MMAC: A MMAC: A MMobility-obility-Adaptive, Collision-Free Adaptive, Collision-Free MACMAC Protocol for Protocol for Wireless Sensor Wireless Sensor NetworksNetworks

Muneeb Ali, Tashfeen Suleman, and Zartash Muneeb Ali, Tashfeen Suleman, and Zartash Afzal UzmiAfzal Uzmi

IEEE Performance, Computing, and CommuIEEE Performance, Computing, and Communications Conference (IPCCC), 2005 nications Conference (IPCCC), 2005

OutlineOutline

IntroductionIntroduction ConceptConcept MMAC (MMAC (MMobility-Adaptive, obility-Adaptive,

Collision-Free Collision-Free MACMAC)) Simulation resultsSimulation results ConclusionsConclusions

Introduction(1)Introduction(1)

Traditional MAC protocols for Traditional MAC protocols for wireless networks were designed wireless networks were designed to to – Maximize channel utilizationMaximize channel utilization– Promote fair usage of channelPromote fair usage of channel– Reduce latencyReduce latency

Introduction(2)Introduction(2)

MAC protocols for sensor MAC protocols for sensor networks sometimes assume networks sometimes assume – Static sensor nodesStatic sensor nodes– Energy efficiencyEnergy efficiency

Introduction(3)Introduction(3)

In mobile environments, the fixed In mobile environments, the fixed frame time of current MAC frame time of current MAC protocols cause performance protocols cause performance degradationdegradation

1.1. Joining of Mobile nodes have to wait Joining of Mobile nodes have to wait for a long timefor a long time

2.2. Packets collisions in contention-based Packets collisions in contention-based MAC protocolsMAC protocols

3.3. 2-hop information in schedule-based 2-hop information in schedule-based MAC protocols is inconsistentMAC protocols is inconsistent

Goal of MMACGoal of MMAC

To introduce a mobility-adaptive To introduce a mobility-adaptive frame time to dynamically adapt frame time to dynamically adapt to changes in mobility patterns to changes in mobility patterns

Concept(1)Concept(1)

Concept(2)Concept(2)

Mobility in Sensor Mobility in Sensor NetworksNetworks Weak mobilityWeak mobility

– A node failsA node fails– A node joinsA node joins

Strong mobilityStrong mobility– Concurrent nodes joins/failuresConcurrent nodes joins/failures– Nodes physical move from their Nodes physical move from their

locationlocation– Nodes have motion in the mediumNodes have motion in the medium

Problem Definition(1)Problem Definition(1)

Problem Definition(2)Problem Definition(2)

If a node β is expected to leave If a node β is expected to leave NN22(α) during (α) during FFii, then β, then β NN22((αα)) from the START of from the START of FFii

from the START of from the START of FFii

Mobility Estimation(1)Mobility Estimation(1)

Mobility Estimation(2)Mobility Estimation(2)

The mobile node’s state is defined by The mobile node’s state is defined by a column vectora column vector

– SStt is the mobility state is the mobility state– ((xxtt, , yytt) specify position) specify position– specify velocityspecify velocity– specify accelerationspecify acceleration– ‘ ‘ specifies the matrix transpose operatorspecifies the matrix transpose operator

Mobility-Adaptive Mobility-Adaptive Algorithm(1)Algorithm(1)

1.1. For all nodes, calculate optimal For all nodes, calculate optimal predicted statespredicted stateswhere where maxmax = frame time, = frame time, tt = = starting time of starting time of FFi+1 i+1

2.2.

To estimate the mobility state infoand to calculate the position of α in Fi

Logical meaning:

Mobility-Adaptive Mobility-Adaptive Algorithm(2)Algorithm(2)

To calculate nodes who will join or part from β’s 2-hop neighborsLogical meaning:

Mobility-Adaptive Mobility-Adaptive Algorithm(3)Algorithm(3)

If the number of nodes who willjoin and part from β greater than

λmax , decrease the frame timeLogical meaning:

If the number of nodes who willjoin and part from β less than λmax , increase the frame time

Logical meaning:

Protocol IssuesProtocol Issues

Mobility InformationMobility Information– Mobility information could not be Mobility information could not be

known by all 2-hop neighborsknown by all 2-hop neighbors SynchronizationSynchronization

– Nodes could independently calculate Nodes could independently calculate frame times different from each frame times different from each otherother

Solution to Protocol Solution to Protocol IssuesIssues A variation of the cluster head A variation of the cluster head

selection and rotation mechanism of selection and rotation mechanism of LEACH is appliedLEACH is applied– Use cluster heads to Use cluster heads to collect and collect and

disseminatedisseminate the mobility information the mobility information within a clusterwithin a cluster

– Use cluster heads to let all nodes within Use cluster heads to let all nodes within a cluster have the a cluster have the same frame lengthsame frame length

Simulation ParametersSimulation Parameters

Simulation is based on ns2Simulation is based on ns2 Transmission range: 100mTransmission range: 100m Deploy area: 500m X 500mDeploy area: 500m X 500m All sinks are corner-sinksAll sinks are corner-sinks Nodes forward packets to the Nodes forward packets to the

node closer to the sinknode closer to the sink

Average Packet Delay Average Packet Delay vs. Packet Generation vs. Packet Generation raterate

Average Packet Delay Average Packet Delay vs. Mobility Speedvs. Mobility Speed

Packet Received % vs. Packet Received % vs. Packet Generation ratePacket Generation rate

Packet Received % vs. Packet Received % vs. Mobility SpeedMobility Speed

Avg. Energy Used vs. Avg. Energy Used vs. LoadLoad

Avg. Energy Used vs. MobilAvg. Energy Used vs. Mobility Speedity Speed

ConclusionsConclusions

This paper presents a new This paper presents a new scheduled-based MAC protocol scheduled-based MAC protocol (MMAC) for WSN(MMAC) for WSN

According to mobility, MMAC According to mobility, MMAC adaptsadapts– Frame timeFrame time– Transmission slotsTransmission slots– Random-access slotsRandom-access slots

Thank you!!Thank you!!

Cluster Head SelectionCluster Head Selection

P: the cluster-head probabilityr : the number of current roundsG: set of nodes have not been cluster-heads in the last 1/P roundsE: energy

Node α Receives 2 Node α Receives 2 Different Frame Different Frame LengthsLengths

α keeps silent during this overlap period