# RF Wireless World

## LTE Code Rate Calculator | LTE Code Rate Calculation

This page mentions LTE Code Rate Calculator. The calculation of LTE code rate is done based on MCS, PRBs and OFDM symbols per slot. The LTE code rate calculator outputs code rate. It takes into account percent of REs used in control channel operation. The PRBs stands for Physical Resource Blocks allocated to the UE by eNB. The MCS stands for Modulation and Coding Scheme.

MCS (Enter: Any number from 0 to 31):

Number of Allocated PRBs, N_PRBs (Enter: Any number from 1 to 110) :

OFDM Symbols in a slot (N_symbols) (Enter:7(normal CP) or 6 (extended CP) ) :

Percent of REs allocated for control channel (percent_REs_CC, Enter 10 by default):

LTE Code Rate (Output#1):

Number of bits per subcarrier (bits) (Output#2):

TBS size (bits) (Output#3):

LTE Code Rate CALCULATOR EXAMPLE:
Input : MCS = 20 ; Number of PRBs = 2; OFDM symbols per slot = 7; REs for control channel (%) = 10
Outputs : Code rate = 0.44, Number of bits/subcarrier = 6 bits, TBS size = 776 bits

### LTE code rate calculation method | LTE code rate Calculator

Following equations/formula are used in this LTE Code Rate Calculator.
➨ LTE Code Rate = (TBS + CRC)/(N_REs*Qm) ...Equation-1
➨ N_REs = N_PRBs*12*N_symbols*2* (1-((percent_REs_CC/100))) ...Equation-2
N_symbols = Number of OFDM symbols in a slot i.e. 7 for normal cyclic prefix and 6 for extended cyclic prefix.
➨ Following steps are used in lte code rate calculation:
*Step-1: Determine Qm and TBS Index(i.e.ITBS) from MCS based on Table 7.1.7.1-1 mentioned below. (Here Qm = Bits per RE as per modulation scheme, 2 for QPSK, 4 for 16QAM and 6 for 64QAM)
*Step-2: From ITBS obtained in step-1 and N_PRBs entered by user obtain TBS (Transport Block Size) from the table 7.1.7.2.1-1 mentioned in the standard 3GPP TS 36.213 V9.2.0. Part of this table is depicted below for explaination purpose.
*Step-3: By putting values obtained TBS (in step-2), Qm (in step-1) and CRC of 24 bits in the equation-1 we can calculate LTE code rate. Calculate N_REs using Equation-2.

Table-1 LTE MCS Table:- Table-2 LTE TBS Table:- The above LTE code rate calculator uses all the 11 tables of Transport block size mentioned in the 3GPP TS 36.213 document. Table consists of TBS size for ITBS in the range from 0 to 26 and NPRB in the range from 1 to 110. This LTE code rate calculation is very useful for LTE system designers and LTE test teams.