Dr Arunprakash Jayaprakash

Satellites will play an indispensable part in 5G roll out and the common use of new radio (NR) air interface will enable this. Satellite-terrestrial integration requires adaptations to the existing NR standards and demands further study on the potential areas of impact. From a physical layer perspective, the candidate waveform has a critical role in addressing design constraints to support non-terrestrial networks (NTN). In this paper, the adaptability of frequency-localized orthogonal frequency division multiplexing (OFDM)-based candidate waveforms and solutions are discussed in the context of physical layer attributes of non-linear satellite channel conditions. The performance of the new air interface waveforms are analysed in terms of spectral confinement, peak-to-average power ratio (PAPR), power amplifier efficiency, robustness against non-linear distortions and carrier frequency offset (CFO).

This paper analyses the New Radio (NR) air interface waveforms and numerologies in the context of current activities and studies of 3GPP related to the feasibility and standardisation of necessary adaptations for the 5G NR to support integrated-satellite-terrestrial networks with low earth orbit (LEO) satellites. Frequency-localized orthogonal frequency division multiplexing (OFDM)-based candidate waveforms are recommended by 3GPP as the waveforms for the NR in order to preserve the advantages of OFDM as well as maintain backward compatibility. 5G New Radio enables diverse service support, efficient synchronization and channel adaptability using a multinumerology concept, which defines a family of parameters of the parent waveform, that are related to each other by scaling. The major design challenges in the LEO satellite scenario are power limited link budget and high Doppler effects which can be addressed by choosing waveforms with small peak to average power ratio (PAPR) and sub-carrier bandwidth adaptation respectively. Hence, the selection of the right waveform and numerology is of prime relevance for the proper adaptation of 5G NR for LEO satellite terrestrial integration. The performance evaluation of the new air interface waveforms, with different numerologies, are carried out under the effect of carrier frequency offset (CFO), multipath effects, non-linearity, phase noise and additive white Gaussian noise (AWGN).