To set threshold for multi-user signals overlapping with similar distance in two-dimensional optical coding access network link monitoring system

a link state recognition algorithm based on signal correlation is proposed. By analyzing the correlation between the normal signal and the detected signal

the link state is determined according to the self-defined correlation coefficient with compensation and the coding rules of the system. The simulation results show that the proposed algorithm can solve the problem of multi-link reflected signals overlapping with equal distance or similar distance. A 32-user experimental system with 3 equal-distance links is built. When one of the 3 equal-distance links is disconnected

the correlation coefficient is 0.626 1; when two of the 3 equal-distance links are disconnected

the correlation coefficients are 0.342 1 and 0.386 5

respectively

which are within the threshold interval. The self-defined correlation coefficient can effectively solve the problem of multi-user signals overlapping in the two-dimensional optical coding access network link monitoring system.