IMS Call Setup Optimization via Selective HPA and NRSPCA
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Solution Overview
Problem
In satellite-based IP Multimedia Subsystem (IMS) networks, call setup times are prolonged due to excessive SIP messaging and inefficient use of satellite radio resources when establishing calls between satellite User Equipments (UEs), especially when the called UE is out of satellite coverage, leading to increased latency and resource consumption.
Innovation Solution
Implementing Network Requested Secondary PDP Context Activation (NRSPCA) on Offer and selectively using High Penetration Alert (HPA) pages to optimize IMS message exchanges, allowing the originating AS to control QoS parameters and reduce unnecessary messaging by checking for HPA subscriptions before initiating NRSPCA and HPA pages only for conversational or interactive calls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If HPA pages are transmitted on every SIP INVITE to reach satellite UEs, then call establishment reliability is improved, but satellite radio resource consumption increases significantly
Solution Approach 1:
The patent changes the parameter of HPA page transmission from universal (every SIP INVITE) to selective (based on service type and subscription status). The system modifies transmission parameters by checking service subscriptions and call types before initiating HPA pages, thereby reducing unnecessary transmissions while maintaining reliability for eligible calls.
Solution Approach 2:
Instead of applying HPA pages universally to all calls, the patent implements partial action by selectively applying them only to conversational and interactive calls where the subscriber has appropriate service subscriptions. This partial application reduces overall resource consumption while maintaining effectiveness for targeted scenarios.
2Reliability
If NRSPCA on Answer is used for satellite calls, then network resource reservation is improved, but call setup time increases due to extensive SIP messaging
Solution Approach 1:
The patent implements preliminary action by performing NRSPCA on Offer rather than on Answer. This allows the PDP context to be activated and network resources to be reserved earlier in the call setup process, before the actual answer is received, thereby reducing the overall call setup time while maintaining resource reservation reliability.
Solution Approach 2:
The patent skips the traditional NRSPCA on Answer sequence by rushing through the resource activation earlier in the offering phase. This accelerates the call setup process by eliminating the delay of waiting for answer confirmation before activating the PDP context, thus reducing SIP messaging rounds and overall setup time.
3Device complexity
If standard NRSPCA on Answer procedure is followed, then resource allocation control is improved, but the number of SIP message exchanges increases
Solution Approach 1:
The patent performs resource allocation control preliminarily through NRSPCA on Offer, allowing the PCRF to establish charging rules and activate PDP contexts before the call is answered. This preliminary resource allocation maintains control while reducing the number of subsequent SIP message exchanges needed for resource setup.
Solution Approach 2:
The patent extracts the resource allocation and activation steps from the traditional NRSPCA on Answer sequence and moves them to the offering phase. By taking out these critical resource management functions and performing them earlier, the system maintains allocation control while streamlining the overall signaling flow and reducing message exchanges.
Data Source
AI summary
IMS nodes and a satellite radio access node (RAN) are described herein which are operative to establish certain calls (e.g., voice calls) with reduced latency and selectively using a High Penetration Alert (HPA) page to reach a terminating satellite user equipment (UE).