  Modern mobile terminals produce massive small data packets. For these
short-length packets, it is inefficient to follow the current multiple access
schemes to allocate transmission resources due to heavy signaling overhead. We
propose a non-orthogonal many-access scheme that is well suited for the future
communication systems equipped with many receive antennas. The system is
modeled as having a block-sparsity pattern with unknown sparsity level (i.e.,
unknown number of transmitted messages). Block precoding is employed at each
single-antenna transmitter to enable the simultaneous transmissions of many
users. The number of simultaneously served active users is allowed to be even
more than the number of receive antennas. Sparsity-aware recovery is designed
at the receiver for joint user detection and symbol demodulation. To reduce the
effects of channel fading on signal recovery, normalized block orthogonal
matching pursuit (BOMP) algorithm is introduced, and based on its approximate
performance analysis, we develop interference cancellation based BOMP (ICBOMP)
algorithm. The ICBOMP performs error correction and detection in each iteration
of the normalized BOMP. Simulation results demonstrate the effectiveness of the
proposed scheme in small packet services, as well as the advantages of ICBOMP
in improving signal recovery accuracy and reducing computational cost.
