Dual SIM Dual Standby Packet Data Session Tear Down

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Solution Overview

Problem

In wireless communication systems, particularly in dual subscriber identity module (SIM) dual standby user equipment (UE), there is a challenge in efficiently transitioning packet data sessions from one radio access technology (RAT) to another, leading to data stall issues due to lingering sessions on the old RAT subscription after a transition to a new RAT subscription.

Innovation Solution

The method involves transitioning a packet data session from a first RAT associated with a first subscription to a second RAT associated with a second subscription and transmitting specific messages, such as a Packet Data Network (PDN) Disconnect Request or PDU Session Release Request, to tear down the packet data session over the first RAT, ensuring seamless routing of data to the appropriate subscription.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a packet data session is transitioned from a first RAT to a second RAT in a DSDS UE, then data routing to the new subscription is achieved, but data stall issues occur due to lingering sessions on the old RAT

Engineering Contradiction:

ImproveRAT subscription transition capabilityVSAvoiddata session continuity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by proactively initiating the tear down of the packet data session on the first RAT before or during the transition to the second RAT. The UE sends a PDN Disconnect Request message to the network to preemptively close the old session, preventing data stall issues that would occur if the old session lingered. This advance action ensures clean session transition without data routing conflicts.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the packet data session is torn down on the first RAT after transition to the second RAT, then data stall problems are resolved, but additional signaling messages are required

Engineering Contradiction:

Improvedata session transition efficiencyVSAvoidsignaling message overhead

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent extracts the necessary tear down signaling from the overall session transition process by sending a dedicated PDN Disconnect Request message specifically for closing the session on the first RAT. This separates the session termination function from the session establishment on the second RAT, allowing independent optimization of each phase while maintaining clear procedural boundaries.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If downlink packet data is received on the first RAT after transition to the second RAT, then data routing correctness is verified, but latency is introduced requiring triggered message transmission

Engineering Contradiction:

Improvedata routing accuracyVSAvoidsession tear down latency

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements feedback by monitoring for downlink packet data arrival on the first RAT after transition to the second RAT. When downlink data is detected on the old RAT, this triggers the transmission of the PDN Disconnect Request message to tear down the lingering session. The feedback mechanism ensures the tear down action is taken only when necessary, optimizing the balance between data routing verification and minimizing unnecessary signaling latency.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20240022974A1Tearing down a packet data session after a transition to a different subscription of a dual subscriber identity module dual standby user equipment

Publication Date: 2024.01.18 QUALCOMM INC

AI summary

Disclosed are techniques for wireless communication. In an aspect, a subscriber identity module (SIM) dual standby (DSDS) user equipment (UE) may transition a packet data session from a first radio access technology (RAT) associated with a first subscription to a second RAT associated with a second subscription, and may further transmit, over the first RAT responsive to the packet data session transition to the second RAT, one or more messages to tear down the packet data session over the first RAT.