Mobile traffic growth requires the advancement of not only the wireless access networks but also their backhaul and fronthaul. Terabit-class wireless backhaul and fronthaul can be an alternative to optical fiber transmission and will be one of the key technologies to construct a more flexible and less expensive network infrastructure for sixth-generation mobile networks (6G). However, it is a challenge to provide an extremely high-capacity wireless link for point-to-point connection without spatial multiplexing gain obtained by the multi-path rich environment. We demonstrated the world’s highest wireless transmission data rate of 1.58 Tbps in the sub-terahertz (sub-THz) band for 6G backhaul and fronthaul networks on the basis of the orbital angular momentum (OAM) multiplexing technology with a wideband Butler matrix. Terabit-class wireless transmission was achieved by designing a wideband $8\times 8$ Butler matrix with two types of 3-dB couplers for the structure without crossover and differential phase shifters that give the desired phase difference over wide bandwidth. Our Butler matrix is capable of multiplexing eight OAM beams and show a high mode isolation of greater than 15 dB and low insertion loss of less than 1.5 dB from 135 to 170 GHz. We implemented the Butler matrices in our OAM multiplexing transmission system, in which the physical-layer data rate of 1.58 Tbps wireless transmission was confirmed with eight OAM modes and dual polarization using the 32 GHz bandwidth.

中文翻译：

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1.58 Tbps OAM 多路复用无线传输，采用宽带 Butler 矩阵，适用于次太赫兹频段


移动流量的增长不仅需要无线接入网络的进步，还需要其回程和前程的进步。太比特级无线回传和前传可以作为光纤传输的替代方案，并将成为为第六代移动网络（6G）构建更灵活、更便宜的网络基础设施的关键技术之一。然而，在没有多路径丰富环境所获得的空间复用增益的情况下，为点对点连接提供极高容量的无线链路是一个挑战。我们基于轨道角动量 (OAM) 复用技术和宽带巴特勒矩阵，在 6G 回传和前传网络的亚太赫兹 (sub-THz) 频段展示了全球最高的 1.58 Tbps 无线传输数据速率。太比特级无线传输是通过设计一个宽带 $8\times 8$ Butler 矩阵来实现的，该矩阵具有两种类型的 3dB 耦合器，其结构没有交叉和差分移相器，可在宽带宽上提供所需的相位差。我们的 Butler 矩阵能够复用 8 个 OAM 光束，并在 135 至 170 GHz 范围内表现出大于 15 dB 的高模式隔离度和小于 1.5 dB 的低插入损耗。我们在 OAM 复用传输系统中实现了 Butler 矩阵，其中使用 32 GHz 带宽的 8 个 OAM 模式和双极化确认了 1.58 Tbps 无线传输的物理层数据速率。