Peak LTE data rate can be calculated using the following parameters:
1 Time-slot=0.5 ms (i.e 1 Sub-frame = 1 ms)
1 Time-slot=7 Modulation Symbols (when normal CP length is used)
1 Modulation Symbol=6 bits; if 64 QAM is used as modulation scheme
Data rate for a single carrier=Number of symbols per time slot*Bits per symbol/Duration of a time slot=7*6/0.5e-3=84kbps
If 1200 carriers (100RBs) are used then the aggregated throughput would be=1200*84kbps=100.8Mbps
If 4×4 MIMO is used then the capacity would increase four fold to=403.2Mbps
With 3/4 channel coding the data rate would be reduced to=302.4Mbps
1. A Resource Block (RB)=12 Carriers
2. Actual data rate would depend upon the instantaneous channel conditions and number of users sharing the resources e.g. going down from 64QAM to QPSK in adverse channel conditions would reduce the data rate from 302.4Mbps to 100.8Mbps. Changing the code rate from 3/4 to 1/3 would further reduce the data rate to 44.8Mbps.
In the previous post we calculated the Shannon Capacity of LTE as a function of bandwidth. We now calculate the capacity as a function of SNR (bandwidth fixed at 20MHz and signal power varied). We also use the concept of effective bandwidth to get a more realistic estimate of the capacity. The modified Shannon Capacity formula is given as:
eff1=0.9=due to adjacent channel leakage ratio and practical filter issues
eff2=0.93=due to cyclic prefix
eff3=0.94=due to pilot assisted channel estimation
eff4=0.715=due to signalling overhead
Note: This is the capacity in a SISO channel with no fading.