5G TTI

5G NR physical layer uses time-frequency resource (physical resource block) for transmission. A resource grid consists of N size,μgrid,x subcarriers and N subframe,μ symb number of OFDM symbols (Table 2 and 3).22 Şub 2022

The E-UTRA uses the concept of VRB (Virtual Resource Block) when allocating resources . It defines two types: LVRB (Local Virtual Resource Block) – this is the same as the PRBs; DVRB (Distributed Virtual Resource Block) – this identifies a distribution of the resources required over a number of PRBs.

RBG is the resource block group size when PDSCH has resource allocation type 0 . Type 0 resource allocation has distributed PRB allocation for UE. This distribution is based on the PRB group. PRB group size depends on BW.

In 5G NR, similar to 4G the resource allocation is done in Time domain and frequency domain . Time domain resource allocation defines which symbols are allocated to UE and frequency domain allocation defines which RBs are allocated to the UE.

In 5G, One NR Resource Block (RB) contains 12 sub-carriers in frequency domain similar to LTE . In LTE resource block bandwidth is fixed to 180 KHz but in NR it is not fixed and depend on sub-carrier spacing.24 Nis 2019