Sparse complex FxLMS for active noise cancellation over spatial regions

In this paper, we investigate active noise control over large 2D spatial regions when the noise source is sparsely distributed. The l1 relaxation technique originated from compressive sensing is adopted and based on that we develop the algorithm for two cases: multipoint noise cancellation and wave domain noise cancellation. This results in two new variants (i) zero-attracting multi-point complex FxLMS and (ii) zero-attracting wave domain complex FxLMS. Both approaches use a feedback control system, where a microphone array is distributed over the boundary of the control region to measure the residual noise signals and a loudspeaker array is placed outside the microphone array to generate the anti-noise signals. Simulation results demonstrate the performance and advantages of the proposed methods in terms of convergence rate and spatial noise reduction levels.This work is supported by Australian Research Council (ARC) Discovery Projects funding scheme (project no. DP140103412). The work of J. Zhang was sponsored by the China Scholarship Council with the Australian National University

Improved performance robustness of DSP-enabled flexible ROADMs free from optical filters and O-E-O conversions

Utilizing Hilbert-pair-based digital filtering, intensity modulation, and passive optical coupling, digital signal processing (DSP) enabled flexible reconfigurable optical add/drop multiplexers (ROADMs) are reported, which are free from optical filters and optical-electrical-optical (O-E-O) conversions and offer excellent flexibility, color-lessness, gridlessness, contentionlessness, adaptability, and transparency to physical-layer network characteristics. In this paper, the ROADM performance robustness against variations in numerous network design aspects is, for the first time to the best of our knowledge, extensively explored in intensity-modulation- and direct-detection-based optical network nodes. Numerical results show that DSPs not only enable the ROADMs to dynamically and flexibly perform add/drop operations at wavelength, subwavelength, and spectrally overlapped orthogonal subband levels but also considerably improve the ROADM performance robustness against variations in modulation formats, transmission system characteristics/impairments, and terminal equipment configurations