HSS DDN Failure Flags for Mobile-Terminated Service Reliability
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Solution Overview
Problem
Existing solutions for supporting mobile-terminated application services in Power Saving Mode (PSM) are inefficient, leading to issues like packet discard, frequent retransmissions, and unnecessary signaling costs, particularly for devices in long PSM durations.
Innovation Solution
A method that enables network applications to trigger mobile-terminated services by pre-configuring the Home Subscriber Server (HSS) to notify associated network applications when a User Equipment (UE) becomes reachable again after a Downlink Data Notification failure, using dynamic 'DDN failure' flags to manage UE reachability across subscribed Access Point Names (APNs).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network sends downlink data to a UE in Power Saving Mode, then the UE can receive mobile-terminated services, but the network incurs unnecessary signaling costs and packet loss due to UE unreachability
Solution Approach 1:
The network performs preliminary actions by detecting UE unreachability early through Downlink Data Notification failures and setting DDN failure flags before actual data transmission attempts. This allows the network to proactively manage data buffering and retry strategies, preventing unnecessary signaling to unreachable UEs while ensuring reliable delivery when UEs become reachable again.
Solution Approach 2:
The network implements feedback mechanisms by monitoring UE reachability status through DDN responses and updating DDN failure flags accordingly. When UEs become reachable again, the network receives feedback through TAU/RAU procedures or direct data transmission success, allowing dynamic adjustment of data forwarding strategies and reducing signaling costs by avoiding repeated attempts to unreachable UEs.
2Reliability
If the network retries data transmission to unreachable UEs, then delivery reliability improves, but network resources are wasted through frequent retransmissions
Solution Approach 1:
The network sets DDN failure flags as a preliminary action when initial data transmission fails, marking these packets for special handling. This preliminary marking allows the network to differentiate between reachable and unreachable UE data transmissions, enabling efficient resource allocation by buffering data for unreachable UEs rather than immediately retrying or discarding.
Solution Approach 2:
The network changes the state parameter of data packets by setting DDN failure flags, transforming normal data packets into marked packets that trigger different handling procedures. This parameter change enables the network to track and manage data for unreachable UEs separately, improving resource efficiency by avoiding futile retransmissions while maintaining delivery reliability through conditional retry mechanisms.
3Reliability
If the network buffers data for unreachable UEs, then delivery reliability improves, but data transmission delay increases
Solution Approach 1:
The network dynamically adjusts data buffering and forwarding based on UE reachability status. When DDN failure flags indicate UE unreachability, data is buffered with delayed forwarding. When UEs become reachable (detected through TAU/RAU or successful data transmission), the network immediately forwards buffered data, minimizing delay while ensuring delivery reliability.
Solution Approach 2:
The network uses DDN failure flags as state parameters to dynamically change data transmission behavior. Packets marked with DDN failure flags undergo different timing handling - buffered during UE unreachability and forwarded when reachable. This parameter-based dynamic handling balances delivery guarantee with minimal delay by adapting transmission timing to actual UE availability.
Data Source
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AI summary
In an embodiment, there is provided a method for support of mobile-terminated application services in a mobile system, said method comprising: - based on a User Equipment UE subscription, enabling, for one or more subscribed Access Point Name APN, triggering of at least one network Application associated with a given of said one or more APN, upon said UE being reachable again after failure of a mobile network procedure to reach said UE via a Packet Data Network PDN connection established for said UE and said APN.