Home NodeB Control Message Modification for SRVCC Handover
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Solution Overview
Problem
Current wireless communication systems lack a mechanism to seamlessly handover voice calls between Home NodeBs and macrocells for UEs with and without Single Radio Voice Call Continuity (SRVCC) capability, leading to suboptimal use of VoIP and increased load on core networks.
Innovation Solution
A functional component in the Home NodeB subsystem modifies control messages to simulate SRVCC capability for legacy UEs and strips SRVCC extensions from handover commands when necessary, allowing for transparent handover procedures between IMS and CS domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the network implements different handout procedures based on UE capabilities, then SRVCC-capable UEs can use VoIP handover, but the system complexity increases and legacy UEs cannot benefit from SRVCC
Solution Approach 1:
The HNB acts as an intermediary between the core network and UEs, modifying control messages to simulate SRVCC capability for legacy UEs. This allows the HNB to present a unified interface to the core network, enabling SRVCC handover for all UEs while maintaining backward compatibility with legacy devices that do not natively support SRVCC.
Solution Approach 2:
The HNB modifies parameters in control messages (specifically setting the SRVCC capability indicator) to change the perceived capability status of UEs. By altering these message parameters, the HNB enables SRVCC handover procedures to be applied uniformly across different UE types without requiring the core network to distinguish between SRVCC-capable and legacy UEs.
2Adaptability or versatility
If legacy UEs without SRVCC capability are served through HNB, then they can use CS procedures, but they cannot benefit from VoIP handover even when macrocells support it
Solution Approach 1:
The HNB creates a virtual copy of SRVCC capability information for legacy UEs by modifying control messages. This simulated capability information allows the core network to treat legacy UEs as SRVCC-capable, enabling VoIP handover procedures to be applied to them even though they do not natively support SRVCC, thereby improving voice service quality and handover reliability.
3Device complexity
If the core network treats all calls as IMS PS calls through HNB, then handover procedures are simplified, but legacy UEs without IMS clients cannot properly utilize CS procedures
Solution Approach 1:
The HNB serves as an intermediary that translates between different capability representations. It modifies control messages to present a unified SRVCC-capable interface to the core network, while internally managing the differences between SRVCC-capable and legacy UEs. This allows the core network to use simplified handover procedures for all UEs while the HNB ensures proper capability matching at the radio access level.
Data Source
AI summary
There is described a method of processing control messages received by a wireless communication network from a wireless communication device. The method comprises: monitoring received control messages sent by the wireless communication device to identify control messages conveying information indicating whether or not the wireless communication device has a handover capability associated with performing a handover between the packet-switched and circuit-switched domains; for any such identified control message which indicates that the corresponding wireless communication device does not have said handover capability, modifying the control message to indicate that said corresponding wireless communication device does have said handover capability and forwarding the modified control message to the core network; and storing data indicative of whether or not the wireless communication device has said handover capability.