How DL/UL stuff works in LTE?
DL Link Adaptation
1.UE reports CQI, PMI, RI in PUCCH (or PUSCH)
2.Scheduler at eNB dynamically allocated DL resources to the UE (PDCCH)
3.eNB sends user data in PDSCH
4.UE attempts to decode the received packet and sends ACK/NACK using PUCCH (or PUSCH)
UL Scheduling – w/o resource
1.If UE does not have UL-SCH resources, UE sends SR on PUCCH (In absence of PUCCH resources, UE must complete a RACH procedure to request UL-SCH resources.)
2.Scheduler at eNB allocates resources (PRBs and MCS to be used) to UE through “uplink grant” on PDCCH
3.UE sends user data on PUSCH
4.If eNB decodes the uplink data successfully, it sends ACK on PHICH
UL Scheduling – modifying resource
1.UE sends BSR (Buffer Status Report) & PHR (Power Headroom Report) to network on PUSCH
2.Scheduler at eNB dynamically adjusts resources assigned to UE - Grant on PDCCH is adjusted
3.Based on the adjusted grant, UE sends user data on PUSCH
4.If eNB decodes the uplink data successfully, it toggles NDI (New Data Indicator) on PDCCH, and sends ACK on PHICH
1.UE reports CQI, PMI, RI in PUCCH (or PUSCH)
2.Scheduler at eNB dynamically allocated DL resources to the UE (PDCCH)
3.eNB sends user data in PDSCH
4.UE attempts to decode the received packet and sends ACK/NACK using PUCCH (or PUSCH)
UL Scheduling – w/o resource
1.If UE does not have UL-SCH resources, UE sends SR on PUCCH (In absence of PUCCH resources, UE must complete a RACH procedure to request UL-SCH resources.)
2.Scheduler at eNB allocates resources (PRBs and MCS to be used) to UE through “uplink grant” on PDCCH
3.UE sends user data on PUSCH
4.If eNB decodes the uplink data successfully, it sends ACK on PHICH
UL Scheduling – modifying resource
1.UE sends BSR (Buffer Status Report) & PHR (Power Headroom Report) to network on PUSCH
2.Scheduler at eNB dynamically adjusts resources assigned to UE - Grant on PDCCH is adjusted
3.Based on the adjusted grant, UE sends user data on PUSCH
4.If eNB decodes the uplink data successfully, it toggles NDI (New Data Indicator) on PDCCH, and sends ACK on PHICH
1 comments:
Good page to understand the basics. Do share the links or resource materials about UL channel allocations /scheduling
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