Flexible RLC PDU Packaging for Accurate SDU Boundary Detection
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Solution Overview
Problem
In the 3GPP communication system, user equipment (UE) behavior is unspecified when configured with flexible RLC PDU sizes and 7-bit LI sizes, leading to inaccuracies in retrieving service data units (SDUs) beyond 123 octets, causing issues in data transmission.
Innovation Solution
A protocol data unit (PDU) packaging method in the radio link control (RLC) layer that uses a 7-bit length indicator (LI), a special header extension (HE) field, or an alternative E-bit to indicate the end of SDUs, ensuring accurate packaging and transmission by configuring the UE to handle flexible PDU sizes and complete SDUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a 7-bit LI size is used in flexible RLC PDU configuration, then the PDU size flexibility is improved, but the accuracy of indicating SDU end position deteriorates when SDU exceeds 123 octets
Solution Approach 1:
The patent segments the SDU indication mechanism into two parts: the 7-bit LI field for indicating the first 123 octets, and an additional indicator field for indicating whether the SDU continues beyond 123 octets. This segmentation allows the system to maintain 7-bit LI size while accurately representing SDUs larger than 123 octets by combining the LI value with the continuation indicator.
Solution Approach 2:
The patent introduces an intermediary indicator mechanism (continuation indicator or header extension) that mediates between the limited 7-bit LI field and the need to represent larger SDU sizes. This intermediary allows the receiver to understand that the SDU extends beyond the 123 octets indicated by the LI field, resolving the precision loss without increasing the fundamental LI field size.
2Device complexity
If flexible PDU size is configured without special HE field or alternative E-bit interpretation, then the device complexity is reduced, but the reliability of SDU retrieval deteriorates
Solution Approach 1:
The patent enables the existing HE field or E-bit to serve dual purposes: its traditional function and the new function of indicating SDU continuation beyond 123 octets. This self-service approach allows the system to gain additional functionality without adding dedicated new fields, maintaining configuration simplicity while improving SDU retrieval reliability through existing infrastructure.
3Ease of operation
If the UE behavior is left unspecified under certain configurations, then the ease of operation is improved, but the manufacturing precision of protocol implementation deteriorates
Solution Approach 1:
The patent changes the interpretation parameters of existing fields (HE field or E-bit) based on specific configuration conditions. When flexible PDU size is configured with certain parameters, the HE field or E-bit is reinterpreted to indicate SDU continuation. This parameter change approach provides clear implementation rules that ensure consistent protocol behavior across different UEs while maintaining configuration flexibility through conditional parameter interpretation.
Data Source
AI summary
A user equipment (UE) and a flexible protocol data unit (PDU) packaging method thereof are provided. The user equipment performs a flexible PDU packaging procedure in a radio link control (RLC) layer when receiving configuration information that configures a 7-bit length indicator (LI) size and a flexible PDU size from a base station. The user equipment uses an exactly-filled LI to indicate the end of a service data unit (SDU) occurring at the end of the previous one PDU and an accumulated SDU size of the previous one PDU exceeds 123 octets. In addition, the user equipment utilizes a special value of a header extension (HE) field or an alternative E-bit of the header to indicate that the PDU includes only one SDU and the SDU is a complete SDU.