Extended SGs+ Interface for SMS Over LTE Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is no satisfactory system and method for providing circuit-switched (CS) services over SAE/LTE networks, particularly for supporting the Short Message Service (SMS) in CS Fallback and CSoLTE-Integrated networks.
Innovation Solution
An extended SGs interface (SGs+) is utilized for Mobility Management procedures, enabling the support of both Mobile Terminated and Mobile Originated SMS services by extending the non-access stratum (NAS) signaling between the User Equipment (UE) and the Mobility Management Entity (MME), allowing for the transmission of upper layer packet data units using connectionless or connection-oriented Signaling Connection Control Part (SCCP) operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only Packet Switched (PS) domain is specified for SAE/LTE networks, then network simplicity is improved, but circuit-switched (CS) services cannot be provided
Solution Approach 1:
The patent introduces an intermediary mechanism (SMS over SGs interface with extended NAS signaling) that enables CS service support without requiring full CS domain infrastructure. The SGs interface acts as a mediator between the PS domain (MME) and CS services (MSC-S), allowing SMS transmission while maintaining network simplicity.
Solution Approach 2:
The NAS signaling protocol is extended to serve multiple functions: it handles both standard LTE mobility management and CS service signaling (SMS). This multi-functionality allows the PS domain infrastructure to support CS services without requiring separate dedicated signaling paths.
2Adaptability or versatility
If CS Fallback or CSoLTE-Integrated networks are deployed, then CS service support is improved, but network complexity increases
Solution Approach 1:
The patent extracts only the essential CS service functionality (SMS) from the full CS domain, transmitting it over the existing PS domain infrastructure via extended NAS signaling. This avoids the complexity of implementing complete CS domain while retaining critical CS service capabilities.
Solution Approach 2:
The patent changes the operational parameters of the NAS signaling protocol to enable CS service support. By modifying existing signaling parameters and procedures rather than introducing entirely new protocols, the solution reduces implementation complexity compared to full CS domain deployment.
3Adaptability or versatility
If SAE/LTE bearers are deactivated during SMS operations, then SMS compatibility with traditional CS networks is improved, but service continuity deteriorates
Solution Approach 1:
The patent establishes the extended NAS signaling path and SGs+ interface in advance, before SMS operations begin. This preliminary configuration allows SMS to be transmitted over active SAE/LTE bearers without requiring bearer deactivation, maintaining both compatibility and service continuity.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A method of providing a circuit-switched, CS, service to a User Equipment, UE, over an SAE core network (11) and an LTE radio access network (12), said method comprising the steps of: extending an SGs interface to provide an SGs+ interface between a Mobility Management Entity, MME, in the SAE core network and a Mobile Switching Center Server, MSC-S, wherein the SGs+ interface supports transmission of upper layer packet data units; transferring CS service messages in SGs+ messages sent between the MSC-S and the MME utilizing the SGs+ interface, wherein the step of transferring CS service messages includes sending from the MSC-S to the MME, an SGs+ downlink data transfer message including upper layer packet data units destined for a terminating UE, or sending from the MME to the MSC-S, an SGs+ uplink data transfer message including upper layer packet data units originated by an originating UE; and transferring CS service message contents between the MME and the UE via the LTE radio access network in non access stratum, NAS, messages, wherein the CS service is a Short Message Service, SMS, and the step of transferring CS service messages includes sending from the MSC-S to the MME, an SGs+ downlink data transfer message, said SGs+ downlink data transfer message including SMS message content destined for the terminating UE. According to said method a system for providing a circuit-switched, CS, service to a User Equipment and an apparatus in a Mobility Management Entity are specified.