Method, terminal, and system for cell reselection

Abstract

A method and terminal are disclosed for cell reselection. In the disclosure, the terminal obtains a dedicated priority list and a valid time of the dedicates priority list for cell reselection from a first communication system, such as a Long Term Evolution (LTE) system, when the terminal is in a cell of the fists communication system. In case that the terminal camps on a cell of a second communication system, such as a non-LTE system (for example, a UMTS system), and before the valid time expire, the terminal performs cell reselection using the dedicated priority list.

What is claimed is: 
     
         1 . A method for cell reselection comprising:
 sending, by a first network device of a first system, a dedicated priority list and a valid time of the dedicated priority list to a terminal;   obtaining, by the terminal, the dedicated priority list and the valid time of the dedicated priority list from a first system;   sending, by a second network device of a second system, a public priority list to the terminal and an indication indicating whether the public priority list from the second system is usable or not;   obtaining, by the terminal, the public priority list and the indication indicating whether the public priority list from the second system is usable or not;   performing, by the terminal, cell reselection according to the dedicated priority list, when the terminal camps on a cell of the second system; and   when the terminal camps on the cell of the second system, performing cell reselection according to the public priority list from the second system when the indication indicating the public priority list from the second system is usable and when the dedicated priority list is invalid after the valid time expires.   
     
     
         2 . The method according to  claim 1 , wherein the first system is a Long Term Evolution (LTE) system and the second system is a non-LTE system. 
     
     
         3 . The method according to  claim 1 , wherein the dedicated priority list and the valid time are carried in a dedicated signaling. 
     
     
         4 . The method according to  claim 1 , further comprising: deleting, by the terminal, the dedicated priority list when the valid time expires. 
     
     
         5 . The method according to  claim 1 , wherein the dedicated priority list comprises priority information of different radio access technologies (RATs). 
     
     
         6 . The method according to  claim 5 , wherein the priority information comprises priority information of frequencies of the different RATs. 
     
     
         7 . The method according to  claim 1 , wherein the dedicated priority list comprises frequency priority information of the LTE system and the non-LTE system. 
     
     
         8 . A communications system, comprising:
 a first network device of a first system, configured to send a dedicated priority list and a valid time of the dedicated priority list to a terminal;   a second network device of a second system, configured to send a public priority list to the terminal and an indication indicating whether the public priority list from the second system is usable or not;   a terminal, configured to obtain the dedicated priority list and the valid time of the dedicated priority list from a first system, obtain the public priority list and the indication indicating whether the public priority list from the second system is usable or not, perform cell reselection according to the dedicated priority list, when the terminal camps on a cell of the second system; and when the terminal camps on the cell of the second system, the terminal is further configured to perform cell reselection according to the public priority list from the second system when the indication indicating the public priority list from the second system is usable and when the dedicated priority list is invalid after the valid time expires.   
     
     
         9 . The system according to  claim 8 , wherein the first system is a Long Term Evolution (LTE) system and the second system is a non-LTE system. 
     
     
         10 . The system according to  claim 8 , wherein the dedicated priority list and the valid time are carried in a dedicated signaling. 
     
     
         11 . The system according to  claim 8 , the terminal is further configured to delete the dedicated priority list when the valid time expires. 
     
     
         12 . The system according to  claim 8 , wherein the dedicated priority list comprises priority information of different radio access technologies (RATs). 
     
     
         13 . The system according to  claim 12 , wherein the priority information comprises priority information of frequencies of the different RATs. 
     
     
         14 . The system according to  claim 8 , wherein the dedicated priority list comprises frequency priority information of the LTE system and the non-LTE system.