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>Recapping the DL <strong>and</strong> UL Frames• Exactly 1 allocation per UE in DL <strong>and</strong> UL• Allocation represented as a burst identified as (Start index, Number of allocationblocks, Start time, Delay, MCS index)• DL MPDU must not be created if no HARQ feedback mechanism on the UL canbe ensured• If the UE does not have PUCCH in n+4, a UL grant must exist: if the UE has notrequested data, or if the scheduler does not schedule this UE, this grant will consist of aminimum 1 allocation block <strong>and</strong> will be used exclusively for sending controlinformation (HARQ ACK/NACK)• DL data (PDSCH) <strong>and</strong> control (PDCCH) space is shared. PDCCH can be resizedto make bigger space for the data• A scheduler can aim to reduce the amount of control channel elements by restricting thenumber of UEs served in the same subframe, which can create more space for downlinkdata• HARQ retransmissions are part of the framing process• For uplink, both non-adaptive <strong>and</strong> adaptive HARQ retransmissions are supported• For downlink, asynchronous HARQ retransmissions are supported, in which retransmissioncan happen in any subframe >= n+8CONFIDENTIAL ─ 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.56
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