Spectrum Utilization using Multiple Access Techniques
Gazal Sinha, Sandeep Ojha, Alok Kumar Mishra · Technix International Journal for Engineering Research · 2025
Spectrum bands serve as the foundation for wireless networks, with each user allocated a portion of the fixed spectrum. However, the static allocation of these bands struggles to meet the growing demands of wireless communication. Cognitive Radio (CR) networks and multiple access techniques have emerged as promising solutions to address these challenges. While multiple access schemes enable the simultaneous transmission of data for multiple users, CR networks dynamically utilize underutilized spectrum bands. Among existing multiplexing methods, Orthogonal Frequency Division Multiple Access (OFDMA) is widely regarded as the most efficient for advanced wireless networks, supporting numerous users with high data rates.With the proliferation of smart devices and high-bandwidth applications, the demand for spectrum has increased exponentially, prompting interest in Non-Orthogonal Multiple Access (NOMA). NOMA enhances spectral efficiency through superposition coding at the transmitter and successive interference cancellation at the receiver, making it a strong candidate for addressing future spectrum demands in CR networks. Despite advancements, a comprehensive classification and review of multiple access schemes for CR networks remain unavailable. This paper bridges that gap by presenting a detailed survey and generic classification of recent developments in multiple access techniques tailored for CR networks. It highlights active research trends, categorizes existing methods, and examines challenges, research gaps, and potential directions to inspire future innovations in the field.