How to Implement Network Backhaul in ns2

To implement the Network backhaul is refers to the intermediate links among the core network like internet and the edge of the network that requires to encompass the access points, base stations, or local networks. This backhaul is a crucial component of the modern networks that specifically in cellular (4G/5G) and wireless networks, as it connects access networks to the core network. In the simulation NS2 (Network Simulator 2), executing a backhaul network contains simulating various kinds of nodes such as routers, and base stations, backhaul links (wired or wireless), and traffic flows from the access nodes to core networks through backhaul connections.

If you’re looking to set up Network Backhaul in NS2, we’ve got your back with timely support. Keep in touch with us for fresh assistance. For the best guidance, don’t forget to check out ns2project.com.

Steps to Implement Network Backhaul in NS2

  1. Understand the Backhaul Architecture
  • Access Network (AN): Encompasses devices like user equipment (UE), mobile stations, or Wi-Fi devices connected to base stations (BS) or access points (AP).
  • Backhaul Network: These network delivers the connection among the base stations (BS) or access points (AP) and the core network.
  • Core Network (CN): This network denotes the central part of the network, normally connected to the internet or central processing units.

In this situation we will replicate the several access points or base stations connected to the core network via a backhaul network. The backhaul links can be wired such as fiber, Ethernet or wireless.

  1. Set up NS2 Environment

Make certain NS2 is installed and appropriately configure on the computer. If NS2 is not installed, we follow given steps:

wget https://sourceforge.net/projects/nsnam/files/latest/download -O ns-allinone-2.35.tar.gz

tar -xzvf ns-allinone-2.35.tar.gz

cd ns-allinone-2.35

./install

  1. Design the Network Topology

Design a network topology in which:

  • Base stations or access points (AN) are connect to a core network through a backhaul network.
  • Backhaul links can wire or wireless.
  • The traffic flows from the base stations to the core network and vice versa.

3.1. Create Nodes for Access Network, Backhaul, and Core Network

We can make a nodes in the simulation NS2 to denote the access points, backhaul links, and core networks.

Example OTcl Script to Create Nodes:

# Create a simulator object

set ns [new Simulator]

# Open the NAM trace file

set nf [open out.nam w]

$ns namtrace-all $nf

# =======================

# Access Network (AN)

# =======================

# Create access nodes (representing base stations or access points)

set bs1 [$ns node]

set bs2 [$ns node]

set bs3 [$ns node]

# =======================

# Backhaul Network

# =======================

# Create backhaul nodes (intermediate routers/switches)

set bh1 [$ns node]

set bh2 [$ns node]

# =======================

# Core Network (CN)

# =======================

# Create the core network node

set core [$ns node]

# ==========================

# Define Backhaul Connections

# ==========================

# Link the access nodes (base stations) to backhaul nodes

$ns duplex-link $bs1 $bh1 1Gb 5ms DropTail  ;# Fiber link from BS1 to BH1

$ns duplex-link $bs2 $bh1 1Gb 5ms DropTail  ;# Fiber link from BS2 to BH1

$ns duplex-link $bs3 $bh2 1Gb 5ms DropTail  ;# Fiber link from BS3 to BH2

# Connect backhaul nodes to the core network

$ns duplex-link $bh1 $core 10Gb 2ms DropTail  ;# High-speed link from BH1 to Core

$ns duplex-link $bh2 $core 10Gb 2ms DropTail  ;# High-speed link from BH2 to Core

In this example:

  • These base Stations bs1, bs2, bs3 are connect to the Backhaul nodes bh1, bh2.
  • The backhaul nodes are connect to the Core Network (core) through high-speed links.
  1. Simulate Traffic over the Backhaul

To replicate the network traffic over the backhaul, we can use the agents TCP and UDP to produce traffic from access points to the core network.

4.1. Create Traffic from Access Nodes to the Core Network

We can make both TCP and UDP agents to replicate various kinds of traffic in the backhaul network.

Example OTcl Script for Traffic Generation:

# Create a TCP agent and attach it to base station 1 (bs1)

set tcp1 [new Agent/TCP]

$ns attach-agent $bs1 $tcp1

# Create a TCP sink and attach it to the core network node

set sink1 [new Agent/TCPSink]

$ns attach-agent $core $sink1

# Connect the TCP agent to the sink (for traffic from BS1 to Core)

$ns connect $tcp1 $sink1

# Create a CBR (Constant Bit Rate) application to generate traffic over the TCP connection

set cbr1 [new Application/Traffic/CBR]

$cbr1 attach-agent $tcp1

$cbr1 set packetSize_ 1000  ;# Packet size of 1000 bytes

$cbr1 set rate_ 50Mb        ;# 50 Mbps traffic rate

$ns at 1.0 “$cbr1 start”

# Create UDP traffic from base station 2 (bs2) to core network

set udp2 [new Agent/UDP]

$ns attach-agent $bs2 $udp2

set sink2 [new Agent/Null]

$ns attach-agent $core $sink2

$ns connect $udp2 $sink2

# Generate UDP traffic from BS2 to Core

set cbr2 [new Application/Traffic/CBR]

$cbr2 attach-agent $udp2

$cbr2 set packetSize_ 800    ;# 800-byte packets

$cbr2 set rate_ 30Mb         ;# 30 Mbps UDP traffic

$ns at 2.0 “$cbr2 start”

# End the simulation after 10 seconds

$ns at 10.0 “finish”

proc finish {} {

global ns nf

$ns flush-trace

close $nf

exit 0

}

$ns run

In this script:

  • TCP traffic is generated from bs1 to the core network.
  • UDP traffic is generated from bs2 to the core network.
  • CBR (Constant Bit Rate) applications are used to produce the traffic flows.
  1. Simulate Wireless Backhaul Links

In some cases, the backhaul may be wireless like connecting rural areas or hard-to-reach locations. To mimic the wireless backhaul, we can make the wireless nodes and also we describe the proper wireless links.

5.1. Simulate Wireless Backhaul

Example OTcl Script for Wireless Backhaul:

# Define wireless channel and propagation model

set opt(chan)   Channel/WirelessChannel

set opt(prop)   Propagation/TwoRayGround

set opt(netif)  Phy/WirelessPhy

set opt(mac)    Mac/802_11

set opt(ifq)    Queue/DropTail/PriQueue

set opt(ll)     LL

set opt(ant)    Antenna/OmniAntenna

set opt(ifqlen) 50

set opt(adhocRouting) DSDV

# Create a wireless backhaul node

set bh_wireless [$ns node]

# Connect base station bs3 to the wireless backhaul node

$ns duplex-link $bs3 $bh_wireless 100Mb 20ms DropTail

# Connect the wireless backhaul node to the core network

$ns duplex-link $bh_wireless $core 1Gb 10ms DropTail

In this setup:

  • The base station bs3 is connected to the wireless backhaul node (bh_wireless) through a wireless link.
  • The wireless backhaul node connects to the core network using a wired link.
  1. Enable Trace Files and Visualize the Simulation

We can allow the trace file generation and use NAM (Network Animator) to envision the backhaul traffic and also we evaluate the performance.

6.1. Enable Trace Files:

Append the following to the OTcl script to generate trace files:

# Create a trace file to record simulation data

set tracefile [open “out.tr” w]

$ns trace-all $tracefile

6.2. Run and Visualize the Simulation:

After running the simulation:

ns your_script.tcl

nam out.nam

We can visualize the simulation in NAM that will display how traffic flows from access nodes to the core network via the backhaul.

  1. Analyse Backhaul Performance

To assess the behaviour of the backhaul, we can estimate the metrics such as:

  • End-to-end delay: Time taken for packets to traverse from the access nodes to the core.
  • Throughput: The rate of successful data transfer among the nodes.
  • Packet loss: The percentage of packets which are dropped while transmission.

We can estimate the trace files using AWK or custom scripts.

  1. Future Enhancements

Given below are some ideas for improving the backhaul simulation:

  1. Dynamic Load Balancing: Execute the load balancing among several backhaul paths to enhance performance.
  2. Quality of Service (QoS): Launch the QoS mechanisms to prioritize particular kinds of traffic across the backhaul.
  3. Mobile Nodes: To replicate the user devices which are mobile and generate traffic that must be transferred through the backhaul network.
  4. Advanced Wireless Backhaul Technologies: Mimic furthered wireless backhaul technologies, like mmWave or 5G NR.

We executed a step-by-step approach, implementing and evaluating the Network Backhaul through the simulator NS2. Further precise information on this topic will be shared as well.