Method for searching cells in mobile communication system

Abstract

A rapid cell search method is disclosed for a mobile station in a mobile communication system. Upon detection of a power-off request, the mobile station stores in a memory PN information of adjacent cells in association with receiving power levels of the adjacent cells. Upon power on, it is determined whether the mobile station is presently located in a same cell group where it was located at a power-off time. When the mobile station is located in the same cell group, it sequentially reads the PN information from the memory in order of receiving power level to search the adjacent cells. Further, the mobile station searches a cell registered at the power-off time prior to searching the adjacent cells.

1. A method for searching cells in a mobile communication system, comprising the steps of:
 upon detection of a power-off request, storing in a memory for a plurality of adjacent cells PN (Pseudo Noise) information and a receiving power level;    upon power on, determining whether the mobile station is presently located in a same cell group where the mobile station was located at a power-off time; and    sequentially reading the PN information from the memory in order of receiving power level to search the adjacent cells, when the mobile station is located in the same cell group.    
     
     
       2. The method as claimed in  claim 1 , further comprising the step of searching a cell registered at the power-off time prior to searching the adjacent cells. 
     
     
       3. A method for searching cells in a mobile communication system, comprising the steps of:
 detecting a power-off request from a user;  
 upon detection of the power-off request, measuring receiving power levels of adjacent cells by performing power-off location registration;  
 storing in a memory PN information for the adjacent cells and an  associated measured receiving power level,  levels for a plurality of adjacent cells and cutting off power;  
 upon detection of a power-on request from a user, providing the power;  
 determining whether the mobile station is presently located in a same cell group where the mobile station was located at a power-off time;  
 searching an initial cell whose location was registered at the power-off time, when the mobile station is located in the same cell group; and  
 upon failure to search the initial cell, searching the adjacent cells by sequentially reading the PN information from the memory  searching PN codes of the adjacent cells in order of receiving power level.  
 
     
     
       4. A method for searching cells in a mobile communication system, comprising the steps of:
 measuring receiving power levels of adjacent cells to perform a handoff during a call;  
 detecting a power-off request from a user;  
 upon detection of a power-off request, storing in a memory PN information for the adjacent cells and an  associated measured receiving power levels for a plurality of adjacent cells, and cutting off power;  
 upon detection of a power-on request from the user, providing the power;  
 determining whether the mobile station is presently located in a same cell group where the mobile station was located at a power-off time;  
 searching an initial cell whose location was registered at the power-off time, when the mobile station is located in the same cell group; and  
 upon failure to search the initial cell, searching the adjacent cells by sequentially reading the PN information from the memory  searching PN codes of the adjacent cells in order of receiving power level.  
 
     
     
       5. A method for searching cells in a mobile communication system, comprising the steps of:
 ( a )  upon detection of a power - off request, storing in a memory receiving power levels of a plurality of adjacent cells;      ( b )  upon power on, determining if the mobile station is presently located in a same cell group where the mobile station was located at a power - off time; and      ( c )  sequentially searching PN codes of the adjacent cells in order of the receiving power level, when the mobile station is located in the same cell group.     
     
     
       6. The method as claimed in  claim 5 , further comprising the step of searching a cell registered at the power- off time prior to searching the adjacent cells.   
     
     
       7. The method as claimed in  claim 5 , further comprising the steps of:
   measuring said receiving power levels by performing power - off location registration;        searching for an initial cell whose location was registered at the power - off time; and        performing step  ( c )  upon failure to find the initial cell.     
     
     
       8. The method as claimed in  claim 5 , further comprising the steps of:
   measuring said receiving power levels during handoff;        searching for an initial cell whose location was registered at the power - off time; and        performing step  ( c )  upon failure to find the initial cell.