BabbleSim is a simulator of the physical layer of shared medium networks.

Its main objective is to be an aid to develop network protocols and network devices, and to be able to develop, debug and regression test target code in a controlled environment.

BabbleSim’s physical layer simulation is, by design, meant to support very heterogenous devices and methods to simulate or run real devices code. In a simulation, a device may be as simple as a python script, or as complex as a simulated multi processor system with a multitude of peripherals.

Completely different types of devices may be run together and communicate in a simulation over a given Phy. BabbleSim allows this by setting almost no requirements on the way the rest of the device is simulated. For a device to be able to run in a simulation all it needs is to relay to the BabbleSim Phy its transmissions and reception attemps. You can find an introduction to the BabbleSim architecture here

Different types of shared mediums have different Phys. For ex. BLE radios, over the 2.4GHz ISM band, use the 2.4GHz Phy

In a simulation, several devices are run together with one Phy for each type of shared medium. A device is, in general, a network device, for ex. a phone, a wireless headset, an interferer…

The Phy is in charge of:

Diagram of the simulation split between the devices and the phy

Phy-device interface

BabbleSim is fast

All components of the simulator are designed to run fast, to allow running long system level simulations with multiple devices in short time. The simulation speed limit is set by the execution speed of the devices. The Phy and channel emulation overhead are quite minor: Simulations with a few simple devices with BLE like activity will run in the order of 100x-1000x faster than real time in a modern computer with the 2G4_phy

BabbleSim is modular

By its nature, BabbleSim is highly modular. Reflecting this modular approach, BabbleSim is organized in a set of separate git repositories. In general one fetches and builds only the repositories/components one is interested on. In BabbleSim a component is understood as a device, phy, or library, which is typically placed in the components/ folder.

You can find the BabbleSim repositories here. Typically all users will fetch the base repository.

You can find more information on how to fetch the different components in this page.

It is easy to debug any device

By design, the Phy will wait for any device and block other devices when neccessary. That means that you can run any device (or several of them), in a debugger or instrument them without affecting the simulation results.

Folder structure

Here you can find both the recommended folder structure, as well as how to work with off-tree components.


Find here instructions on how to build

How to use

The best way to understand how BabbleSim works is by trying it. Here you can find an example on how to run a simple case.

What BabbleSim includes

To ease implementation and to allow developing consistent devices, BabbleSim incudes a set of optional libraries which provide functonalities like tracing, results dumping, command line argument parsing, random number generation, etc.

Moreover, a set of simple debug aid/ancillary devices are included in the base repository.

For BLE (BT Smart) development, it includes:

Zephyr’s NRF52_bsim and the NRF52 HW models

Even though BabbleSim does not set how the CPU is emulated (if at all), or how the HW should be modelled, the BabbleSim GitHub organization does contain a git repository with models of the NRF52 HW.
These models can be used together with Zephyr’s nrf52_bsim board to execute Zephyr and use BabbleSim’s 2G4 Phy to simulate the BLE communication over the 2.4GHz ISM band. A quick guide on how to get this device up and running can be found in this board’s page

Design choices

This is BabbleSim’s list of design choices & objectives

License and contributing to BabbleSim

Here you can find our contribution guidelines and an introduction to BabbleSim’s license

More information