Be it Latency is increased and Throughout is comprised.
So if retx exceeds it’s a drop call?
Yes, correct.
But in VoLTE we have RLC UM that’s why TTI bundling is used.
As there is no concept of retx there.
I am not sure about MAC level HARQ.
I am talking about PHY layer HARQ.
I wanted to know about MAC HARQ, how it behaves.
Aren’t these 32 retransmissions RLC retransmissions not HARQ retransmissions?
Ya, so in HARQ retransmission what should be set?
I think it’s max 4 only.
Or more than that in case of LTE and NR?
Did anyone change RLC mode to AM for VoLTE?
I think for VoLTE RLC can only be UM.
Only for VoNR it is possible for RLC to be AM or UM.
So for VoLTE packets only retransmissions are HARQ retrans but no RLC retransmissions.
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32 is retransmission times of RLC PDU packet.
4 is total trans time of MAC TB.
So when RLF happens after RLC max retx or after completing both?
To go to t310.
RLC UM is mostly preferred for VoLTE as it requires lower latency and can tolerate a little higher packer loss rate.
RLC UM lets you deliver VoLTE Packets without delays due to retransmission ad reduced the control signaling overheads of RLC and PDCP layers.
This is the reason RLC UM is always and mostly used for VoLTE.
I believe that there is no such thing as PHY layer HARQ.
It’s only the MAC layer HARQ that triggers Retransmissions at PHY layer.
Yes, but PHY has to combine current LLRs with old LLRs.
T310 is for out of sync, when PDCCH hypotetical decoding failure rate is higher than 10% for N310 duration.
What’s LLR? Can you please give more info?
Also, it doesn’t make sense to configure a real time data(which is not important after the jitter buffer time) to be configured as RLC AM. App layer in general is expected to extrapolate the missed packets with UM operation. Also, if a packet Retransmission reaches max RLC retx, RRC will declare RLF which doesn’t seem correct when a voice call is in progress.
Soft bit values at receiver.
Combining is performed before LDPC decoding.
My understanding is that HARQ process start when BLER exceeds dltargetbler that CRC not matched and UE start sending nack for DL packets on PUCCH.
maxharq parameter indicates how many time UE can try for HARQ process like value is 8 in LTE and 16 in NR.
If HARQ process exhaust then it move to ARQ process at RLC if still packet not constructed then it will drop finally.
But in TDD what’s the value of HARQ process? Is it 4?
Does it mean HARQ retransmission in short?
Where did you find TDD value is 4?
Please provide reference…