TTI Bundling In Lte

Question

1. What happens to data already stored in UPLINk & Downlink Buffer when TTI Bundling Is triggered.???
2. HArq RTT & BUNDLE Size
3. TTI Bundling Configuration at both ENB & UE side.??
4. DCI0 info for particular UE in BUNDLE size TTIs interval ???
5. Role of Uplink & Downlink Scheduler at eNB side.

Comments

Are these 5 questions or 1. Would be great if you can edit the question and possible ask to the point, so that people can respond.

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Hi.Salil , all question are related to same topic i.e TTI Bundling.

Answer 1

I am not sure about downlink but for uplink data due to poor radio channel condition ue may need to re-transmit packets for real time application packet (like VoIP) which is not acceptable.

To be decoded successfully a transmitted packet, UE sends same transport block four time consequently with different coding which is also known as TTI bundling. eNodB sends HARQ for a bundle.

RRC layer at eNodeB enable/disable TTI bundling for an UE. please check MAC-main config which is carried by RRC Connection Reconfiguration message.

I think only uplink scheduler has to care care of since TTI is associated with UL-SCH configuration but not sure.

Comments

@Vimal : Thanx for the comment but what about retransmission ??
what shoud be HARQ RTT ?? And what about Downlink Harq ??

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While testing some LTE network, I found that TTIBundling = True which is part of RRCreconfiguration Message, I observed that eNodeB is triggering X2-HO with source and target cell ID as same. Is it right behaviour to enable this

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Please state your question clearly.