Why there is no mapping for RACH transport channel to any logical channel? Why RACH is terminated in MAC?
RACH doesn't actual carry a logical (or transport) channel. It's purely a physical signal (a preamble) used to indicate to the eNodeB that a UE is attempting to access the system. Once the UE receives an access acknowledgement from the eNodeB (and a corresponding uplink grant), then it will transmit its normal logical/transport/physical channel.
In the process of random access resource selection preambles are selected from group A and B with certain criteria.
Now my question is why we have to use this two sets instead of one set of 64 preambles?
What is size and content of RACH first message (Random Access Preamble transmission) by UE to eNodeB.
Also if someone can explain the fields and sizes?
Actually i am trying to learn RACH procedures and getting lots of hurdles to understand. I am posting my queries whatever is coming to my mind so that i will get the descriptive answers. I hope someone will help me here to learn it. Thanks in advance.
How many symbols are present in RACH sequence and what about its length?