Understanding LTE Model Internals and Interfaces
Understanding LTE Model Internals and Interfaces
Understanding LTE Model Internals and Interfaces
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1581 <strong>Underst<strong>and</strong>ing</strong> <strong>LTE</strong> <strong>Model</strong> <strong>Internals</strong> <strong>and</strong> <strong>Interfaces</strong>HARQ Support for DL• Asynchronous adaptive HARQ• An open HARQ process must be found for new MPDU transmissions• Eight HARQ processes supported.• HARQ context is exclusively signaled on the control channel• Signaling occurs on PDCCH. DCI format 1 is set for downlink carryingHARQ process ID, NDI bit <strong>and</strong> the redundancy version• HARQ retransmission can be scheduled any time at any location on the framestarting from n+8• Technically it can also carry any MCS index, although it is not done bydefault• All retransmissions served before any new transmission• Acknowledgment mechanism:• Either PUCCH or PUSCH channel is used for sending ACK back• If PUCCH is absent at n+4, the DL frame generator also reserves 1 resourceblock for this UE on PUSCH, which may be reused by the UL frame generatorCONFIDENTIAL ─ RESTRICTED ACCESS: This information may not be disclosed, copied, or transmitted in any format without the prior written consent of OPNET Technologies, Inc. © 2010 OPNET Technologies, Inc.50