Modern mobile terminals often produce a large number of small data packets.
For these packets, it is inefficient to follow the conventional medium access
control protocols because of poor utilization of service resources. We propose
a novel multiple access scheme that employs block-spreading based precoding at
the transmitters and sparsity-aware detection schemes at the base station. The
proposed scheme is well suited for the emerging massive multiple-input
multiple-output (MIMO) systems, as well as conventional cellular systems with a
small number of base-station antennas. The transmitters employ precoding in
time domain to enable the simultaneous transmissions of many users, which could
be even more than the number of receive antennas at the base station. The
system is modeled as a linear system of equations with block-sparse unknowns.
We first adopt the block orthogonal matching pursuit (BOMP) algorithm to
recover the transmitted signals. We then develop an improved algorithm, named
interference cancellation BOMP (ICBOMP), which takes advantage of error
correction and detection coding to perform perfect interference cancellation
during each iteration of BOMP algorithm. Conditions for guaranteed data
recovery are identified. The simulation results demonstrate that the proposed
scheme can accommodate more simultaneous transmissions than conventional
schemes in typical small-packet transmission scenarios.Comment: submitted to IEEE Transactions on Wireless Communication
