Mobility Management Node EPC Session Reuse for LTE-WLAN Handover
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Solution Overview
Problem
Conventional Wi-Fi access deployments face inefficiencies in handover scenarios due to extensive signaling and latency, lack of location information for untrusted access, and difficulty in access steering, particularly when handovers occur between LTE and Wi-Fi networks.
Innovation Solution
A method involving a mobility management node that selects a Packet Data Network Gateway (PGW) and Serving Gateway (SGW) based on an access point name (APN), generates session requests with TEID parameters, and establishes control and user plane tunnels to manage handovers efficiently, while also utilizing location information and access selection mechanisms to optimize network performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional Wi-Fi access deployment is used with separate authentication and session management, then integration with mobile core network is achieved, but extensive signaling occurs during handover between LTE and Wi-Fi
Solution Approach 1:
The patent combines authentication and session management functions into a unified EPC session framework. The mobility management node integrates both LTE and Wi-Fi session contexts, allowing the network to maintain a single consolidated session rather than separate authentication and session establishment procedures. This merging eliminates redundant signaling during handover between LTE and Wi-Fi access types.
Solution Approach 2:
The mobility management node pre-establishes session contexts for both LTE and Wi-Fi access types before handover occurs. When a handover is initiated, the node can immediately activate the pre-configured session without requiring new authentication or session setup procedures. This preliminary preparation of session contexts significantly reduces handover latency.
2Reliability
If new session is created during handover between LTE and Wi-Fi, then connectivity is maintained, but signaling overhead increases
Solution Approach 1:
The mobility management node creates a copy of the existing EPC session context for the target access type before handover. Instead of establishing a completely new session, the node replicates the necessary session parameters and identifiers, allowing rapid activation of connectivity on the new access type while minimizing signaling exchanges with the core network.
Solution Approach 2:
The patent implements a mechanism where the mobility management node maintains multiple session contexts simultaneously (for both source and target access types) and selectively activates or deactivates them during handover. The old session context is preserved but deactivated, while the new context is activated. This approach ensures connectivity continuity while avoiding the need to completely re-establish sessions, thereby reducing signaling overhead.
3Reliability
If PGW recreates dedicated bearers during handover, then bearer continuity is ensured, but handover latency increases
Solution Approach 1:
The mobility management node pre-configures dedicated bearer contexts for both LTE and Wi-Fi access types, including all necessary QoS parameters and tunnel endpoint identifiers. Before handover occurs, the bearer contexts are prepared and validated, allowing the node to simply activate the appropriate bearer on the target access type without recreating it during handover. This preliminary preparation ensures bearer continuity while minimizing handover latency.
4Adaptability or versatility
If S6b procedure is used to set PGW id in HSS, then handover support is enabled, but HSS load and AAA load increase
Solution Approach 1:
The patent extracts the PGW identification and session management functions from the HSS and concentrates them in the mobility management node. The S6b procedure between PGW and HSS is replaced by local session context management at the mobility management node, which maintains both LTE and Wi-Fi session contexts. This extraction eliminates the need for frequent S6b signaling during handover, significantly reducing HSS and AAA load while maintaining full handover support.
Data Source
AI summary
A method performed in a mobility management node includes the mobility management node receiving a first Packet Data Network (PDN) activation request from a wireless local area network (WLAN) access gateway, the first PDN activation request specifying an access point name (APN) and a tunnel endpoint identifier (TEID) parameter for identifying the WLAN access gateway, the WLAN access gateway connected to a user equipment (UE). The method further includes in response to receiving the PDN activation request, the mobility management node (i) selecting a Packet Data Network Gateway (PGW) based on the specified APN, (ii) generating a second PDN activation session request that includes the TEID parameter for identifying the WLAN access gateway, (iii) selecting a serving gateway (SGW), and (iv) forwarding the second PDN activation request to the selected SGW.