ABSTRACT
The sources as well as the demand for wireless data are expanding rapidly and incessantly. The already congested and spectrally well efficient legacy sub-6 GHz bands can no further take additional service requests. So, first associational millimeter-wave (mmWave) wireless personal area network (WPAN), wireless local area network and mobile network standards were published in December 2008 (ECMA-387), December 2012 (IEEE 802.11ad) and December 2017 (3GPP Release 15), respectively, whereas submm wave used at present only has the IEEE 802.15.3d WPAN standard issued in October 2017.
In line with these, this chapter focuses on the preliminary utilization of the terahertz band for non-terrestrial networks through intersatellite communications links (ISLs). First, a review of the development of ISL technologies, namely microwave and optical solutions, is presented. State-of-the-art technologies are then compared in terms of their suitability for ISL adoption. Afterwards, a terahertz band ISL system is proposed considering the developments in the area during the last decade. Subsequently, link budgets for a typical usage scenario are calculated, helping to explain the propagation mechanisms. Finally, the chapter concludes setting directions for future research and challenges that may accompany them.
