Research in OFDM-Based High-Speed In-Vehicle Network Connectivity for Cameras and Displays

Growing trends of connected and autonomous vehicles have pushed for increased resolutions of cameras to 8Mpix and displays to 4K/8K, leading to requirements for high-speed interfaces that support 10Gbps and beyond. Unlike data center or enterprise networks which normally operates under controlled indoor environments, in-vehicle networks are required to operate in harsh temperature and interference environments. Due to cost restrictions, the use of single pair wire is prevalent for in-vehicle networks. In general, as data transmission speed increase, signal spectrum spreads across greater frequency range. Since insertion loss of a channel increases in proportion to signal frequency, it becomes more difficult to secure SNR (signal-to-noise ratio) margins as bit rate increases. This makes it increasingly difficult for a device (e.g. ECUs, sensors, and displays) with high-speed communication interface to meet EMC (electromagnetic compatibility) criteria imposed by automotive OEMs. If this is solely addressed through the improvement of wire harnesses, development will become increasingly challenging and costly, and will certainly reach its limit at some point. This paper will introduce the application of OFDM (orthogonal frequency-division multiplexing) for in-vehicle networks. OFDM enables the manipulation of each carrier frequency independently of each other, enhancing spectral efficiency. Bit rate can be improved by taking advantage of the low insertion loss of low-frequency carriers. Further increase in bit rate can be achieved by redistributing the transmission power to low-frequency sub-carriers. This promising method is expected to realize high-speed communication beyond 14Gbps while satisfying EMC requirements without resorting to costly development of cables.