WiFO: Hybrid WiFi and Free-Space Optical Communication System with PAM Optimal Decoding

We describe WiFO, a novel communication system that integrates free space optical communication and WiFi technologies to provide an order of magnitude improvement in wireless capacity. To provide high bit rates and large coverage, WiFO employs an array of LED-based transmitters. Each modulates a beam of invisible light using a Pulse Amplitude Modulation (PAM) scheme. A WiFO receiver is capable of receiving signals from multiple transmitters simultaneously. We describe a PAM decoding scheme that estimates the channel parameters, then use them to determine the decoding thresholds for minimizing the bit error rate. Furthermore, we characterize the conditions on channel parameters for perfect signal recovery. Simulations and theoretical analyses are provided to validate the proposed scheme.