Transmitting-Side Apparatus Window Control for Out-of-Order Acknowledgement
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Solution Overview
Problem
In LTE mobile communication systems, the RLC sublayer of the transmitting-side apparatus initiates unnecessary RLC reset processing due to out-of-order acknowledgement information, leading to communication quality degradation when the MAC sublayer does not perform reordering processing for received STATUS-PDUs, causing the sequence number of packets to fall outside the acknowledgement information reception window.
Innovation Solution
The transmitting-side apparatus manages an acknowledgement information reception window with a lower limit set to the oldest expected acknowledgement response sequence number and an upper limit set to the latest sequence number transmitted, and only performs window control and retransmission processing based on acknowledgement information within this window, ignoring out-of-range sequence numbers to prevent RLC reset processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmitting-side apparatus performs window control processing and retransmission control processing for all received acknowledgement information, then complete retransmission control is achieved, but unnecessary RLC reset processing is initiated when out-of-order STATUS-PDUs are processed, degrading communication quality
Solution Approach 1:
The patent applies local quality by differentiating the processing of acknowledgement information based on sequence number validity. The RLC sublayer selectively processes only valid STATUS-PDUs (those with sequence numbers within the reception window) while ignoring invalid out-of-order STATUS-PDUs, thereby preventing unnecessary RLC reset processing and maintaining communication quality without compromising retransmission control reliability
2Reliability
If the MAC sublayer performs reordering processing for received STATUS-PDUs, then out-of-order acknowledgement information is corrected, but processing complexity increases
Solution Approach 1:
The patent extracts the reordering function from the MAC sublayer and relocates it to the RLC sublayer. The RLC sublayer directly manages the reception window and processes STATUS-PDUs based on sequence number validity, eliminating the need for complex reordering processing in the MAC sublayer while maintaining reliable acknowledgement information handling
3Productivity
If the transmitting-side apparatus updates the acknowledgement information reception window for all received STATUS-PDUs, then complete window control is achieved, but out-of-range sequence numbers cause unnecessary RLC reset processing
Solution Approach 1:
The patent applies preliminary action by pre-establishing the reception window boundaries (lower and upper sequence number limits) before processing STATUS-PDUs. The RLC sublayer checks whether received STATUS-PDUs fall within the predetermined window range before processing, thereby preventing unnecessary RLC reset processing while maintaining efficient window control for in-range sequence numbers
Data Source
AI summary
In a retransmission control method, a transmitting-side apparatus manages an acknowledgement information reception window and the transmitting-side apparatus does not perform the window control processing and the retransmission control processing of a packet on the basis of the acknowledgement information for a sequence number of the packet which is included in the acknowledgement information received from the receiving-side apparatus, when the sequence number takes a value outside a range of the acknowledgement information reception window.