In RLC Layer , I have one doubt regarding ReTransmission of RLC AMD PDU. In spec 3GPP 36.322 in section 5.2.1 , it is mentioned like this
When an AMD PDU or a portion of an AMD PDU is considered for retransmission, the transmitting side of the AMRLC entity shall:- if the AMD PDU is considered for retransmission for the first time:- set the RETX_COUNT associated with the AMD PDU to zero;- else, if it (the AMD PDU or the portion of the AMD PDU that is considered for retransmission) or a portion of itis not pending for retransmission already:- increment the RETX_COUNT;- if RETX_COUNT = maxRetxThreshold:
- indicate to upper layers that max retransmission has been reached.
In spec it was not explained properly how to indicate to above layers (PDCP)?
This is an implementation, dependents. It depends on, how you want to implement it.
These are internal layer signalling.
RLC will signal RRC of this failure, for example; RLC_TO_RRC_ERROR_IND with error type (maxRetx)
RRC will then release PDCP, RLC, MAC, etc.
RLC signal's RRC of this failure, for example; RLC_TO_RRC_ERROR_IND with error type (maxRetx)
See RRC actions in 3GPP TS 36.331, chapter 126.96.36.199 Detection of radio link failure
1> upon indication from RLC that the maximum number of retransmissions has been reached:
2> consider radio link failure to be detected;
You can read further...
If you are implementing;
you can also signal RLC_TO_RRC_ERROR_IND, either with error type (maxRetx or radio link failure)