Graph Signal Inference by Learning Narrowband Spectral Kernels
This work addresses the challenge of modeling complex graph signal spectra for researchers in graph signal processing, though it is incremental as it builds on existing smoothness and band-limited assumptions.
The authors tackled the problem of graph signal inference when the signal spectrum is concentrated at multiple frequency regions, by proposing a model that combines narrowband spectral kernels and jointly learning kernel parameters and signal coefficients from a collection of signals. The method achieved satisfactory signal interpolation accuracy compared to various reference approaches in experiments on several graph datasets.
While a common assumption in graph signal analysis is the smoothness of the signals or the band-limitedness of their spectrum, in many instances the spectrum of real graph data may be concentrated at multiple regions of the spectrum, possibly including mid-to-high-frequency components. In this work, we propose a novel graph signal model where the signal spectrum is represented through the combination of narrowband kernels in the graph frequency domain. We then present an algorithm that jointly learns the model by optimizing the kernel parameters and the signal representation coefficients from a collection of graph signals. Our problem formulation has the flexibility of permitting the incorporation of signals possibly acquired on different graphs into the learning algorithm. We then theoretically study the signal reconstruction performance of the proposed method, by also elaborating on when joint learning on multiple graphs is preferable to learning an individual model on each graph. Experimental results on several graph data sets shows that the proposed method offers quite satisfactory signal interpolation accuracy in comparison with a variety of reference approaches in the literature.