Toward Smart and Flexible Spectrum Usage: Application of Horizontal Model Algorithm in Cognitive Radio Systems

Abstract

The growing need for wireless communication services has resulted in a pressing need for more enhanced exploitation of available spectrum bandwidth.Cognitive Radio (CR) technology emerges as a potential solution, facilitating secondary users, in their ability to opportunistically access underutilized spectral resources without causing harmful interference to primary users.In this paper, we propose and analyze a horizontal spectrum-sharing model for CR systems operating in wideband environments.Unlike traditional orthogonal access schemes, the horizontal model enforces exclusive subband transmission per user in the Time-Division Duplex (TDD) framework, combined with the water-filling power allocation strategy to maximize spectral efficiency.We develop an analytical framework to characterize the spectral efficiency and capacity achievable by the proposed model and assess its asymptotic behavior under Rayleigh fading channels.Extensive simulations are conducted to validate the theoretical findings, comparing the horizontal model to the classical orthogonal model across various Signal-to-Noise Ratio (SNR) regimes.Results demonstrate that the horizontal sharing approach significantly improves spectral efficiency, especially in low-SNR conditions, and converges to the orthogonal performance in high-SNR environments.This work provides valuable insights into the design of future CR systems, highlighting the advantages of opportunistic spectrum pooling strategies for enhancing overall network performance.