Senior Design Project OPNET Modeler

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Senior Design ProjectOPNET Modeler
Short-Range Wireless Routing

• Erin Butler Emmy Lai
• Advisor Professor H. C. Chang

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Grant

• Funded by a grant from CRA-W, a subset of the
  National Science Foundation,

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Objective of Project

• Research Existing Wireless Routing Algorithms
• Design and Implement these Algorithms
• Explore OPNET Modeler
• A network technology development environment
• Simulate a Variety of Networks, Observing
  Performance Metrics

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OPNET Modeler

• Three Main Domains
• Network
• Node
• Process

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Network Domain

• Subnetworks
• Encapsulates other network objects
• Communication Nodes
• Model network objects with definable internal
  structure
• Communication Links
• Mechanism to transport information between nodes
• Fixed, Mobile, Satellite Variations

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Node Domain

• Node Model defines the internal structure of the
  communication nodes
• Node Modules
• Processor primary building block, sends/receives
  packets, overall processing
• Queue extended functionality of processor, array
  of internal resources, subqueues
• Transmitter interface between internal packet
  streams external communication links
• Receiver interface between external
  communication links internal packet streams
• Connections
• Packet Stream support flow of data between
  modules
• Statistic Wires support transmission of
  numerical state information
• Logical Associations bind two modules, allowing
  them to perform function together

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Process Domain

• The Process Model defines the behavior of the
  processor and queue modules
• Interrupt Driven Execution
• Caused by the invocation of an event
• Alternating Blocked and Active states
• Dynamic Processes
• Processes invoked by other processes
• Share Memory Architecture
• Parent-Child establish pair establish block of
  memory for two-way communication

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Process Domain (cont.)

• Dynamic Library operations
• State Transition Diagrams
• State a mode the process can enter, state
  information
• Enter Exit Executives
• Unforced state wait for interrupt
• Forced state continual execution of state
• Transition possible movements of a process from
  state to state
• Source destination state, condition executive
  expression
• Input Output Streams

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Data Analysis

• Analysis Tool
• Graphs
• Statistics
• Output Scalar Files data collected in vector
  files during a simulation run, combine results
  from multiple simulations

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OPNET Editors

• Project Editor
• Node Editor
• Process Model Editor
• Link Model
• Path Editor
• Packet Format Editor
• Antenna Pattern Editor

• Interface Control Information Editor
• Probability Density Function Editor
• Probe Editor
• Simulation Tool
• Analysis Tool
• Filter Editor

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Project Editor

• Main staging area for creating a network
  simulation
• Create a network model using models from the
  standard library
• Collect statistics about the network
• Run the simulation
• View Results

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Node Editor

• Define the behavior, which is defined by modules,
  of each network object
• A network object is made up of multiple modules
  defining its behavior
• Each module models some internal aspect of the
  node behavior (ex data creation/storage)

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Process Model Editor

• Create process models which control the
  underlying functionality of the node models
  created in node editor
• Represented by finite state machines
• Created with icons that represent states and
  lines that represent transitions between states
• Operations performed in each state or for a
  transition are described in embedded c or c
  code blocks

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Link Model

• Create new types of link objects
• Each new type of link can have different
  attribute interfaces and representation

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Path Editor

• Create new path objects which define a traffic
  route
• Any protocol model that uses logical connections
  or virtual circuits (MPLS, ATM, Frame Relayetc)
  can use paths to route traffic

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Packet Format Editor

• Defines the internal structure of a packet as a
  set of fields
• A packet format contains one or more fields,
  represented in the editor as colored rectangular
  boxes
• Size of the box is proportional to the number of
  bits specified as the fields size

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Antenna Pattern Editor

• Models the direction dependent gain properties of
  antennas
• Gain patterns are used to determine gain values,
  given knowledge of the relative positions of
  nodes

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Interface Control Information Editor

• Defines the internal structure of ICIs (Interface
  Control Information) which are used to formalize
  interrupt-based inter-process communication

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Probability Density Function Editor

• Describes the spread of probability over a range
  of possible outcomes
• Models the likelihoods associated with packet
  interarrival times
• Models the probability of transmission errors

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Probe Editor

• Specifies the statistic to be collected during
  simulation
• Sets additional characteristics of each probe
• Different probes collect different statistics
  including global statistics, link statistics,
  node statistics, attribute statistics, and
  several types of animation statistics.

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Simulation Tool

• Specifies additional simulation constraints
• Simulation sequences are represented by
  simulation icons which contain a set of
  attributes that control that simulations
  run-time characteristics

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Analysis Tool

• Creates scalar graphs and parametric studies
• Defines templates to which statistical data is
  applied
• Creates analysis configurations

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Filter Editor

• Creates additional filters on top of the ones
  that are already provided by OPNET
• Built by combining existing models with each
  other

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OPNET Overview Layout
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Carrier Sense Multiple Access Protocol (CSMA)

• Protocols in which stations listens for a carrier
  or transmission and act accordingly
• Three versions of CSMA
• 1 persistent
• non persistent
• p persistent

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1 persistent CSMA

• When a station has data to send, it first listens
  to the channel to see if anyone else is
  transmitting at that moment
• If the channel is busy, the station waits until
  it becomes idle
• When the station detects an idle channel, it
  transmits a frame
• If a collision occurs, the station waits a random
  amount of time and starts all over again
• Transmits with a probability of 1 whenever it
  finds the channel idle

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Non-persistent CSMA

• Attempts to be less greedy than 1-persistent
• Before sending, a station senses the channel
• If no one else is sending, the station begins
  doing so itself
• If the channel is already in use, it waits a
  random period of time and then repeats the
  algorithm
• Leads to a better channel utilization and longer
  delays than 1-persistent

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p-persistent CSMA

• Applies to slotted channels
• When a station becomes ready to send, it senses
  the channel
• If it is idle, it transmits with a probability p
• A probability of q1-p is deferred until the next
  slot
• If that slot is also idle, it either transmits or
  defers again, with the probabilities p and q
• Process repeats until either the frame has been
  transmitted or another station has begun
  transmitting
• If another station has begun transmitting, it
  acts as if there had been a collision (ie, it
  waits a random time and starts again)
• If the station initially senses the channel busy,
  it waits until the next slot and applies the
  above algorithm

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OPNET CSMA

• Basic Components
• CSMA project network
• Transmitter Node Model sends packets
• Receiver Node Model performs network monitoring

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CSMA Process Model

• Verifies the channel is free before transmitting
• If channel is not free, enters the wt_free state
  until a channel goes free interrupt is received

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CSMA

• At the node level, the statistic wire is
  triggered when the busy statistic changes to
  0.0.
• The trigger is activated by enabling the wires
  falling edge trigger attribute

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CSMA Scenario

• CSMA network model
• 20 transmitter nodes
• Uses transmitter nodes designed previously in
  node editor
• Network is ready for simulation

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CSMA Simulation

• Change attributes to run simulation
• Duration time
• Seed
• Value per statistics
• In this case, for the CSMA, seed is changed to 11

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CSMA Simulation Results

• Graph of channel throughput S vs. channel traffic
  G
• Achieves maximum throughput at about 0.5

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Comparing Protocols (CSMA vs. Aloha)
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Introduction to Dynamic Wireless Networks

• These networks consist of mobile hosts that
  communicate to one another over wireless links
  without any static network interaction
• Due to the limited range of wireless
  transceivers, mobile hosts communication links
  only implemented in their geographic reason
• Need for a complex network to handle and maintain
  the forwarding of data packets

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Previous Work Routing Standards

• Set of Conventional Standards
• Simplicity
• Loop-free
• Low Convergence time
• Low computation transmission overhead
• Problems in terms of Dynamic Networks
• Frequent broadcast cause high overhead due to
  changing topology
• Heavy computational burden
• Limited bandwidth in wireless networks

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Temporally Ordered Routing Algorithm (TORA)

• A network routing protocol which has been
  designed for use in Mobile Wireless Networks
• Envisioned as a collection of routers which are
  free to move about arbitrarily
• Routers are equipped with wireless
  receivers/transmitters
• Status of communication links between routers is
  a function of their positions, transmission power
  levels, antenna patterns, cochannel interference
  levels.etc
• Designed to minimize reaction to topological
  changes

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Properties that makes TORA well suited for use in
the mobile wireless networking environment

• Executes distributedly
• Provides loop-free routes
• Provides multiple routes (to alleviate
  congestion)
• Establishes routes quickly (so as to be used
  before the topology changes)
• Minimize algorithmic reactions/communication
  overhead (to conserve available BW and increase
  adaptability)

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Methods to minimize overhead maximize routing
efficiency

• Establish routes only when necessary by
  constructing a direct acyclic graph rooted at the
  destination using a query/reply process
• React to link failure only when necessary (ex
  when a node loses its last downstream link)
• Scope of failure reactions minimized (ie the
  number of nodes that must participate)
• No reaction to link activation

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TORAs Link Reversal Algorithm

• When a node has no downstream links, it reverses
  the direction of one or more links
• Links are directed based on a metric, maintained
  by nodes in the network, that can conceptually be
  viewed as a height
• Goals
• Discover routes on demand
• Provide multiple routes to a destination
• Establish routes quickly
• Minimize overhead
• Make shortest path routing of second importance

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TORA Basic Functions

• Creating Routes Query/Reply on demand
• Query packet (QRY) is flooded through network
• Update packet (UPD) propagates back if routes
  exist
• Maintaining Routes Base on link-reversal
  algorithm
• UPD packets reorient the route structure
• Erasing Routes
• Clear packet (CLR) is flooded through network to
  erase invalid routes

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TORA FSM
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Create Route State Diagram
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Maintain Route State Diagram
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Erase Route State Diagram
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TORA Application

• A separate copy of TORA is run at each node
• Node adjust height at a discovery of an invalid
  route
• Node without neighbor of finite height with
  respect to destination, attempts to find new
  route
• Sends CLR packet upon network partition
• Exchange of UPD packets

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TORA Application cont

• Complete path can be found using distance table
• Each router maintains its own information with
  respect to its neighbor

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Node Height

• Each height table for a node contains the
  following information
• Hi (?i, oid, ri, ?i, i)
• ?I time tag
• oid originator ID
• ri bit used to divide each reference level into
  2 sublevels
• ?I integer used to order nodes
• I unique identifier of node
• Height of each node (except for the destination)
  is initially set to NULL Hi ( -, -, -, -, i)

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Route Creation
(-,-,-,-,A)
(-,-,-,-,B)
QRY
(-,-,-,-,C)
(-,-,-,-,E)
(-,-,-,-,D)
(-,-,-,-,G)
(-,-,-,-,F)
DEST
(-,-,-,-,H)
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Route Creation
(-,-,-,-,A)
QRY
(-,-,-,-,B)
(-,-,-,-,C)
(-,-,-,-,E)
(-,-,-,-,D)
QRY
(-,-,-,-,G)
(0,0,0,0,F)
DEST
(-,-,-,-,H)
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Route Creation
(-,-,-,-,A)
(-,-,-,-,B)
(-,-,-,-,C)
(-,-,-,-,E)
(-,-,-,-,D)
(-,-,-,-,G)
(0,0,0,0,F)
DEST
(0,0,0,1,H)
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Route Creation
(-,-,-,-,A)
(-,-,-,-,B)
(-,-,-,-,C)
(0,0,0,1,E)
(0,0,0,2,D)
(0,0,0,2,G)
(0,0,0,0,F)
DEST
(0,0,0,1,H)
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Route Creation
(0,0,0,3,A)
(0,0,0,2,B)
(0,0,0,3,C)
(0,0,0,1,E)
(0,0,0,2,D)
(0,0,0,2,G)
(0,0,0,0,F)
DEST
(0,0,0,1,H)
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Route Creation Complete
(0,0,0,3,A)
(0,0,0,2,B)
(0,0,0,3,C)
(0,0,0,1,E)
(0,0,0,2,D)
(0,0,0,2,G)
(0,0,0,0,F)
DEST
(0,0,0,1,H)
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Cluster-Based Algorithm for Dynamic Network
Routing

• Main objective To replace individual nodes
  (mobile hosts) with a cluster
• Lower overhead during topology changes
• Basic algorithm
• Divide the graph into a number of overlapping
  clusters
• Change in topology change in cluster membership

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Cluster Definitions

• Graphs an organization of nodes or mobile hosts
• Node list of neighbors, list of clusters it
  belongs to, list of boundary nodes
• Boundary nodes connection from one cluster to
  another
• Clusters
• Size of cluster C, S(C) number of nodes
• Edges edges between the nodes that are members
  of the clusters
• Cluster-connected graph union of clusters covers
  the whole graph, a path from exists from each
  node to every other in the graph
• Redundant cluster, if removed, does not affect
  the connection between a pair

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Four Main Topology Changes

• H5 turns ON
• H6 turns OFF
• HA connects to HB
• HA disconnects from HB

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Procedures Data Structures

• Two main Procedures Switch ON, Switch OFF
• Each execute a similar algorithm of cluster
  manipulation
• CreateCluster
• FindEssential
• FindRedundant
• Data Structures
• Clus_List list of clusters
• Bound_List list of boundary nodes

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Performance Metrics

• Time Complexity
• Number of steps for a network to form after
  topology change
• Communication Complexity
• Number of messages required to form new network
• Routing Overhead
• Ratio of path length between source and
  destination

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Dynamic Cluster Implementation

• Bottom-Up approach
• Process Model defines behavior of nodes, state
  diagram and transitions
• Node Model contains objects (receiver,
  transmitter, processor) consisting of process
  models
• Network Model overall topology

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Process Models

• Decision Tree Switch ON or Switch OFF

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Switch ON State Diagram
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Switch OFF State Diagram
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Node Model

• Wireless LAN Model MAC sublayer, Physical Layers

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Network Model
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C Language ImplementationMain Functions Data
Structures

• Three Basic Functions
• CreateCluster
• FindEssential
• FindRedundant
• Globally Declared Data Structures
• NeighborList list of all neighbors of each node
• Clus_List contains list of clusters

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C Language ImplementationCreateCluster

• Input Parameter node ID
• Using the the node ID and its NeighborList,
  determines all existing clusters

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C Language ImplementationFindEssential

• Input Parameter node ID
• Ensures that no one node, except the node ID,
  exists in more than one essential class
• Design series of reiterative looping and
  comparisons
• If all nodes are found in another essential
  cluster, cluster is marked non-essential

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C Language ImplementationFindRedundant

• Input Parameter node ID
• Uses essential list
• Determines whether or not the removal of a
  cluster affects the cluster-connectivity between
  any pair of nodes
• Output is the final Clus_List for the node ID

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C Language ImplementationSimulation (initial)
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C Language ImplementationSimulation (H5 ON,
nodeID0)
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C Language ImplementationSimulation (H2 OFF,
node 5)
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C Language ImplementationSimulation (H3
disconnect H4, node 0)
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AND NOWGRADUATION!!