  Massive number of internet of things (IoT) devices are expected to
simultaneously connect to the mMTC and beyond future generations of wireless
network, posing severe challenge to aspects such as RACH procedure, user
equipment detection and channel estimation. Although spatial combining has
provided significant gains in conventional grant-based transmission, this
technique is stuck in dilemma when it comes to autonomous grant-free
transmission tailored for IoT use cases. To address this, blind spatial
combining and its incorporation in the data-only MUD are elaborated in this
paper answering to both the academic and industry's concern in the overloading
potential of autonomous grant-free (AGF) transmission. Blind spatial combining
could be interpreted as blind receive beamforming heuristically. Simulation
results show that the blind spatial combining enhanced data-only MUD
performance for AGF transmission is rather impressive.
