SRVCC Media Gateway Selection via IMS Feedback
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Solution Overview
Problem
During Single Radio Voice Call Continuity (SRVCC) handovers from Packet Switched (PS) to Circuit Switched (CS) access networks, existing methods lead to speech quality degradation and inefficient resource use due to unknown codec selection and sub-optimal allocation of Media Gateways (MGWs), resulting in transcoding and inefficient node seizures.
Innovation Solution
A method where the Mobile Switching Centre (MSC) server obtains an indication of already-seized MGWs from the IMS network, selects an appropriate MGW based on this information, and initiates resource allocation and session transfer, allowing for optimal MGW selection and codec specification to avoid transcoding and reduce node seizures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If an MGW is selected without obtaining indication of already-seized MGWs, then the handover procedure is simpler and faster, but speech quality degrades and resources are used inefficiently due to transcoding
Solution Approach 1:
The patent applies preliminary action by obtaining indication of already-seized MGWs from the IMS network before selecting an MGW for the handover. This allows the MSC server to make an informed selection that avoids transcoding and ensures speech quality continuity, rather than making a hasty selection without sufficient information.
Solution Approach 2:
The patent uses feedback by obtaining indication information about already-seized MGWs from the IMS network. This feedback mechanism provides the MSC server with knowledge of existing MGW allocations, enabling it to select an appropriate MGW that maintains speech quality and avoids unnecessary transcoding operations.
2Productivity
If codec selection is made without obtaining indication from IMS network, then the handover process is faster, but transcoding occurs causing speech quality degradation
Solution Approach 1:
The patent applies preliminary action by obtaining codec indication information from the IMS network before finalizing the handover. This allows the MSC server to pre-determine the appropriate codec selection, avoiding the need for transcoding during handover and maintaining speech quality while still achieving efficient processing.
Solution Approach 2:
The patent uses feedback by receiving indication of the codec in use from the IMS network. This feedback enables the MSC server to make an informed codec selection that matches the existing session parameters, thereby avoiding transcoding operations that would degrade speech quality.
3Adaptability or versatility
If multiple MGWs are seized for different sessions, then resource allocation is more flexible, but resource wastage increases due to sub-optimal MGW selection
Solution Approach 1:
The patent applies universality by enabling a single MGW to serve multiple sessions when appropriate. By obtaining indication of already-seized MGWs and selecting from these existing resources, the system allows one MGW to handle multiple sessions, reducing the need to seize additional MGWs and thereby reducing resource wastage while maintaining allocation flexibility.
Solution Approach 2:
The patent applies parameter changes by optimizing MGW selection based on obtained indication information. The MSC server changes the selection parameters to consider existing MGW allocations, enabling more efficient resource utilization through informed decision-making rather than random or simplistic selection.
4Device complexity
If MGW selection is made without obtaining indication from IMS, then the signaling requirements are reduced, but node seizures become inefficient
Solution Approach 1:
The patent applies preliminary action by obtaining indication of already-seized MGWs from the IMS network before the handover process. This preliminary information gathering enables the MSC server to make efficient MGW selection decisions, improving node seizure efficiency while the signaling overhead remains manageable as it occurs once during the handover preparation phase.
Data Source
AI summary
A mechanism is presented for performing a session transfer with Single Radio Voice Call Continuity, SRVCC, from a Packet Switched, PS, access to a Circuit Switched, CS, access of a telecommunications session that has been established over the PS access via an IP Multimedia Subsystem, IMS, network. The method includes receiving a request for the transfer of the session to the CS access. An indication of an already-seized media gateway, MGW, that has been established for use in one or more other sessions over the CS access is obtained from the IMS network. A MGW is selected as a Mobile-Media Gateway, M-MGW, for the session based on the obtained indication. Allocation of resources for the session in the CS access network is initiated, including specifying the MGW to be used as the Mobile-Media Gateway, M-MGW. Transfer of the session to the CS access is then initiated.