Real-time realization of interference suppression for robust wireless optical communication

A robust short-range wireless optical communication system with direct sequence spread spectrum modulation and additional interference suppression is presented. The real-time system is implemented on a DSP/FPGA development board. The intensity modulation and direct detection system is designed to operate in the wireless optical indoor channel under strong non-Gaussian interference. An interference model with a combination of narrowband and pulsed wide-band components is assumed. Multiple stages of interference suppression based on non-linear signal processing and adaptive filtering are applied. A soft limiter with robust estimation of limiting thresholds is employed. The coefficients of an adaptive transversal filter are computed by means of parametric spectral estimation with Burg´s method. The real-time system is implemented on a rapid prototyping platform using model based design and high level code synthesis. Algorithms, simulation results as well as implementation and final measurements are presented.