Huawei RB calculation vs NSN

[mohammed83]

Hello all,

I have TDD system of bandwidth 20MHz with DL-to-UL Conf 0 ==> DSUUUSDUUU and Special subframe format 10:2:2 so the DL/UL Ratio is 34.28% / 60%
Now I have to plan the AMR 12.2 kbps using the specific codecs rate becomes 288kbps. Cell edge user is using on DL at least 0-QPSK MCS and in UL 5-QPSK MCS.
Now the prblem I am getting is why NSN are calculating RBs differentky from Huawei since we have the same standard and same TBS tables!!!


DL
NSN formula for 0-QPSK : Nrb =Fx*2* E[(288/0.3428)*2/100] = 32 ===> E[x] = integer part of x; Fx=x-QPSK factor => F0=0-QPSK factor = 1 (I guess it's bit/symbol)
Huawei value (I don't have the formula) ==> Nrb= 13

UL 5-QPSK
NSN ==> Nrb = F5*2* (288/0.6)*2/100 = (5/8)*2*(480*2/100)=6

Huawei ==> Nrb = 5

WHY this difference if you have any idea help me please?

P.S : Ihave a problem with Ressource Block Group Size values (0;1;2;3 or 4), meaning and impact!

[mohammed83]

does anyone have any idea on what I am talking about??? any help please?

[giegala]

Hi,

it is difficult to understand what you mean here. Is it NRB on cell edge? Maybe Huawei is assuming that UL is very much limited as compared to DL. Then MCS0 is not needed in DL - it would be higher and as a result less NRB.

BTW, what are you planning - VoLTE capacity or coverage?

[mohammed83]

Hi,

it is difficult to understand what you mean here. Is it NRB on cell edge? Maybe Huawei is assuming that UL is very much limited as compared to DL. Then MCS0 is not needed in DL - it would be higher and as a result less NRB.

BTW, what are you planning - VoLTE capacity or coverage?


Thank you for your reply!
So I am planning coverage and the number of RBs I need to calculate is for cell edge user in order to have the MAPL by the end of the link budget! this calculation is essential in order to obtain the TBS and to calculate the required SINR (I know that It is link level simulation but I have my own macros to do the same calculation)!
The configuration of the UL and DL is like I said : "TDD system of bandwidth 20MHz with DL-to-UL Conf 0 ==> DSUUUSDUUU and Special subframe format 10:2:2 so the DL/UL Ratio is 34.28% / 60%".
my issue here is that I think that the way NSN is calculating N of RBs is much more logical than Huawei's that's why I am trying to understand how Huawei does its calculation I can give example of results of NRBs for Huawei :
Assuming 2 PATH transmission with 2Tx-2Rx MIMO SFBC DL and 1Tx-2Rx UL:
Service AMR12.2 kbps => after adding headers becomes 288 kbps (Huawei configuration of codecs which I don't know which one) DL QPSK 0.12 NRB = 13; UL QPSK 0.31 NRB=5
Data service 512 kbps => DL QPSK 0.3 NRB = 25; UL QPSK 0.31 NRB=12

Data service 1024 kbps => DL QPSK 0.3 NRB = 48; UL QPSK 0.31 NRB=24
Data service 2048 kbps => DL QPSK 0.3 NRB = 94; UL QPSK 0.31 NRB=45
Data service 4096 kbps => DL QPSK 0.59 NRB = 95; UL QPSK 0.38 NRB=75

??? :(