5G Radio Frame & Subcarrier Info

5G support flexible SCS(Sub Carrier Spacing ) and time slot , which is based on the new concept “Numerologies”

In specification 38.211 chapter 4.2 numerologies is described like below :


So if μ=0,sub carrier spacing is 15kHz , time slot duration is 1 ms. TTI=1 ms.
If μ=1, sub carrier spacing is 30kHz ,time slot duration is 0.5ms, TTI=0.5ms.
Same as other configuration of μ.
So we can find 5G scheduling is based on TIME SLOT which is totally different from 4G. 4G scheduling is based on SUBFRAME. Because 5G time slot is flexible , so 5G TTI is flexible .
One time slot in 4G include 7symbols ,but 5G include 14symbols .
Take the most common scenario 30kHz SCS as example .
For a given 5G cell 100MHz bandwidth , there are 273 RB. Each time slot duration is 0.5ms.
Maximum MSC can support 256QAM, MIMO order can be 4*4.
So the theoretical peak throughput can be calculated as following roughly:
273(RB No.)*12(N_“sc” ^“RB” )*14(symbols No in one TimeSlot)*8bit(256QAM)*4(MIMO)/0.5ms(1Time Slot).

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@alaa_thabit what’s the no.of subcarriers for different numerologies?

Also, it’s important to note that for mm waves we use SCS 120 which contribute in reducing latency and phase noise.