RLC Questions

 Why do we need segmentation or concatenation for the RLC re-transmission?

Because LTE radio is very dynamic and it is not sure same amount of radio resources would be granted to transmit RLC PDU.
That is the reason in case of re-transmission RLC can re-segment the last unacknowledged RLC PDU which is kept in buffer.
LTE radio PDSCH is shared channel which is not dedicated to one UE.

 Why concatenation is removed from RLC NR?

Without concatenation hoe RLC process more grant from MAC?


RLC Segmentation size depands upon what ?

RLC Segmentation : If an RLC SDU is large, or the available radio data rate is low (resulting in small transport blocks), the RLC SDU may be split among several RLC PDUs. If the RLC SDU is small, or the available radio data rate is high, several RLC SDUs may be packed into a single PDU.
Check US patent 9781630

RLC reodering & reassembly mechanism

https://patents.google.com/patent/US20120155438A1/en

https://www.prodevelopertutorial.com/lte-rlc-arq-procedure/