How to Implement Network Scheduling Cell Resource in NS2
To implement cell resource scheduling in NS2, we have to follow the steps that contain to mimic how resources in a cellular network like an LTE or 5G system are distributed to users or devices. Resource scheduling in cellular networks usually denotes to handling the radio resources such as time, frequency, or resource blocks to increase efficiency and make sure fair access.
NS2 doesn’t natively support the elaborated cellular resource scheduling as in LTE or 5G, however we can replicate the characteristics of cell resource scheduling by generating a simplified model that shares bandwidth, frequency, or time slots to different users. This can be completed by executing different types of queuing mechanisms and traffic management techniques.
Here’s a procedure on how to mimic a simplified cell resource scheduling mechanism in NS2:
Step-by-Step Implementation:
- Understand the Concept of Resource Scheduling:
- Resource blocks (in LTE/5G) denote small time-frequency chunks assigned to users.
- Scheduling algorithms in a base station distribute resources to users according to the conditions such as throughput, fairness, priority, and network conditions.
- Common scheduling techniques that include:
- Round Robin: Equal time slices for each user.
- Proportional Fair: Users with better channel conditions receive more resources.
- Max Throughput: Concentrates on maximizing the overall network throughput.
- Basic NS2 Setup:
Initiate by setting up a cellular-like network environment in NS2. We can use multiple mobile nodes that denote users connected to a base station (a fixed node). Resources are modelled as available bandwidth, and scheduling controls how that bandwidth is distributed among the users.
set ns [new Simulator]
# Create trace file
set tracefile [open “tracefile.tr” w]
$ns trace-all $tracefile
# Create nodes (base station and mobile users)
set base_station [$ns node] ;# Base station node
set mobile_node1 [$ns node] ;# Mobile user 1
set mobile_node2 [$ns node] ;# Mobile user 2
- Defining the Link with Resource Allocation:
In NS2, we can replicate resource scheduling by handling the bandwidth available to each node. We can enthusiastically distribute the bandwidth according to a predefined scheduling algorithm.
# Define duplex link between the base station and mobile nodes
# Here, 1Mb link simulates available bandwidth between the base station and mobile users.
$ns duplex-link $base_station $mobile_node1 1Mb 10ms DropTail
$ns duplex-link $base_station $mobile_node2 1Mb 10ms DropTail
- Implementing Resource Scheduling:
To execute resource scheduling, we can control the queue at the base station. A common method is to replicate time-frequency resource blocks by adapting the bandwidth allocation (queue behavior) for each mobile node according to different scheduling techniques.
Example: Round Robin Scheduling
In Round Robin scheduling, each mobile user becomes an equivalent share of resources (bandwidth).
# Create traffic for mobile user 1 (UDP)
set udp1 [new Agent/UDP]
$ns attach-agent $mobile_node1 $udp1
set cbr1 [new Application/Traffic/CBR]
$cbr1 set packetSize_ 1000
$cbr1 set rate_ 500Kb ;# Allocating 500Kb/s to mobile user 1
$cbr1 attach-agent $udp1
# Create traffic for mobile user 2 (UDP)
set udp2 [new Agent/UDP]
$ns attach-agent $mobile_node2 $udp2
set cbr2 [new Application/Traffic/CBR]
$cbr2 set packetSize_ 1000
$cbr2 set rate_ 500Kb ;# Allocating 500Kb/s to mobile user 2
$cbr2 attach-agent $udp2
# Connect traffic sources to sinks
set null1 [new Agent/Null]
$ns attach-agent $base_station $null1
$ns connect $udp1 $null1
set null2 [new Agent/Null]
$ns attach-agent $base_station $null2
$ns connect $udp2 $null2
In this scenario, both mobile users are distributed an equal share of bandwidth (500Kb each), that mimics a simple Round Robin scheduling.
Example: Proportional Fair Scheduling
To replicate Proportional Fair scheduling, in which users with better channel conditions get more resources, that can dynamically adapts the bandwidth allocation according to conditions (for example, favouring one node with higher bandwidth):
# Adjust bandwidth dynamically based on scheduling algorithm
set cbr1_rate 700Kb ;# Mobile user 1 gets 700Kb
set cbr2_rate 300Kb ;# Mobile user 2 gets 300Kb
$cbr1 set rate_ $cbr1_rate
$cbr2 set rate_ $cbr2_rate
We can adapt these values energetically during the simulation to replicate varying network conditions like signal quality, user mobility.
- Monitoring Queue Behavior and Bandwidth Utilization:
We can observe on how the queues at the base station act as in diverse resource scheduling algorithms. To permits queue tracing in NS2 to capture information about packet scheduling and bandwidth usage.
# Enable queue tracing for the link between base station and mobile nodes
$ns trace-queue $base_station $mobile_node1 [open “queue1.tr” w]
$ns trace-queue $base_station $mobile_node2 [open “queue2.tr” w]
# Run the simulation
$ns run
- Implementing More Advanced Scheduling Algorithms:
- Weighted Round Robin (WRR): We can execute this by assign diverse weights (bandwidth) to different nodes according to predefined criteria.
- Max Throughput Scheduling: We can design this by enthusiastically adapt the bandwidth according the throughput requirements of each mobile user.
For more cutting-edge scheduling mechanisms such as Weighted Fair Queuing (WFQ) or Deficit Round Robin (DRR), we can either replicate them via custom scripts that adapt the bandwidth dynamically, or adjust the NS2 source code to establish new queue types that executes these algorithms.
- Simulating LTE/5G-Like Resource Blocks:
To design resource blocks in LTE/5G, we can divide the total bandwidth into smaller chunks (time-frequency slots) and distribute them to users. In NS2, this can be completed by breaking the total bandwidth into parts and transfer them according to the scheduling logic.
# Simulate time-frequency resource blocks by allocating different time slots to users
set total_bandwidth 1000Kb
# Divide the total bandwidth into 100Kb resource blocks
set rb_size 100Kb
# Dynamically assign resource blocks to users (round robin)
$cbr1 set rate_ [expr $rb_size * 7] ;# User 1 gets 700Kb
$cbr2 set rate_ [expr $rb_size * 3] ;# User 2 gets 300Kb
We can further optimize the script by executing time-slot-based scheduling such as users get bandwidth for certain periods, simulating time-division.
- Running the Simulation:
After configuring the traffic, links, and resource scheduling, we can execute the simulation and observes the outcomes to assess the impacts of the scheduling algorithm.
# Finish the simulation and close trace files
proc finish {} {
global ns tracefile
$ns flush-trace
close $tracefile
exit 0
}
# Schedule the end of the simulation
$ns at 10.0 “finish”
# Start the simulation
$ns run
- Post-Simulation Analysis:
After executing the simulation, evaluate the trace files to observe the performance of diverse scheduling algorithms. Key metrics to evaluate include:
- Throughput: Verify the data rate received by each user.
- Fairness: make sure fair allocation of resources according to the chosen scheduling algorithm.
- Packet loss: Observes if any packets were dropped owing to buffer overflow or bandwidth limitations.
We can envision the performance using tools such as XGraph to plot the throughput or latency of different users over time.
In this demonstration, we utterly distinguish how to implement the simple setup simulation and identify how to accomplish the cell resource scheduling in ns2 simulator tool. If you have any query regarding this process we also help to clarify it.
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