Package: inet.networklayer.probabilistic

ProbabilisticBroadcast

simple module

Multi-hop ad-hoc data dissemination protocol based on probabilistic broadcast.

This method reduces the number of packets sent on the channel (reducing the broadcast storm problem) at the risk of some nodes not receiving the data. It is particularly interesting for mobile networks. Parameter maxNbBcast sets the maximum number of broadcast transmissions of a packet, parameter beta gives the transmission probability for each attempt, parameter bcperiod sets the time between two transmission attempts. Parameter maxFirstBcastBackoff sets a backoff window before first transmission attempt, and parameter timeInQueueAfterDeath sets the time during which a node remembers a packet whose time to live (TTL) expired, avoiding retransmitting it in case it comes back in the network because of some problem.

Inheritance diagram

The following diagram shows inheritance relationships for this type. Unresolved types are missing from the diagram.

Known subclasses

Name	Type	Description
AdaptiveProbabilisticBroadcast	simple module	Multi-hop ad-hoc data dissemination protocol based on probabilistic broadcast, with adaptive parameters.

Extends

Name	Type	Description
NetworkProtocolBase	simple module	Module base for different network protocols.

Parameters

Name	Type	Default value	Description
interfaceTableModule	string
headerLength	int	100b	length of the network packet header (in bits)
bcperiod	double	2 s	period between two probabilistic broadcast attempts
beta	double	0.8	probability of broadcast for each attempt
maxNbBcast	int	1	maximal number of broadcast attempts for each packet.
maxFirstBcastBackoff	double	1 s	maximal back-off before first broadcast attempt [seconds]. if don't want to use this parameter, simply set it to a value that is greater than bcperiod.
timeToLive	double	10 s
timeInQueueAfterDeath	double	60 s	How many seconds the message should be kept in queue after its died. That way the message is known if the node receives one of its copy that isn't dead because of TTL de-synchronization due to MAC backoff, propagation delay and clock drift.

Properties

Name	Value	Description
display	i=block/fork
class	ProbabilisticBroadcast

Gates

Name	Direction	Size	Description
upperLayerIn [ ]	input
upperLayerOut [ ]	output
lowerLayerIn [ ]	input
lowerLayerOut [ ]	output

Signals

Name	Type	Unit
packetReceivedFromUpper	cPacket
packetReceivedFromLower	cPacket
packetFromLowerDropped	cPacket
packetFromUpperDropped	cPacket
packetSentToLower	cPacket
packetSentToUpper	cPacket

Source code

//
// Multi-hop ad-hoc data dissemination protocol based on probabilistic broadcast.
//
// This method reduces the number of packets sent on the channel (reducing the
// broadcast storm problem) at the risk of some nodes not receiving the data.
// It is particularly interesting for mobile networks.
// Parameter maxNbBcast sets the maximum number of broadcast transmissions of a packet,
// parameter beta gives the transmission probability for each attempt,
// parameter bcperiod sets the time between two transmission attempts.
// Parameter maxFirstBcastBackoff sets a backoff window before first transmission attempt,
// and parameter timeInQueueAfterDeath sets the time during which a node remembers
// a packet whose time to live (TTL) expired, avoiding retransmitting it in case it comes back
// in the network because of some problem.
//
simple ProbabilisticBroadcast extends NetworkProtocolBase like INetworkProtocol
{
    parameters:
        @class(ProbabilisticBroadcast);
        int headerLength @unit(bit) = default(100b); // length of the network packet header (in bits)
        // period between two probabilistic broadcast attempts
        double bcperiod @unit(s) = default(2 s);
        // probability of broadcast for each attempt
        double beta = default(0.8);
        // maximal number of broadcast attempts for each packet.
        int maxNbBcast = default(1);
        // maximal back-off before first broadcast attempt [seconds].
        // if don't want to use this parameter, simply set it
        // to a value that is greater than bcperiod.
        double maxFirstBcastBackoff @unit(s) = default(1 s);

        double timeToLive @unit(s) = default(10 s);
        // How many seconds the message should be kept in queue after its died.
        // That way the message is known if the node receives one of its
        // copy that isn't dead because of TTL de-synchronization due to
        // MAC backoff, propagation delay and clock drift.
        double timeInQueueAfterDeath @unit(s) = default(60 s);
}

File: src/inet/networklayer/probabilistic/ProbabilisticBroadcast.ned