Interference Graph Based Two-Stage Dynamic Spectrum Allocation with Adjustable Protect Zone

In this paper, we propose a dynamic spectrum allocation model to optimize spectrum allocation between primary users (PUs) and secondary users (SUs). Our model aims to improve both spectrum utilization and economic efficiency by maximizing total social welfare. We introduce an interference graph based two-stage allocation scheme. In the first stage, we allocate spectrum to high priority SUs by constructing an interference graph and applying an improved graph coloring algorithm, ensuring minimal interference and maximal benefits. In the second stage, we introduce a protect zone adjustment strategy for low priority SUs, by adjusting the coverage of low priority SUs, subject to interference constraints. Simulation results demonstrate that the proposed algorithm performs better in densely user environments compared to other algorithms, enhancing both spectrum utilization and total social welfare.