the uplink RATHIs have equal impact, but the downlink transmit BS distortion has a greater impact than the receive hardware impairment of the user. Thus, the transmit BS hardware should be of better quality than user's receive hardware. Furthermore, we characterise both the coverage probability and user rate in terms of the time variation of the channel. It is shown that both of them decrease with increasing user mobility, but after a specific value of the normalized Doppler shift, they increase again. Actually, the time variation, following the Jakes autocorrelation function, mirrors this effect on coverage probability and user rate. Finally, we consider space-division multiple access (SDMA), single-user beamforming (SU-BF), and baseline single-input single-output transmission. A comparison among these schemes reveals that the coverage by means of SU-BF outperforms SDMA in terms of coverage.