Why broadcast messages are carried in TM mode ?

Question

RLC is one of the L2 layer in LTE radio protocol stack. It does many functions such as segmentation, re-assembling and along with that it supports various transmissions mode like transparent mode, acknowledgement mode and un-acknowledgement mode.
Now I want to understand for which type of RLC SDUs and PDUs transparent mode transmission is used.
Does the RLC create single RLC entity at cell level or at the UE level or at the bearer level ?

Answer 1

Broadcast messages comes under the TM mode since there is segmentation and reassembling. Purpose of broadcast messages is to convey the cell/system information to all the UEs within the cell. Since these messages are not UE specific that's why there is no need to check whether messages have been delivered or not. System information is always transmitted in fullest even though there is a radio resource crunch due to overload. That's why there is no need to segmentation.

Comments

In TM mode there is no segmentation and reassmbly.

Regards
Vikram