High‐speed data transfer and high‐performance imaging can be realized by using radio‐waves in high‐frequency bands, such as millimeter‐waves and THz‐waves, where wide frequency bands are available. However, the cell size would be smaller than a few hundred meters, due to large free space propagation loss and large atmospheric attenuation. Thus, many base stations, which are connected by networks, are required to offer nationwide or global network services by such high‐frequency radio‐bands. The networks would be constructed by various transmission media including optical fibers and fixed wireless links, where many media converters are required. This paper reviews various technologies for seamless bridges between radio and optical links. For the time being, congestion of radio spectrum in THz bands is not significant. However, if we look at the history of radio‐wave technologies, spectral congestion has been high even in newly developed high frequency bands. In active radio services in millimeter‐wave or THz‐wave bands, interference mitigation with passive services such as radio astronomy and Earth observation satellites is an important issue, as of now. This paper describes research trends of THz‐wave technologies from the point of view of a figure of merit defined by a product of the carrier frequency and spectral efficiency, to discuss the significance of spectral efficiency enhancement in the high‐frequency region. Analysis of power consumption of short‐distance radio systems is also shown to discuss expected performance of THz‐wave links.

中文翻译：

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太赫兹和光子学的无缝短距离链路，用于未来的移动网络

通过使用毫米波和太赫兹波等高频带的可用无线电波，可以实现高速数据传输和高性能成像。但是，由于较大的自由空间传播损耗和较大的大气衰减，单元的大小将小于几百米。因此，许多通过网络连接的基站需要通过这种高频无线电频带提供全国性或全球性的网络服务。该网络将由各种传输媒体（包括光纤和固定无线链路）构成，其中需要许多媒体转换器。本文回顾了无线电和光链路之间无缝桥接的各种技术。暂时而言，太赫兹频段的无线电频谱拥塞并不明显。然而，如果我们回顾一下无线电波技术的历史，即使在新开发的高频带中，频谱拥塞也很高。到目前为止，在毫米波或太赫兹波段的有源无线电服务中，对诸如无线电天文学和地球观测卫星之类的无源服务的干扰缓解是一个重要问题。本文从载频和频谱效率乘积定义的品质因数的角度描述了太赫兹波技术的研究趋势，以讨论在高频区域增强频谱效率的重要性。还显示了对短距离无线电系统功耗的分析，以讨论THz波链路的预期性能。到目前为止，在毫米波或太赫兹波段的有源无线电服务中，对诸如无线电天文学和地球观测卫星之类的无源服务的干扰缓解是一个重要问题。本文从载频和频谱效率乘积定义的品质因数的角度描述了太赫兹波技术的研究趋势，以讨论在高频区域增强频谱效率的重要性。还显示了对短距离无线电系统功耗的分析，以讨论THz波链路的预期性能。到目前为止，在毫米波或太赫兹波段的有源无线电服务中，对诸如无线电天文学和地球观测卫星之类的无源服务的干扰缓解是一个重要问题。本文从载频和频谱效率乘积定义的品质因数的角度描述了太赫兹波技术的研究趋势，以讨论在高频区域增强频谱效率的重要性。还显示了对短距离无线电系统功耗的分析，以讨论THz波链路的预期性能。本文从载频和频谱效率乘积定义的品质因数的角度描述了太赫兹波技术的研究趋势，以讨论在高频区域增强频谱效率的重要性。还显示了对短距离无线电系统功耗的分析，以讨论THz波链路的预期性能。本文从载频和频谱效率乘积定义的品质因数的角度描述了太赫兹波技术的研究趋势，并讨论了提高频谱效率在高频区域中的重要性。还显示了对短距离无线电系统功耗的分析，以讨论THz波链路的预期性能。