Patent ID: 9735991
Date: 2017-08-15
CPC Classifications: H04B,H04J,H04L

Claim:
1. A method for autonomously determining the modulation format of an optical signal from among 16QAM, BPSK, OPSK, and OOK, the method comprising: receiving an optical signal having a modulation format selected from the group consisting of 16QAM, BPSK, OPSK, and OOK; converting the optical signal into an input signal; mapping the input signal to Stokes space to generate a three-dimensional representation of the input signal, wherein the three-dimensional representation comprises a particular number of three-dimensional clusters, and wherein each of the particular number of three-dimensional clusters comprises a weight; modeling a probabilistic weight distribution of at least each of the particular number of three-dimensional clusters as a joint Dirichlet distribution to provide a first joint Dirichlet distribution model of the probabilistic weight distribution; applying a Variational Bayesian method to the three-dimensional representation of the input signal to estimate a plurality of concentration parameters of the first joint Dirichlet distribution model of the probabilistic weight, wherein each concentration parameter of the first joint Dirichlet distribution model of the probabilistic weight distribution is a proxy for the weight of each of the particular number of three-dimensional clusters; defining a cost function based on the plurality of estimated concentration parameters; evaluating the cost function over a range of considered number of three-dimensional clusters values to generate a plurality of confidence values, wherein each confidence value corresponds to a particular considered number of three-dimensional clusters value, wherein a considered number of three-dimensional clusters value is a potential value of the particular number of three-dimensional clusters, and wherein a particular confidence value quantifies the confidence of having a corresponding considered number of three-dimensional clusters value equal the particular number of three-dimensional clusters; selecting the considered number of three-dimensional clusters value corresponding to the highest confidence value as representative of the particular number of three-dimensional clusters; responsive to determining the selected considered number of three-dimensional clusters value is above a predetermined value, wherein the predetermined value partitions modulation formats into exclusive sets comprising at least one predetermined modulation format, selecting a modulation format from a first exclusive set that comprises 16QAM; responsive to determining the selected considered number of three-dimensional clusters value is below a predetermined value, selecting a modulation format from a second exclusive set that comprises BPSK, OPSK, and OOK, wherein selecting a modulation format from a second exclusive set comprises: