# ns-3.34

- [doc](https://www.nsnam.org/releases/ns-3-34/documentation/)
- [getting started](https://www.nsnam.org/docs/release/3.34/tutorial/html/getting-started.html)

A strong contender of ns-3 is the celebrated OMNET++.
However, a [2016 paper](https://arxiv.org/pdf/1307.4129.pdf) demonstrated that ns-3 won by a slight margin.
The codebase of ns-3 is well-designed from a C++ programming perspective.
- Better yet, ns-3 introduced a pattern named [*direct code execution*](https://www.nsnam.org/about/projects/direct-code-execution/) (DCE), which reuses the existing linux network stack to perform simulation.
This results in less code and better performance.
- From *my* perspective, there are a few pain points:
- ns-3 uses both *mercurial* and *git* for source control; at times, it's rather confusing!
- ns-3 uses a special build system called *waf*.
I gave up to learning waf; I restricted myself to the simple usage outlined in the tutorials.
How I wish that ns-3 used cmake and vcpkg.
- Due to compatibility, ns-3 restricts to using the C++11 features supported by gcc4.9.
How archaic, considering that C\++20 is already out.
- ns-3 uses the templated `Ptr<>` type which are superceded by the standard defined *smart pointers*.
- ns-3 follows the tasteless [GNU coding style](https://www.nsnam.org/develop/contributing-code/coding-style/).

## Packet Core


## Roadmap

:::info
Essential are the concepts capable of emulation.
To understand the essentials of LTE, look no further than the ns-3 LTE module documentation.
:::

- **Main entry**: [ns-3 Model Library](https://www.nsnam.org/docs/models/html/index.html)
- **Primary**: [LTE Module](https://www.nsnam.org/docs/models/html/lte.html).
The design guide and user guide are *sufficient* to understand LTE.
- [Design Guide](https://www.nsnam.org/docs/models/html/lte-design.html).
Must read!
- [User Guide](https://www.nsnam.org/docs/models/html/lte-user.html).
Must read!
- [Testing Guide](https://www.nsnam.org/docs/models/html/lte-testing.html)
- [Profiling Guide](https://www.nsnam.org/docs/models/html/lte-profiling.html)
- [References](https://www.nsnam.org/docs/models/html/lte-references.html).
Very useful; look no further.
- **Secondary**: [Mobility](https://www.nsnam.org/docs/models/html/mobility.html), [Propagation](https://www.nsnam.org/docs/models/html/propagation.html).
Use these pre-built mobility and propagation models to customize your emulations.
Design your own mobility and propagation models similar to those.
- **Ternary**: [Network Module](https://www.nsnam.org/docs/models/html/network.html), [Wi-Fi Module](https://www.nsnam.org/docs/models/html/wifi.html).
Could these be used to model 5G.

## Programming

- [Quickstart](https://www.nsnam.org/docs/tutorial/html/getting-started.html); prefer this.
- [Official installation guide](https://www.nsnam.org/wiki/Installation)

Ns-3 requires Python 3.
If Python 3 is missing, install it.
It's best to have Python 3.7+; update pip if necessary:

# choose whichever suitable for pip3
pip install --upgrade pip
pip3 install --upgrade pip

I'll call the project root directory `root`.
Install *bake* in `root` and setup a python virtual environment:

mkdir root
cd root
git clone https://gitlab.com/nsnam/bake
python3 -m venv env
source env/bin/activate
cd bake
bake.py check
bake.py configure -e ns-3.34
bake.py show
bake.py deploy -vvv
cd ..
# now you are back in root
ln -s `pwd`/bake/source/ns-3.34 ns-3.34 

The directory layout would now look like this:
- root
- bake
- source
- ns-3.34
- ns-3.34

Test with:

# from root
cd ns-3.34
./waf --run hello-simulator
# Hello Simulator

:::info
Offline documentation can be obtained [here](https://www.nsnam.org/releases/ns-3-34/documentation/).
:::

## Building Custom Scripts

./waf clean
./waf configure \
    --disable-tests \
    --disable-examples \
    --disable-python \
    --enable-mpi \
    --boost-mt \
    --boost-includes=/opt/homebrew/Cellar/boost/1.76.0/include \
    --boost-libs=/opt/homebrew/Cellar/boost/1.76.0/lib \
    --cxx-standard="-std=c++17"
./waf build # -j8
# ./test

:::info
It doesn't matter that

List of FAILed tests:
    int64x64

:::
In root, do:

mkdir -p sim/src
ln -s $PWD/ns-3.34/build/scratch sim/build
rm -fr ns-3.34/scratch
ln -s $PWD/sim/src ns-3.34/scratch

Create the *executable* `root/sim/compile` with content:

(cd ~/Documents/ns-3/ns-3.34 && exec ./waf)

## ns-3 C++ Library Quickstart

- [entry](https://www.nsnam.org/docs/tutorial/singlehtml/index.html#ns3-namespace)
- [object overview](https://www.nsnam.org/docs/manual/singlehtml/index.html#object-overview)

Basic example with 2 UE and 1 eNB that are all immobile:

#include <ns3/core-module.h>
#include <ns3/lte-module.h>
#include <ns3/mobility-module.h>
#include <ns3/network-module.h>
using namespace ns3;

int main()
{
	auto lteHelper = CreateObject<LteHelper>();
	MobilityHelper mobility;

	NodeContainer enbNodes(1);
	mobility.SetMobilityModel("ns3::ConstantPositionMobilityModel");
	mobility.Install(enbNodes);
	auto enbDevs = lteHelper->InstallEnbDevice(enbNodes);

	NodeContainer ueNodes(2);
	mobility.SetMobilityModel("ns3::ConstantPositionMobilityModel");
	mobility.Install(ueNodes);
	auto ueDevs = lteHelper->InstallUeDevice(ueNodes);

	lteHelper->Attach(ueDevs, enbDevs.Get(0));
	lteHelper->ActivateDataRadioBearer(ueDevs,
									   EpsBearer(EpsBearer::GBR_CONV_VOICE));

	Simulator::Stop(MilliSeconds(5));
	Simulator::Run();
	Simulator::Destroy();
}

## C++17

CXXFLAGS="-std=c++17" ./waf configure