This invention relates to a wireless communication system in which macrocells and femtocells are used in a mixed manner.
In a cell-based wireless communication system, typified by cell phones, in order to transfer data to a terminal in an idle status (quiescent status), processings called “location registration” and “paging” are performed as is described in, for example, 3GPP TS23.401 v8.0.0, General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access (Release 8) pp. 46 to 48, pp. 65 to 67.
The location registration is a processing in which the location of a terminal is registered with a location management server on a location registration area basis. Generally, a location registration area is configured by a plurality of base stations, and each of the base stations broadcasts information regarding its own location registration area to all terminals. The terminal constantly monitors the information regarding the location registration area. Hence, when the information regarding the location registration area, which the terminal is receiving, is changed while the terminal is in motion, the terminal registers the location with the location management server based on the received information regarding the location registration area. With this configuration, the location management server can manage which location registration area each of the terminals is located in. Besides, even when the information regarding the location registration area is not changed, the terminal performs location registration periodically.
Further, the paging is a processing in which a terminal in the idle status is called from the network side and then activated. Upon arrival of data directed to a terminal, the location management server transmits a paging request to all base stations that belong to a location registration area in which the terminal concerned had registered the location thereof last time. Each of the base stations that have received the paging request from the location management server uses a wireless broadcast channel to transfer the paging request to the terminal concerned. Upon reception of the paging request, the terminal concerned activates a wireless channel to thereby start data communication.
As is described above, in the cell-based wireless communication system, the location of the terminal in the idle status is managed on a location registration area basis. Further, when the data has arrived, the terminal is called by all the base stations within the location registration area, and the terminal in the idle status is activated. Then, data transfer to the activated terminal is realized.
The above-mentioned processings of the location registration and the paging are performed via base stations (macrocells, microcells, and picocells) installed by a telecommunications carrier having a radio band license.
On the other hand, a femtocell is a service area that has a coverage area of around several tens of meters, and its applications conceived include expanding the service area to higher floors of a building, which radio waves from a macro base station cannot reach, and improving the communication quality in an ordinary house. The above-mentioned femtocell can be realized by installing a femto base station. In particular, in the case of use in the ordinary house, there is a possibility that an ordinary user who does not have a radio station license installs a femto base station at his/her own discretion.