Demonstration of a 2.34 Gbit/s Real-Time Single Silicon-Substrate Blue LED-Based Underwater VLC System

Abstract

We develop a real-time discrete multi-tone (DMT) transceiver based on field programmable gate array (FPGA) chips for a single chip silicon-substrate light-emitting diode (LED) based underwater visible light communication (UVLC). On-chip resource usages are analyzed and discussed. To improve bit error rate (BER) performance, a novel channel estimation technique utilizing hybrid inter-symbol frequency-averaging (Inter-SFA) and intrasymbol frequency-averaging (Intra-SFA) is proposed and investigated. The real-time DMT transceiver is experimentally verified in a silicon substrate blue LED-based UVLC system with a 1.2 m underwater link. By using the enhanced channel estimation, a gross bit rate of 2.34 Gbit/s real-time DMT signal over 1.2 m underwater transmission can be achieved with the BER of 3.5 × 10 −3. What's more, multiple-symbol interleaved Reed-Solomon (RS) codes are employed to further improve BER performance. The real-time measured post-FEC BER of the DMT-UVLC with multiple-symbol interleaved RS (255, 191) codes can be improved by more than six orders of magnitude. As a result, error-free (less than 1 × 10 −9) transmission is observed in our real-time experiment. Furthermore, 1.485 Gbit/s 720p high-definition video underwater transmission is successfully demonstrated. To the best of our knowledge, it is the first time to demonstrate a real-time LED-based UVLC system with DMT modulation beyond Gbit/s.

Visible‐Light Laser Diodes and Superluminescent Diodes: Characteristics and Applications

“…In highly turbid water, however, it was shown using VCSELs that the use of red light is more practical, due to the lower attenuation in these environments [61]. The use of visible-light LEDs is also possible, but they cannot offer the broad bandwidth of laser diodes [62][63][64]. While SLDs in underwater communication is also possible, laser diodes are preferred in any scenario in which simultaneous illumination is not needed due to their higher speed and optical power.…”

50 m/187.5 Mbit/s real-time underwater wireless optical communication based on optical superimposition

“…In 2019, a 50 Mbit/s UWOC system with a 16-QAM scheme based on FPGA was presented over an underwater distance of 3 m [15] . In 2020, a real-time LED-based UWOC system with DMT modulation was demonstrated, and a gross bit rate of 2.34 Gbit/s over 1.2 m underwater transmission can be achieved [16] . In the same year, a real-time, full-duplex, pointto-point UWOC system based on FPGA was designed, successfully achieving a 10 m underwater video transmission at a data rate of 1 Mbit/s [17] .…”

“…Spatial summing is effective in improving the performance, which has been widely used in the visible light communication (VLC) system to mitigate the nonlinear effect. [12] LD/APD 60 (tap water) / / 2.5 Gbit/s OOK AWG/OSC 2019 [5] LD/APD 56 (tap water) 0.0876 m −1 4.9056 3.31 Gbit/s QAM AWG/OSC 2020 [13] LD/MPPC 100 (pool water) 0.24 m −1 24 8.4 Mbit/s OOK AWG/OSC 2020 [6] LD/PMT 100 (pool water) 0.0585 m −1 5.85 200 Mbit/s OOK AWG/OSC 2021 [7] LD/PMT 150 (pool water) 0.053 m −1 8.775 500 Mbit/s PAM AWG/OSC 2021 [8] LD/PMT 200 (pool water) 0.0325 m −1 6.5 500 Mbit/s PAM AWG/OSC 2021 [9] LD/PMT 100.6 (tap water) 0.0658 m −1 6.6195 3 Gbit/s OOK AWG/OSC 2022 [10] LD/PMT 5 (turbid water) / / 10 Mbit/s PPM FPGA 2016 [14] LD/PIN 3 (artificial seawater) 0.481 m −1 1.443 50 Mbit/s QAM FPGA 2019 [15] LED/PIN 1.2 (tap water) / / 2.34 Gbit/s DMT FPGA 2020 [16] LED/APD 10 (tap water) 0.056 m −1 0.56 1 Mbit/s FSK FPGA 2020 [17] LD/APD 3.6 (tap water) / / 2.2 Gbit/s OFDM FPGA 2020 [18] LD/SPAD 2 (tap water) / / 6.21 Mbit/s PPM FPGA 2021 [11] LD/PMT 50 (pool water) 0.1307 m −1 In 2013, a VLC transmitter employing discrete power level stepping was proposed to address the nonlinearity, restricted dynamic range, and complex system designs of the conventional optical transmitters [22] . In 2017, a highly compact array of micro-LED pixels was proposed to generate a discrete optical signal, which achieved a data rate up to 200 Mbit/s [23] .…”

Ambient Light Effect on Receiver for Visible Light Communication Systems

“…In another paper that is used OFDM system, authors have been achieved data rate of 1.84Gbit/s for the future heterogeneous in-house network [16]. The authors of [17] have been further developed the data rate of VLC links to implement on underwater communication systems. The data rate of improved FPGA-based system that has BER performance of 3.5x10 -3 reaches to 2.34Gbit/s over transmission distance of 2.5m.…”