Performance analysis and experimental verification of SPAD receivers without photon counting for optical wireless communications

Single photon avalanche diode (SPAD) attracts increasing interests to realize photon-sensitive receivers for op-tical wireless communications (OWC). In SPAD receivers, the bit information is extracted by photon counting process, which will increase the burden of data processing and storage. To remove complex photon counting process, we propose a scheme of letting recording pulses pass through low-pass finite impulse response (FIR) filter to realize a SPAD receiver without photon counting. Based on the SPAD operation principles, the Monte -Carlo model of SPAD-based OWC system is built and verified with experimental results. Moreover, based on the signal-dependent noise model, a simple and accurate signal estimation and decision algorithm is developed to demodulate the low-pass signal. On this basis, the system error performance under different operation conditions is investigated. The results indicate that utilizing the proposed algorithm, the system error performance is improved 1-to 3-orders of magnitude better than conventional algorithm, which depends on additive Gaussian noise model.