Next-Generation CamCom

PI: Michael Tsai (National Taiwan University), CoPI: Kate Lin (Natioanal Chiao Tung University)

Champion: Richard Roberts (Intel)

Project Objective:
      In the past one and a half years, the Next-Generation Camera Communications (CamCom) project has made some exciting progress. Through the development of several experimental prototypes, in the first year we have built confidence that the polarization of light can indeed be utilized to carry digital information and facilitate positioning, effectively addressing several unsolved issues in prior arts – most notably, the short operation range of a CamCom system that is usually only a few meters. Specifically, all prior arts need to use small exposure duration for the receiving camera to clearly observe the high-frequency signal, which is required to eliminate flickers. However, the small exposure duration also limits the received power over long range and constitutes to the short operation range problem.

    The experimental results from the prototyping effort of Polarization-RGB MIMO has shown great promise that, as we expected, the combination of linear polarizer and optical rotatory disperser can indeed create transmissions that do not generate visible flickers to human eyes even when low frequency component exists in the transmitted waveform, while the color image sensor at the receiver can be fully leveraged to boost the system throughput. Our novel polarization intensity modulation allows the service range of the system to reach 40 meters, a significant improvement over any state-of-the-art. Although currently the system throughput is only in the range of tens of bytes (70 Byte/s in our latest result), we are confident that through further development we will be able to optimize the developed techniques and improve the throughput. We also intend to investigate suitable use cases which can utilize the developed techniques in the indoor and outdoor, automotive contexts.

We also had some positive results in developing the techniques to identify a certain object with a polarized marker (similar to the concept of a RFID tag, but using optical signal). Such a tag emits light with varying polarization waveform, which corresponds to the ID of the object. The camera observing such a tag would be able to detect and recognize the object comparing the received waveform with several known waveforms. Our latest results have demonstrated that a small 3.6cm x 3.6cm marker can still be reliably detected with some camera movements. Most previous works produce unreliable results as they make use of either a simple thresholding scheme or complex computer vision techniques. We are hoping that this work leads way to a more computational efficient method, and can perform reliably even at long distance and with low resolution images. In the next few quarters, we aim to further reduce the computational complexity of the detection algorithm, such that it can be applied in real-time applications. We also intend to investigate the environment’s impact on the transmitted polarized signal, such as surface reflection, refraction caused by objects, and interference from complex scenes with lots of artificial light sources.

The project has attracted high level of interest from the industry. Delta Electronics have expressed intention in spinning off a new indoor visible light positioning project in 2017, based on some fundamental technology developed in this project and its predecessor (the first 5-year project in the original Intel-NTU Connected Computing Center. The project team also continues the effort in standardizing its Rolling Shutter – Frequency Shift Keying (RS-FSK) camera communication waveform (developed in the predecessor project) in the IEEE 802.15.7m standard committee, with the goal of generating wider impact in future commercial products. Furthermore, the team has also been communicating with several Taiwan-based LED or lighting equipment manufacturers to seek further collaboration opportunities in the near future. (updated in Feb, 2017)