System and method for packet data servicing node (PDSN) initial assignment and reselection

Abstract

An method for PDSN (Packet Data Serving Node) initial assignment and re-selection in a wireless communication system is provided. The method is implemented in PCF (Packet Control Function) within a third-generation (3G) CDMA Radio Access Network (RAN). The methodology reduces the number of point-to-point (PPP) re-establishments, when a Mobile Station (MS) roams to a different packet zone/PCF. The method generates a table of PDSN identification numbers cross-referenced to the PDSN Internet protocol (IP) addresses, residing with each PCF. A PDSN Id number is selected from the table using the MS IMSI (International Mobile Station Identifier) as a key to perform the selection. The present invention methodology addresses the issue of forward and backward compatibility, scalability, reliability, and load sharing in the PDSN selection.

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       28 . In a wireless communication system including one Packet Control Function (PCF) and at least one Packet Data Serving Node (PDSN), a method for determining which PDSN should be used for packet data communications with a mobile station (MS), the method comprising: 
 maintaining a configuration table at the PCF being communicatively coupled between the MS and at least one PDSN, said configuration table having at least one unique PDSN identification (Id) number listed therein, said at least one unique PDSN Id number being respectively associated with the at least one PDSN; and    selecting a PDSN in response to a number of the PDSN Id numbers in the configuration table.    
   
   
       29 . The method of  claim 28  further comprising: 
 assigning a unique MS Id number to the MS, wherein selecting the PDSN further includes selecting in response to the MS Id number.    
   
   
       30 . The method of  claim 29 , wherein assigning the unique MS Id number includes using an International Mobile Station Identifier (IMSI) of the MS for such assignment.  
   
   
       31 . The method of  claim 29 , wherein the MS Id number is the IMSI.  
   
   
       32 . The method of  claim 29 , wherein the at least one PDSN comprises n PDSNs, further wherein each of the n PDSNs has a unique Internet protocol (IP) address, and further wherein the configuration table has an ascending ordered sequence of the n PDSN Id numbers based on the unique IP addresses of the n PDSNs.  
   
   
       33 . The method of  claim 32 , wherein the selection of the PDSN includes dividing the unique MS Id number by n.  
   
   
       34 . The method of  claim 33 , wherein the selection of the PDSN includes selecting the PDSN Id number equal to the remainder in the quotient.  
   
   
       35 . The method of  claim 32 , wherein the configuration table includes one cross-reference between the at least one PDSN Id number and a respective unique IP address associated with the PDSN being communicatively coupled to the PCF.  
   
   
       36 . The method of  claim 35 , wherein the configuration table includes one cross-reference between the at least one PDSN Id number and a dummy address associated with one of the n PDSNs that is not communicatively coupled to the PCF.  
   
   
       37 . The method of  claim 36  further comprising reselecting an alternative PDSN if the selection yields the PDSN Id number being cross-referenced with the dummy address.  
   
   
       38 . The method of  claim 37 , wherein the reselection of the alternative PDSN includes selecting the alternative PDSN in response to the PDSN Id number associated with the selected PDSN.  
   
   
       39 . The method of  claim 37 , wherein the reselection of the alternative PDSN includes selecting the alternative PDSN in response to the unique MS Id number.  
   
   
       40 . The method of  claim 29 , wherein the at least one PDSN includes n PDSNs, further wherein each of the n PDSNs has a unique Internet protocol (IP) address, and further wherein the configuration table has an ascending ordered sequence of some of the PDSN Id numbers based on unique IP addresses of the PDSNs associated with said some of the PDSN Id numbers.  
   
   
       41 . The method of  claim 40 , wherein the configuration table includes cross-references between the PDSN Id numbers and respective unique IP addresses associated with the PDSNs being communicatively coupled to the PCF.  
   
   
       42 . The method of  claim 41 , wherein the configuration table includes one cross-reference between one of the PDSN Id numbers and a dummy address associated with one of the n PDSNs that is not communicatively coupled to the PCF.  
   
   
       43 . The method of  claim 41  further comprising reselecting an alternative PDSN if the selection yields the PDSN Id number being cross-referenced with the dummy address.  
   
   
       44 . The method of  claim 32 , wherein m of the n PDSNs are communicatively coupled to the PCF, further the configuration table includes cross-references between the IP addresses of the m PDSNs and the respective PDSN Id numbers and cross-references between dummy addresses and the respective (n−m) PDSN Id numbers, and further wherein the PDSNs associated with the dummy addresses are not communicatively coupled to the PCF.  
   
   
       45 . A Packet Control Function (PCF) for selecting which one of n Packet Data Serving Nodes (PDSNs) should be used for packet data communications with a mobile station (MS), said PCF being communicatively coupled between the MS and at least one PDSN and being configured to: 
 maintain a configuration table, said configuration table having at least one unique PDSN identification (Id) number listed therein, said at least one unique PDSN Id number being respectively associated with the at least one PDSN; and    select a PDSN in response to a number of the PDSN Id numbers in the configuration table.    
   
   
       46 . The PCF of  claim 45  further being configured to assign a unique MS Id number to the MS, wherein the PCF selects the PDSN in response to the MS Id number.  
   
   
       47 . The PCF of  claim 46 , wherein the PCF uses an International Mobile Station Identifier (IMSI) of the MS to assign the unique MS Id number.