Communication system and communication controlling method

Abstract

A communication method in LIPA/SIPTO architecture is provided which, when a user equipment (UE) is to connect from a serving area to an external network, allows re-selection of an optimal gateway. The communication method allows selecting a gateway apparatus physically or topologically close to a site, where the user equipment is attached.

1 . A communication method in Selected IP Traffic Offload (SIPTO) architecture, the method comprising:
 a mobility management entity (MME) sending a first signal for setting re-attachment to a user equipment, when the MME decides that it is necessary to re-select a gateway apparatus on receipt of a tracking area (TA) update signal from the user equipment;   the user equipment, on receipt of the first signal, transmitting a second signal for re-attachment to the MME; and   the MME performing re-selection of a gateway apparatus.   
     
     
         2 . A communication method in Selected IP Traffic Offload (SIPTO) architecture, the method comprising:
 a Serving General Packet Radio Service Support Node (SGSN) sending a first signal for setting re-attachment to a user equipment, when the SGSN decides that it is necessary to re-select a gateway apparatus on receipt of a routing area (RA) update signal from the user equipment;   the user equipment, on receipt of the first signal, transmitting a second signal for re-attachment to the SGSN; and   the SGSN performing re-selection of a gateway apparatus.   
     
     
         3 . The communication method according to  claim 1 , wherein the gateway apparatus includes at least one of a serving gateway apparatus, a packet data network gateway apparatus and a Gateway General Packet Radio Service Support Node (GGSN). 
     
     
         4 . The communication method according to  claim 2 , wherein the gateway apparatus includes at least one of a serving gateway apparatus, a packet data network gateway apparatus and a Gateway General Packet Radio Service Support Node (GGSN). 
     
     
         5 . A communication system in Selected IP Traffic Offload (SIPTO) architecture, the system comprising:
 a user equipment;   a mobility management entity (MME); and   a plurality of gateway apparatuses, wherein   the MME sends a first signal for setting re-attachment to the user equipment, when the MME decides that it is necessary to re-select the gateway apparatus on receipt of a tracking area update signal from the user equipment;   the user equipment, on receipt of the first signal, transmits a second signal for re-attachment to the MME; and   the MME performs re-selection of the gateway apparatus.   
     
     
         6 . A communication system in Selected IP Traffic Offload (SIPTO) architecture, the system comprising:
 a user equipment;   a Serving General Packet Radio Service Support Node (SGSN); and   a plurality of gateway apparatuses, wherein   the SGSN sends a first signal for setting re-attachment to the user equipment, when the SGSN decides that it is necessary to re-select the gateway apparatus on receipt of a routing area (RA) update signal from the user equipment;   the user equipment, on receipt of the first signal, transmits a second signal for re-attachment to the SGSN; and   the SGSN performs re-selection of the gateway apparatus.   
     
     
         7 . The communication system according to  claim 5 , wherein the gateway apparatus includes at least one of a serving gateway apparatus, a packet data network gateway apparatus and a Gateway General Packet Radio Service Support Node (GGSN). 
     
     
         8 . The communication system according to  claim 6 , wherein the gateway apparatus includes at least one of a serving gateway apparatus, a packet data network gateway apparatus and a Gateway General Packet Radio Service Support Node (GGSN). 
     
     
         9 . A user equipment in a communication system by Selected IP Traffic Offload (SIPTO) architecture, wherein the user equipment transmits a tracking area (TA) update signal to a mobility management entity (MME) and receives a first signal that sets re-attachment from the MME, and the user equipment transmits a second signal for re-attachment to the MME, to cause the MME to perform re-selection of a gateway apparatus. 
     
     
         10 . A user equipment in a communication system by Selected IP Traffic Offload (SIPTO) architecture, wherein the user equipment transmits a routing area (RA) update signal to a Serving General Packet Radio Service Support Node (SGSN) and receives a first signal that sets re-attachment from the SGSN, and the user equipment transmits a second signal for re-attachment to the SGSN, to cause the SGSN to perform re-selection of a gateway apparatus. 
     
     
         11 . The user equipment according to  claim 9 , wherein the gateway apparatus includes at least one of a serving gateway apparatus, a packet data network gateway apparatus, and a Gateway General Packet Radio Service Support Node (GGSN). 
     
     
         12 . The user equipment according to  claim 10 , wherein the gateway apparatus includes at least one of a serving gateway apparatus, a packet data network gateway apparatus, and a Gateway General Packet Radio Service Support Node (GGSN).