NB-IoT Reestablishment Redirection to Preserve Pending Data
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Solution Overview
Problem
NB-IoT devices do not support handover, leading to loss of pending data and increased latency when redirecting communications to new cells in high mobility environments like NTNs, which can result in reduced reliability and battery consumption.
Innovation Solution
A reestablishment procedure with redirection is performed by sending an RRC message to NB-IoT devices to switch communications to a second cell, preserving pending data and reducing latency and battery consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover is used for redirecting NB-IoT devices to new cells, then communication continuity can be maintained, but NB-IoT devices do not support handover leading to loss of pending data and increased latency
Solution Approach 1:
The patent changes the procedural parameters of the redirection process by introducing a suspension mechanism. When a NB-IoT device receives a redirection command, it suspends pending uplink data transmissions and waits for confirmation from the target cell before aborting the reestablishment procedure. This parameter change (suspending rather than immediately aborting) preserves pending data while enabling redirection, resolving the contradiction between communication reliability and data loss.
2Device complexity
If redirection is performed without data preservation, then device complexity is reduced, but latency increases due to data loss and retransmission
Solution Approach 1:
The patent applies preliminary action by having the NB-IoT device suspend pending data transmissions before completing the redirection to the target cell. This preliminary suspension prevents data loss without requiring complex handover procedures. The device maintains the pending data in buffer during the redirection process, and only aborts the reestablishment procedure after receiving confirmation from the target cell, thereby reducing latency while keeping device complexity low.
3Speed
If NB-IoT devices perform reestablishment procedure without suspension, then redirection speed is improved, but pending data is lost requiring retransmission
Solution Approach 1:
The patent implements a feedback mechanism where the target cell sends a confirmation message to the NB-IoT device indicating whether to proceed with or abort the reestablishment procedure. This feedback allows the device to maintain pending data during redirection by suspending transmissions until confirmation is received. The feedback loop ensures data integrity while maintaining relatively fast redirection speed, as the device only waits for confirmation rather than performing full handover procedures.
Data Source
AI summary
Certain aspects of the present disclosure provide techniques for performing a reestablishment procedure to redirect communications for a device from a first cell to a second cell. For example, a network entity may send a radio resource control (RRC) message to the device, and the RRC message may include an indication for the device to redirect the communications to the second cell. Subsequently, the device may perform a reestablishment procedure to redirect the communications to the second cell based on receiving the RRC message. In some embodiments, the RRC message may be an RRC release message that includes an IE used to indicate redirection of the communications to the second cell. Additionally or alternatively, the RRC message may be an RRC reestablishment message that includes an IE used to indicate the redirection. In some embodiments, the device may operate in a control plane Internet of Things (IoT) optimization mode.