why not having separate transmitting and receiving RLC entity in RLC AM mode?

Question

As per very first diagram in LTE RLC specification its having separate transmitting and receiving RLC entites for UM and TM ? why not for AM mode???

Answer 1

Hi sripathi,

The diagram says, RLC AM mode need acknoledgement form the recived entity , once recieving entity sents ack then transmitter route thosh ack to RLC control, If it is a DATA PDU then transmitter entity forward those to upper layer.basically It should be coupled to route the Status PDU and data PDU. in case of TM and UM mode routing is not needed becaue there is no uplink response , so what ever you recive in transmitter side it is purely data PDU.

Comments

"  If it is a DATA PDU then transmitter entity forward those to upper layer." ... what does it mean jaganathan... can you clarify

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Hi,

Say there is simultaneous data transfer between UE and ENB (DL/UL), Enb have transmitted some DL packets then he will be waititng for the response(ack / nack), But in the response there can be a data corresponding to UL transmission of UE(because simultaneous transmission is going on) or Status PDU for the corresponding DL transmission. In order differentiate these two type routing is used and routed accordingly.

:)