RLC PDU Re-segmentation for Adaptive HSPA Transmission
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Solution Overview
Problem
In high-speed packet access (HSPA) networks, the inflexibility of RLC PDU size in channel conditions can lead to inefficient transmission and retransmission, especially during handovers between different network releases, where larger PDUs may fail due to changing channel conditions.
Innovation Solution
A method for acknowledge mode data re-segmentation is introduced, where the original PDU is segmented into smaller PDUs if it exceeds the updated maximum size, and further sub-segmentation occurs if necessary, with additional header information to manage reassembly and status reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a flexible RLC PDU size is implemented to reflect channel conditions, then transmission efficiency is improved, but device complexity increases due to the need for dynamic size adjustment and re-segmentation logic
Solution Approach 1:
The RLC PDU size is made dynamic rather than fixed, allowing the RLC entity to adjust PDU sizes based on current channel conditions. The maximum RLC PDU size is determined by taking the minimum of the configured RLC maximum transport block size and the configured MAC maximum transport block size, enabling adaptive response to changing radio conditions while maintaining efficient transmission.
Solution Approach 2:
The patent implements re-segmentation capability where a previously transmitted RLC PDU can be segmented into multiple smaller PDUs for retransmission if the current maximum PDU size has decreased. This is achieved by checking if the stored PDU size exceeds the current maximum size and performing segmentation accordingly, thereby resolving the complexity of managing variable-size transmissions.
2Productivity
If a large RLC PDU size is used to maximize data throughput, then productivity is improved, but reliability deteriorates when channel conditions change and the PDU cannot be successfully transmitted
Solution Approach 1:
The system dynamically adjusts RLC PDU size based on real-time channel conditions by continuously monitoring the maximum transport block size configurations. This allows the system to transmit larger PDUs when conditions permit (maximizing throughput) while automatically switching to smaller PDUs when conditions deteriorate (maintaining reliability).
Solution Approach 2:
The RLC entity stores the original RLC PDU in a buffer before transmission. This preliminary storage allows the system to retransmit the original PDU or re-segment it based on updated channel conditions, ensuring that transmission attempts are adapted to current conditions rather than being constrained by the original size decision.
3Adaptability or versatility
If the RLC PDU size is changed via higher layer signaling, then adaptability to channel conditions is improved, but loss of time increases due to the requirement for re-establishment of the AM RLC entity
Solution Approach 1:
The patent enables dynamic adjustment of RLC PDU size without requiring RLC entity re-establishment. The maximum PDU size is determined by comparing configured parameters at the time of transmission needs, allowing the entity to adapt to changing conditions while maintaining its established state and avoiding time-consuming re-initialization procedures.
Solution Approach 2:
The system pre-determines the maximum RLC PDU size by taking the minimum of configured RLC and MAC transport block sizes before transmission. This preliminary determination allows the RLC entity to operate with optimized parameters without requiring subsequent re-establishment when size adjustments are needed, thereby reducing time loss.
Data Source
AI summary
A method and apparatus for acknowledge mode data (AMD) re-segmentation are disclosed. An AMD protocol data unit (PDU) is generated from at least one RLC SDU. The AMD PDU size is within a flexible maximum AMD PDU size. The original AMD PDU is stored in a retransmission buffer, and transmitted. If transmission of the original AMD PDU fails and the original AMD PDU size is larger than an updated maximum AMD PDU size, the original AMD PDU is segmented to segmented AMD PDUs. If transmission of one of the segmented AMD PDUs fails, the original AMD PDU may be re-segmented to smaller size AMD PDUs.