  In this paper, we propose a new downlink non-orthogonal multiuser
superposition transmission scheme for future 5G cellular networks, which we
refer to as the lattice partition multiple access (LPMA). In this proposed
design, the base station transmits multilevel lattice codes for multiple users.
Each user's code level corresponds to a distinct prime and is weighted by a
product of all distinct primes of the other users excluding its own. Due to the
structural property of lattice codes, each user can cancel out the interference
from the other code levels by using the modulo lattice operation in a
successive/parallel manner. LPMA can overcome the drawback of non-orthogonal
multiple access (NOMA), which arises when users have similar channel
conditions. We demonstrate that the proposed LPMA shows a clear throughput
enhancement over the current NOMA scheme.
