I would like to understand the relation between the TB size calculation in the TS36.213 document and in the Vienna Simulator https://www.nt.tuwien.ac.at/research/mobile-communications/vienna-lte-a-simulators . I’m going to make an example so maybe you can help me to see this relation:

**Method 1 (from the TS36.213)**

Calculation Procedure for downlink(PDSCH) is as follows :

i) refer to TS36.213 Table 7.1.7.1-1

ii) get I_TBS for using MCS value (Let’s assume MCS is 1. in this case, I_TBS is 1 )

iii) refer to TS36.213 Table7.1.7.2.1

iv) go to column header indicating the number of RB (Let’s assume that RB is 50)

v) go to row header ‘1’ which is I_TBS

vi) we would get 1800 (if the number of RB is 50 and I_TBS is 9)

vii) (This is Transport Block Size per 1 ms for one Antenna)

And this is method 2 (in the simulator):

i) This is the formula:

TB_size_bits = max(8*round(1/8*(the_RB_grid.sym_per_RB_nosync .* num_assigned_RB .* modulation_order .* coding_rate * 2))-24,0);

ii) if the_RB_grid.sym_per_RB_nosyn= 80

iii) num_assigned_RB=50

iv) modulation_order = 2

v) coding_rate=0.0762

vi) That gives TB_size_bits = 11952 bits

Do you know how I can go from one method to another or if there is any relation?