openwifi

openwifi: Linux mac80211 compatible full-stack IEEE802.11/Wi-Fi design based on SDR (Software Defined Radio).

This repository includes Linux driver and software. openwifi-hw repository has the FPGA design. It is YOUR RESPONSIBILITY to follow your LOCAL SPECTRUM REGULATION or use CABLE to avoid potential interference over the air.

[Quick start] [Project document] [Application notes] [Videos] [Publications and How to Cite] [maillist]

Openwifi code has dual licenses. AGPLv3 is the opensource license. For non-opensource and advanced feature license, please contact [email protected]. Openwifi project also leverages some 3rd party modules. It is user's duty to check and follow licenses of those modules according to the purpose/usage. You can find an example explanation from Analog Devices for this compound license conditions. [How to contribute].

Features:

• 802.11a/g/n [IEEE 802.11n (Wi-Fi 4)]
• 20MHz bandwidth; 70 MHz to 6 GHz frequency range
• Mode tested: Ad-hoc; Station; AP, Monitor
• DCF (CSMA/CA) low MAC layer in FPGA (10us SIFS is achieved)
• 802.11 packet injection and fuzzing
• CSI: Channel State Information, freq offset, equalizer to computer
• CSI fuzzer: Create artificial channel response in WiFi transmitter
• CSI radar: Moving detection. Joint radar and communication
• [IQ capture]: real-time AGC, RSSI, IQ sample to computer. [Dual antenna version]
• Configurable channel access priority parameters:
  • CCA threshold, receiver sensitivity, etc
  • duration of RTS/CTS, CTS-to-self
  • SIFS/DIFS/xIFS/slot-time/CW/etc
• Time slicing based on MAC address (time gated/scheduled FPGA queues)
• Easy to change bandwidth and frequency:
  • 2MHz for 802.11ah in sub-GHz
  • 10MHz for 802.11p/vehicle in 5.9GHz
• 802.11ax under development

Performance (best case: aggregation/AMPDU on):

• iperf: TCP 40~50Mbps; UDP 50Mbps
• EVM -38dB; MCS0 sensitivity -92dBm; MCS7 -73dBm. (FMCOMMS2 2.4GHz; cable and OTA test)

Supported SDR platforms:

• Check Porting guide for your new board if it isn't in the list.
• board_name is used to identify FPGA design in openwifi-hw/boards/ and FPGA image in openwifi-hw-img/boards
• Don't have any boards? Or you like JTAG boot instead of SD card? Check our test bed w-iLab.t tutorial.

[Quick start] [Basic operations] [Update FPGA] [Update Driver] [Update sdrctl] [Easy Access and etc]

[Build openwifi Linux img from scratch] [Special note for 11b] [Porting guide] [Project document] [Application notes]

Quick start

• Download openwifi img, unzip and burn it into a SD card (>=16GB). After this operation, the SD card should have two partitions: BOOT and rootfs. To flash the SD card, SD card tool software (such as Startup Disk Creator in Ubuntu) or dd command can be used:

  sudo dd bs=512 count=31116288 if=openwifi-xyz.img of=/dev/your_sdcard_dev
  (To have correct count value, better to check the .img file actual situation by "fdisk -l img_filename")
  

• Config the correct files in the BOOT partition according to the board you have by operation on your computer:

  • Copy files in BOOT/openwifi/board_name to the base directory of BOOT partition.
  • Delete the rootfs/root/kernel_modules directory (if exist).
  • Delete the rootfs/etc/network/interfaces.new directory (if exist).

• Insert the SD card to the board. Configure the board in SD booting mode. Connect antennas. Power on.

• Login to the board from your PC (PC Ethernet should have IP 192.168.10.1) with password openwifi.

  ssh [email protected]
  

• If not successful, check known issue

• Then, run openwifi AP and the on board webserver

  raspi-config --expand-rootfs (Only needed when your SD card > 16GB. Run and reboot)
  ./openwifi/setup_once.sh (Reboot the board. Only need to run once for new board)
  cd openwifi
  ./wgd.sh
  ./fosdem.sh
  (Use "./wgd.sh 1" to enable experimental AMPDU aggregation on top of 11n)
  (Use "./fosdem-11ag.sh" to force 11a/g mode)
  

  NOTE adrv9361z7035 has ultra low TX power in 5GHz. Move CLOSER when you use that board in 5GHz!!!

• After you see the "openwifi" SSID on your device (Phone/Laptop/etc), connect it (password: openwifi). If not get 192.168.13.* IP automatically, check known issue. Browser to 192.168.13.1 on your device, you should see the webpage hosted by the webserver on board.

  • Note 1: If your device doesn't support 5GHz (ch44), please change the hostapd-openwifi.conf on board and re-run fosdem.sh.
  • Note 2: After ~2 hours, the Viterbi decoder will halt (Xilinx Evaluation License). Just reload FPGA (method) or simply power cycle the board if it happens. (If output of "./sdrctl dev sdr0 get reg rx 20" is always the same, it means the decoder halts)

• To give the Wi-Fi client internet access, configure routing/NAT on the PC:

  sudo sysctl -w net.ipv4.ip_forward=1
  sudo iptables -t nat -A POSTROUTING -o NICY -j MASQUERADE
  sudo ip route add 192.168.13.0/24 via 192.168.10.122 dev ethX
  

  ethX is the PC NIC name connecting the board ethernet. NICY is the PC NIC name connecting internet (WiFi or another ethernet).

  If you want, uncommenting "net.ipv4.ip_forward=1" in /etc/sysctl.conf to make IP forwarding persistent on PC.

• To monitor real-time CSI (Chip State Information), such as timestamp, frequency offset, channel state, equalizer, please refer to [CSI notes].

Basic operations

The board actually is an Linux/Ubuntu computer which is running hostapd to offer Wi-Fi AP functionality over the Wi-Fi Network Interface (NIC). The NIC is implemented by openwifi-hw FPGA design. We use the term "On board" to indicate that the commands should be executed after ssh login to the board. "On PC" means the commands should run on PC.

• Bring up the openwifi NIC sdr0:

  cd ~/openwifi && ./wgd.sh
  (Use "./wgd.sh 1" to enable experimental AMPDU aggregation)
  

• Use openwifi as client to connect other AP (Change wpa-connect.conf on board firstly):

  route del default gw 192.168.10.1
  wpa_supplicant -i sdr0 -c wpa-connect.conf &
  dhclient sdr0
  

• Use openwifi in ad-hoc mode: Please check sdr-ad-hoc-up.sh, sdr-ad-hoc-join.sh and this app note.
• Use openwifi in monitor mode: Please check monitor_ch.sh and this app note.
• The Linux native Wi-Fi tools/Apps (iwconfig/ifconfig/iwlist/iw/hostapd/wpa_supplicant/etc) can run over openwifi NIC in the same way as commercial Wi-Fi chip.
• sdrctl is a dedicated tool to access openwifi driver/FPGA, please check project document for more information.

Update FPGA

(Check Driver and FPGA dynamic reloading app note for more convenient way of updating FPGA and driver files without rebooting/power-cycle)

Since the pre-built SD card image might not have the latest bug-fixes/updates, it is recommended to always copy the latest files in the user_space directory on to the board. Then update the fpga bitstream and driver (see next section) on to the board.

• Install Vivado 2021.1. Make sure install Vitis as well. You should have this directory: your_Xilinx_install_directory/Vitis (NOT Vitis_HLS!)
  • If the Vitis is not installed, you can add it by running "Xilinx Design Tools --> Add Design Tools for Devices 2021.1" from Xilinx program group/menu in your OS start menu.
• Setup environment variables (use absolute path):

  export XILINX_DIR=your_Xilinx_install_directory
  (Example: export XILINX_DIR=/opt/Xilinx. The Xilinx directory should include sth like: Downloads, Vitis, etc.)
  export OPENWIFI_HW_IMG_DIR=your_openwifi-hw-img_directory
  (The directory where you get the open-sdr/openwifi-hw-img repo via git clone)
  export BOARD_NAME=your_board_name
  

• Pick the FPGA bitstream from openwifi-hw-img, generate system_top.bit.bin and transfer it on board via ssh channel:

  cd openwifi/user_space; ./boot_bin_gen.sh $XILINX_DIR $BOARD_NAME $OPENWIFI_HW_IMG_DIR/boards/$BOARD_NAME/sdk/system_top.xsa
  scp ./system_top.bit.bin [email protected]:openwifi/
  

• Now the system_top.bit.bin is onboard in /root/openwifi/ directory. When wgd.sh runs onboard from that directory, it will discover the FPGA img file system_top.bit.bin and load it before loading driver .ko files.

Update Driver

(Check Driver and FPGA dynamic reloading app note for more convenient way of updating FPGA and driver files without rebooting/power-cycle)

Since the pre-built SD card image might not have the latest bug-fixes/updates, it is recommended to always copy the latest files in the user_space directory on to the board. Then update the fpga bitstream (see previous section) and driver on to the board.

• Prepare Analog Devices Linux kernel source code (only need to run once):

  sudo apt install flex bison libssl-dev device-tree-compiler u-boot-tools -y
  cd openwifi/user_space; ./prepare_kernel.sh $XILINX_DIR ARCH_BIT
  (For Zynq 7000, ARCH_BIT should be 32, for Zynq MPSoC, ARCH_BIT should be 64)
  

• Compile the latest openwifi driver

  cd openwifi/driver; ./make_all.sh $XILINX_DIR ARCH_BIT
  (For Zynq 7000, ARCH_BIT should be 32, for Zynq MPSoC, ARCH_BIT should be 64)
  (More arguments (max 5) beyond above two will be converted to "#define argument" in pre_def.h for conditional compiling)
  

• Copy the driver files to the board via ssh channel

  cd openwifi/driver; scp `find ./ -name \*.ko` [email protected]:openwifi/
  

  Now you can use wgd.sh on board to load the new openwifi driver. wgd.sh also tries to reload FPGA img if system_top.bit.bin presents in the same directory. Find more information in Driver and FPGA dynamic reloading app note.

  Note: If you have symbol or version error while loadng the driver, it could be because the kernel in the SD card image is too old. In this case, you need put the linux kernel image generated by prepare_kernel.sh (check [Update Driver]) to the BOOT partition of SD card. The kernel image file name: adi-linux/arch/arm/boot/uImage (32bit); adi-linux-64/arch/arm64/boot/Image (64bit).

Update sdrctl

• Copy the sdrctl source files to the board via ssh channel

  cd openwifi/user_space/sdrctl_src; scp `find ./ -name \*` [email protected]:openwifi/sdrctl_src/
  

• Compile the sdrctl on board:

  cd ~/openwifi/sdrctl_src/ && make clean && make && cp sdrctl ../ && cd ..
  

Easy Access and etc

• Check Driver and FPGA dynamic reloading app note for more convenient way of updating FPGA and driver files without rebooting/power-cycle.
• FPGA and driver on board update scripts
  • Setup ftp server on PC, allow anonymous and change ftp root directory to the openwifi directory.
  • On board:

  ./sdcard_boot_update.sh $BOARD_NAME
  (Above command downloads uImage, BOOT.BIN and devicetree.dtb, then copy them into boot partition. Remember to power cycle)
  ./wgd.sh remote
  (Above command downloads driver files, and brings up sdr0)
  

• Access the board disk/rootfs like a disk:
  • On PC: "File manager --> Connect to Server...", input: sftp://[email protected]/root
  • Input password "openwifi"

Build openwifi Linux img from scratch

• For the latest ADI Kuiper image, please check kuiper.md

Special note for 11b

Openwifi only applies OFDM as its modulation scheme and as a result, it is not backward compatible with 802.11b clients or modes of operation. This is usually the case during beacon transmission, connection establishment, and robust communication.

As a solution to this problem, openwifi can be fully controlled only if communicating with APs/clients instantiated using hostapd/wpa_supplicant userspace programs respectively.

For hostapd program, 802.11b rates can be suppressed using configuration commands (i.e. supported_rates, basic_rates) and an example configuration file is provided (i.e. hostapd-openwifi.conf). One small caveat to this one comes from fullMAC Wi-Fi cards as they must implement the NL80211_TXRATE_LEGACY NetLink handler at the device driver level.

On the other hand, the wpa_supplicant program on the client side (commercial Wi-Fi dongle/board) cannot suppress 802.11b rates out of the box in 2.4GHz band, so there will be an issue when connecting openwifi (OFDM only). A patched wpa_supplicant should be used at the client side.

sudo apt-get install libssl1.0-dev
cd openwifi/user_space; ./build_wpa_supplicant_wo11b.sh

Porting guide

This section explains the porting work by showing the differences between openwifi and Analog Devices reference design. openwifi is based on 2021_r1 of HDL Reference Designs.

• Open the fmcomms2 + zc706 reference design at hdl/projects/fmcomms2/zc706 (Please read Analog Devices help)
• Open the openwifi design zc706_fmcs2 at openwifi-hw/boards/zc706_fmcs2 (Please read openwifi-hw repository)
• "Open Block Design", you will see the differences between openwifi and the reference design. Both in "diagram" and in "Address Editor".
• The address/interrupts of FPGA blocks hooked to the ARM bus should be put/aligned to the devicetree file openwifi/kernel_boot/boards/zc706_fmcs2/devicetree.dts. Linux will parse the devicetree.dtb when booting to know information of attached device (FPGA blocks in our case).
• We use dtc command to get devicetree.dts converted from devicetree.dtb in Analog Devices Linux image, then do modification according to what we have added/modified to the reference design.
• Please learn the script in [Build openwifi Linux img from scratch] to understand how we generate devicetree.dtb, BOOT.BIN, Linux kernel and put them together to build the full SD card image.

License

This project is available as open source under the terms of the AGPL 3.0 Or later. However, some elements are being licensed under GPL 2-0 or later and BSD 3 license . For accurate information, please check individual files.