ns3::NrMacSchedulerSrs Class Reference

MAC scheduler SRS interface. More...

#include "nr-mac-scheduler-srs.h"

Inheritance diagram for ns3::NrMacSchedulerSrs:

Classes
struct	SrsPeriodicityAndOffset
	Struct to indicate to the scheduler the periodicity and the offset, in slots. More...

Public Member Functions
virtual	~NrMacSchedulerSrs ()=default
	Default.
virtual SrsPeriodicityAndOffset	AddUe ()=0
	Function called when the scheduler needs to know what is the offset and periodicy of a newly added ue.
virtual bool	DecreasePeriodicity (std::unordered_map< uint16_t, std::shared_ptr< NrMacSchedulerUeInfo > > *ueMap)=0
	Decrease the periodicity and assign to all UEs a different offset.
virtual bool	IncreasePeriodicity (std::unordered_map< uint16_t, std::shared_ptr< NrMacSchedulerUeInfo > > *ueMap)=0
	Increase the periodicity and assign to all UEs a different offset.
virtual void	RemoveUe (uint32_t offset)=0
	Function called when the scheduler has to release a previously owned periodicity and offset.

Detailed Description

MAC scheduler SRS interface.

This class is an interface for various SRS periodicity algorithms. An algorithm must assign a periodicity and an offset to a newly added UE. At this moment, the constraint is that two (or more) UEs cannot send the SRS in the same slot.

SRS management: how it works in the standard

The SRS periodicity and offset are set by the RRC layer, and communicated to the UE. In the NR standard, complex operations as frequency-hopping SRS are also defined. Luckily, there is also another opportunity, which is a scheduler-based SRS. The GNB informs the UE (through a DCI format 2_3) of the resources that are available to such UE to transmit its SRS.

SRS management in the NR module: how it is modeled

Deciding the SRS offset and periodicity at RRC would involve the scheduler as well, because the scheduler must not schedule any data that would be on the same resources as the expected SRS (DL or UL). Hence, implementing the decision at RRC would have lead to the complexity of modifying RRC plus the complexity of informing the scheduler of such decision, including multiple SAP interface modifications to allow intra-layer communication.

Therefore, we went for implementing such decision inside the scheduler, which will create a DCI format 2_3 to inform the UE about its scheduled time for sending SRS. Note that this reuses most of the structures and code used for data scheduling, and so it takes into account the various L1L2 latency plus the K latencies.

This interface will be used by the scheduler to ask the offset/periodicity for a UE, and various implementation can be written to simulate different algorithms.

Note: This interface assumes that all the UEs will share the same periodicity. If that's not the case, the API would have to be updated.

Definition at line 53 of file nr-mac-scheduler-srs.h.

Member Function Documentation

AddUe()

virtual SrsPeriodicityAndOffset ns3::NrMacSchedulerSrs::AddUe ( )

pure virtual

Function called when the scheduler needs to know what is the offset and periodicy of a newly added ue.

Returns

a struct that contains the periodicity and the offset. If the struct is not valid, an increase in periodicity is probably needed.

See also

IncreasePeriodicity

Implemented in ns3::NrMacSchedulerSrsDefault.

DecreasePeriodicity()

virtual bool ns3::NrMacSchedulerSrs::DecreasePeriodicity ( std::unordered_map< uint16_t, std::shared_ptr< NrMacSchedulerUeInfo > > *  ueMap )

pure virtual

Decrease the periodicity and assign to all UEs a different offset.

Parameters

ueMap

the UE map

Returns

true if the operation was done

The method decreases the periodicity, and then re-assign offsets and periodicity to all the UEs to avoid conflicts.

Implemented in ns3::NrMacSchedulerSrsDefault.

IncreasePeriodicity()

virtual bool ns3::NrMacSchedulerSrs::IncreasePeriodicity ( std::unordered_map< uint16_t, std::shared_ptr< NrMacSchedulerUeInfo > > *  ueMap )

pure virtual

Increase the periodicity and assign to all UEs a different offset.

Parameters

ueMap

the UE map

Returns

true if the operation was done

The method increases the periodicity, and then re-assign offsets and periodicity to all the UEs to avoid conflicts.

Implemented in ns3::NrMacSchedulerSrsDefault.

RemoveUe()

virtual void ns3::NrMacSchedulerSrs::RemoveUe ( uint32_t  offset )

pure virtual

Function called when the scheduler has to release a previously owned periodicity and offset.

Parameters

offset

The offset used by the UE

Note: This interface assumes that all the UEs will share the same periodicity. If that's not the case, the API would have to be updated.

Implemented in ns3::NrMacSchedulerSrsDefault.

---

The documentation for this class was generated from the following file:

• nr-mac-scheduler-srs.h