Beam Size Design for New Radio Satellite Communications Systems

Satellite Communication (SatCom) systems are a promising solution to extend and complement terrestrial networks in un-/under- served areas, as reflected by several recent commercial and standardisation endeavours. Recently, 3GPP initiated a Study Item for 5G (New Radio, NR) Non-Terrestrial Networks (NTN) to foster the integration of SatCom in future 5G systems. After the definition of the system architecture and main design parameters, the focus is currently on the feasibility assessment of NR PHY/MAC layer procedures when a satellite channel is involved. In this letter, we propose a flexible methodology to design the beam footprint taking into account any source of differential delay between User Terminals (UTs) as, e.g., Random Access (RA) and Timing Advance (TA) procedures. In the numerical assessment, we compare the obtained beam footprint sizes with those currently being considered within 3GPP NTN studies, showing that larger/smaller dimensions can be assumed when considering the RA and TA procedures.