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 UL• Synchronous non-adaptive/adaptive HARQ• Synchronous: HARQ process number fixed.• PID = (10*frame_number + subframe_number) modulo 8• Non-adaptive: The eNodeB does not signal HARQ RTX control informationon PDCCH.• Implicit RTX made by UE• Adaptive: The eNodeB may have a valid reason to move the retransmissionsomewhere else in the subframe• E.g. if the RTX burst collides with RACH• Adaptive RTX has the cost of having extra control information in PDCCH• If RTX cannot be scheduled, the UE remains blocked for this subframe!• Different from downlink – in downlink, a new TX would have happened ona new process• RTX can remain blocked for a long time in pathological cases• Appendix E gives the Uplink HARQ retransmission processing flowchart along with function namesCONFIDENTIAL ─ 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.55
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