Communication system that communicates position information of roaming mobile stations

Abstract

A communication system communicates position request and information over a communication channel that is used for communicating roaming data between mobile stations. Over the communication channel, a first local PLMN transmits a position request to a second remote PLMN covering a remote service area within which a roaming mobile station is positioned. In response to the position request, the second PLMN transmits position information related to the roaming mobile station to the first PLMN, preferably, over the same communication channel.

What is claimed is:  
     
         1 . A cellular communication system for communicating position information of mobile stations that roam between at least two Public Land Mobile Network (PLMNs), comprising: 
 a first transmitter that transmits a position request from a first PLMN to a second PLMN over a communication channel that is used for communicating roaming data between mobile stations; and    a second transmitter that is responsive to the position request for transmitting position information related to a roaming mobile station from the second PLMN to the first PLMN.    
     
     
         2 . The cellular communication system of    claim 1   , wherein the position information is transmitted over the communication channel used for communicating roaming data between mobile stations.  
     
     
         3 . The cellular communication system of    claim 1   , wherein the communication channel is used for a short messaging service.  
     
     
         4 . The cellular communication system of    claim 1   , wherein the first transmitter transmits the position request based on information contained in a home location register (HLR) associated with the roaming mobile station.  
     
     
         5 . The cellular communication system of    claim 4   , wherein the HLR contains an address for a visiting location register (VLR).  
     
     
         6 . The cellular communication system of    claim 5   , wherein the address of the VLR is an address pointing to the second PLMN.  
     
     
         7 . A communication system that supports roaming among at least two PLMNS, comprising: 
 a first Mobile Positioning Center (MPC) located in a first PLMN that transmits a position request over a communication channel requesting position information of a roaming mobile station; and    a second MPC located in a second PLMN that in response to receiving the position request over the communication channel initiates a positioning procedure for determining the position of the roaming mobile station.    
     
     
         8 . The communication system of    claim 7   , wherein the second MPC transmits the position information of the roaming mobile station to the first MPC.  
     
     
         9 . The communication system of    claim 7   , wherein the position request is transmitted over a communication channel used for communicating roaming data between the mobile stations.  
     
     
         10 . The communication system of    claim 9   , wherein the position information is transmitted over the communication channel used for communicating roaming data between the mobile stations.  
     
     
         11 . The communication system of    claim 9   , wherein the communication channel is used for a short messaging service.  
     
     
         12 . The communication system of    claim 7   , wherein the first MPC transmits the position request based on information contained in a home location register (HLR) associated with the roaming mobile station.  
     
     
         13 . The communication system of    claim 12   , wherein the HLR contains an address for a visiting location register (VLR).  
     
     
         14 . The communication system of    claim 13   , wherein the address of the VLR is an address pointing to the second PLMN.  
     
     
         15 . A cellular positioning system for a communication network that supports roaming among a first PLMN and a second PLMN, comprising: 
 a first mobile positioning center (MPC) located in the first PLMN that transmits a position request requesting position information of a roaming mobile station in the second PLMN; and    a second MPC located in the second PLMN that in response to receiving the position request initiates a positioning procedure for determining the position of the roaming mobile station, wherein the second MPC transmits the position information of the roaming mobile station to the first MPC.    
     
     
         16 . The cellular positioning system of    claim 15   , wherein the first MPC transmits the positioning request over a communication channel used for communicating roaming data.  
     
     
         17 . The cellular positioning system of    claim 16   , wherein the communication channel is used for a short messaging service.  
     
     
         18 . The cellular positioning system of    claim 16   , wherein the second MPC transmits the position information over the communication channel used for a short messaging service.  
     
     
         19 . The cellular positioning system of    claim 15   , wherein the first MPC transmits the position request based on information contained in a home location register (HLR) associated with the roaming mobile station.  
     
     
         20 . The cellular positioning system of    claim 19   , wherein the HLR contains an address for a visiting location register (VLR).  
     
     
         21 . The cellular positioning system of    claim 20   , wherein the address of the VLR is an address pointing to the second PLMN.  
     
     
         22 . A method for communicating position information related to a roaming mobile station in a communication network, comprising: 
 transmitting a position request form a first PLMN to a second PLMN over a communication channel that is used for communicating roaming data between roaming mobile stations; and    transmitting position information related to a roaming mobile station to the fist PLMN in response to receiving the position request in the second PLMN.    
     
     
         23 . The method of    claim 22   , wherein the position information is transmitted over the communication channel that is used for communicating subscriber data between roaming mobile stations.  
     
     
         24 . The method of    claim 22   , wherein the communication channel is used for a short messaging service.  
     
     
         25 . The method of    claim 22   , wherein the position request is transmitted based on information contained in a home location register (HLR) associated with the roaming mobile station.  
     
     
         26 . The method of    claim 25   , wherein the HLR contains an address for a visiting location register (VLR).  
     
     
         27 . The method of    claim 26   , wherein the address of the VLR is an address pointing to the second PLMN.