Method and apparatus for accessing old network through temporary id of evloved network

Abstract

A method for accessing an old network through a temporary ID of an evolved network includes these steps: a User Equipment (UE) adds Mobility Management Entity (MME) information for uniquely identifying an MME accessed by the UE on an evolved network to an access message sent to an old network when the UE accesses the old network through a temporary ID of the evolved network; and the old network selects a corresponding Serving GPRS Support Node (SGSN) for the UE according to the access message. After the MME information for uniquely identifying an MME is added to the access message sent to the old network, the old network can determine and find the MME that is accessed by the UE in the evolved network without changing a Radio Network Controller (RNC) and an SGSN on the old network. In addition, with the method for accessing the evolved network through a temporary ID of the old network, a combined SGSN/MME can be accessed to prevent unnecessary node relocation.

1 . A method for accessing old network through temporary ID of evolved network, comprising:
 adding, by a User Equipment, UE, Mobility Management Entity information, MME information, for uniquely identifying an MME accessed by the UE in an evolved network, to an access message;   sending the access message to an old network when the UE accesses the old network through a temporary ID of the evolved network; the access message being used for selecting, by the old network, a corresponding Serving GPRS Support Node, SGSN, for the UE.   
   
   
       2 . The method of  claim 1 , wherein after the selecting, by the old network, a corresponding Serving GPRS Support Node, SGSN, the method further comprises:
 determining, by the SGSN, the MME according to the MME information added to the access message if the SGSN is not a node registered by the UE; and   requesting the UE information from the MME.   
   
   
       3 . The method of  claim 2 , wherein the determining, by the SGSN, the MME according to the MME information comprises:
 upgrading configuration information or DNS of the SGSN; and   finding, by the SGSN, the MME in the configuration information or DNS according to the MME information.   
   
   
       4 . The method of  claim 1 , wherein the MME information comprises an MME-id in an SAE-TMSI, accordingly, adding, by the UE, MME information to an access message sent to an old network comprises: adding the MME-id to the P-TMSI information of the access message and/or the RAI information of the access message. 
   
   
       5 . The method of  claim 4 , wherein the adding the MME-id to the P-TMSI information of the access message comprises: setting the NRI information in the P-TMSI information carried in the access message as the MME-id. 
   
   
       6 . The method of  claim 5 , wherein the method further comprises: setting the NRI information of a combined MME/SGSN the same as the MME-id; and
 selecting, by the old network, the combined MME/SGSN for the UE when the UE enters the old network from the evolved network within the same pool as the old network.   
   
   
       7 . The method of  claim 4 , wherein the method further comprises:
 adding the information of the SAE-TMSI other than the MME information of the SAE-TMSI to the signature of the P-TMSI.   
   
   
       8 . The method of  claim 1 , wherein the MME information comprises the Pool-id and the MME-id in an SAE-TMSI, accordingly, adding, by a UE, MME information for uniquely identifying an Mobility Management Entity to an access message sent to an old network comprises: adding the MME-id and the Pool-id to the P-TMSI information of the access message and/or the RAI information of the access message. 
   
   
       9 . The method of  claim 1 , wherein the MME information comprises a PLMN-id and the Pool-id and MME-id in an SAE-TMSI,
 and accordingly, the adding, by a UE, MME information for uniquely identifying an Mobility Management Entity, MME, accessed by the UE on an evolved network, to an access message sent to an old network comprises: adding the PLMN-id, Pool-id and MME-id to the P-TMSI information and/or RAI information.   
   
   
       10 . The method of  claim 9 , wherein the adding the PLMN-id, Pool-id and MME-id to the P-TMSI information and/or RAI information comprises: setting the NRI information of the P-TMSI information as MME-id; and adding the PLMN-id to the RAI information; adding the Pool-id to the RAI information and/or P-TMSI information. 
   
   
       11 . The method of  claim 1 , wherein the method further comprises: selecting, by the evolved network, for the UE, the MME preferentially of which the MME-id is the NRI value of the P-TMSI. 
   
   
       12 . The method of  claim 1 , wherein the access message comprises Radio Resource Control message, RRC message, and the MME information comprises MME-id; accordingly, the adding, by a User Equipment, UE, Mobility Management Entity, MME information for uniquely identifying an Mobility Management Entity, MME, accessed by the UE on an evolved network, to an access message sent to an old network comprises:
 adding the MME-id to the NRI information in the P-TMSI information carried in the RRC message.   
   
   
       13 . The method of  claim 12 , wherein the method further comprises:
 adding the MME information to the P-TMSI and/or RAI of NAS information in the RRC message and mapping the information of SAE-TMSI other than MME information into the P-TMSI, RAI or P-TMSI Signature of the NAS information.   
   
   
       14 . A user equipment, UE, wherein the UE comprises an access message sending module and an MME information adding module;
 the access message sending module is adapted to send access message to an old network when the UE is accessing an evolved network; and   the MME information adding module is adapted to add MME information to the access message sent by the access message sending module, and the MME information is used for identifying an MME accessed by the UE in the evolved network.   
   
   
       15 . The UE of  claim 14 , wherein the MME information adding module comprises a P-TMSI information adding submodule, adapted to add the MME-id in an SAE-TMSI to the P-TMSI information of the access message. 
   
   
       16 . The UE of  claim 14 , wherein the MME information adding module comprises an RAI information adding submodule, adapted to add Pool-id, PLMN-id or TAI in the SAE-TMSI to the RAI information adding submodule. 
   
   
       17 . The UE of  claim 14 , wherein the MME information adding module further comprises an NRI setting submodule, adapted to set the NRI information in the P-TMSI information of the access message as the MME-id. 
   
   
       18 . The UE of  claim 14 , wherein the UE further comprises P-TMSI signature adding module, adapted to add other information in the SAE-TMSI except the MME information to the P-TMSI Signature. 
   
   
       19 . A method for enabling a UE to access an old network, wherein the method comprises:
 receiving, by the old network, an access message sent by a UE that accesses the old network though a temporary ID of an evolved network, where the access message comprises Mobility Management Entity information, MME information, for uniquely identifying an MME accessed by the UE in the evolved network; and   selecting, by the old network, a corresponding SGSN for the UE according to the access message.   
   
   
       20 . The method of  claim 19 , wherein the MME information comprises Pool-id and MME-id of PLMN-id and S-TMSI, and the PLMN-id, the Pool-id, and the MME-id are contained in P-TMSI information and/or RAI information.