Handover algorithm implementation based on RSRQ measurements, Event A2 and Event A4. More...

#include "a2-a4-rsrq-handover-algorithm.h"

Inheritance diagram for ns3::A2A4RsrqHandoverAlgorithm:

Collaboration diagram for ns3::A2A4RsrqHandoverAlgorithm:

Classes
class	UeMeasure
	Measurements reported by a UE for a cell ID. More...

Public Member Functions
	A2A4RsrqHandoverAlgorithm ()
	Creates an A2-A4-RSRQ handover algorithm instance.

	~A2A4RsrqHandoverAlgorithm () override

LteHandoverManagementSapProvider *	GetLteHandoverManagementSapProvider () override
	Export the "provider" part of the Handover Management SAP interface.

void	SetLteHandoverManagementSapUser (LteHandoverManagementSapUser *s) override
	Set the "user" part of the Handover Management SAP interface that this handover algorithm instance will interact with.

Public Member Functions inherited from ns3::LteHandoverAlgorithm
	LteHandoverAlgorithm ()

	~LteHandoverAlgorithm () override

Public Member Functions inherited from ns3::Object
	Object ()
	Constructor.

	~Object () override
	Destructor.

void	AggregateObject (Ptr< Object > other)
	Aggregate two Objects together.

void	Dispose ()
	Dispose of this Object.

AggregateIterator	GetAggregateIterator () const
	Get an iterator to the Objects aggregated to this one.

TypeId	GetInstanceTypeId () const override
	Get the most derived TypeId for this Object.

template<typename T >
Ptr< T >	GetObject () const
	Get a pointer to the requested aggregated Object.

template<>
Ptr< Object >	GetObject () const
	Specialization of () for objects of type ns3::Object.

template<typename T >
Ptr< T >	GetObject (TypeId tid) const
	Get a pointer to the requested aggregated Object by TypeId.

template<>
Ptr< Object >	GetObject (TypeId tid) const
	Specialization of (TypeId tid) for objects of type ns3::Object.

void	Initialize ()
	Invoke DoInitialize on all Objects aggregated to this one.

bool	IsInitialized () const
	Check if the object has been initialized.

void	UnidirectionalAggregateObject (Ptr< Object > other)
	Aggregate an Object to another Object.

Public Member Functions inherited from ns3::SimpleRefCount< Object, ObjectBase, ObjectDeleter >
	SimpleRefCount ()
	Default constructor.

	SimpleRefCount (const SimpleRefCount &o)
	Copy constructor.

uint32_t	GetReferenceCount () const
	Get the reference count of the object.

SimpleRefCount &	operator= (const SimpleRefCount &o)
	Assignment operator.

void	Ref () const
	Increment the reference count.

void	Unref () const
	Decrement the reference count.

Public Member Functions inherited from ns3::ObjectBase
virtual	~ObjectBase ()
	Virtual destructor.

void	GetAttribute (std::string name, AttributeValue &value, bool permissive=false) const
	Get the value of an attribute, raising fatal errors if unsuccessful.

bool	GetAttributeFailSafe (std::string name, AttributeValue &value) const
	Get the value of an attribute without raising errors.

void	SetAttribute (std::string name, const AttributeValue &value)
	Set a single attribute, raising fatal errors if unsuccessful.

bool	SetAttributeFailSafe (std::string name, const AttributeValue &value)
	Set a single attribute without raising errors.

bool	TraceConnect (std::string name, std::string context, const CallbackBase &cb)
	Connect a TraceSource to a Callback with a context.

bool	TraceConnectWithoutContext (std::string name, const CallbackBase &cb)
	Connect a TraceSource to a Callback without a context.

bool	TraceDisconnect (std::string name, std::string context, const CallbackBase &cb)
	Disconnect from a TraceSource a Callback previously connected with a context.

bool	TraceDisconnectWithoutContext (std::string name, const CallbackBase &cb)
	Disconnect from a TraceSource a Callback previously connected without a context.

Static Public Member Functions
static TypeId	GetTypeId ()
	Get the type ID.

Static Public Member Functions inherited from ns3::LteHandoverAlgorithm
static TypeId	GetTypeId ()
	Get the type ID.

Static Public Member Functions inherited from ns3::Object
static TypeId	GetTypeId ()
	Register this type.

Static Public Member Functions inherited from ns3::ObjectBase
static TypeId	GetTypeId ()
	Get the type ID.

Protected Member Functions
void	DoDispose () override
	Destructor implementation.

void	DoInitialize () override
	Initialize() implementation.

void	DoReportUeMeas (uint16_t rnti, LteRrcSap::MeasResults measResults) override
	Implementation of LteHandoverManagementSapProvider::ReportUeMeas.

Protected Member Functions inherited from ns3::LteHandoverAlgorithm
void	DoDispose () override
	Destructor implementation.

Protected Member Functions inherited from ns3::Object
	Object (const Object &o)
	Copy an Object.

virtual void	NotifyNewAggregate ()
	Notify all Objects aggregated to this one of a new Object being aggregated.

Protected Member Functions inherited from ns3::ObjectBase
void	ConstructSelf (const AttributeConstructionList &attributes)
	Complete construction of ObjectBase; invoked by derived classes.

virtual void	NotifyConstructionCompleted ()
	Notifier called once the ObjectBase is fully constructed.

Private Types
typedef std::map< uint16_t, Ptr< UeMeasure > >	MeasurementRow_t
	Measurements reported by a UE for several cells.

typedef std::map< uint16_t, MeasurementRow_t >	MeasurementTable_t
	Measurements reported by several UEs.

Private Member Functions
void	EvaluateHandover (uint16_t rnti, uint8_t servingCellRsrq)
	Called when Event A2 is detected, then trigger a handover if needed.

bool	IsValidNeighbour (uint16_t cellId)
	Determines if a neighbour cell is a valid destination for handover.

void	UpdateNeighbourMeasurements (uint16_t rnti, uint16_t cellId, uint8_t rsrq)
	Called when Event A4 is reported, then update the measurements table.

Private Attributes
std::vector< uint8_t >	m_a2MeasIds
	The expected measurement identities for A2 measurements.

std::vector< uint8_t >	m_a4MeasIds
	The expected measurement identities for A4 measurements.

LteHandoverManagementSapProvider *	m_handoverManagementSapProvider
	Receive API calls from the eNodeB RRC instance.

LteHandoverManagementSapUser *	m_handoverManagementSapUser
	Interface to the eNodeB RRC instance.

MeasurementTable_t	m_neighbourCellMeasures
	Table of measurement reports from all UEs.

uint8_t	m_neighbourCellOffset
	The `NeighbourCellOffset` attribute.

uint8_t	m_servingCellThreshold
	The `ServingCellThreshold` attribute.

Friends
class	MemberLteHandoverManagementSapProvider< A2A4RsrqHandoverAlgorithm >
	let the forwarder class access the protected and private members

Additional Inherited Members
Related Symbols inherited from ns3::ObjectBase
static TypeId	GetObjectIid ()
	Ensure the TypeId for ObjectBase gets fully configured to anchor the inheritance tree properly.

Detailed Description

Handover algorithm implementation based on RSRQ measurements, Event A2 and Event A4.

Handover decision made by this algorithm is primarily based on Event A2 measurements (serving cell's RSRQ becomes worse than threshold). When the event is triggered, the first condition of handover is fulfilled.

Event A4 measurements (neighbour cell's RSRQ becomes better than threshold) are used to detect neighbouring cells and their respective RSRQ. When a neighbouring cell's RSRQ is higher than the serving cell's RSRQ by a certain offset, then the second condition of handover is fulfilled.

When the first and second conditions above are fulfilled, the algorithm informs the eNodeB RRC to trigger a handover.

The threshold for Event A2 can be configured in the ServingCellThreshold attribute. The offset used in the second condition can also be configured by setting the NeighbourCellOffset attribute.

The following code snippet is an example of using and configuring the handover algorithm in a simulation program:

Ptr<LteHelper> lteHelper = CreateObject<LteHelper> ();

NodeContainer enbNodes;
// configure the nodes here...

lteHelper->SetHandoverAlgorithmType ("ns3::A2A4RsrqHandoverAlgorithm");
lteHelper->SetHandoverAlgorithmAttribute ("ServingCellThreshold",
                                          UintegerValue (30));
lteHelper->SetHandoverAlgorithmAttribute ("NeighbourCellOffset",
                                          UintegerValue (1));
NetDeviceContainer enbLteDevs = lteHelper->InstallEnbDevice (enbNodes);

Note: Setting the handover algorithm type and attributes after the call to LteHelper::InstallEnbDevice does not have any effect to the devices that have already been installed.

Definition at line 70 of file a2-a4-rsrq-handover-algorithm.h.

Member Typedef Documentation

◆ MeasurementRow_t

typedef std::map<uint16_t, Ptr<UeMeasure> > ns3::A2A4RsrqHandoverAlgorithm::MeasurementRow_t

private

Measurements reported by a UE for several cells.

The structure is a map indexed by the cell ID.

Definition at line 150 of file a2-a4-rsrq-handover-algorithm.h.

◆ MeasurementTable_t

typedef std::map<uint16_t, MeasurementRow_t> ns3::A2A4RsrqHandoverAlgorithm::MeasurementTable_t

private

Measurements reported by several UEs.

The structure is a map indexed by the RNTI of the UE.

Definition at line 156 of file a2-a4-rsrq-handover-algorithm.h.

Constructor & Destructor Documentation

◆ A2A4RsrqHandoverAlgorithm()

ns3::A2A4RsrqHandoverAlgorithm::A2A4RsrqHandoverAlgorithm ( )

Creates an A2-A4-RSRQ handover algorithm instance.

Definition at line 34 of file a2-a4-rsrq-handover-algorithm.cc.

References m_handoverManagementSapProvider, MemberLteHandoverManagementSapProvider< A2A4RsrqHandoverAlgorithm >, and NS_LOG_FUNCTION.

◆ ~A2A4RsrqHandoverAlgorithm()

ns3::A2A4RsrqHandoverAlgorithm::~A2A4RsrqHandoverAlgorithm ( )

override

Definition at line 44 of file a2-a4-rsrq-handover-algorithm.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ DoDispose()

void ns3::A2A4RsrqHandoverAlgorithm::DoDispose ( )

overrideprotectedvirtual

Destructor implementation.

This method is called by Dispose() or by the Object's destructor, whichever comes first.

Subclasses are expected to implement their real destruction code in an overridden version of this method and chain up to their parent's implementation once they are done. i.e, for simplicity, the destructor of every subclass should be empty and its content should be moved to the associated DoDispose() method.

It is safe to call GetObject() from within this method.

Reimplemented from ns3::Object.

Definition at line 118 of file a2-a4-rsrq-handover-algorithm.cc.

References m_handoverManagementSapProvider, and NS_LOG_FUNCTION.

◆ DoInitialize()

void ns3::A2A4RsrqHandoverAlgorithm::DoInitialize ( )

overrideprotectedvirtual

Initialize() implementation.

This method is called only once by Initialize(). If the user calls Initialize() multiple times, DoInitialize() is called only the first time.

Subclasses are expected to override this method and chain up to their parent's implementation once they are done. It is safe to call GetObject() and AggregateObject() from within this method.

Reimplemented from ns3::Object.

Definition at line 90 of file a2-a4-rsrq-handover-algorithm.cc.

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◆ DoReportUeMeas()

void ns3::A2A4RsrqHandoverAlgorithm::DoReportUeMeas	(	uint16_t	rnti,
		LteRrcSap::MeasResults	measResults )

overrideprotectedvirtual

Implementation of LteHandoverManagementSapProvider::ReportUeMeas.

Parameters

rnti	Radio Network Temporary Identity, an integer identifying the UE where the report originates from
measResults	a single report of one measurement identity

Implements ns3::LteHandoverAlgorithm.

Definition at line 125 of file a2-a4-rsrq-handover-algorithm.cc.

References EvaluateHandover(), ns3::LteRrcSap::MeasResults::haveMeasResultNeighCells, m_a2MeasIds, m_a4MeasIds, m_servingCellThreshold, ns3::LteRrcSap::MeasResults::measId, ns3::LteRrcSap::MeasResults::measResultListEutra, ns3::LteRrcSap::MeasResults::measResultPCell, NS_ASSERT_MSG, NS_LOG_FUNCTION, NS_LOG_WARN, ns3::LteRrcSap::MeasResultPCell::rsrqResult, and UpdateNeighbourMeasurements().

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◆ EvaluateHandover()

void ns3::A2A4RsrqHandoverAlgorithm::EvaluateHandover	(	uint16_t	rnti,
		uint8_t	servingCellRsrq )

private

Called when Event A2 is detected, then trigger a handover if needed.

Parameters

rnti	The RNTI of the UE who reported the event.
servingCellRsrq	The RSRQ of this cell as reported by the UE.

Definition at line 164 of file a2-a4-rsrq-handover-algorithm.cc.

References IsValidNeighbour(), m_handoverManagementSapUser, m_neighbourCellMeasures, m_neighbourCellOffset, NS_LOG_FUNCTION, NS_LOG_LOGIC, NS_LOG_WARN, and ns3::LteHandoverManagementSapUser::TriggerHandover().

Referenced by DoReportUeMeas().

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◆ GetLteHandoverManagementSapProvider()

LteHandoverManagementSapProvider * ns3::A2A4RsrqHandoverAlgorithm::GetLteHandoverManagementSapProvider ( )

overridevirtual

Export the "provider" part of the Handover Management SAP interface.

Returns: the reference to the "provider" part of the interface, typically to be kept by an LteEnbRrc instance

Implements ns3::LteHandoverAlgorithm.

Definition at line 83 of file a2-a4-rsrq-handover-algorithm.cc.

References m_handoverManagementSapProvider, and NS_LOG_FUNCTION.

◆ GetTypeId()

TypeId ns3::A2A4RsrqHandoverAlgorithm::GetTypeId ( )

static

Get the type ID.

Returns: the object TypeId

Definition at line 50 of file a2-a4-rsrq-handover-algorithm.cc.

References m_neighbourCellOffset, m_servingCellThreshold, ns3::MakeUintegerAccessor(), ns3::MakeUintegerChecker(), and ns3::TypeId::SetParent().

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◆ IsValidNeighbour()

bool ns3::A2A4RsrqHandoverAlgorithm::IsValidNeighbour ( uint16_t cellId )

private

Determines if a neighbour cell is a valid destination for handover.

Currently always return true.

Parameters

cellId The cell ID of the neighbour cell.

Returns: True if the cell is a valid destination for handover.

Todo: In the future, this function can be expanded to validate whether the neighbour cell is a valid target cell, e.g., taking into account the NRT in ANR and whether it is a CSG cell with closed access.

Definition at line 211 of file a2-a4-rsrq-handover-algorithm.cc.

References NS_LOG_FUNCTION.

Referenced by EvaluateHandover().

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◆ SetLteHandoverManagementSapUser()

void ns3::A2A4RsrqHandoverAlgorithm::SetLteHandoverManagementSapUser ( LteHandoverManagementSapUser * s )

overridevirtual

Set the "user" part of the Handover Management SAP interface that this handover algorithm instance will interact with.

Parameters

s	a reference to the "user" part of the interface, typically a member of an LteEnbRrc instance

Implements ns3::LteHandoverAlgorithm.

Definition at line 76 of file a2-a4-rsrq-handover-algorithm.cc.

References m_handoverManagementSapUser, and NS_LOG_FUNCTION.

◆ UpdateNeighbourMeasurements()

void ns3::A2A4RsrqHandoverAlgorithm::UpdateNeighbourMeasurements	(	uint16_t	rnti,
		uint16_t	cellId,
		uint8_t	rsrq )

private

Called when Event A4 is reported, then update the measurements table.

If the RNTI and/or cell ID is not found in the table, a corresponding entry will be created. Only the latest measurements are stored in the table.

Parameters

rnti	The RNTI of the UE who reported the event.
cellId	The cell ID of the measured cell.
rsrq	The RSRQ of the cell as measured by the UE.

Definition at line 225 of file a2-a4-rsrq-handover-algorithm.cc.

References ns3::Create(), m_neighbourCellMeasures, NS_ASSERT, and NS_LOG_FUNCTION.

Referenced by DoReportUeMeas().

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Friends And Related Symbol Documentation

◆ MemberLteHandoverManagementSapProvider< A2A4RsrqHandoverAlgorithm >

friend class MemberLteHandoverManagementSapProvider< A2A4RsrqHandoverAlgorithm >

friend

let the forwarder class access the protected and private members

Definition at line 86 of file a2-a4-rsrq-handover-algorithm.h.

Referenced by A2A4RsrqHandoverAlgorithm().

Member Data Documentation

◆ m_a2MeasIds

std::vector<uint8_t> ns3::A2A4RsrqHandoverAlgorithm::m_a2MeasIds

private

The expected measurement identities for A2 measurements.

Definition at line 130 of file a2-a4-rsrq-handover-algorithm.h.

Referenced by DoInitialize(), and DoReportUeMeas().

◆ m_a4MeasIds

std::vector<uint8_t> ns3::A2A4RsrqHandoverAlgorithm::m_a4MeasIds

private

The expected measurement identities for A4 measurements.

Definition at line 132 of file a2-a4-rsrq-handover-algorithm.h.

Referenced by DoInitialize(), and DoReportUeMeas().

◆ m_handoverManagementSapProvider

LteHandoverManagementSapProvider* ns3::A2A4RsrqHandoverAlgorithm::m_handoverManagementSapProvider

private

Receive API calls from the eNodeB RRC instance.

Definition at line 179 of file a2-a4-rsrq-handover-algorithm.h.

Referenced by A2A4RsrqHandoverAlgorithm(), DoDispose(), and GetLteHandoverManagementSapProvider().

◆ m_handoverManagementSapUser

LteHandoverManagementSapUser* ns3::A2A4RsrqHandoverAlgorithm::m_handoverManagementSapUser

private

Interface to the eNodeB RRC instance.

Definition at line 177 of file a2-a4-rsrq-handover-algorithm.h.

Referenced by DoInitialize(), EvaluateHandover(), and SetLteHandoverManagementSapUser().

◆ m_neighbourCellMeasures

MeasurementTable_t ns3::A2A4RsrqHandoverAlgorithm::m_neighbourCellMeasures

private

Table of measurement reports from all UEs.

Definition at line 159 of file a2-a4-rsrq-handover-algorithm.h.

Referenced by EvaluateHandover(), and UpdateNeighbourMeasurements().

◆ m_neighbourCellOffset

uint8_t ns3::A2A4RsrqHandoverAlgorithm::m_neighbourCellOffset

private

The NeighbourCellOffset attribute.

Minimum offset between the serving and the best neighbour cell to trigger the handover. Expressed in quantized range of [0..34] as per Section 9.1.7 of 3GPP TS 36.133.

Definition at line 174 of file a2-a4-rsrq-handover-algorithm.h.

Referenced by EvaluateHandover(), and GetTypeId().

◆ m_servingCellThreshold

uint8_t ns3::A2A4RsrqHandoverAlgorithm::m_servingCellThreshold

private

The ServingCellThreshold attribute.

If the RSRQ of the serving cell is worse than this threshold, neighbour cells are consider for handover. Expressed in quantized range of [0..34] as per Section 9.1.7 of 3GPP TS 36.133.

Definition at line 167 of file a2-a4-rsrq-handover-algorithm.h.

Referenced by DoInitialize(), DoReportUeMeas(), and GetTypeId().

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

src/lte/model/a2-a4-rsrq-handover-algorithm.h
src/lte/model/a2-a4-rsrq-handover-algorithm.cc

Classes

Public Member Functions

Static Public Member Functions

Protected Member Functions

Private Types

Private Member Functions

Private Attributes

Friends

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ MeasurementRow_t

◆ MeasurementTable_t

Constructor & Destructor Documentation

◆ A2A4RsrqHandoverAlgorithm()

◆ ~A2A4RsrqHandoverAlgorithm()

Member Function Documentation

◆ DoDispose()

◆ DoInitialize()

◆ DoReportUeMeas()

◆ EvaluateHandover()

◆ GetLteHandoverManagementSapProvider()

◆ GetTypeId()

◆ IsValidNeighbour()

◆ SetLteHandoverManagementSapUser()

◆ UpdateNeighbourMeasurements()

Friends And Related Symbol Documentation

◆ MemberLteHandoverManagementSapProvider< A2A4RsrqHandoverAlgorithm >

Member Data Documentation

◆ m_a2MeasIds

◆ m_a4MeasIds

◆ m_handoverManagementSapProvider

◆ m_handoverManagementSapUser

◆ m_neighbourCellMeasures

◆ m_neighbourCellOffset

◆ m_servingCellThreshold