4. WHAT IS A SCHEDULER?
• A mechanism of L2, which helps base station to allocate resource to users through
scheduling algorithm.
• It does scheduling according to report from users. (CQI, HARQ Ind.)
5. WHY SCHEDULER IS IMPORTANT FOR
5G NR?
• Higher network efficiency
– Resource Allocation
– Higher Throughput
– Higher Reliability
– Lower Latency
– Power Management
6. WHAT ARE THE CHALLENGES IN
DESIGNING A SCHEDULER FOR 5G?
• Intelligent and Efficient scheduling
• Flexible and free designing platform (OAI, etc.)
8. WHAT DIFFERENT BETWEEN OAI AND
O-RAN SCHEDULER?
MAC
SCH
RLC
MAC SCH
RLC
DU APP
OAI architecture O-RAN architecture
9. WHAT IS THE ARCHITECTURE OF O-RAN
SCHEDULER?
• DL/UL Resource Scheduler:
– This corresponds to functionality of time-
domain and frequency domain scheduling
in DL and UL, respectively.
• DL/UL Link Adaptation (LA):
– This functionality performs per UE Link
Adaptation in DL and UL, respectively.
10. • UL Tx Power Control:
– Performs Closed loop UL power control for
PUSCH, SRS and PUCCH.
• DL/UL MIMO Mode Control:
– Determines per UE the MIMO mode, in DL
and UL, respectively, to be used along with
the corresponding precoding matrix.
• Timing Advance (TA) Manager:
– Estimating the TA Command for UE based
on feedback from L1 using PUSCH, PUCCH
and SRS.
11. O-RAN PROVIDES APIS FOR
SCHEDULER
• The APIs ensure any scheduler
implementation interworks with MAC.
This ensures the freedom of choice for
OEMs and operators to plug in a
scheduler implementation of choice from
a third-party vendor in O-DU.
12. WHAT APIS ARE PROVIDED BY AN O-RAN
SCHEDULER?
MAC to SCH SCH to MAC
Cell Configuration Request Cell (Re)Configuration Response, DL Broadcast
Allocation
Cell Delete Request Cell Deletion Response
Add UE Configuration Request, Modify UE
Configuration Request
UE (Re)Configuration Response
Delete UE Request UE Deletion Response
Paging Indication Contents DL Paging Allocation
13. OTHER SCH TO MAC APIS
• Scheduled Byte in DL/UL
– SCH provides scheduling information for a given TTI for scheduling DL/UL data.
• RAR Information
– SCH shares the RAR and UL scheduling and Msg3 scheduling information with MAC.
• DL Control Channel Information
– SCH provides information for DCI scheduling on PDCCH to MAC.
• DL Paging Allocation
– SCH provides information for paging message on a paging channel to MAC.
17. WHAT ARE THE CHALLENGES IN
DESIGNING A SCHEDULER FOR
SUPPORTING URLLC?
• URLLC
– For Reliability
• Interference (Inter-cell Interference, etc.)
• Channel State
• Coverage
• Packet dropping
– For Latency
• Transmission delay
• Queueing delay
• Processing delay
• Retransmission
36. f
t
360kHz
URLLC user 1
URLLC user 2
180kH
z
360kH
z
eMBB user 1
540kHz
180kH
z
eMBB user 2
eMBB user 3
mini-slot
URLLC user 3
37. f
t
360kHz
URLLC user 1
URLLC user 2
180kH
z
360kH
z
eMBB user 1
540kHz
180kH
z
eMBB user 2
eMBB user 3
mini-slot
URLLC user 3
Editor's Notes
DL/UL Resource Scheduler
Resource scheduling is performed per scheduling period and may be performed for a single slot or multiple slots.
It may include functions such as beam selection, selecting of UEs and associated bearers per scheduling period, allocation of radio resources for PDCCH, PUSCH, PDSCH and associated channels like DMRS.
DL/UL Link Adaptation (LA)
LA would return effective MCS to be used for channel allocation to the UE.
UL Tx Power Control
It may estimate the UL Tx power based on UE feedback (eg: Power Headroom Report) or measured UL channels.