Gangle Sun Mengyao Cao Wenjin Wang 0001 Wei Xu 0001 Christoph Studer Joint Active User Detection, Channel Estimation, and Data Detection for Massive Grant-Free Transmission in Cell-Free Systems. 406-410 2023 SPAWC https://doi.org/10.1109/SPAWC53906.2023.10304473 conf/spawc/2023 db/conf/spawc/spawc2023.html#SunCWXS23