Position allocator for hexagonal tiling. More...

#include "hex-grid-position-allocator.h"

Inheritance diagram for ns3::HexGridPositionAllocator:

Collaboration diagram for ns3::HexGridPositionAllocator:

Public Member Functions
	HexGridPositionAllocator ()
	Default constructor.

	HexGridPositionAllocator (double radius)
	Construct a new HexGridPositionAllocator object with given radius.

	~HexGridPositionAllocator () override
	Destructor.

int64_t	AssignStreams (int64_t stream) override
	Assign a fixed random variable stream number to the random variables used by this model.

Vector	GetNext () const override

double	GetRadius () const
	Get the radius of the circle inscribed in the hexagonal tiles.

void	SetRadius (double radius)
	Set the radius of the circle inscribed in the hexagonal tiles.

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

	~PositionAllocator () override

virtual int64_t	AssignStreams (int64_t stream)=0
	Assign a fixed random variable stream number to the random variables used by this model.

virtual Vector	GetNext () const =0

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) 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 ()
	Register this type.

Static Public Member Functions inherited from ns3::PositionAllocator
static TypeId	GetTypeId ()
	Register this type with the TypeId system.

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
std::vector< Vector >	AddRing (std::vector< Vector > positions)
	This method adds to the given list of positions an outer ring of positions.

Private Attributes
std::vector< Vector >::const_iterator	m_next
	The iterator pointing to the next position to return.

std::vector< Vector >	m_positions
	The current list of positions.

double	m_radius
	The radius of a cell (defined as the half the distance between two adjacent nodes, that is, the radius of the circle inscribed in each hexagonal tile)

Static Private Attributes
static const double	pi = std::acos(-1)
	Pi.

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.

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

Position allocator for hexagonal tiling.

Starting with a first hexagon in the axes' center, following tiles are added in outward rings. The first position returned for a new ring is always the top one, followed by the others in anti-clockwise rotation.

Visual example with 10 tiles, indexed 0-9:

                _____
               /     \
         _____/   8   \
        /     \   ˙   /
       /   9   \_____/
       \   ˙   /     \
  next  \_____/   1   \_____
    ˙   /     \   ˙   /     \
       /   2   \_____/   7   \
       \   ˙   /     \   ˙   /
        \_____/   0   \_____/
        /     \   ˙   /     \
       /   3   \_____/   5   \
       \   ˙   /     \   ˙   /
        \_____/   4   \_____/
              \   ˙   /
               \_____/

The size of tiles can be configured by setting the radius $\rho_{i}$ of the circle inscribed within hexagons (i.e., the internal circle).

Let's say that we are placing access points, and we want to cover a square/circular area with hexagonal tiles. This leaves us with two questions: (i) which value should we choose for the internal radius? (ii) how many access point nodes (i.e., tiles) do we need to instantiate?

For instance, to guarantee that no point is further than 1km from the center of any tile (i.e., to have no uncovered patches), we can choose the radius $\rho_{c}$ of the circumscribed (external) circle of each hexagonal tile to be exactly 1km. Then, question (i) can be solved by setting the internal radius to $\rho_{i}=\frac{\sqrt{3}}{2}\rho_{c}$ using the properties of equilateral triangles.

To understand how many tiles need to be instantiated (that is, in this example, the number of access point nodes), it is often useful to start from the complete area's diagonal or radius, and to derive the number of complete rings required for coverage. Let's say we want to be able to cover a distance of at least km from the center. One way to do this can be to take the floor of divided by the distance between access points (the tiles' centers), which happens to be $2\rho_{i}$ , and adding one/two ring for good measure. More formally, starting from a single central tile, we would need at least $r=\left\lfloor\frac{d}{2\rho_{i}}\right\rfloor+1$ additional rings around it. Then, the total number of tiles in a tiling of complete rings around a central tile evaluates to $n=3r^{2}-3r+1$ providing a possible solution for question (ii).

Todo:: Move this into the module .rst documentation

Definition at line 83 of file hex-grid-position-allocator.h.

Constructor & Destructor Documentation

◆ HexGridPositionAllocator() [1/2]

ns3::HexGridPositionAllocator::HexGridPositionAllocator ( )

Default constructor.

Definition at line 46 of file hex-grid-position-allocator.cc.

References AddRing(), m_next, m_positions, and NS_LOG_FUNCTION_NOARGS.

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◆ ~HexGridPositionAllocator()

ns3::HexGridPositionAllocator::~HexGridPositionAllocator ( )

override

Destructor.

Definition at line 83 of file hex-grid-position-allocator.cc.

References NS_LOG_FUNCTION_NOARGS.

◆ HexGridPositionAllocator() [2/2]

ns3::HexGridPositionAllocator::HexGridPositionAllocator ( double radius )

Construct a new HexGridPositionAllocator object with given radius.

Parameters

radius The radius length of the circle inscribed in the hexagonal tiles.

Definition at line 64 of file hex-grid-position-allocator.cc.

References AddRing(), m_next, m_positions, and NS_LOG_FUNCTION_NOARGS.

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Member Function Documentation

◆ AddRing()

std::vector< Vector > ns3::HexGridPositionAllocator::AddRing ( std::vector< Vector > positions )

private

This method adds to the given list of positions an outer ring of positions.

Parameters

positions The list of position around which to create the new positions.

Returns: The input list of position with an added outer ring.

Definition at line 118 of file hex-grid-position-allocator.cc.

References ns3::CalculateDistance(), m_radius, NS_LOG_DEBUG, NS_LOG_FUNCTION, and pi.

Referenced by HexGridPositionAllocator().

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◆ AssignStreams()

int64_t ns3::HexGridPositionAllocator::AssignStreams ( int64_t stream )

overridevirtual

Assign a fixed random variable stream number to the random variables used by this model.

Return the number of streams (possibly zero) that have been assigned.

This method must be implement in subclasses.

Parameters

stream first stream index to use

Returns: the number of stream indices assigned by this model

Implements ns3::PositionAllocator.

Definition at line 112 of file hex-grid-position-allocator.cc.

◆ GetNext()

Vector ns3::HexGridPositionAllocator::GetNext ( ) const

overridevirtual

Returns: the next chosen position.

This method must be implement in subclasses.

Implements ns3::PositionAllocator.

Definition at line 103 of file hex-grid-position-allocator.cc.

References m_next.

◆ GetRadius()

double ns3::HexGridPositionAllocator::GetRadius ( ) const

Get the radius of the circle inscribed in the hexagonal tiles.

Returns: The radius length.

Definition at line 91 of file hex-grid-position-allocator.cc.

References m_radius.

◆ GetTypeId()

TypeId ns3::HexGridPositionAllocator::GetTypeId ( )

static

Register this type.

Returns: The object TypeId.

Definition at line 31 of file hex-grid-position-allocator.cc.

References m_radius, ns3::MakeDoubleAccessor(), and ns3::TypeId::SetParent().

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◆ SetRadius()

void ns3::HexGridPositionAllocator::SetRadius ( double radius )

Set the radius of the circle inscribed in the hexagonal tiles.

Parameters

radius The radius length.

Definition at line 97 of file hex-grid-position-allocator.cc.

References m_radius.

Member Data Documentation

◆ m_next

std::vector<Vector>::const_iterator ns3::HexGridPositionAllocator::m_next

mutableprivate

The iterator pointing to the next position to return.

Definition at line 131 of file hex-grid-position-allocator.h.

Referenced by HexGridPositionAllocator(), and GetNext().

◆ m_positions

std::vector<Vector> ns3::HexGridPositionAllocator::m_positions

private

The current list of positions.

Definition at line 129 of file hex-grid-position-allocator.h.

Referenced by HexGridPositionAllocator().

◆ m_radius

double ns3::HexGridPositionAllocator::m_radius

private

The radius of a cell (defined as the half the distance between two adjacent nodes, that is, the radius of the circle inscribed in each hexagonal tile)

Definition at line 132 of file hex-grid-position-allocator.h.

Referenced by AddRing(), GetRadius(), GetTypeId(), and SetRadius().