From sub-Terahertz to Terahertz: challenges and design considerations

NR Rel-15 physical layer specifications (released on December 2018) by 3GPP targeting IMT 2020 can support deployments in frequency ranges 410 MHz - 7.125 GHz and 24.25 GHz - 52.6 GHz. The support of higher frequency bands with large chunks of contiguous spectrum was deemed essential to fulfilling IMT 2020 vision of 20 Gbps peak data-rate in realistic deployment scenarios. It is also expected that global IMT traffic will grow 10 - 100 times from 2020 to 2030 and in order to support such growth Terahertz spectrum provides an attractive choice. In this paper, we describe the challenges in power amplifier, analog-to-digital design and impairments from phase noise that is expected in such regime. Considering such impairments, we show that realistic power amplifier backoff ratios are strongly correlated with the choice of a waveform. We provide results to show that phase noise could be mitigated by an appropriate choice of waveform for compensation while a judicious choice of frame structure can be used to maintain reasonable scheduling and processing complexity. In order to maintain simultaneous connectivity to multiple base-stations resulting in large timing differences at the receiver, the isolation between panels at the user equipment can be successfully used.