Method to optimize call establishment in mobile satellite communication systems

Abstract

Call placement to or from satellite UEs is optimized by reducing IMS message exchanges, the originating party has control over QoS parameters, a HPA subscription service is made available, and calls to a terminating satellite UE that is shielded from satellite coverage are completed by selectively employing HPA pages. For a call request without preconditions, an IMS node associated with an originating UE uses the NRSCPA on Offer instead of using the standard terminating node initiated NRSCPA on Answer. An IMS node associated with a terminating UE checks for HPA subscription by the user. If subscribed, the terminating INVITE request is for a “Conversational” or “Interactive” service, and the terminating UE is in PMM_IDLE state, the satellite RAN pages the terminating UE using HPA.

What is claimed is: 
     
         1 . A method of establishing a telecommunication session with a motile satellite terminal having an IP Multimedia System (IMS) client, comprising:
 establishing an IMS Packet Data Protocol (PDP) context activation by a Proxy Call Session Control Function (P-CSCF) associated with the calling User Equipment (UE) prior to exchanging any Session Initiation Protocol (SIP) signaling with a proxy associated with the called UE; and   using a High Penetration Alert (HPA) directed to the called UE only if the called UE subscribes to a HPA service, and only for calls having a conversational or interactive traffic class.   
     
     
         2 . The method of  claim 1  wherein establishing an IMS PDP context activation comprises initiating a Network Requested Secondary POP Context Activation (NRSPCA) on Offer. 
     
     
         3 . The method of  claim 2  wherein initiating a NRSPCA on Offer comprises the P-CSCE associated with the calling UE requesting a NRSPCA on Offer from a Policy and Charging Rule Function (PCRF) associated with the calling UE. 
     
     
         4 . The method of  claim 3  wherein requesting a NRSPCA on Offer from the PCRF comprises the P-CSCF sending the PCRF an Authorize and Authenticate Request (AAR). 
     
     
         5 . The method of  claim 3  wherein requesting a NRSPCA on Offer from the PCRF comprises the P-CSCE sending the PCRF an Attribute-Value Pair (AVP) indicating NRSPCA on Offer. 
     
     
         6 . The method of  claim 2  wherein initiating NRSPCA on Offer further comprises the PCRF
 sending a Packet Data Protocol (POP) context activation request to a Gateway GPRS Service Node (GGSN) associated with the calling UE; and 
 withholding an acknowledgement to the P-CSCF until receiving an indication of successful POP context activation from the GGSN. 
 
     
     
         7 . The method of  claim 6  wherein the PCRF sending a PDP context activation request to the GGSN comprises sending a Diameter Re-Auth-Request (RAR) message to the GGSN. 
     
     
         8 . The method of  claim 6  wherein initiating a NRSCPA on Offer further comprises the GGSN sending a POP context activation request to a Serving GPRS Support Node (SGSN) associated with the calling UE. 
     
     
         9 . The method of  claim 8  wherein initiating a NRSPCA on Offer further comprises
 the GGSN sending a PDP context activation request to the calling UE; and 
 the GGSN, SGSN, and calling UE cooperatively creating the PDP context activation. 
 
     
     
         10 . The method of  claim 1  wherein using a HPA only for calls having a conversational or interactive traffic class comprises a Serving GPRS Support Node (SGSN) mapping an Allocation Retention Policy (ARP) to a paging cause and sending a HPA to a UE based on a value of the paging cause. 
     
     
         11 . The method of  claim 1  wherein using a HPA directed to the called UE comprises
 receiving an SIP INVITE message by a P-SCSF associated with the called UE; 
 the P-SCSF associated with the called UE requesting a preliminary Quality of Service (QoS) authorization from a Policy and Charging Rule Function (PCRF) associated with the called UE; and 
 if the called UE has a HPA subscription, the PCRF associated with the called UE requesting a Gateway GPRS Service Node (GGSN) associated with the calling UE to perform a Network Requested Secondary POP Context Activation (NRSPCA) with HPA. 
 
     
     
         12 . An IP Multimedia System (IMS) network node operative to receive a Session Initiation Protocol (SIP) INVITE message from an originating User Equipment (UE) and, in response to the contents of the SIP INVITE message, establish an IMS Packet Data Protocol (PDP) context activation prior to exchanging any SIP signaling with a proxy associated with a terminating UE. 
     
     
         13 . The IMS node of  claim 12  wherein the node establishes a PDP context by initiating a Network Requested Secondary POP Context Activation (NRSCPA) on Offer procedure. 
     
     
         14 . The IMS node of  claim 12  wherein the node is operative to establish a POP context activation prior to exchanging any SIP signaling with a proxy associated with a terminating UE if a configurable system parameter is set to indicate POP context activation on Offer. 
     
     
         15 . The IMS node of  claim 14  wherein the node is operative to establish a PDP context activation prior to exchanging any SIP signaling with a proxy associated with a terminating UE if a Require header field and a Supported header field in the received SIP INVITE message do not contain preconditions and the SDP portion of the INVITE message does not contain “desired QoS” and “current QoS.” 
     
     
         16 . An IP Multimedia System (IMS) network node operative to receive a Session Initiation Protocol (SIP) INVITE message from another IMS node and, in response to the contents of the SIP INVITE message and further in response to a called party identified in the SIP INVITE message subscribing to a High Penetration Alert (HPA) paging service, page User Equipment (UE) associated with the called party using a HPA page. 
     
     
         17 . The IMS node of  claim 15  wherein, if the called party does not subscribe to a HPA service, sending a SIP INVITE message to the called party's UE. 
     
     
         18 . The IMS node of  claim 15  wherein the node pages the called party's UE using a HPA page only if the received SIP INVITE message identifies a Traffic Class as Conversational or Interactive. 
     
     
         19 . The IMS node of  claim 17  wherein the node further pages the called party's UE using a HPA page only if the called party's UE is in a Packet Mobility Management (PMM) state of PMM_IDLE.