2D-OFDM for Optical Camera Communication

OFDM is well-known for LiFi; however, it is still fresh advanced waveform for OCC. This post shares an implementation of 2D-OFDM for Screen-to-Camera communication system in which a massive number of display cells brings a great advantage for communication.

• A full journal version of this topic is available online at IEEE Access.

Video demonstration:

System Features:

• MIMO-OFDM screen-camera
  • MIMO channel with sub-channels consisting of subcarriers for reliable communication.
  • Configurable size of Tx, with OFDM symbols based on experimentally verifying the channel in conjunction with the channel analysis
• The new design of Tx that jointly supports critical functionalities
  • 360-degree rotation support.
  • Asynchronous communication with frame rate variation support.
  • Correction of perspective distortion.
• Complete system architecture and detailed implemental guidance.
  • OFDM symbol creation and Tx post-processing (2D-cyclic prefix insertion and clipping processes).
  • Scaling and DC-bias control.
  • 2D pilots design and channel equalization.
  • PHY frame format PPDU co-existent to 802.15 standards.
  • Effective FEC.
• Comprehensive Rx processing and decoding guidance
  • Specific decoding processes are given based on implemental results, significantly including
  • Spatial downsampling and the correction of perspective distortion,
  • Temporal downsampling to deal with frame rate variation, and
  • Rotation correction

The transmitter design:

• The bolder area: to support the detection and extraction of the code.
• The rotation tracking corners: to determine the rotation.
• Clock cells at the surrounding of the code: to support the Rx determining the proper sampling ratio under the presence of perspectivedistortion.