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. More...

virtual	~A2A4RsrqHandoverAlgorithm ()

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

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

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

virtual	~LteHandoverAlgorithm ()

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

virtual	~Object ()

void	AggregateObject (Ptr< Object > other)

void	Dispose (void)
	Run the DoDispose methods of this object and all the objects aggregated to it. More...

AggregateIterator	GetAggregateIterator (void) const

virtual TypeId	GetInstanceTypeId (void) const

template<typename T >
Ptr< T >	GetObject (void) const

template<typename T >
Ptr< T >	GetObject (TypeId tid) const

void	Initialize (void)
	This method calls the virtual DoInitialize method on all the objects aggregated to this object. More...

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

	SimpleRefCount (const SimpleRefCount &o)
	Copy constructor. More...

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

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

void	Ref (void) const
	Increment the reference count. More...

void	Unref (void) const
	Decrement the reference count. More...

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

void	GetAttribute (std::string name, AttributeValue &value) const

bool	GetAttributeFailSafe (std::string name, AttributeValue &attribute) const

void	SetAttribute (std::string name, const AttributeValue &value)

bool	SetAttributeFailSafe (std::string name, const AttributeValue &value)

bool	TraceConnect (std::string name, std::string context, const CallbackBase &cb)

bool	TraceConnectWithoutContext (std::string name, const CallbackBase &cb)

bool	TraceDisconnect (std::string name, std::string context, const CallbackBase &cb)

bool	TraceDisconnectWithoutContext (std::string name, const CallbackBase &cb)

Static Public Member Functions
static TypeId	GetTypeId ()

Static Public Member Functions inherited from ns3::LteHandoverAlgorithm
static TypeId	GetTypeId ()

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

Static Public Member Functions inherited from ns3::SimpleRefCount< Object, ObjectBase, ObjectDeleter >
static void	Cleanup (void)
	Noop. More...

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

Protected Member Functions
virtual void	DoDispose ()
	This method is called by Object::Dispose or by the object's destructor, whichever comes first. More...

virtual void	DoInitialize ()
	This method is called only once by Object::Initialize. More...

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

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

virtual void	NotifyNewAggregate (void)
	This method is invoked whenever two sets of objects are aggregated together. More...

Protected Member Functions inherited from ns3::ObjectBase
void	ConstructSelf (const AttributeConstructionList &attributes)

virtual void	NotifyConstructionCompleted (void)
	This method is invoked once all member attributes have been initialized. More...

Private Types
typedef std::map< uint16_t, Ptr< UeMeasure > >	MeasurementRow_t

typedef std::map< uint16_t, MeasurementRow_t >	MeasurementTable_t

Private Member Functions
void	EvaluateHandover (uint16_t rnti, uint8_t servingCellRsrq)

bool	IsValidNeighbour (uint16_t cellId)

void	UpdateNeighbourMeasurements (uint16_t rnti, uint16_t cellId, uint8_t rsrq)

Private Attributes
uint8_t	m_a2MeasId

uint8_t	m_a4MeasId

LteHandoverManagementSapProvider *	m_handoverManagementSapProvider

LteHandoverManagementSapUser *	m_handoverManagementSapUser

MeasurementTable_t	m_neighbourCellMeasures

uint8_t	m_neighbourCellOffset

uint8_t	m_servingCellThreshold

Friends
class	MemberLteHandoverManagementSapProvider< A2A4RsrqHandoverAlgorithm >

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.

Config Paths

ns3::A2A4RsrqHandoverAlgorithm is accessible through the following paths with Config::Set and Config::Connect:

/NodeList/[i]/DeviceList/[i]/$ns3::LteEnbNetDevice/LteHandoverAlgorithm/$ns3::A2A4RsrqHandoverAlgorithm
/NodeList/[i]/DeviceList/[i]/$ns3::LteNetDevice/$ns3::LteEnbNetDevice/LteHandoverAlgorithm/$ns3::A2A4RsrqHandoverAlgorithm

Attributes

ServingCellThreshold: If the RSRQ of the serving cell is worse than this threshold, neighbour cells are consider for handover
- Set with class: ns3::UintegerValue
- Underlying type: uint8_t 0:34
- Initial value: 30
- Flags: construct write read
NeighbourCellOffset: Minimum offset between serving and best neighbour cell to trigger the Handover
- Set with class: ns3::UintegerValue
- Underlying type: uint8_t 0:255
- Initial value: 1
- Flags: construct write read

No TraceSources are defined for this type.

Definition at line 80 of file a2-a4-rsrq-handover-algorithm.h.

Member Typedef Documentation

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

private

Definition at line 133 of file a2-a4-rsrq-handover-algorithm.h.

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

private

Definition at line 135 of file a2-a4-rsrq-handover-algorithm.h.

Constructor & Destructor Documentation

ns3::A2A4RsrqHandoverAlgorithm::A2A4RsrqHandoverAlgorithm ( )

Creates an A2-A4-RSRQ handover algorithm instance.

Definition at line 46 of file a2-a4-rsrq-handover-algorithm.cc.

References m_handoverManagementSapProvider, and NS_LOG_FUNCTION.

ns3::A2A4RsrqHandoverAlgorithm::~A2A4RsrqHandoverAlgorithm ( )

virtual

Definition at line 58 of file a2-a4-rsrq-handover-algorithm.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

void ns3::A2A4RsrqHandoverAlgorithm::DoDispose ( void )

protectedvirtual

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

Subclasses are expected to implement their real destruction code in an overriden 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::LteHandoverAlgorithm.

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

References m_handoverManagementSapProvider, and NS_LOG_FUNCTION.

void ns3::A2A4RsrqHandoverAlgorithm::DoInitialize ( void )

protectedvirtual

This method is called only once by Object::Initialize.

If the user calls Object::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 103 of file a2-a4-rsrq-handover-algorithm.cc.

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

protectedvirtual

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 140 of file a2-a4-rsrq-handover-algorithm.cc.

References EvaluateHandover(), ns3::LteRrcSap::MeasResults::haveMeasResultNeighCells, m_a2MeasId, m_a4MeasId, m_servingCellThreshold, ns3::LteRrcSap::MeasResults::measId, ns3::LteRrcSap::MeasResults::measResultListEutra, NS_ASSERT_MSG, NS_LOG_FUNCTION, NS_LOG_WARN, ns3::LteRrcSap::MeasResults::rsrqResult, and UpdateNeighbourMeasurements().

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

private

Definition at line 179 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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LteHandoverManagementSapProvider * ns3::A2A4RsrqHandoverAlgorithm::GetLteHandoverManagementSapProvider ( )

virtual

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 95 of file a2-a4-rsrq-handover-algorithm.cc.

References m_handoverManagementSapProvider, and NS_LOG_FUNCTION.

TypeId ns3::A2A4RsrqHandoverAlgorithm::GetTypeId ( void )

static

Definition at line 65 of file a2-a4-rsrq-handover-algorithm.cc.

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

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

private

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 231 of file a2-a4-rsrq-handover-algorithm.cc.

References NS_LOG_FUNCTION.

Referenced by EvaluateHandover().

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