EPC Node Mimicking SGSN for CS Voice in LTE
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Solution Overview
Problem
Mobile terminals operating in packet-switched-only networks cannot receive circuit-switched voice calls due to lack of registration mechanisms and signaling for paging messages, and are restricted to using either packet-switched or circuit-switched services simultaneously, limiting user experience and network efficiency.
Innovation Solution
A network node and method that mimics the messaging functionality of a Serving GPRS Service Node (SGSN) in a packet-switched-only network, connecting to a Mobile Switching Center/Visitor Location Register (MSC/VLR) via a Gs interface to forward paging messages and enable circuit-switched voice calls, while the mobile terminal switches between packet-switched and circuit-switched communication protocols as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a mobile terminal operates in a packet-switched-only network, then it can use PS services with high bandwidth, but it cannot receive circuit-switched voice calls
Solution Approach 1:
The patent introduces a gateway as an intermediary component that bridges the packet-switched network and the circuit-switched network. This gateway translates and forwards paging messages between the two network domains, enabling the mobile terminal to receive CS voice calls while operating in the PS-only network without requiring dual radio capabilities or simultaneous network connectivity.
2Adaptability or versatility
If a mobile terminal supports both CS and PS services, then it can receive CS voice calls in combined networks, but it cannot use more than one radio technology at the same time due to battery consumption and interference
Solution Approach 1:
The patent segments the network functionality by separating the PS-only network operations from CS voice call reception. The mobile terminal maintains its PS connection continuously while the gateway handles CS network interactions separately, allowing the terminal to use a single radio technology at any given time while still supporting both service types through network-side intelligence.
Solution Approach 2:
The gateway acts as an intermediary that manages the terminal's interactions with both network types. It translates paging messages from the CS network into PS-compatible formats, allowing the terminal to receive CS calls without directly connecting to the CS network, thus avoiding the need for simultaneous multi-radio operation.
3Quantity of substance
If a mobile terminal uses a PS-only network, then it maintains high bandwidth for data services, but there is no signaling mechanism for forwarding paging messages from MSC/VLR to the mobile terminal
Solution Approach 1:
The gateway serves as a messaging intermediary that receives paging messages from the MSC/VLR in the CS network and translates them into appropriate PS network messages that can be delivered to the mobile terminal through the PS network infrastructure. This ensures no loss of paging information while maintaining PS-only network operation.
Solution Approach 2:
The gateway creates a copy of the CS paging message and translates it into the PS domain messaging format. This copying mechanism ensures that the essential information from the original CS paging message is preserved and delivered to the terminal through the PS network, bridging the signaling gap between the two network types.
4Reliability
If operators implement CS voice services, then they provide reliable voice calling, but they must heavily invest in VoIP services infrastructure
Solution Approach 1:
The gateway serves as a cost-effective intermediary that enables CS voice service delivery through the PS network without requiring full VoIP infrastructure implementation. By translating and forwarding paging messages between networks, it allows operators to maintain CS voice reliability while avoiding the heavy investment needed for complete VoIP deployment.
Data Source
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AI summary
A network node, method, and mobile terminal for providing circuit-switched (CS) voice calls to a mobile terminal operating in a packet-switched (PS)-only network. A control node such as an EPC node in an SAE/LTE PS-only network is modified to mimic the messaging functionality of a Serving GPRS Service Node (SGSN). The EPC node is connected to an MSC/VLR in a CS network through a Gs interface. The EPC node registers the terminal with the MSC/VLR and provides a VLR TMSI to the terminal. When the MSC/VLR receives an incoming CS voice call for the terminal, the MSC/VLR notifies the EPC node, which sends a paging message to the terminal. To set up the CS voice call, the terminal sends a paging response directly to the MSC/VLR.