What is the sub carrier spacing used in NR RACH transmission?

Question

As far as i see, 15Khz is the minimum we come across in LTE, is it same in 5G?

If it is less than 15Khz then how do they maintain orthogonal property as indicated in LTE?

Answer 1

I think the subcarrier spacing depend on PRACH preamble sequence.As per 3gpp specs
Subcarrier spacing 1.25 or 5 Khz used for long sequence (L_RA = 839).
subcarrier spacing 15,30,60 or 120 Khz for short sequence (L_RA = 139) .
where L_RA 839 or 139 depending on the PRACH preamble format .