  This paper studies advanced multi-access techniques to support high volumes
of concurrent access in wireless networks. Sparse code multiple access (SCMA),
as a code-domain Non-Orthogonal Multiple Access (NOMA), serves multiple users
simultaneously by adopting frequency-domain coding. Blind Interference
Alignment, in contrast, applies time-domain coding to accommodate multiple
users. Unlike beamforming, both of them need no Channel State Information at
the Transmitter (CSIT), which saves control overheads on channel information
feedback. To further increase multiplexing gain and diversity order, we propose
a new multiple access framework, which utilizes both time and frequency coding
by combining SCMA and BIA, which is CIAMA (sparseCode-and-bIA-based multiple
access). Two decoding schemes, namely the two-stage decoding scheme consisting
of zero-forcing and Message Passing Algorithm (MPA), and the Joint Message
Passing Algorithm (JMPA) enhanced by constructing a virtual factor graph, have
been analyzed. Simulation results indicate that although the performance of the
two-stage decoding scheme is inferior to both BIA and SCMA, it has a relatively
low decoding complexity. Nonetheless, the JMPA decoding scheme achieves the
same diversity gain as an STBC-based SCMA and with an even higher multiplexing
gain, which makes the CIAMA with JMPA decoding scheme a promising MA scheme for
next-gen wireless networks.
