A generalized FSK-based PHY layer design for wireless sensor networks

A generalized FSK modulation employing FSK, PPM and APSK modulation alphabets is considered. The modulation combines a traditional APSK alphabet extended with a zero-symbol and the multiple-access. Analysis of the power spectral density (PSD) reveals that the bandwidth is significantly expanded whenever the transmission is periodically turned on and off. The overall probability of bit error and the overall data rate for multiple parallel generalized FSK transmissions are compared in single-user and multiuser scenarios. A rate-one repetition diversity scheme for real-valued transmitted signals is proposed to overcome the time and frequency correlations of communication channels between nodes. The overall energy consumption is shown to be reduced with the FSK modulation order, and by using multiple parallel FSK transmissions.