Characterization of Propagation Phenomena Relevant for 300 GHz Wireless Data Center Links
Characterization of Propagation Phenomena Relevant for 300 GHz Wireless Data Center Links
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DOI：
10.1109/tap.2019.2949135
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发表时间：
2020-02
影响因子：
5.7
通讯作者：
Chia-Lin Cheng;A. Zajić
中科院分区：
文献类型：
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作者：
Chia-Lin Cheng;A. Zajić
本文详细介绍了针对类似数据中心环境中的无线机架到机架(R2R)和刀片到刀片(B2B)通信的300 GHz通道特征的广泛通道测量活动和后续统计通道模型。测量在各种场景下进行，例如R2R视线(LOS)、R2R受阻视线(OLOS)、R2R反射非视距(RNLoS)、R2R受阻RNLoS(ORNLoS)、B2B RNLoS、B2B ORNLoS和B2B LOS场景。在上述场景中，我们探讨了发射器(Tx)/接收器(Rx)未对准以及电缆、金属机柜和网状结构等障碍物对太赫兹(THz)传播的影响，以及使用现有金属对象作为NLOS链路反射器的可行性。对于R2R视距场景，使用光学透镜来延长Tx-Rx间隔距离。这导致了测量的通道中的波导效应，从而导致路径损耗指数(PLE)为1.48，阴影增益为0.7分贝。当存在电缆障碍物时，ORNLoS链路的性能优于OLOS链路，阴影增益低2.5db，多径较弱。RNLoS链路中的反射器在所有入射角度下的反射系数都非常接近1。对于B2B方案，建议使用双反射器太赫兹收发器机架系统，以实现跨垂直堆叠服务器的无线链路，并便于服务器的维护和维修。测量的路径损耗与LOS链路和具有中空垂直地平面的RNLoS链路中的Friis值非常接近。当存在电缆障碍时，ORNLoS链路的路径损耗比RNLoS链路高5-10分贝，相干带宽平均比RNLoS链路低0.25 GHz。测量的统计信道特性表明，光缆集群引起的阴影增益服从对数正态分布。
This article presents details about an extensive channel measurement campaign and subsequent statistical channel models for the characterization of 300 GHz channels for wireless rack-to-rack (R2R) and blade-to-blade (B2B) communications in a data center-like environment. Measurements were conducted in various scenarios such as R2R line-of-sight (LoS), R2R obstructed-LoS (OLoS), R2R reflected-non-LoS (RNLoS), R2R obstructed-RNLoS (ORNLoS), B2B RNLoS, B2B ORNLoS, and B2B LoS scenarios. In the aforementioned scenarios, we explored the impact of transmitter (Tx)/receiver (Rx) misalignment and obstructions such as cables, metal cabinets, and mesh structures on terahertz (THz) propagation, as well as feasibility of using existing metal objects as reflectors for NLoS links. For the R2R LoS scenario, an optical lens was used to extend the Tx-Rx separation distance. This led to a waveguide effect in the channels measured thereby resulting into a path loss exponent (PLE) of 1.48 with a shadowing gain of 0.7 dB. When obstructions of cables are present, ORNLoS link outperforms OLoS link with 2.5 dB lower shadowing gain and weaker multipath. Reflector in the RNLoS link has reflection coefficients very close to 1 for all incident angles. For the B2B scenario, a dual-reflector THz transceiver rack system is proposed to enable wireless links across vertically stacked servers and allow easy maintenance and repair of servers. The measured path loss closely follows the Friis values in the LoS link and in the RNLoS link with hollow vertical ground plane. When obstructions of cables are present, the ORNLoS link experiences 5–10 dB higher path loss and on average 0.25 GHz lower coherence bandwidth than the RNLoS link. The measured statistical channel properties show that the shadowing gain caused by cable clusters follows the log-normal distribution.