PDCP Status Reporting for Reliable 5G Multicast Transmission
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Solution Overview
Problem
In existing 5G multicast and broadcast services (MBS), there is no reliable mechanism to ensure that multiple terminals successfully receive the same packet data convergence protocol (PDCP) data units (PDUs) in point-to-multipoint (PTM) transmission, as feedback channels are absent for multicast transmission.
Innovation Solution
A packet data convergence protocol (PDCP) status reporting method where terminals trigger and transmit PDCP status reports on designated uplink channels based on preset conditions, such as packet loss thresholds, poll requests, cell handover, or bearer reconfiguration, using RLC acknowledged or unacknowledged modes to ensure reliable PDCP PDU transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If point-to-multipoint (PTM) transmission is used for multicast and broadcast services, then service coverage and efficiency are improved, but reliability of data transmission deteriorates due to lack of feedback channels
Solution Approach 1:
The patent introduces a feedback channel as an intermediary mechanism between terminals and the network side. This feedback channel allows terminals to send PDCP status reports (containing packet loss information) to the network side, enabling the network to identify and retransmit lost packets, thus resolving the reliability issue while maintaining PTM transmission efficiency
Solution Approach 2:
The patent implements a feedback mechanism where terminals monitor PDCP PDU reception status and send status reports back to the network side when packet loss is detected. The network side uses this feedback information to trigger retransmissions, creating a closed-loop system that ensures reliable delivery without sacrificing the efficiency benefits of PTM transmission
2Reliability
If feedback channels are introduced for PDCP status reporting in PTM transmission, then transmission reliability is improved, but system complexity increases
Solution Approach 1:
The patent makes the PDCP layer entity universal by equipping it with both original PDCP functions and new status reporting functions. The same PDCP entity that handles packet assembly and decryption also monitors packet loss and generates status reports, eliminating the need for separate feedback management structures and reducing overall system complexity
Solution Approach 2:
The terminal's PDCP entity autonomously monitors its own packet reception status and generates feedback reports without requiring external control or complex coordination mechanisms. This self-service approach simplifies the system by eliminating the need for centralized feedback management while ensuring reliable transmission
3Reliability
If PDCP status reports are transmitted frequently to ensure data integrity, then transmission reliability is improved, but uplink channel resource consumption increases
Solution Approach 1:
Instead of continuous feedback transmission, the patent employs periodic feedback where terminals send PDCP status reports only at specific intervals or when triggered by certain conditions (such as detecting packet loss). This periodic reporting mechanism ensures data integrity while significantly reducing uplink resource consumption compared to continuous feedback
Solution Approach 2:
The patent implements selective feedback where terminals send status reports only when necessary (e.g., when packet loss is detected or at configured intervals) rather than transmitting feedback for every packet. This partial action approach maintains sufficient data integrity while minimizing unnecessary uplink resource usage
Data Source
AI summary
Disclosed are a packet data convergence protocol status reporting method, a packet data convergence protocol status receiving method, a terminal and devices. The method at the terminal side includes: in case of receiving the MBS, triggering to report a packet data convergence protocol (PDCP) status according to a preset condition; transmitting a PDCP status report on a predetermined uplink channel.