Efficient NOMA Design without Channel Phase Information using
Amplitude-Coherent Detection
Abstract
This paper presents the design and bit error rate (BER) analysis of a
phase-independent non-orthogonal
multiple access (NOMA) system. The proposed NOMA system can utilize
amplitude-coherent detection
(ACD) which requires only the channel amplitude for equalization
purposes. In what follows, three
different designs for realizing the detection of the proposed NOMA are
investigated. One is based on the
maximum likelihood (ML) principle, while the other two are based on
successive interference cancellation
(SIC). Closed-form expressions for the BER of all detectors are derived
and compared with the BER of
the coherent ML detector. The obtained results, which are corroborated
by simulations, demonstrate that,
in most scenarios, the BER is dominated by multiuser interference rather
than the absence of the channel
phase information. Consequently, the BER using ML and ACD are comparable
for various cases of
interest. The paper also shows that the SIC detector is just an
alternative approach to realize the ML
detector, and hence, both detectors provide the same BER performance.