This repository contains an IEEE 802.11ah transceiver implementation in GNUradio. It has been tested with the Ettus USRP N210, but should work with other high-bandwidth Software Defined Radios (SDRs) as well. It relies on a few other repositories, mainly the one created by Bastian Bloessl.
For some background knowledge, I suggest checking out the following papers:
- Description of IEEE 802.11ah standard
- Implementation of IEEE 802.11a/g/p receiver in gnuradio
- First steps in creating an IEEE 802.11ah transceiver
Also, use Google a lot, it is an extremely valuable resource :).
If you're starting this project as a total beginner like me, first things first is setting up your Linux distribution. I heavily recommend to install Linux natively, if you'd like to know why please read the section GNUradio in a VM at the bottom of this README. Any distribution should work fine, Ubuntu is the most commonly used one so that is my preferred choice.
Next is installing GNUradio. There are many ways to install GNUradio, some being much easier than others. The one I initially tried was just doing an apt install gnuradio command. However, if you choose to do this you need to install all the dependencies manually, and if only one version mismatches with another (for example, one hasn't been updated for a while) there is a possibility nothing works. For me, after a lot of hassle and manually fixing stuff I had an apparently unfixable library mismatch.
This led to me reinstalling everything using PyBOMBS, which I can now say is by far the easiest method. To do this, start by installing pip:
sudo apt install python-pip
Then follow the instructions posted on The GNUradio PyBOMBS Github repository. For the impatient, these were the commands that did the trick the last time I checked:
pip install PyBOMBS
pybombs auto-config
pybombs recipes add-defaults
pybombs prefix init ~/prefix -a myprefix -R gnuradio-default
This last step can easily take a few hours, so be patient. After this, GNUradio should be installed in the folder "prefix" located in your home directory (~/prefix). Normally, Linux would install everything in various locations; doing this ensures everything is installed in one folder. This is really useful if you mess things up, since you can simply delete the prefix folder and try again. Now, every time you want to start GNUradio in a new terminal, execute the following commands:
source ~/prefix/setup_env.sh
gnuradio-companion
Try to make it a habit to execute source ~/prefix/setup_env.sh command before you do anything else in terminal related to GNUradio, or even better: add the command in ~/.bashrc. Forgetting this has cost me a lot of extra hassle at times. Now GNUradio should be working!
Next up is installing the repository by Bastian Bloessl, you can find out how to do this in detail here. Some tips to overcome obstacles I encountered are:
- If you installed using PyBOMBS, make sure you are on the master branch on both Bastian's repositories (gr-foo and gr-ieee-802-11), and not on the next branch. If you're not, you'll get some weird errors later on. To do this, type git checkout master after cloning each git repository.
- Make sure you've typed source ~/prefix/setup_env.sh in the terminal you're working in, or cmake won't know where to find the gnuradio files.
- It doesn't really matter where you clone the repositories gr-foo and gr-ieee802-11 to, since the cmake command you run later will automatically install everything in the right location. I recommend creating a folder like ~/Documents/gnuradio and install everything there to keep things clear.
- Make sure to open and run /examples/wifi_phy_hier.grc in GNUradio, in order to install the wifi_phy_hier block.
Now, you should have Bastian's blocks working. Try to go through some of his examples to see if they are working.
Now, all you need to do is open the 802_11_ah_txrx file in this repository and everything should be working! Note that this is not a full 802.11ah implementation: just the PHY layer has been implemented (basic sending and receiving), not the MAC layer. Feel free to pick this up if you're interested!
If things don't work out, please check Bastian's repository first. If your solution is not there and/or on the internet, feel free to open an issue or contact me personally.
I thought it would be the most practical to set everything up on a VM (VirtualBox/VMware), however in the end this proved to involve a large amount of extra operations I had to carry out to make everything working. In the end after hours of fixing small VM-specific errors I received underflow/overflow errors from my SDR: my ethernet driver could not connect to the SDR fast enough, even though it was a full-duplex 1Gbit/s adapter. I tried to mess around with installing and changing custom drivers for my ethernet adapter, but all to no avail. Installing native Linux immediately solved this and many other problems. Therefore I heavily recommend to isntall Linux natively, especially if you are not an advanced Linux user like me.