Difference between NB-IOT and LTE in RACH

Question

LTE RACH procedure include 4 steps. In 1st step UE sends preamble to eNB. UE use 6 RB for sending preamble.
In NB-IoT same 4 steps exist. But I do not know how many RBs are needs for sending preamble.
Also I read it is hierarchical and it depend on repetition level. what is repetition level?

I want to know about difference between LTE-A and NB-IoT.

Answer 1

Hi,

Yes same 4 step exist in NB Rach but there is an change like repetition level and UL BW.

repetition level is used because NB IOT device is not that great like smartphone to perform, so to accommodate low cost and effectiveness they introduced repetitive transmission. this makes the signal receives to ENB without loss. repetition levels are communicated to UE via SIB signalling.

NB UE used 180Khz as UL bandwidth to transmit UL data. I don't know exactly how many RB this uses.

Answer 2

NBIoT uses single PRB