Adaptive Handover Framework between NOMA and OFDM for Enhanced Bandwidth Efficiency in Fading Cellular Channels

With the proliferation of users and multimedia services, optimizing bandwidth efficiency has become pivotal in modern cellular networks. Bandwidth remains a finite and shared resource; therefore, innovative strategies are needed to maximize spectral utilization. This paper introduces an adaptive hybrid system that integrates Non-Orthogonal Multiple Access (NOMA) with Orthogonal Frequency Division Multiplexing (OFDM), leveraging Successive Interference Cancellation (SIC) and a Bit-Error-Rate (BER)-based automatic fallback—or “vertical handover”—mechanism. The proposed method monitors the instantaneous BER and dynamically switches between NOMA and OFDM based on predefined thresholds, maintaining optimal communication quality even under fading channel conditions. Unlike static multi-access systems, our approach adapts in real time to changing channel metrics, ensuring seamless transitions while minimizing performance degradation. Comparative analysis demonstrates that this hybrid handover design requires lower Signal-to-Noise Ratio (SNR) than existing schemes to maintain target BER performance, making it more practical and resilient in fading environments. The results highlight the potential for enhanced bandwidth and reliability in next-generation cellular systems by combining NOMA's power-domain multiplexing with OFDM's robustness to interference.