Exploiting Simultaneous Low-Rank and Sparsity in Delay-Angular Domain for Millimeter-Wave/Terahertz Wideband Massive Access

Millimeter-wave (mmW)/Terahertz (THz) wideband communication employing a large-scale antenna array is promising technique of the sixth-generation (6G) wireless network for realizing massive machine-type communications (mMTC). To reduce access latency and signaling overhead, we design grant-free random scheme based on joint active device detection channel estimation (JADCE) mmW/THz access. In particular, by exploiting simultaneously sparse low-rank structure channels with spreads in delay-angular domain, propose two multi-rank aware JADCE algorithms via applying quotient geometry product complex rank- $L$ matrices number clusters . It proved that proposed require smaller measurements than currently known bounds conventional recovery algorithms. Statistical analysis also shows can linearly converge to ground truth low computational complexity. Finally, extensive simulation results confirm superiority terms accuracy both activity estimation.