PDCP Reordering Buffer for RoHC Decompression in 5G
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Solution Overview
Problem
The reception of unordered data packets by the Robust Header Compression (RoHC) functional entity of the PDCP layer in 5G mobile communication systems leads to disorder in header compression context updates, resulting in failed data decompression due to out-of-order delivery from the Radio Link Control (RLC) layer.
Innovation Solution
A method and apparatus for data processing that reorders received PDCP data packets based on their serial numbers within a Reordering_Window, ensuring correct delivery to the RoHC entity for accurate header decompression, even when packets are delivered out-of-order from the lower layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data packets are transmitted through MN and SN simultaneously in a split bearer configuration, then network throughput and reliability are improved, but packet delivery order is disrupted causing RoHC decompression failure
Solution Approach 1:
The patent introduces a reordering buffer as an intermediary component between the RLC layer and RoHC entity. This buffer temporarily stores out-of-order packets and releases them in the correct sequence, mediating the conflict between parallel transmission benefits and decompression requirements. The buffer acts as a mediator that preserves packet sequence without blocking the overall throughput improvement from split bearer operation.
Solution Approach 2:
The patent implements preliminary reordering action by checking packet sequence numbers and buffering packets before they reach the RoHC entity. This preliminary sorting ensures that packets are reordered in advance of decompression processing, preventing decompression failures while maintaining the parallel transmission advantage. The reordering happens proactively rather than reactively to decompression errors.
2Adaptability or versatility
If packets are delivered out-of-order from RLC layer to PDCP layer, then transmission flexibility is improved, but header compression context update becomes disordered
Solution Approach 1:
The reordering buffer serves as an intermediary that decouples the flexible out-of-order delivery from the RoHC entity's sequential processing requirements. This intermediary absorbs the complexity of context update ordering, allowing the RLC layer to maintain transmission flexibility while the RoHC entity receives properly ordered packets for simplified context management.
3Speed
If parallel transmission through multiple nodes is implemented, then data rate is improved, but packet ordering is lost leading to decompression errors
Solution Approach 1:
The reordering buffer acts as a precision-correcting intermediary that receives high-speed parallel packets from multiple nodes and outputs them in the correct sequence. This buffer absorbs the sequence disorder introduced by parallel transmission while maintaining the high data rate benefit, effectively decoupling speed improvement from sequence accuracy degradation.
Data Source
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AI summary
A method and an apparatus of data processing, applied to a packet data convergence protocol (PDCP) layer, are provided. The method includes: reordering a received PDCP data packet according to a serial number of the PDCP data packet; determining whether the serial number of the reordered PDCP data packet is inside or outside a Reordering_Window, delivering the reordered PDCP data packet to a robust header compression (RoHC) entity in a serial number order of the reordered PDCP data packet, and obtaining a data packet resulting from header decompression performed by the RoHC entity on the PDCP data packet.