One-Stage SCMA Codebook Design Based on Bit Error Rate Criterion

Designing codebooks for high bit rates and overload ratios is a central goal in SCMA codebook design. Traditional designs mainly focus on specific size of factor graphs. Also, codebooks designed solely based on the minimum euclidean distance criterion do not ensure optimal performance with MPA decoders. This paper introduces a novel one-stage optimization method for SCMA codebook design, prioritizing the bit error rate (BER) of the message passing algorithm (MPA) decoder as the primary optimization criterion. Smaller factor graphs are used to reduce the optimization complexity. By employing a heuristic optimization method, simulation results demonstrate that our method achieves a significant reduction in BER.