Implementation of the strongest cell handover algorithm, based on RSRP measurements and Event A3. More...

#include <a3-rsrp-handover-algorithm.h>

Inheritance diagram for ns3::A3RsrpHandoverAlgorithm:

Collaboration diagram for ns3::A3RsrpHandoverAlgorithm:

Public Member Functions
	A3RsrpHandoverAlgorithm ()
	Creates a strongest cell handover algorithm instance. More...

virtual	~A3RsrpHandoverAlgorithm ()

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 Member Functions
bool	IsValidNeighbour (uint16_t cellId)

Private Attributes
LteHandoverManagementSapProvider *	m_handoverManagementSapProvider

LteHandoverManagementSapUser *	m_handoverManagementSapUser

double	m_hysteresisDb

uint8_t	m_measId

Time	m_timeToTrigger

Friends
class	MemberLteHandoverManagementSapProvider< A3RsrpHandoverAlgorithm >

Detailed Description

Implementation of the strongest cell handover algorithm, based on RSRP measurements and Event A3.

The algorithm utilizes Event A3 (Section 5.5.4.4 of 3GPP TS 36.331) UE measurements and the Reference Signal Reference Power (RSRP). It is defined as the event when the UE perceives that a neighbour cell's RSRP is better than the serving cell's RSRP.

Handover margin (a.k.a. hysteresis) and time-to-trigger (TTT) can be configured to delay the event triggering. The values of these parameters apply to all attached UEs.

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::A3RsrpHandoverAlgorithm");
lteHelper->SetHandoverAlgorithmAttribute ("Hysteresis",
                                          DoubleValue (3.0));
lteHelper->SetHandoverAlgorithmAttribute ("TimeToTrigger",
                                          TimeValue (MilliSeconds (256)));
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::A3RsrpHandoverAlgorithm is accessible through the following paths with Config::Set and Config::Connect:

/NodeList/[i]/DeviceList/[i]/$ns3::LteEnbNetDevice/LteHandoverAlgorithm/$ns3::A3RsrpHandoverAlgorithm
/NodeList/[i]/DeviceList/[i]/$ns3::LteNetDevice/$ns3::LteEnbNetDevice/LteHandoverAlgorithm/$ns3::A3RsrpHandoverAlgorithm

Attributes

Hysteresis: Handover margin (hysteresis) in dB (rounded to the nearest multiple of 0.5 dB)
- Set with class: ns3::DoubleValue
- Underlying type: uint8_t 0:15
- Initial value: 3
- Flags: construct write read
TimeToTrigger: Time during which neighbour cell's RSRP must continuously higher than serving cell's RSRP in order to trigger a handover
- Set with class: ns3::TimeValue
- Underlying type: Time -9223372036854775808.0ns:+9223372036854775807.0ns
- Initial value: +256000000.0ns
- Flags: construct write read

No TraceSources are defined for this type.

Definition at line 65 of file a3-rsrp-handover-algorithm.h.

Constructor & Destructor Documentation

ns3::A3RsrpHandoverAlgorithm::A3RsrpHandoverAlgorithm ( )

Creates a strongest cell handover algorithm instance.

Definition at line 36 of file a3-rsrp-handover-algorithm.cc.

References m_handoverManagementSapProvider, and NS_LOG_FUNCTION.

ns3::A3RsrpHandoverAlgorithm::~A3RsrpHandoverAlgorithm ( )

virtual

Definition at line 44 of file a3-rsrp-handover-algorithm.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

void ns3::A3RsrpHandoverAlgorithm::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 115 of file a3-rsrp-handover-algorithm.cc.

References m_handoverManagementSapProvider, and NS_LOG_FUNCTION.

void ns3::A3RsrpHandoverAlgorithm::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 91 of file a3-rsrp-handover-algorithm.cc.

References ns3::EutranMeasurementMapping::ActualHysteresis2IeValue(), ns3::LteHandoverManagementSapUser::AddUeMeasReportConfigForHandover(), ns3::Object::DoInitialize(), ns3::LteRrcSap::ReportConfigEutra::EVENT_A3, ns3::LteRrcSap::ReportConfigEutra::eventId, ns3::Time::GetMilliSeconds(), m_handoverManagementSapUser, m_hysteresisDb, m_measId, m_timeToTrigger, ns3::LteRrcSap::ReportConfigEutra::MS1024, NS_LOG_FUNCTION, NS_LOG_LOGIC, and ns3::LteRrcSap::ReportConfigEutra::RSRP.

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void ns3::A3RsrpHandoverAlgorithm::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 123 of file a3-rsrp-handover-algorithm.cc.

References ns3::LteRrcSap::MeasResults::haveMeasResultNeighCells, IsValidNeighbour(), m_handoverManagementSapUser, m_measId, ns3::LteRrcSap::MeasResults::measId, ns3::LteRrcSap::MeasResults::measResultListEutra, NS_LOG_FUNCTION, NS_LOG_LOGIC, NS_LOG_WARN, ns3::LteRrcSap::MeasResults::rsrpResult, and ns3::LteHandoverManagementSapUser::TriggerHandover().

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LteHandoverManagementSapProvider * ns3::A3RsrpHandoverAlgorithm::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 83 of file a3-rsrp-handover-algorithm.cc.

References m_handoverManagementSapProvider, and NS_LOG_FUNCTION.

TypeId ns3::A3RsrpHandoverAlgorithm::GetTypeId ( void )

static

Definition at line 51 of file a3-rsrp-handover-algorithm.cc.

References m_hysteresisDb, m_timeToTrigger, ns3::MakeTimeChecker(), and ns3::TypeId::SetParent().

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bool ns3::A3RsrpHandoverAlgorithm::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 180 of file a3-rsrp-handover-algorithm.cc.

References NS_LOG_FUNCTION.

Referenced by DoReportUeMeas().

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