I/Q-Modulated Sparse Vector Coding for Short-Packet Communications

Sparse vector coding (SVC), akin to compressed sensing, has gained broad interest in short-packet communications due to its simplicity and reliability. To further enhance its transmission performance, this work proposes a novel SVC scheme based on in-phase (I) and quadrature-phase (Q) modulations (IQ-SVC). The core idea involves simultaneously mapping transmitted bits into corresponding I and Q vectors. A vector shifting operation is then applied to ensure conflict-free combination of the I/Q vectors, enabling the construction of shorter sparse vectors to transmit a given number of bits. Performance analysis confirms the superiority of IQ-SVC scheme in sparse mapping. Simulation results demonstrate that the proposed scheme can achieve the best block error rate (BLER) performance compared to existing SVC schemes. Notably, its BLER advantage becomes increasingly prominent at higher coding rates.