PRACH Preamble Design for 6G Wireless Systems

Motivated by cutting-edge applications such as the massive Internet of Things, next-generation wireless networks are expected to accommodate millions of devices per square kilometer. Such massive access places rigorous demands on the design of physical random access channel preambles, which are required to possess high capacity, Doppler robustness, and ideal correlation properties. However, existing sequences that meet these criteria are usually hindered by prohibitive detection complexity. To tackle this challenge, a Kronecker-product structured (KPS) sequence is proposed that naturally embeds a multi-segment structure, enabling the low-complexity detection. Furthermore, a two-stage low-complexity detection algorithm is proposed, which decouples inner and outer correlations and simplifies the Doppler compensation process in order to substantially reduce the computational overhead. Simulation results demonstrate that employing KPS sequences with the proposed detection algorithm achieves accurate detection while maintaining low overhead.