Lattice Partition Multiple Access: A New Method of Downlink   Non-orthogonal Multiuser Transmissions
  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. 
Dong Fang, Yu-Chih Huang, Zhiguo Ding, Giovanni Geraci, Shin-Lin Shieh   and Holger Claussen
cs.IT math.IT