Enhancing Spectral Access through Adaptive Terahertz Communication Systems

在过去的几十年里，由于人们创建和共享信息的方式发生了巨大的变化，高速无线通信引起了人们的广泛关注。预计到2020年，满足客户需求的数据速率将达到100 Gbit/s。然而，当今无线通信系统的速度受到现有发射机和接收机的窄带宽以及高达60 GHz的电磁频谱的大量使用的限制。这一趋势迫使研究人员将收发器的载波频率推向更高的频率，以允许在尚未分配给任何特定活动服务的频段上运行。为了增加信道容量，研究人员一直试图在太赫兹频率下工作，该频率覆盖电磁频谱中0.3-10 THz的频率范围。虽然迄今为止难以开发具有如此高的载波频率的通信系统，但是由于太赫兹光子学和电子学的最新进展，在10-20米距离上以超过100 Gbit/s的数据速率在太赫兹频率下操作的数据链路现在被认为是可行的。该计划的研究部分计划在太赫兹载波频率下开发用于室内通信应用的高数据速率无线通信系统。具有这种能力的系统可以非常适合于下一代室内无线通信系统，例如无线局域网和无线个域网、信息亭下载、无线回程、数据中心连接和可穿戴设备的实时数据分析。此外，该计划计划通过开发新课程，招募和参与本科生以及组织高中研讨会，将研究与教育和推广活动相结合。在这个计划中，定向太赫兹收发器系统的基础上的自适应二维阵列的等离子体光混合器下运行的新的通信协议的设计，制造和实验证明。拟议的工作提出了一个全新的视角，对太赫兹带宽的潜在用途，提高无线通信数据速率的水平，不能想象以前由于低输出功率和有限的适应性，现有的太赫兹发射机。这种限制可以通过使用等离子体光混合器阵列来解决，与其他太赫兹发射器候选者相比，等离子体光混合器阵列提供显著更高的太赫兹辐射功率和更高水平的发射器适应性。此外，所提出的太赫兹收发器系统的自适应性质允许通过波束成形和非视线通信链路补偿意外的未对准和阴影效应。虽然理论研究提供了对基于等离子体光混合器阵列的太赫兹收发器系统的基本物理限制和可实现的无线通信数据速率的深刻理解，但实验工作提供了有价值的数据来开发太赫兹频率下的准确信道模型，以便利用适当的通信模态，均衡技术，以及自适应信号跟踪系统，以减轻室内太赫兹通信系统中的信号衰落。

High-speed wireless communication has attracted extensive attention in the past decades because of dramatic changes in the ways people create and share information. The expected data rate to satisfy the needs of the customers is projected to be 100 Gbit/s by 2020. However, the speed of today's wireless communication systems is limited by the narrow bandwidth of existing transmitters and receivers and the heavy use of the electromagnetic spectrum up to 60 GHz. This trend has been forcing researchers to push the carrier frequencies of transceivers to higher frequencies to allow operation at frequency bands which have not been allocated to any specific active service yet. In order to increase the channel capacity, researchers have been trying to operate at terahertz frequencies, which cover the frequency range of 0.3-10 THz in the electromagnetic spectrum. While communication systems with such high carrier frequencies have been hard to develop so far, a data link operating at terahertz frequencies with data rates exceeding 100 Gbit/s over 10-20 meters distance is believed to be viable now thanks to recent advancements in terahertz photonics and electronics. The research component of this program plans to develop such a high data rate wireless communication system at terahertz carrier frequencies for indoor communication applications. A system with this capability can be very suitable for the next generation indoor wireless communication systems such as wireless local area networks and wireless personal area networks, kiosk downloads, wireless backhauling, data center connection, and real-time data analysis for wearable devices. Additionally, this program plans to integrate research with education and outreach activities by developing new courses, recruitment and involvement of undergraduate students, and organizing high-school seminars. During this program a directional terahertz transceiver system based on an adaptive two-dimensional array of plasmonic photomixers operating under novel communication protocols is designed, fabricated, and experimentally demonstrated. The proposed work presents an entirely new perspective on the potential use of terahertz bandwidth for increasing wireless communication data rates to levels that could not be envisioned before due to low output power and limited adaptability of existing terahertz transmitters. This limitation can be tackled through use of plasmonic photomixer arrays that offer significantly higher terahertz radiation powers and higher level of transmitter adaptability compared to other terahertz transmitter candidates. Additionally, the adaptive nature of the proposed terahertz transceiver system allows compensation for accidental misalignments and shadowing effects through beam-forming and non-line-of-sight communication links. While theoretical investigations provide a deep understanding of fundamental physical limitations of terahertz transceiver systems based on plasmonic photomixer arrays and achievable wireless communication data rates, the experimental effort provides valuable data to develop accurate channel models at terahertz frequencies in order to utilize appropriate communication modalities, equalization techniques, and adaptive signal tracking systems to mitigate signal fading in indoor terahertz communication systems.