Network Protocol Programming Lab (PPL)

Hardware

• Beagleboard Black
• CC1200

Links

• Begleboard getting-started
• Begleboard Linux
• TKN Wiki
• User’s Guide of the CC1200
• Overleaf

Systemd services (cc1200d and 4C)

• Copy the ./docs/*.service files to /etc/systemd/system/.
• Extract ./archives/* to /srv/.
  • /srv/cc1200d/cc1200d needs to be executable
  • /usr/bin/node /srv/CC1200-Control-Center/4C.js needs to be executable
  • in /srv/CC1200-Control-Center/4C.js change BeagleBone to 127.0.0.1
  • in /srv/CC1200-Control-Center/4C.js at the end change the port of the webapp accordingly
• sudo systemctl daemon-reload
• sudo systemctl enable <name>.service
• sudo systemctl start <name>.service or sudo reboot

Building

• Use the script fake for that: https://github.com/bchmnn/fake
• The resulting executable will be ./target/target

Building - Cross compiling

Setup - Toolchain

• Install ninja
• Download toolchain from: https://releases.linaro.org/components/toolchain/binaries/
• Select a version (latest-7 worked for me)
• Download, extract, copy to desired location, add to path
• Let vscode generate c_cpp_properties.json for you and then change "configurations"."compilerPath" to the gcc version of the linaro toolchain
• Also change cStandard in c_cpp_properties.json to gnu99
• On windows do not set cppStandard in c_cpp_properties.json as it breaks the CMake generation process
• The .vscode/settings.json should look like this:

  "cmake.preferredGenerators": ["Ninja"],
  "cmake.configureArgs": ["-DCMAKE_SYSTEM_NAME=Generic"],
  "cmake.parallelJobs": 8,
  "cmake.buildDirectory": "${workspaceFolder}/target"

Setup - Fake

• Create a file in the repositories root folder:
  • Windows: fake.conf.ps1
  • Unix: fake.conf.sh
• This file will be sourced by the fake script
• Use this file to set some environment variables (ps1):

  # ps1 version (unix analog)
  $env:CC=(which arm-linux-gnueabihf-gcc)
  $FAKE_CMAKE_FLAGS='-D CMAKE_SYSTEM_NAME=Generic -G "Ninja"'
  $FAKE_EXEC_HOST="beagle1"

• If the SSH banner is annoying you:
  • sudo vim /etc/ssh/sshd_config: comment out the banner line
  • sudo service sshd reload

Protocol

=================Definitions=================
Actors:
  1 - sender/receiver
  2 - sender/receiver
  3 - interrupter
---------------------------------------------
Stages:
  1 - HANDSHAKE (CONNECT)
  2 - CHAT
  3 - INTERRUPTED
  4 - RECONNECT
---------------------------------------------
Message:
  - max size: 255 bytes
  - format: <len><type:uint8><msg><checksum>
  - checksum for type+msg
  - types:
    - 0: handshake
    - 1: handshake-ack: <msg> = rssi
    - 2: chat: <msg> = text
    - 3: chat-ack:  <msg> = rssi
    - 4: i'm here
    - 5: i'm here-ack: <msg> = rssi
    - 6: ciao!
==================Protocol===================
1. HANDSHAKE (CONNECT)
  - predefined meeting frequency: 920 hz
  - 1 and 2 handshake:
    - 2 answers with RSSI (Ack)
    - RSSI in Ack is used as SEED
    - (opt: keep key exchange in ming for crypto)
2. CHAT
  - receive message:
    - Check Message:
      - if rssi >> average rssi (SEED) than swtich stage to INTERRUPTED
      - else if Message == <ciao> than swtich stage to DISCONNECT
      - else store Message in buffer transmist chat-ack
    - switch to Transmit
  - transmit massage:
      - check if Massage to transmiting
        - send Massage:
          - wait for massage ack
            - if timeout than Send Massage again or check Rssi
            - else do stuff,(Ciao or interrupt )
      - switch to receive message
3. INTERRUPTED
  - 1/2 meassure high CRC and low RSSI
    - channel is corrupt
    - reduce symbol rate
    - if problem persists reduce further or
      switch to other frequency
  - 1/2 meassure high RSSI
    - possibility of 3 - interrupter
    - switch frequency acording to SEED
4. RECONNECT
  - 1 loops: send "i'm here", listen for ACK
    -> 1 goes into chatting listen mode
  - 2 loop: listen "i'm here" -> on receive: send ACK
    -> 2 goes into chatting listen mode
    -> if recv "i'm here" -> resend ACK
5. DISCONNECT
  - free buffer
  - preparation for new connection request
  - switch to handshake mode 

Notes

• google for: packet discrimination / ursache paket fehler

Links:

• Wiki: Interference
• Satcom RFI Recognition&Classification
• RFI Classification

Vocabulary

• RSSI/SNR - Signal to noice ratio
• SIR - Signal to interference ratio
• Symbolrate - Symbols per second
• Bitrate - Bits per second