Mac80211 Class Reference
[macLayer - MAC layer modules]

An implementation of the 802.11b MAC. More...

#include <Mac80211.h>

Inherits BasicLayer.

Inheritance diagram for Mac80211:

[legend]Collaboration diagram for Mac80211:

[legend]List of all members.

Public Member Functions
	Module_Class_Members (Mac80211, BasicLayer, 0)
virtual void	initialize (int)
	Initialization of the module and some variables.
virtual void	finish ()
Protected Types
typedef std::list< Mac80211Pkt * >	MacPktList
typedef std::list< NeighborEntry >	NeighborList
enum	timerType { TIMEOUT, NAV, CONTENTION, END_SIFS }
enum	State {   WFDATA = 0, QUIET = 1, IDLE = 2, CONTEND = 3,   WFCTS = 4, WFACK = 5, BUSY = 6 }
Protected Member Functions
virtual void	receiveBBItem (int category, const BBItem *details, int scopeModuleId)
	Called by the Blackboard whenever a change occurs we're interested in.
virtual void	handleSelfMsg (cMessage *)
	Handle self messages such as timer...
virtual void	handleUpperMsg (cMessage *)
	Handle messages from upper layer.
virtual void	handleLowerMsg (cMessage *)
	Handle messages from lower layer.
virtual void	handleLowerControl (cMessage *)
	Handle messages from lower layer.
virtual void	handleEndContentionTimer ()
	handle end of contention
void	handleMsgNotForMe (cMessage *af, double duration)
	handle a message that is not for me or errornous
void	handleMsgForMe (Mac80211Pkt *)
	handle a message that was meant for me
void	handleBroadcastMsg (Mac80211Pkt *)
void	handleEndTransmission ()
	handle the end of a transmission...
void	handleEndSifsTimer ()
	handle end of SIFS
void	handleTimeoutTimer ()
	handle time out
void	handleNavTimer ()
	NAV timer expired, the exchange of messages of other stations is done.
void	handleRTSframe (Mac80211Pkt *)
void	handleDATAframe (Mac80211Pkt *)
void	handleACKframe (Mac80211Pkt *)
void	handleCTSframe (Mac80211Pkt *)
virtual void	sendDATAframe (Mac80211Pkt *)
	send data frame
void	sendACKframe (Mac80211Pkt *)
	send Acknoledgement
void	sendCTSframe (Mac80211Pkt *)
	send CTS frame
virtual void	sendRTSframe ()
	send RTS frame
void	sendBROADCASTframe ()
	send broadcast frame
Mac80211Pkt *	encapsMsg (cMessage *netw)
	encapsulate packet
cMessage *	decapsMsg (Mac80211Pkt *frame)
	decapsulate packet
virtual void	beginNewCycle ()
	start a new contention period
double	backoff ()
	Compute a backoff value.
int	contentionWindow ()
	Compute a new contention window.
void	testMaxAttempts ()
	Test if maximum number of retries to transmit is exceeded.
double	timeOut (frameType_802_11 type, double br)
	return a timeOut value for a certain type of frame
double	packetDuration (double bits, double br)
	computes the duration of a transmission over the physical channel, given a certain bitrate
const char *	stateName (State state)
	Produce a readable name of the given state.
void	setState (State state)
	Sets the state, and produces a log message in between.
bool	rtsCts (Mac80211Pkt *m)
	Check whether the next packet should be send with RTS/CTS.
void	suspendContention ()
	suspend an ongoing contention, pick it up again when the channel becomes idle
double	retrieveBitrate (int destAddress)
	figure out at which bitrate to send to this particular destination
void	addNeighbor (Mac80211Pkt *af)
	add a new entry to the neighbor list
NeighborList::iterator	findNeighbor (int id)
	find a neighbor based on his address
NeighborList::iterator	findOldestNeighbor ()
	find the oldest neighbor -- usually in order to overwrite this entry
Protected Attributes
int	myMacAddr
	MAC address (simply module id).
cMessage *	timeout
	Timer used for time-outs after the transmission of a RTS, a CTS, or a DATA packet.
cMessage *	nav
	Timer used for the defer time of a node. Also called NAV : networks allocation vector.
cMessage *	contention
	Timer used for contention periods.
cMessage *	endSifs
	Timer used to indicate the end of a SIFS.
State	state
	Current state of the MAC.
RadioState::States	radioState
	Current state of active channel (radio), set using radio, updated via BB.
int	catRadioState
	category number given by bb for RadioState
MediumIndication::States	medium
	last medium state
int	catMedium
	category number given by bb for RSSI
double	defaultBitrate
	Default bitrate.
double	bitrate
	Current bit rate at which data is transmitted.
int	catBitrate
	and category number
bool	autoBitrate
	Auto bit rate adaptation -- switch.
std::vector< double >	snrThresholds
	Hold RSSI thresholds at which to change the bitrates.
SingleChannelRadio *	radio
	cached pointer to radio module
unsigned	queueLength
	Maximal number of packets in the queue; should be set in the omnetpp.ini.
bool	nextIsBroadcast
	Boolean used to know if the next packet is a broadcast packet.
MacPktList	fromUpperLayer
	Buffering of messages from upper layer.
unsigned	longRetryCounter
	Number of frame transmission attempt.
unsigned	shortRetryCounter
	Number of frame transmission attempt.
simtime_t	remainingBackoff
	remaining backoff time. If the backoff timer is interrupted, this variable holds the remaining backoff time.
int	rtsCtsThreshold
	Number of bits in a packet before RTS/CTS is used.
double	delta
	Very small value used in timer scheduling in order to avoid multiple changements of state in the same simulation time.
unsigned	neighborhoodCacheSize
	Keep information for this many neighbors.
simtime_t	neighborhoodCacheMaxAge
	Consider information in cache outdate if it is older than this.
NeighborList	neighbors
bool	switching
int	fsc
Classes
struct	NeighborEntry

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Detailed Description

An implementation of the 802.11b MAC.

For more info, see the NED file.

Author:

David Raguin

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Member Enumeration Documentation

enum Mac80211::State [protected]

Definition of the states

enum Mac80211::timerType [protected]

Definition of the timer types

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Member Function Documentation

double Mac80211::backoff (   )  [protected]

Compute a backoff value. Compute the backoff value.

void Mac80211::beginNewCycle (   )  [protected, virtual]

start a new contention period Start a new contention period if the channel is free and if there's a packet to send. Called at the end of a deferring period, a busy period, or after a failure. Called by the HandleMsgForMe(), HandleTimer() HandleUpperMsg(), and, without RTS/CTS, by handleMsgNotForMe().

int Mac80211::contentionWindow (   )  [protected]

Compute a new contention window. Compute the contention window with the binary backoff algorithm.

Mac80211Pkt * Mac80211::encapsMsg (  cMessage *  netw  )  [protected]

encapsulate packet Encapsulates the received network-layer packet into a MacPkt and set all needed header fields.

void Mac80211::handleACKframe (  Mac80211Pkt *  af  )  [protected]

Handle ACK and delete corresponding packet from queue

void Mac80211::handleBroadcastMsg (  Mac80211Pkt *  af  )  [protected]

Handle a broadcast packet. This packet is simply passed to the upper layer. No acknowledgement is needed. Called by handleLowerMsg(Mac80211Pkt *af)

void Mac80211::handleCTSframe (  Mac80211Pkt *  af  )  [protected]

Handle a CTS frame. Called by HandleMsgForMe(Mac80211Pkt* af)

void Mac80211::handleDATAframe (  Mac80211Pkt *  af  )  [protected]

Handle a frame which expected to be a DATA frame. Called by HandleMsgForMe()

void Mac80211::handleEndContentionTimer (   )  [protected, virtual]

handle end of contention The node has won the contention, and is now allowed to send an RTS/DATA or Broadcast packet. The backoff value is deleted and will be newly computed in the next contention period

void Mac80211::handleEndSifsTimer (   )  [protected]

handle end of SIFS Handle the end sifs timer. Then sends a CTS, a DATA, or an ACK frame

void Mac80211::handleEndTransmission (   )  [protected]

handle the end of a transmission... Handle the end of transmission timer (end of the transmission of an ACK or a broadcast packet). Called by HandleTimer(cMessage* msg)

void Mac80211::handleLowerMsg (  cMessage *  msg  )  [protected, virtual]

Handle messages from lower layer. Handle all messages from lower layer. Checks the destination MAC adress of the packet. Then calls one of the three functions : handleMsgNotForMe(), handleBroadcastMsg(), or handleMsgForMe(). Called by handleMessage(). Implements BasicLayer.

void Mac80211::handleMsgForMe (  Mac80211Pkt *  af  )  [protected]

handle a message that was meant for me Handle a packet for the node. The result of this reception is a function of the type of the received message (RTS,CTS,DATA, or ACK), and of the current state of the MAC (WFDATA, CONTEND, IDLE, WFCTS, or WFACK). Called by handleLowerMsg()

void Mac80211::handleMsgNotForMe (  cMessage *  af, double  duration )  [protected]

handle a message that is not for me or errornous Handle all ACKs,RTS, CTS, or DATA not for the node. If RTS/CTS is used the node must stay quiet until the current handshake between the two communicating nodes is over. This is done by scheduling the timer message nav (Network Allocation Vector). Without RTS/CTS a new contention is started. If an error occured the node must defer for EIFS. Called by handleLowerMsg()

void Mac80211::handleNavTimer (   )  [protected]

NAV timer expired, the exchange of messages of other stations is done. Handle the NAV timer (end of a defering period). Called by HandleTimer(cMessage* msg)

void Mac80211::handleRTSframe (  Mac80211Pkt *  af  )  [protected]

Handle aframe wich is expected to be an RTS. Called by HandleMsgForMe()

void Mac80211::handleSelfMsg (  cMessage *  msg  )  [protected, virtual]

Handle self messages such as timer... handle timers Implements BasicLayer.

void Mac80211::handleTimeoutTimer (   )  [protected]

handle time out Handle the time out timer. Called by handleTimer(cMessage* msg)

void Mac80211::handleUpperMsg (  cMessage *  msg  )  [protected, virtual]

Handle messages from upper layer. This implementation does not support fragmentation, so it is tested if the maximum length of the MPDU is exceeded. Implements BasicLayer.

void Mac80211::initialize (  int  stage  )  [virtual]

Initialization of the module and some variables. First we have to initialize the module from which we derived ours, in this case BasicModule. This module takes care of the gate initialization. Reimplemented from BasicLayer.

double Mac80211::packetDuration (  double  bits, double  br )  [protected]

computes the duration of a transmission over the physical channel, given a certain bitrate Computes the duration of the transmission of a frame over the physical channel. 'bits' should be the total length of the MAC packet in bits.

void Mac80211::receiveBBItem (  int  category, const BBItem *  details, int  scopeModuleId )  [protected, virtual]

Called by the Blackboard whenever a change occurs we're interested in. Handle change nofitications. In this layer it is usually information about the radio channel, i.e. if it is IDLE etc. Reimplemented from BasicModule.

void Mac80211::sendACKframe (  Mac80211Pkt *  af  )  [protected]

send Acknoledgement Send an ACK frame.Called by HandleEndSifsTimer()

void Mac80211::sendBROADCASTframe (   )  [protected]

send broadcast frame Send a BROADCAST frame.Called by handleContentionTimer()

void Mac80211::sendCTSframe (  Mac80211Pkt *  af  )  [protected]

send CTS frame Send a CTS frame.Called by HandleEndSifsTimer()

void Mac80211::sendDATAframe (  Mac80211Pkt *  af  )  [protected, virtual]

send data frame Send a DATA frame. Called by HandleEndSifsTimer() or handleEndContentionTimer()

void Mac80211::sendRTSframe (   )  [protected, virtual]

send RTS frame Send a RTS frame.Called by handleContentionTimer()

void Mac80211::testMaxAttempts (   )  [protected]

Test if maximum number of retries to transmit is exceeded. Test if the maximal retry limit is reached, and delete the frame to send in this case.

double Mac80211::timeOut (  frameType_802_11  type, double  br )  [protected]

return a timeOut value for a certain type of frame Return a time-out value for a type of frame. Called by SendRTSframe, sendCTSframe, etc.

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Member Data Documentation

double Mac80211::defaultBitrate [protected]

Default bitrate. The default bitrate must be set in the omnetpp.ini. It is used whenever an auto bitrate is not appropriate, like broadcasts.

int Mac80211::fsc [protected]

sequence control -- to detect duplicates

unsigned Mac80211::longRetryCounter [protected]

Number of frame transmission attempt. Incremented when the SHORT_RETRY_LIMIT is hit, or when an ACK or CTS is missing.

bool Mac80211::switching [protected]

take care of switchover times

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

• Mac80211.h
• Mac80211.cc

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