Wireless communication system, communication control method, mobility management apparatus, mobile terminal and base station

#This inventions are related to a technical field of a wireless communication system, a communication control method in the system, and a mobility management apparatus, a mobile terminal and a base station, which are used in the system, and more particularly, to a technical field of a control performed at the time of paging for a mobile terminal.

#In a wireless communication system, a location of a mobile terminal (UE: User Equipment) expected to move by straddling cells provided by base stations is managed. At this time, a mobility management entity included in upper node of a network manages a location of each mobile terminal not in units of base stations of visited cells but in units of location registration areas each composed of a set of cells. In a Long Term Evolution (LTE) wireless system that is one of next-generation wireless systems, these mobility management entity and location registration area are called MME (Mobility Management Entity) and a Tracking Area (TA), respectively.

#Additionally, when an incoming call to a mobile terminal occurs, the MME pages the mobile terminal by transmitting a paging signal to all base stations within a TA to which a location of the mobile terminal is registered.

#FIG. 1 illustrates a configuration example of a wireless communication system;

#FIG. 2 illustrates a configuration example of a mobility management apparatus;

#FIG. 3 is a block diagram illustrating a configuration of a mobile terminal;

#In recent years, in a wireless communication system such as LTE or the like, introduction of small base stations such as a so-called micro-cell, a femto-cell or the like having relatively low transmission power for accommodating a small number of mobile terminals has been studied. Such small base stations can provide a communication environment at a point that is arranged, for example, within a building and cannot be fully covered by a conventional base station. If such small base stations are popularized and arranged in each home or each building in the future, the number of base stations is expected to explosively increase. For this reason, small base stations are popularized and arranged in each home or each building in the future, the number of base stations accommodated in one TA is expected to explosively increase.

#Incidentally, a TA managed by MME accommodates a plurality of base stations as described above, and the MME cannot grasp in which cell a mobile terminal to be paged is visiting at the time of paging in the present situation. If the MME performs paging for a mobile terminal within a TA in such a state, a paging signal is transmitted to all base stations within the TA, leading to a significant increase in a processing load.

#The prior art document discloses a configuration where an individual TA is set for each small base station and MME makes location registration in units of TAs respectively set for small base stations in addition to location registration made in units of conventional TAs. However, the above described technique causes a new technical problem such that the location registration process is needed each time a mobile terminal enters/exits a relatively small cell of a small base station, leading to an increase in a load. This technique also causes a problem such that the number of small base stations that can be installed is restricted due to an upper limit number of preset TAs in a standard such as LTE or the like.