Re-transmission at lower layers

Question

Hi,

I have one query, what's the benefit of having re-transmission at lower layers, not in higher layers.

Sushant

Answer 1

Hi,

Here lower layers means RLC and MAC ,both does re-transmission in some case,higher layer means RRC which doesn't send any data then how will it re transmit.

Comments

Hi jaganathan,

Thanks for your reply, then why not in PDCP ?why only with RLC and MAC

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PDCP also does re transmission at handover time to another ENB, But re-transmitting at RLC and MAC itself adds leads lot of latency to the packet and re-transmitting at RLC proved that error rate is negotiable so PDCP re transmission is not required

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i didn't understand ,please explain this point, " re-transmitting at RLC proved that error rate is negotiable so PDCP re transmission is not required"

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I meant to say RLC re-transmission is efficient if RLC re-transmission also fails the no point if re transmitting at PDCP because there may be any other problem for the CRC error. Say e.g HARQ retx is 4 and RLC max Retx is 4 then for every PDU there will be minimum of 16 retx is all these fails what is the point re transmitting at PDCP.