ns3::DcfState Class Reference

keep track of the state needed for a single DCF function. More...

#include <dcf-manager.h>

List of all members.

Public Member Functions
void	SetAifsn (uint32_t aifsn)
void	ResetCw (void)
void	UpdateFailedCw (void)
void	StartBackoffNow (uint32_t nSlots)
uint32_t	GetCw (void) const
bool	IsAccessRequested (void) const
Private Member Functions
virtual void	DoNotifyAccessGranted (void)=0
virtual void	DoNotifyInternalCollision (void)=0
virtual void	DoNotifyCollision (void)=0
virtual void	DoNotifyChannelSwitching ()=0

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Detailed Description

keep track of the state needed for a single DCF function.

Multiple instances of a DcfState can be registered in a single DcfManager to implement 802.11e-style relative QoS. DcfState::SetAifsn and DcfState::SetCwBounds allow the user to control the relative QoS differentiation.

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Member Function Documentation

virtual void ns3::DcfState::DoNotifyAccessGranted

(

void

)

[private, pure virtual]

Called by DcfManager to notify a DcfState subclass that access to the medium is granted and can start immediately.

virtual void ns3::DcfState::DoNotifyChannelSwitching

(

)

[private, pure virtual]

Called by DcfManager to notify a DcfState subclass that a channel switching occured.

The subclass is expected to flush the queue of packets.

virtual void ns3::DcfState::DoNotifyCollision

(

void

)

[private, pure virtual]

Called by DcfManager to notify a DcfState subclass that a normal collision occured, that is, that the medium was busy when access was requested.

The subclass is expected to start a new backoff by calling DcfState::StartBackoffNow and DcfManager::RequestAccess is access is still needed.

virtual void ns3::DcfState::DoNotifyInternalCollision

(

void

)

[private, pure virtual]

Called by DcfManager to notify a DcfState subclass that an 'internal' collision occured, that is, that the backoff timer of a higher priority DcfState expired at the same time and that access was granted to this higher priority DcfState.

The subclass is expected to start a new backoff by calling DcfState::StartBackoffNow and DcfManager::RequestAccess is access is still needed.

uint32_t ns3::DcfState::GetCw

(

void

)

const

Returns:

the current value of the CW variable. The initial value is minCW.

bool ns3::DcfState::IsAccessRequested

(

void

)

const

Returns:

true if access has been requested for this DcfState and has not been granted already, false otherwise.

void ns3::DcfState::ResetCw

(

void

)

Update the value of the CW variable to take into account a transmission success or a transmission abort (stop transmission of a packet after the maximum number of retransmissions has been reached). By default, this resets the CW variable to minCW.

void ns3::DcfState::SetAifsn

(

uint32_t

aifsn

)

Parameters:

aifsn

the number of slots which make up an AIFS for a specific DCF. a DIFS corresponds to an AIFSN = 2.

Calling this method after DcfManager::Add has been called is not recommended.

void ns3::DcfState::StartBackoffNow

(

uint32_t

nSlots

)

Parameters:

nSlots

the number of slots of the backoff.

Start a backoff by initializing the backoff counter to the number of slots specified.

void ns3::DcfState::UpdateFailedCw

(

void

)

Update the value of the CW variable to take into account a transmission failure. By default, this triggers a doubling of CW (capped by maxCW).

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

• src/devices/wifi/dcf-manager.h