Two-Dimensional Orthogonal Pattern Division Multiple Access for Shadow Fading Mitigated by Intelligent Reflecting Surface

This paper introduces a two-dimensional orthogonal pattern division multiple access (OPDMA) communication method based on optimal frequency hopping patterns and explores the use of intelligent reflecting surface (IRS) to mitigate shadow attenuation in wireless systems. Although IRS implementation may introduce additional multipath interference, the ideal autocorrelation and cross-correlation properties of the optimal frequency hopping patterns effectively counteract interference from multipath fading, Doppler effects, and user-to-user interference. In the context of cellular network architecture, algebraic Costas arrays are employed to design the optimal frequency hopping patterns through two-dimensional cyclic shifts, followed by simulation analysis. The results demonstrate that OPDMA effectively mitigates small-scale interference, such as multipath effects, and reduces bit error rate. Moreover, IRS contributes to reducing large-scale interference, such as shadowing, with performance improvements in OPDMA systems assisted by IRS surpassing those in CDMA and FDMA systems with IRS assistance.