Frequency selection method and cognitive wireless system

摘要

A frequency to be used in a cognitive wireless system is determined appropriately. A DB apparatus manages white spaces (WS) for each frequency, and calculates and reports, to a mobile terminal, WS vectors (distances from a mobile terminal location to an interference area in the four directions, north, south, east and west) for each frequency. The mobile terminal refers to the WS vectors and uses a frequency providing the longest available distance in a direction of movement. The available distance is calculated by interpolation (triangular interpolation, elliptical interpolation, rectangular interpolation) of WS boundaries using various methods. Desirably, the mobile terminal reports a direction of movement to the DB apparatus, and the DB apparatus reports the distance to an interference area only in the two directions near to the direction of movement. Furthermore, desirably, information indicating whether the interference areas in the two directions are the same area or different areas is added to the WS vectors, and the interpolation method employed by the mobile terminal is changed in accordance with this information.

主权项

1. A frequency determination method for determining a frequency to be used for communication by a mobile communication apparatus, in a wireless communications system including a database apparatus which stores, for each frequency, a prohibited area which is an area where a licensed user is using radio waves, and the mobile communication apparatus which is capable of wireless communications with the database apparatus; the method comprising:
a step in which the mobile communication apparatus acquires location information of the mobile communication apparatus; a step in which the mobile communication apparatus reports the location information to the database apparatus; a step in which the database apparatus determines, for each frequency, a first distance, which is a distance in a first direction to the prohibited area from the location indicated by the reported location information, and a second distance, which is a distance in a second direction to the prohibited area from the location indicated by the reported location information, and generating distance information including the first distance and the second distance; a step in which the database apparatus reports the distance information for each frequency, to the mobile communication apparatus; and a step in which the mobile communication apparatus determines a frequency to be used for communication, on the basis of the reported distance information and a direction of movement of the mobile communication apparatus.