How to Implement Zigbee Topology in NS2

To implement a Zigbee topology in Network Simulator 2 (NS2) has encompasses to replicate a wireless sensor network using Zigbee protocol features. Meanwhile NS2 doesn’t support Zigbee directly, so we need to mimic a Zigbee-like environment using IEEE 802.15.4 (the MAC and PHY layer standard for Zigbee) and other sensor network components. The below is implementation process for simple Zigbee topology in NS2:

Steps to Implement Zigbee Topology in NS2

  1. Set up NS2 with Zigbee Patch (Optional)

If we want to utilize the IEEE 802.15.4 standard, ensure the NS2 installation is patched for 802.15.4 support. We need to download and install the IEEE 802.15.4 patch for NS2 if it’s not encompassed in NS2 version.

  1. Create a TCL Script for Zigbee Topology

In NS2, we will mimic the Zigbee-like communication by configuring nodes and setting up the wireless metrics to resemble Zigbee characteristics. The following is an example of how to generate a simple Zigbee topology, like a star or cluster tree.

  1. Define Nodes and Topology Structure

Zigbee has numerous device roles, such as:

  • Coordinator: The central node that handles the network.
  • Routers: Intermediate devices that forward packets.
  • End Devices: Devices that interact with the coordinator or routers.

In the sample below, a star topology is mimicked with one coordinator and several end devices.

Example TCL Script for Zigbee Star Topology:

# Define simulator

set ns [new Simulator]

# Open trace files

set tracefile [open out.tr w]

set namfile [open out.nam w]

$ns trace-all $tracefile

$ns namtrace-all $namfile

# Create the topography object for wireless nodes

set topo [new Topography]

# Create a wireless channel

set chan [new Channel/WirelessChannel]

# Define parameters for wireless PHY and MAC layers (IEEE 802.15.4 parameters)

Phy/WirelessPhy set CPThresh_ 10.0

Phy/WirelessPhy set CSThresh_ 1.0e-10

Phy/WirelessPhy set RXThresh_ 1.0e-10

Phy/WirelessPhy set bandwidth_ 250Kb  ;# Typical Zigbee bandwidth

# Set up the topography object

$topo load_flatgrid 500 500

# Define the nodes (coordinator and end devices)

set coord [$ns node]

$coord set X_ 250.0

$coord set Y_ 250.0

$coord set Z_ 0.0

# Create End Device Nodes (Zigbee end devices)

set node1 [$ns node]

set node2 [$ns node]

set node3 [$ns node]

# Set their positions (nodes in a star arrangement)

$node1 set X_ 200.0

$node1 set Y_ 250.0

$node1 set Z_ 0.0

$node2 set X_ 300.0

$node2 set Y_ 250.0

$node2 set Z_ 0.0

$node3 set X_ 250.0

$node3 set Y_ 200.0

$node3 set Z_ 0.0

# Create wireless links (Zigbee-like communication) – Coordinator to End Devices

$ns duplex-link $coord $node1 250Kb 10ms DropTail

$ns duplex-link $coord $node2 250Kb 10ms DropTail

$ns duplex-link $coord $node3 250Kb 10ms DropTail

# Setup traffic between coordinator and nodes

set udp0 [new Agent/UDP]

set null0 [new Agent/Null]

$ns attach-agent $coord $udp0

$ns attach-agent $node1 $null0

$ns connect $udp0 $null0

set cbr0 [new Application/Traffic/CBR]

$cbr0 set packetSize_ 100

$cbr0 set interval_ 0.01

$cbr0 attach-agent $udp0

$ns at 1.0 “$cbr0 start”

# Run the simulation

$ns at 10.0 “finish”

proc finish {} {

global ns tracefile namfile

$ns flush-trace

close $tracefile

close $namfile

exec nam out.nam &

exit 0

}

$ns run

Key Points:

  1. Zigbee Parameters:
    • Bandwidth: Zigbee usually performs at 250 Kbps, which is set for the link bandwidth in the script.
    • Range: Modify the node positions and RXThresh_ (receiver sensitivity) and CSThresh_ (carrier sense threshold) to mimic the short-range communication typical of Zigbee.
  2. Network Topology:
    • The script states a star topology with a coordinator at the center and end devices that interacting via the coordinator.
    • For a cluster tree topology, we would add routers among the coordinator and end devices and describe routes consequently.
  3. Traffic:
    • The script mimics traffic among the coordinator and an end device using UDP and CBR (Constant Bit Rate) traffic. We can increase more nodes or traffic patterns as needed.
  4. Trace and NAM Visualization:
    • The trace files (out.tr for NS2 and out.nam for NAM visualization) are created and can be evaluated or viewed in NAM (Network Animator) for simulation outcomes.
  1. Run the Simulation:

Save the script as zigbee_topology.tcl and executed it using the following command:

ns zigbee_topology.tcl

If NAM is installed, the topology will open in the visualizer; demonstrate the Zigbee-like network in action.

  1. Customizing the Topology:

We need to adjust the script to contain more nodes, routers, and communication patterns. If needed, additional energy models can be added to mimic the battery-powered end devices.

By using the above simulation, we can replicate a Zigbee-like topology in NS2 for numerous scenarios like home automation, wireless sensor networks, and IoT-based networks.

In the conclusion, we provided the significant procedures and the sample snippets that were help to execute the Zigbee topology in the ns2 simulation tool. Additional specific details regarding the Zigbee topology are also provided.

Get specialized assistance for implementing Zigbee topology within the NS2 tool from our developers. Achieve a comprehensive implementation and a Zigbee-like environment by utilizing IEEE 802.15.4, which serves as the MAC and PHY layer standard for Zigbee, along with support for various sensor network components.