A Low-Complexity Energy-Minimization-Based SCMA Detector and Its Convergence Analysis

Abstract

Sparse code multiple access (SCMA) has emerged as a promising non-orthogonal multiple access technique for the next-generation wireless communication systems. Since the signal of multiple users is mapped to the same resources in SCMA, its detection imposes a higher complexity than that of the orthogonal schemes, where each resource slot is dedicated to a single user. In this paper, we propose a low-complexity receiver for SCMA systems based on the radical variational free energy framework. By exploiting the pairwise structure of the likelihood function, the Bethe approximation is utilized for estimating the data symbols. The complexity of the proposed algorithm only increases linearly with the number of users, which is much lower than that of the maximum a posteriori detector associated with exponentially increased complexity. Furthermore, the convergence of the proposed algorithm is analyzed, and its convergence conditions are derived. Simulation results demonstrate that the proposed receiver is capable of approaching the error probability performance of the conventional message-passing-based receiver.

Investigating High Performance Implementations of Sparse Code Multiple Access (SCMA) Codebook Design

“…The goal of this research is to use a low-complexity energy-minimization-based SCMA detector to achieve the error probability performance of a traditional message-passing-based receiver [41].…”

Sparse Code Multiple Access: Potentials and Challenges

“…Bethe approximation based message passing detection algorithms were proposed for massive MIMO systems [137] and SCMA systems [138], [139]. The idea is to avoid the highcomplexity direct marginalization of the posterior probability of users' symbols by finding its appropriate trail distribution which is approximated by minimizing Bethe free energy.…”

Iterative Joint Channel Estimation, User Activity Tracking, and Data Detection for FTN-NOMA Systems Supporting Random Access

“…It is widely recognized that the optimal receiver's complexity grows exponentially both with the number of ISI taps and with the number of users. Hence, several authors have developed low complexity receivers for FTN signaling [21]- [24] and NOMA [25]- [30]. To elaborate, in [21], an Malgorithm based Bahl-Cocke-Jelinek-Raviv (BCJR) detector was proposed by Prlja and Anderson for eliminating the ISI imposed by FTN signaling.…”

“…Then, by exploiting the 'convexified' variational free energy, the authors of [29] proposed a guaranteed-convergence-MPA receiver for MIMO-NOMA systems. In [30], an energy minimization based detector relying on 'potential-cliques' factorization was proposed and the algorithm's convergence behaviors was analyzed. Despite this research-momentum, there is no literature considering the receiver design problem of the proposed systems.…”