Embodiments of the invention include a universal apparatus for incorporating intelligence into the distribution frame of an optical communication system. The user interface can be associated with a smart light fixture or other component mounted in the parking structure. However, due to the cepstral transform, the temporal smoothing is done in the logarithmic domain rather than the linear domain, and hence results in a certain bias. A second circulating part has first through fourth ports configured to output an optical signal, which is input to a higher-order port thereof, from a lower-order port thereof arranged adjacent to the higher-order port.