Method and system for establishing an emergency call in a communications system

Abstract

A method for establishing an emergency call between a user equipment within a radio coverage area and one of at least two points able to answer the call, the method comprising: receiving said emergency call request; determining a first estimate of the position of said user equipment within said coverage area; interrupting said call establishment by triggering a control point; and using the control point to select, based on said first position estimate, which one of said at least two answering points the call is established with.

What is claimed is: 
     
         1 . A method for establishing an emergency call between a user equipment within a radio coverage area and one of at least two answering points able to answer the call, each of the at least two answering points including a service zone within the radio coverage area, the method comprising:
 invoking, at the user equipment, the call;   transmitting, from the user equipment, first location measurement signals for use in determining a first estimate of the position of the user equipment within the radio coverage area, wherein the first estimate has sufficient accuracy to identify the service zone of the at least two answering points that the user equipment lies within; and   transmitting, from the user equipment, second location measurement signals for use in determining a second estimate of the position of the user equipment within the radio coverage area, wherein the second estimate is more accurate than the first estimate.   
     
     
         2 . The method according to  claim 1 , wherein the second location measurement signals include a measurement based on network transmitted signals. 
     
     
         3 . The method according to  claim 1 , wherein the first location measurement signals are utilized by a network to make position measurements. 
     
     
         4 . The method according to  claim 1 , further comprising transmitting, from the user equipment, the first and second measurement signals to a serving mobile location center. 
     
     
         5 . The method according to  claim 4 , wherein the serving mobile location center resides at a core network level. 
     
     
         6 . The method according to  claim 4 , wherein the serving mobile location center resides at a radio level. 
     
     
         7 . An apparatus comprising:
 at least one processor; and   at least one memory including computer program code for one or more programs, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to perform at least the following:
 invoke an emergency services call between the apparatus that is within a radio coverage area and one of at least two answering points able to answer the call, wherein each of the at least two answering points includes a service zone within the radio coverage area; 
 transmit, from the apparatus, first location measurement signals for use in determining a first estimate of the position of the apparatus within the radio coverage area, wherein the first estimate has sufficient accuracy to identify the service zone of the at least two answering points that the apparatus lies within; and 
 transmit, from the apparatus, second location measurement signals for use in determining a second estimate of the position of the apparatus within the radio coverage area, wherein the second estimate is more accurate than the first estimate. 
   
     
     
         8 . The apparatus of  claim 7 , wherein the second location measurement signals include a measurement based on network transmitted signals. 
     
     
         9 . The apparatus of  claim 7 , wherein the first location measurement signals are utilized by a network to make position measurements. 
     
     
         10 . The apparatus of  claim 7  further causing the apparatus to at least transmit the first and second measurement signals to a serving mobile location center. 
     
     
         11 . The apparatus of  claim 10 , wherein the serving mobile location center resides at a core network level. 
     
     
         12 . The apparatus of  claim 10 , wherein the serving mobile location center resides at a radio level. 
     
     
         13 . A non-transitory computer-readable medium configured to control a processor to perform operations for establishing an emergency call between a user equipment within a radio coverage area and one of at least two answering points able to answer the call, each of the at least two points including a service zone that is within the radio coverage area, the establishing step comprising:
 invoking the call;   transmitting first location measurement signals for use in determining a first estimate of the position of the user equipment within the radio coverage area, wherein the first estimate has sufficient accuracy to identify the service zone of the at least two answering points that the user equipment lies within; and   transmitting second location measurement signals for use in determining a second estimate of the position of the user equipment within the radio coverage area, wherein the second estimate is more accurate than the first estimate.   
     
     
         14 . The non-transitory computer-readable medium of  claim 13 , wherein the second location measurement signals include a measurement based on network transmitted signals. 
     
     
         15 . The non-transitory computer-readable medium of  claim 13 , wherein the first location measurement signals are utilized by a network to make position measurements. 
     
     
         16 . The non-transitory computer-readable medium of  claim 13 , further comprising transmitting the first and second measurement signals to a serving mobile location center. 
     
     
         17 . The non-transitory computer-readable medium of  claim 16 , wherein the serving mobile location center resides at a core network level. 
     
     
         18 . The non-transitory computer-readable medium of  claim 16 , wherein the serving mobile location center resides at a radio level.