PDCP Buffer Handling for Split Bearer Packet Discard
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing packet discard times in multipath operations, particularly when using split bearers with different latency paths, which can lead to packet loss and increased buffer requirements.
Innovation Solution
The implementation of a processor and transceiver system in a wireless transmit/receive unit (WTRU) that configures different discard time periods for packets transmitted over primary and secondary paths, allowing for adaptive packet management based on network and WTRU conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single discard time period is used for all packets in split bearer, then device complexity is reduced, but packet loss increases due to mismatched discard timing with path latency
Solution Approach 1:
The patent segments the single discard time period into multiple distinct discard time periods, with each period corresponding to a specific path (e.g., first path and second path). This segmentation allows each path to have its own discard timing optimized for its latency characteristics, preventing packet loss while maintaining manageable complexity through structured configuration.
Solution Approach 2:
The patent applies local quality by assigning different discard time period characteristics to different paths based on their specific latency properties. Each path receives a tailored discard time period that matches its transmission characteristics, rather than using a uniform approach. This enables optimal packet retention decisions for each path individually.
2Reliability
If discard time period is extended to accommodate maximum path latency, then packet loss is reduced, but buffer size requirements increase
Solution Approach 1:
By segmenting the discard time periods according to path latency characteristics, the system can assign shorter discard times to low-latency paths and longer discard times only to high-latency paths. This prevents the need to extend buffers for all paths uniformly, as each path's buffer requirement is optimized independently based on its actual latency.
Solution Approach 2:
The patent implements dynamic discard time period management where the discard timing is adjusted based on the specific path being used. This dynamic approach allows the system to optimize buffer usage by applying longer discard times only when necessary (for high-latency paths) while using shorter discard times for low-latency paths, thereby reducing overall buffer requirements.
3Productivity
If path switching is implemented for multipath operation, then productivity is improved, but device complexity increases due to additional buffer management requirements
Solution Approach 1:
The patent segments buffer management by associating distinct discard time periods with each path in the multipath configuration. This segmentation simplifies path switching management by providing clear, path-specific discard timing rules, making it easier to track and manage packets across multiple paths without requiring complex unified buffer management algorithms.
Data Source
AI summary
A wireless transmit/receive unit (WTRU) includes a processor and a transceiver that receive a PDCP configuration for a split bearer. The PDCP configuration includes information about first and second discard time periods. The processor stores a first packet and a second packet in a PD-CP transmit buffer. The processor and transceiver start the first discard time period and transmit the first packet over the primary path and start the second discard time period and transmit the second packet over the secondary path. The processor and transceiver discard the first packet stored in the PDCP transmit buffer based on one of expiry of the first discard time period or the receipt of an acknowledgement (ACK) for the first packet, and discard the second packet stored in the PDCP transmit buffer based on one of expiry of the second discard time period or receipt of an ACK for the second packet.