Recent radio communication environments have faced problems of depletion of frequency resources caused due to a rapid increase in data traffic. Accordingly, to increase network density and improve resource efficiency, network configurations in which a plurality of cells including macro cells and small cells are disposed in an overlapping manner can be adopted. For example, heterogeneous networks are networks that are formed in such a manner that various cells in which radio access technologies, cell sizes, or frequency bands differ coexist.
Small cells may, for example, be provided to cover a hot spot, where a significant amount of traffic occurs. Note that hot spots change dynamically, and therefore, it is not always easy to provide a small cell at a location suitable for a hot spot. When a plurality of overlapping cells are provided, it is also important to prevent the cells from adversely interfering with each other. Patent Literature 1 describes a technique for preventing such adverse interference from occurring in a radio communication system. In the technique, a device that will secondarily use a frequency channel senses a state of communication in a primary system or collects sensed data, and based on the communication state, determines whether or not the secondary use is allowed, is advance.
USPTO Backgrounds
USPTO Backgrounds