Visible light communications(VLC)is considered as an effective supplement technology for next-generation(6G)communications due to its abundant spectrum,high power efficiency and easy deployment.Optical orthogonal freq...Visible light communications(VLC)is considered as an effective supplement technology for next-generation(6G)communications due to its abundant spectrum,high power efficiency and easy deployment.Optical orthogonal frequency division multiplexing(O-OFDM)is a common technology to obtain further promotion.In this paper,two typical O-OFDM schemes direct current biased O-OFDM(DCO-OFDM)and asymmetrically clipped O-OFDM(ACO-OFDM)are analyzed in terms of signal clipping at both transmitter and receiver under the constraints of maximum optical power and non-negative optical power.And effective electrical SNR models after signal clipping are proposed and verified by link simulation.Then a noise cancellation scheme is proposed based on received signal clipping and is proved to bring a significant gain for ACO-OFDM.By system simulation,we find that under a certain optical power limitation,most users can achieve above 4 Gbps in indoor scenario when modulation bandwidth of the light emit diode(LED)or laser diode(LD)is 1 GHz.Therefore,it can be expected that the throughput could reach tens Gbps when the LED/LD modulation bandwidth is increased and multiple LEDs/LDs are deployed.展开更多
In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8...In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8/QPSK-OFDM signal for uplink transmission is successfully proposed and experimentally presented in a full-duplex PON based on OFDM system. Here, for the uplink, in order to unit management of the optical line terminal (OLT) and reduce cost, the optical source functioned as the optical subcarrier at optical network units (ONUs) is from OLT in the central station. Moreover, there is an external cavity laser (ECL) with center frequency of 193.2 THz not only employed as optical modulated signal but also acted as LO signal. Our simulation results show that bit error ratio (BER) under hardware detection forward error correction has been successfully gained after 20 km of SSMF transmission. It is observed that the receiver sensitivity of multilevel PSK (M-PSK) is obviously larger than that of the M-QAM in this measurement scheme.展开更多
文摘Visible light communications(VLC)is considered as an effective supplement technology for next-generation(6G)communications due to its abundant spectrum,high power efficiency and easy deployment.Optical orthogonal frequency division multiplexing(O-OFDM)is a common technology to obtain further promotion.In this paper,two typical O-OFDM schemes direct current biased O-OFDM(DCO-OFDM)and asymmetrically clipped O-OFDM(ACO-OFDM)are analyzed in terms of signal clipping at both transmitter and receiver under the constraints of maximum optical power and non-negative optical power.And effective electrical SNR models after signal clipping are proposed and verified by link simulation.Then a noise cancellation scheme is proposed based on received signal clipping and is proved to bring a significant gain for ACO-OFDM.By system simulation,we find that under a certain optical power limitation,most users can achieve above 4 Gbps in indoor scenario when modulation bandwidth of the light emit diode(LED)or laser diode(LD)is 1 GHz.Therefore,it can be expected that the throughput could reach tens Gbps when the LED/LD modulation bandwidth is increased and multiple LEDs/LDs are deployed.
文摘In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8/QPSK-OFDM signal for uplink transmission is successfully proposed and experimentally presented in a full-duplex PON based on OFDM system. Here, for the uplink, in order to unit management of the optical line terminal (OLT) and reduce cost, the optical source functioned as the optical subcarrier at optical network units (ONUs) is from OLT in the central station. Moreover, there is an external cavity laser (ECL) with center frequency of 193.2 THz not only employed as optical modulated signal but also acted as LO signal. Our simulation results show that bit error ratio (BER) under hardware detection forward error correction has been successfully gained after 20 km of SSMF transmission. It is observed that the receiver sensitivity of multilevel PSK (M-PSK) is obviously larger than that of the M-QAM in this measurement scheme.
