UPF Packet Detection Rules for Early TCP Policy Binding
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Solution Overview
Problem
Current 3GPP standards lack a mechanism for non-UE-based applications to activate Transport Control Protocol (TCP)-based application flows for quality-of-service (QoS) and charging control, as the source TCP port is only known after the connection is established, making it difficult to map flows to policies before the connection begins.
Innovation Solution
Utilizing the Type-of-Service (ToS) field in uplink packets, combined with client or server IP or Server Name Indication (SNI), to bind the 5-tuple of a new connection to existing Policy and Charging Control (PCC) rules, and modifying Packet Detection Rules (PDRs) in the User Plane Function (UPF) to handle downlink traffic according to the PCC rule, even without ToS marking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the source TCP port is used to identify traffic flows for policy mapping, then flow identification accuracy is improved, but the ability to apply policies before connection establishment deteriorates because the source port is only known after TCP connection is established
Solution Approach 1:
The patent applies preliminary action by pre-configuring Packet Detection Rules (PDRs) in the UPF with placeholders for 5-tuple information before TCP connections are established. The PCC rule is prepared in advance with the ability to match traffic using alternative criteria (destination port, IP addresses, protocol type) so that policy activation can occur before the source port is known, resolving the timing conflict while maintaining identification accuracy.
Solution Approach 2:
The patent introduces an intermediary mechanism where the UPF uses partial 5-tuple information (excluding source port) combined with ToS field values to temporarily identify and apply policies to TCP flows before complete 5-tuple information is available. This intermediary approach allows policy application to bridge the gap between connection establishment and full flow identification.
2Reliability
If explicit signaling of 5-tuples is used for each TCP connection to activate QoS policies, then policy activation reliability is improved, but signaling overhead increases
Solution Approach 1:
The patent applies self-service by enabling the UPF to automatically match incoming TCP packets against pre-configured PCC rules using packet content (destination port, IP addresses, protocol, ToS field) without requiring explicit 5-tuple signaling from the application layer. The system serves itself by deriving flow identification information directly from the traffic packets, eliminating the need for additional signaling messages while maintaining reliable policy activation.
Solution Approach 2:
The patent extracts the essential flow identification elements (destination port, IP addresses, protocol type, ToS field) from the complete 5-tuple, separating these necessary identifying characteristics from the source port information that becomes available too late. This extraction allows policy matching to proceed with the available information subset, reducing signaling requirements while maintaining sufficient reliability for TCP flow identification.
3Adaptability or versatility
If the Type-of-Service field is used to trigger PCC rule binding for TCP flows, then the ability to apply policies before connection establishment is improved, but compatibility with existing TCP traffic handling deteriorates
Solution Approach 1:
The patent applies universality by designing the PDR matching mechanism to handle multiple packet types and scenarios through a unified approach. The same PDR structure and matching logic process both UDP traffic (where 5-tuples are known beforehand) and TCP traffic (where source ports become available during connection establishment). The ToS field serves as a universal trigger that works across different traffic types, enabling consistent policy activation capabilities without requiring separate handling paths.
Data Source
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AI summary
A method in a User Plane Function (UPF) comprising receiving from a Policy Control Function (PCF), an instruction to create a new Packet Detection Rule (PDR), the instruction comprising an IP address for the wireless device, a value of a ToS field, and a quality-of-service, QoS, reference or charging policy. The method further comprises storing the IP address, the value of the ToS field, and the QoS reference or charging policy as a predetermined PDR. The method further comprises subsequently receiving, from a wireless device, a first packet targeted to an application server, AS, mapping the first packet to the predetermined PDR, based on a value of a ToS, field in the first packet, and adding a 5-tuple associated with the first packet to the predetermined PDR. This serves to bind the new connection to the PDR.