3GPP 38.300 v19.3.0 — the document's own text
10.1 Basic Scheduler Operation
Taught in 5. The radio protocol stack, sublayer by sublayer (TSG RAN — the group that specifies the radio, in depth), 5. The layers a packet falls through, and the three states a device sits in (TSG RAN — the group that specifies the radio, overview).
In order to utilise radio resources efficiently, MAC in gNB includes dynamic resource schedulers that allocate physical layer resources for the downlink and the uplink. In this clause, an overview of the scheduler is given in terms of scheduler operation, signalling of scheduler decisions, and measurements.
Scheduler Operation:
- Taking into account the UE buffer status and the QoS requirements of each UE and associated radio bearers, schedulers assign resources between UEs;
- Schedulers may assign resources taking account the radio conditions at the UE identified through measurements made at the gNB and/or reported by the UE;
- Resource assignment consists of radio resources (resource blocks).
Signalling of Scheduler Decisions:
- UEs identify the resources by receiving a scheduling (resource assignment) channel.
Measurements to Support Scheduler Operation:
- Uplink buffer status reports (measuring the data that is buffered in the logical channel queues in the UE) are used to provide support for QoS-aware packet scheduling;
- Power headroom reports (measuring the difference between the nominal UE maximum transmit power and the estimated power for uplink transmission) are used to provide support for power aware packet scheduling.