Transparent Proxy for GTP-U Tunnel and Bearer IP Association
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Solution Overview
Problem
Current 3GPP specifications for Selective IP Traffic Offload in UMTS and LTE networks do not provide methods for associating unidirectional GTP-U tunnels and their corresponding bearer IP addresses, especially when control plane information is encrypted, which hinders effective content caching and traffic offload in Radio Access Networks.
Innovation Solution
A method is developed to learn and identify associations between unidirectional GTP-U tunnels and their bearer IP addresses using a device acting as a transparent proxy in the Radio Access Network, intercepting both user and control plane protocols on the S1 interface, even when control plane information is encrypted, and to detect mobility of user equipment across different eNodeBs or RNCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a transparent proxy device intercepts user plane and control plane protocols on the S1 interface to enable content caching and traffic offload, then content caching and traffic offload efficiency is improved, but the device cannot associate unidirectional GTP-U tunnels with bearer IP addresses when control plane information is encrypted
Solution Approach 1:
The patent introduces an intermediary mechanism (the transparent proxy device) that mediates between the user plane and control plane by intercepting and correlating packets from both planes. This intermediary correlates GTP-U tunnel identifiers from user plane packets with bearer IP addresses from control plane packets, enabling association even when control plane information is encrypted, thus resolving the contradiction between improving caching efficiency and maintaining information accessibility.
2Productivity
If the transit network device forwards packets based on bearer plane IP addresses and encapsulates traffic with GTP-U tunnel IDs, then traffic offload function is improved, but the device cannot properly associate tunnels when acting as a transparent proxy without control plane visibility
Solution Approach 1:
The patent implements a feedback mechanism where the transparent proxy device monitors and correlates control plane signaling messages with user plane data packets. By observing the bidirectional interaction between control plane setup messages and subsequent user plane traffic, the device automatically learns and maintains the mapping between GTP-U tunnel identifiers and bearer IP addresses, simplifying the association process while maintaining accurate traffic offload functionality.
Data Source
AI summary
A method of learning and identifying two unidirectional GTP-U tunnels corresponding to a user equipment (UE) in a device placed in a LTE network, where the device acts as a transparent proxy intercepting user plane and control plane protocols on the S1 interface, is disclosed. Methods of pairing the two unidirectional tunnels that belong to same UE, when there is no control plane information or when there is Control Plane information, but the NAS portions of the S1 Control that contain bearer IP addresses are encrypted, are disclosed. Control plane and user plane methods for associating GTP-U tunnels and the corresponding bearer plane IP addresses are identified. Additionally, methods for detecting mobility of a UE, as it moves from the coverage area of one E-NodeB to another, are disclosed. Methods for constructing an eNodeB topology map are also disclosed.