Fig. 1. Schematic diagram of multi-wavelength group-based fault detection scheme in PON system

Fig. 2. PON system user distribution diagram and detection signal reception results. (a) Schematic diagram of distribution model; (b) arrival delay of single-wavelength detection signal; (c) arrival delay of multi-wavelength detection signal

Fig. 3. Probability of interference under different wavelengths and number of ONU meets interference conditions. (a) Random grouping; (b) multi-wavelength grouping

Fig. 4. Simulation results of SNR under different detection pulse widths. (a) Relationship between noise component and detection pulse width; (b) relationship between SNR and pulse width

Fig. 5. Simulation results of SNR. (a) Relationship between SNR and detection pulse power; (b) relationship between SNR and the number of ONUs

Fig. 6. Simulation results of SIR. (a) Impact of number of ONUs on SIR; (b) impact of pulse width on SIR

Fig. 7. Simulation of multi-wavelength group-based PON monitoring system. (a) Pulse signal response at the receiver end; (b) detection accuracy for ONU₂