A Unified Block Signal Processing Framework for LPWAN: Sequence Index Modulation Spreading

Low-power wide-area networks (LPWAN) demand high sensitivity and efficient signal processing at the physical layer. This paper proposes a unified framework for generalized block signal transmission in LPWAN systems, addressing the limitations of conventional symbol-by-symbol approaches. The framework is built around three core components: the signal block vector, intra-block structure generator, and signal basis matrix. It establishes a conceptual basis for block synchronization and introduces a unified demodulation structure based on block correlation matching. The framework also provides a systematic method for flexible implementations, demonstrated through its application to existing LPWAN technologies such as frequency shift keying (FSK) and chirp spread spectrum (CSS). This work allows for more scalable and efficient physical layer design in next-generation LPWAN systems.