Dynamic frequency spectrum access method and system for hierarchical wireless network

The invention provides a dynamic frequency spectrum access method and system for a hierarchical wireless network. The method comprises the steps as follows: adding small base stations in a small base station group into the hierarchical wireless network, and sending the position information of the small base stations, perceived frequency spectrum information and judged macro user occupation situations to an FCS (field bus control system); obtaining frequency spectrum occupation rates of macro users, the average business time length of the macro users and the channel transfer probability by the FCS; obtaining the optimal perception cycle of the small base stations according to the parameters by the FCS; perceiving a current channel state by taking the optimal perception cycle as a cycle and sending the current channel state to the FCS by each small base station in the small base station group; and obtaining a power control and frequency spectrum access strategy according to the current channel state and the position information of each small base station in the small base station group and sending the power control and frequency spectrum access strategy to the small base station group by the FCS for the convenience of data transmission by small users in the small base station group according to the power control and frequency spectrum access strategy. According to the method, the interference of the hierarchical wireless network comprising macro cells and small cells is removed and a QoS (quality of service) guarantee is provided for small cell users.