Maintaining triggered session state in secure user plane location (supl) enabled system

Abstract

A method is provided for maintaining session state in a Secure User Plane Location (SUPL) enabled system during a triggered session. The method includes modifying at least one parameter of a session message to include state data indicating the session state, and transmitting a request to a SUPL Enabled Terminal (SET) to initiate the triggered session, the request comprising the session message having the at least one modified parameter to be stored at the SET. The method further includes receiving a triggered message from the SET in response to occurrence of a trigger event detected by the SET, the triggered message comprising the stored state data. The triggered session is identified using the state data received in the triggered message.

What is claimed is: 
     
         1 . A method comprising:
 transmitting, from a server comprising one or more computing devices, a request to a Secure User Plane Location (SUPL) Enable Terminal (SET) over a given communication channel to initiate a triggered session, the request comprising a session message, wherein the session message includes state data sufficient to maintain a session state of the triggered session;   closing, at the server, the given communication channel after the session message is received at the SET;   clearing, from the server, the state data from memory of the server in response to the closing, wherein the SET maintains the only copy of the state data;   receiving, at the server, a triggered message from the SET over another communication channel, the triggered message comprising the stored state data; and   re-establishing, at the server, the triggered session over the other communication channel using the state data received from the SET in the triggered message.   
     
     
         2 . The method of  claim 1 , further comprising:
 calculating, at the server, an estimated position of the SET using position data included in the triggered message.   
     
     
         3 . The method of  claim 1 , wherein the triggered message received from the SET comprises one of a SUPL REPORT message and a SUPL POS INIT message. 
     
     
         4 . The method of  claim 1 , wherein the session message transmitted to the SET comprises an SULP INIT message. 
     
     
         5 . The method of  claim 1 , further comprising determining, at the server, content of the session message that includes the state data. 
     
     
         6 . The method of  claim 5 , wherein the determining comprises setting free bits in at least one of a sessionID field and a slpID field of the SlpSessionID parameter of the session message to include the state data. 
     
     
         7 . The method of  claim 5 , wherein determining content of the session message comprises:
 encrypting the state data, wherein the SET stores the encrypted state data, and is incapable of decrypting the encrypted state data.   
     
     
         8 . The method of  claim 7 , wherein the session message includes a key identifier that identifies a key known only to a SUPL Location Platform (SLP). 
     
     
         9 . The method of  claim 7 , wherein re-establishing the triggered session comprises decrypting the state data received in the triggered message. 
     
     
         10 . The method of  claim 5 , wherein the determining comprises:
 including a message authentication code, wherein the SET stores an unencrypted version of the state data and message authentication code.   
     
     
         11 . The method of  claim 10 , wherein the session message includes a key identifier that identifies a key known only to an SUPL Location Platform (SLP). 
     
     
         12 . The method of  claim 10 , wherein re-establishing the triggered session comprises:
 employing the key identifier to identify an encryption key;   performing a cryptographic hash function using the identified encryption key; and   verifying that the state data received in the triggered message has not been altered using the cryptographic hash function.   
     
     
         13 . The method of  claim 1 , further comprising:
 receiving position data from the SET via the other communication channel, wherein the position data indicates a location of the SET; and   setting an estimated position of the SET to the location indicated in the position data.   
     
     
         14 . The method of  claim 13 , further comprising:
 receiving a request from a location client to initiate the triggered session with the SET; and   sending the estimated position of the SET to the location client.   
     
     
         15 . The method of  claim 1 , wherein the receiving and the re-establishing occur at least one hour after the closing. 
     
     
         16 . A non-transitory computer readable medium having machine readable instructions, the machine readable instructions comprising:
 a transmitting module configured to transmit a request to a Secure User Plane (SUPL) Enabled Terminal (SET) to initiate a triggered session over a given communication channel, the request comprising a session message, wherein the session message includes state data sufficient to maintain a session state of the triggered session;   a closing module configured to close the given communication channel after the session message is received by the SET;   a clearing module configured to clear the state data from memory in response to the closing, such that the SET maintains the only copy of the state data;   a receiving module configured to receive a triggered message from the SET over another communication channel, the triggered message comprising the stored state data; and   an identifying module configured to re-establish the triggered session using the state data received in the triggered message.   
     
     
         17 . The non-transitory machine readable medium of  claim 16 , further comprising:
 a position module configured to set an estimated position of the SET using position data included in the triggered message, wherein the position data characterizes a location of the SET.   
     
     
         18 . The non-transitory machine readable medium of  claim 16 , further comprising:
 an encrypting module configured to encrypt the state data included in the session message, wherein the SET stores the encrypted state data, and is incapable of decrypting the encrypted state data.   
     
     
         19 . A method comprising:
 setting free bits of a SlpSessionID parameter in a session message from a Secure User Plane Location (SULP) Location Platform (SLP) to include state data sufficient to maintain the session state of the triggered session;   transmitting the session message to a SUPL Enabled Terminal (SET) from the SLP to the SET to initiate the triggered session over a given communication channel, the SET storing the free bits of the SlpSessionID;   closing the given communication channel after the SET receives the session message;   clearing the state data from memory of the SLP in response to the closing, wherein the SET maintains the only copy of the state data;   receiving, at the SLP, a SUPL POS INIT message from the SET over another communication channel, the SUPL POS INIT message comprising the stored state data; and   re-establishing, at the SLP, the triggered session using the stored state data in the SUPL POS NIT message.   
     
     
         20 . The method of  claim 19 , further comprising:
 encrypting, at the SLP, the state data included in the at least one modified parameter, wherein the SET stores the encrypted state data, and is incapable of decrypting the encrypted state data.