Transmitting Device RLC Poll Indicator Handling
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Solution Overview
Problem
In wireless communication networks, particularly in 5G technologies like New Radio (NR), there is no effective handling for situations where the PDCP suddenly turns off transmission to one RLC entity, leading to unacknowledged PDUs and potential retransmission issues, causing performance delays and potential failures due to missing poll indicators.
Innovation Solution
A method is implemented in a transmitting device with at least two RLC entities, where if the last transmitted PDU lacks a poll indicator, the device transmits a new or retransmits the same PDU with a poll indicator to ensure acknowledgment and prevent data retransmission errors, thereby maintaining accurate PDCP protocol operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the PDCP suddenly turns off transmission to one RLC entity, then resource allocation is optimized, but unacknowledged PDUs remain causing reliability issues
Solution Approach 1:
The transmitting device checks whether the last transmitted PDU on an RLC entity includes a poll indicator before stopping transmission. If no poll indicator is present, the device transmits another PDU with the poll indicator set to 1 in advance, ensuring that the receiver will send an acknowledgment before the transmitting device stops using that RLC entity. This preliminary action prevents unacknowledged PDUs from remaining in the system.
2Loss of time
If transmission is stopped without sending poll indicator, then latency is reduced, but wraparound faults occur in PDCP receiver
Solution Approach 1:
Before stopping transmission on an RLC entity, the transmitting device ensures that a poll indicator has been sent by checking the last transmitted PDU. If absent, it transmits another PDU with poll indicator set to 1, guaranteeing that the receiver will send an acknowledgment before the transmitting device stops using that RLC entity, thus preventing wraparound faults.
Solution Approach 2:
The poll indicator mechanism establishes a feedback loop where the transmitting device requests status information from the receiver by setting the poll indicator to 1. This ensures that the receiver sends an acknowledgment, providing feedback that confirms proper synchronization before transmission is stopped, preventing wraparound faults in the PDCP receiver.
3Reliability
If poll indicator is always transmitted, then acknowledgment reliability is improved, but overhead increases
Solution Approach 1:
Instead of always transmitting the poll indicator, the transmitting device applies partial action by checking whether the last transmitted PDU already contains a poll indicator. The poll indicator is transmitted only when necessary (when the last PDU lacked it), providing sufficient acknowledgment reliability while minimizing protocol overhead.
Data Source
AI summary
Embodiments herein relate to a method performed by a transmitting device (120) for handling communication in a wireless communications network, wherein the transmitting device (120) comprises at least two radio link control, RLC, entities and is configured with a split bearer to a receiving device (100). The transmitting device (120) identifies that a last transmitted protocol data unit, PDU, of one of the at least two RLC entities, is lacking a poll indicator requesting a status of one or more transmitted PDUs. When identifying that the last transmitted PDU lacks the poll indicator, the transmitting device transmits to the receiving device (100), a PDU comprising a poll indicator.