SDT Termination Signaling for RRC Inactive Uplink Sessions
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Solution Overview
Problem
In cellular communication networks with a radio access network architecture split into centralized baseband units and distributed radio units, there is a challenge in terminating ongoing small data transmission (SDT) transactions comprising multiple uplink small data transmissions without transitioning the user equipment (UE) to an RRC connected state.
Innovation Solution
A client device determines whether an ongoing SDT transaction should be terminated and sends a radio resource control (RRC) message with termination information to the control plane network node device, which initiates the termination procedure based on the received information, allowing the UE to transition back to an inactive RRC state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the RAN architecture is split into centralized baseband units and distributed radio units, then performance and cost benefits are achieved, but the ability to terminate ongoing SDT transactions is lost
Solution Approach 1:
The patent segments the RAN into centralized baseband units (BBUs) and distributed radio units (DRUs), with further division between control plane nodes and user plane nodes. This segmentation enables independent termination functions at different network levels, resolving the contradiction by allowing termination capability to exist at the control plane level even when the radio access is distributed.
Solution Approach 2:
The patent introduces intermediary signaling mechanisms (RRC messages, termination indicators) that mediate between the distributed radio units and centralized baseband units. These intermediaries carry termination information across the split architecture, enabling coordination and termination capability despite the physical separation of functions.
2Loss of substance
If the client device remains in RRC inactive state for multiple small data transmissions, then signaling overhead is reduced, but the ability to terminate the transaction timely is compromised
Solution Approach 1:
The patent enables preliminary termination action by allowing the client device to send termination indicators before completing the full SDT transaction. This preliminary action allows the network to prepare for termination in advance, reducing both signaling overhead by avoiding unnecessary message exchanges and time delay by initiating termination early in the transaction process.
Solution Approach 2:
The patent implements feedback mechanisms where the client device provides termination preferences or indicators to the network, and the network responds with appropriate termination actions. This feedback loop enables timely transaction termination while maintaining low signaling overhead through efficient use of RRC messages and termination indicators.
3Reliability
If the client device sends termination information via RRC message, then SDT transaction can be terminated, but additional signaling is required
Solution Approach 1:
The patent merges termination information with existing RRC messages and uplink small data transmissions. Instead of requiring separate dedicated termination messages, the termination indicators are combined with data transmissions or existing control messages, thereby achieving reliable transaction termination without proportionally increasing signaling overhead.
Solution Approach 2:
The patent makes RRC messages multi-functional by enabling them to carry both data transmission information and termination indicators simultaneously. This universality allows a single message type to serve multiple purposes, achieving reliable termination capability while minimizing additional signaling requirements.
Data Source
AI summary
Devices, methods and computer programs for small data transmission, SDT, transaction termination are disclosed. A client device determines whether an ongoing small data transmission, SDT, transaction comprising one or more uplink, UL, small data transmissions with a control plane network node device is to be terminated. If yes, a radio resource control, RRC, message comprising termination information related to the determined termination of the ongoing SDT transaction is forwarded from the client device to the control plane network node device.