C 3 -LPWA: Chirp-Coded Coherent LPWA

We present C3-LPWA, a coherent Low-Power-Wide-Area (LPWA) physical layer that embeds a continuous sequence of pseudo-random up- and down-chirp pilots alongside π/2-BPSK data symbols. These embedded chirp pilots provide synchronization and channel estimation, and also serve as a unique device signature. This design enables coherent detection and multi-user uplinks at extremely low signal levels. Simulations demonstrate that C3-LPWA achieves BERs around 10−5at SNRs down to −20 dB in AWGN, corresponding to an RF sensitivity on the order of −142 dBm in a 64 kHz channel (with 4 dB noise figure (NF)). Under more challenging fading channels with device speeds of 5 km/h and 100 km/h, a strong LDPC code (rate-1/2) with 4× repetition reliably achieves BER 10−5at SNR −10 to −12 dB with 384 ms airtime for 192 information bits. Doubling the repetition factor to 8× doubles the frame airtime to 768 ms, while extending coverage by approximately 2–4 dB (operating at −12 to −14 dB SNR). Overall, C3-LPWA offers a link budget on par with NB-IoT and ELTRES, despite using only 64 kHz bandwidth and moderate airtime. C3-LPWA’s waveform uniquely leverages continuous chirp pilots for fine synchronization and channel tracking, enabling long-range, mobile IoT communications at low SNR without any external timing or scheduling coordination.