@article{CRSIJ26000210,
                  author = {Sagiru Sabiu, Prof. Samuel N. John, Dr. Ahmad A. Ashraf},
                  title = {Evaluation of Adaptive Against Fixed Modulation in Ring-Core Fibre OAM-based SDM/WDM Transmission: A Benchmarking Perspective},
                  journal = {Cosmo Research and Science International Journal},
                  year = {2025},
                  volume = {1},
                  number = {6},
                  pages = {472-483},
                  issn = {3108-1584},
                  url = {https://cosmorsij.com/published/CRSIJ26000210.pdf},
                  abstract = {The exponential increase in data traffic has raised a high demand for ultra-high-capacity optical transmission networks.  Orbital Angular Momentum-based Space and Wavelength Division Multiplexed (OAM-SDM/WDM) optical communication systems serve as a promising strategy for meeting this demand. However, these systems typically adopt fixed modulation formats and coding schemes. This limits their ability to exploit spatial-spectral signal-to-noise ratio (SNR) variations across channels. A study titled “High spectral-efficiency, ultra-low MIMO SDM transmission over a field-deployed multi-core OAM fibre” serves as the architectural benchmark for this study. The benchmark reference deployed a 7-core Ring-Core Fibber system adopting fixed 8-Quadrature Amplitude Modulation and an effective Forward Error Correction rate of approximately 0.83, achieving an aggregate spectral efficiency of 403.2 bits/s/Hz and a throughput of 201.6 Tb/s. This paper presents a systematic spectral efficiency (SE) benchmarking study comparing an adaptive modulation and coding (MODCOD) scheme against a fixed-modulation baseline. The adaptive framework dynamically assigns modulation orders from 8-QAM to 1024-QAM and Forward Error Correction (FEC) code rates from 0.60 to 0.95 per channel based on instantaneous SNR estimates, augmented by probabilistic amplitude shaping. Simulation results demonstrated a peak aggregate spectral efficiency of 550.8 bits/s/Hz per direction and a net bidirectional throughput of 528.8 Tb/s with a post-FEC bit error rate of 1 × 10-¹⁵. The results confirm that per-channel adaptive modulation and coding improves spatial-spectral resource utilization in OAM-SDM/WDM systems without altering the physical fibre infrastructure.},
                  keywords = {Orbital angular momentum, space division multiplexing, wavelength division multiplexing, adaptive modulation and coding, spectral efficiency, throughput },
                  month = {May}
        }