Long-Range OFDM (LR-OFDM): Physical Layer Alternative for LPWAN

Relying on the excellent autocorrelation properties of constant amplitude zero autocorrelation (CAZAC) sequences, the concept of OFDM mega-symbol is introduced by mapping data over an n-time sequence of OFDM symbols based on sequence selection. As a result, a parallel correlations receiver exploits sequence properties to demodulate data over sequence time length providing optimum results in presence of AWGN. Sequence length and associated properties are found to be determining factors for receiver sensitivity improvements in dB when compared to a single OFDM symbol without sequence mapping. Furthermore, various sequence lengths can be selected to obtain target data rates and sensitivity improvements as typical in these systems.