The "Mean--Deviation" RTT estimator, as discussed by Van Jacobson. More...

#include "rtt-estimator.h"

Inheritance diagram for ns3::RttMeanDeviation:

Collaboration diagram for ns3::RttMeanDeviation:

Public Member Functions
	RttMeanDeviation ()

	RttMeanDeviation (const RttMeanDeviation &r)
	Copy constructor.

Ptr< RttEstimator >	Copy () const override
	Copy object (including current internal state)

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

void	Measurement (Time measure) override
	Add a new measurement to the estimator.

void	Reset () override
	Resets the estimator.

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

	RttEstimator (const RttEstimator &r)
	Copy constructor.

	~RttEstimator () override

virtual Ptr< RttEstimator >	Copy () const =0
	Copy object (including current internal state)

Time	GetEstimate () const
	gets the RTT estimate.

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

uint32_t	GetNSamples () const
	gets the number of samples used in the estimates

Time	GetVariation () const
	Note that this is not a formal statistical variance; it has the the same units as the estimate.

virtual void	Measurement (Time t)=0
	Add a new measurement to the estimator.

virtual void	Reset ()
	Resets the estimation to its initial state.

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.

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) 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.

virtual TypeId	GetInstanceTypeId () const =0
	Get the most derived TypeId for this Object.

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::RttEstimator
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.

Private Member Functions
uint32_t	CheckForReciprocalPowerOfTwo (double val) const
	Utility function to check for possible conversion of a double value (0 < value < 1) to a reciprocal power of two.

void	FloatingPointUpdate (Time m)
	Method to update the rtt and variation estimates using floating point arithmetic, used when the values of Alpha and Beta are not both a reciprocal power of two.

void	IntegerUpdate (Time m, uint32_t rttShift, uint32_t variationShift)
	Method to update the rtt and variation estimates using integer arithmetic, used when the values of Alpha and Beta support the integer conversion.

Private Attributes
double	m_alpha
	Filter gain for average.

double	m_beta
	Filter gain for variation.

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

virtual void	DoDispose ()
	Destructor implementation.

virtual void	DoInitialize ()
	Initialize() implementation.

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.

Protected Attributes inherited from ns3::RttEstimator
Time	m_estimatedRtt
	Current estimate.

Time	m_estimatedVariation
	Current estimate variation.

uint32_t	m_nSamples
	Number of samples.

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

Detailed Description

The "Mean--Deviation" RTT estimator, as discussed by Van Jacobson.

Introspection did not find any typical Config paths.

This class implements the "Mean--Deviation" RTT estimator, as discussed by Van Jacobson and Michael J. Karels, in "Congestion Avoidance and Control", SIGCOMM 88, Appendix A

The default values for the gain (alpha and beta) are set as documented in RFC 6298.

Attributes

Alpha: Gain used in estimating the RTT, must be 0 <= alpha <= 1
- Set with class: ns3::DoubleValue
- Underlying type: double 0:1
- Initial value: 0.125
- Flags: constructwriteread
Beta: Gain used in estimating the RTT variation, must be 0 <= beta <= 1
- Set with class: ns3::DoubleValue
- Underlying type: double 0:1
- Initial value: 0.25
- Flags: constructwriteread

Attributes defined in parent class ns3::RttEstimator

InitialEstimation: Initial RTT estimate
- Set with class: ns3::TimeValue
- Underlying type: Time +9.22337e+18ns:+9.22337e+18ns
- Initial value: +1e+09ns
- Flags: constructwriteread

No TraceSources are defined for this type.
Size of this type is 80 bytes (on a 64-bit architecture).

Definition at line 123 of file rtt-estimator.h.

Constructor & Destructor Documentation

◆ RttMeanDeviation() [1/2]

ns3::RttMeanDeviation::RttMeanDeviation ( )

Definition at line 150 of file rtt-estimator.cc.

References NS_LOG_FUNCTION.

◆ RttMeanDeviation() [2/2]

ns3::RttMeanDeviation::RttMeanDeviation ( const RttMeanDeviation & r )

Copy constructor.

Parameters

r	the object to copy

Definition at line 155 of file rtt-estimator.cc.

References NS_LOG_FUNCTION.

Member Function Documentation

◆ CheckForReciprocalPowerOfTwo()

uint32_t ns3::RttMeanDeviation::CheckForReciprocalPowerOfTwo ( double val ) const

private

Utility function to check for possible conversion of a double value (0 < value < 1) to a reciprocal power of two.

Values of 1/32, 1/16, 1/8, 1/4, and 1/2 (i.e., within the possible range of experimentation for this estimator) are supported.

Parameters

val	value to check

Returns: log base 2 (1/val) if reciprocal power of 2, or zero if not

Definition at line 170 of file rtt-estimator.cc.

References NS_LOG_FUNCTION, and ns3::TOLERANCE.

Referenced by Measurement().

Here is the caller graph for this function:

◆ Copy()

Ptr< RttEstimator > ns3::RttMeanDeviation::Copy ( ) const

overridevirtual

Copy object (including current internal state)

Returns: a copy of itself

Implements ns3::RttEstimator.

Definition at line 269 of file rtt-estimator.cc.

References NS_LOG_FUNCTION.

◆ FloatingPointUpdate()

void ns3::RttMeanDeviation::FloatingPointUpdate ( Time m )

private

Method to update the rtt and variation estimates using floating point arithmetic, used when the values of Alpha and Beta are not both a reciprocal power of two.

Parameters

m	time measurement

Definition at line 202 of file rtt-estimator.cc.

References ns3::Abs(), ns3::Time::FromDouble(), m_alpha, m_beta, ns3::RttEstimator::m_estimatedRtt, ns3::RttEstimator::m_estimatedVariation, NS_LOG_FUNCTION, ns3::Time::S, and ns3::Time::ToDouble().

Referenced by Measurement().

Here is the call graph for this function:

Here is the caller graph for this function:

◆ GetInstanceTypeId()

TypeId ns3::RttMeanDeviation::GetInstanceTypeId ( ) const

overridevirtual

Get the most derived TypeId for this Object.

This method is typically implemented by ns3::Object::GetInstanceTypeId but some classes which derive from ns3::ObjectBase directly have to implement it themselves.