  In non-orthogonal multiple access (NOMA), cell-edge users experience
significantly low spectral density because only some part of the total transmit
power is allocated. This leads to low spectral efficiency for the paired users
in NOMA. To overcome this problem, we propose an integration of NOMA and
generalized space shift keying (GSSK), called NOMA-GSSK, to improve the
spectral efficiency by exploiting the spatial domain. Spectral and energy
efficiency, bit error rate (BER), and computational complexity of the proposed
system were analyzed and compared to those of multiple-input multiple-output
NOMA (MIMO-NOMA). It is shown that NOMA-GSSK outperforms MIMO-NOMA.
