PDCP Count Synchronization for 5G MBS Session Recovery
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Solution Overview
Problem
Existing 5G/NR multicast and broadcast services face challenges in maintaining synchronization of hyper frame numbers and sequence numbers between base stations and user equipment, particularly in point-to-multipoint transmissions, leading to issues with packet ordering and integrity verification, especially in poor radio conditions.
Innovation Solution
A communication method and system that synchronizes the PDCP count values between the gNB and UE by requesting and updating the PDCP variables, including hyper frame numbers and sequence numbers, through dedicated or broadcast signaling, to ensure accurate packet delivery and integrity verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If point-to-multipoint transmission is used for multicast and broadcast services, then service coverage and efficiency are improved, but synchronization between base stations and user equipment deteriorates leading to packet ordering and integrity verification issues
Solution Approach 1:
The patent implements feedback mechanisms where the user equipment sends PDCP status reports to the base station, and the base station adjusts transmission parameters accordingly. This feedback loop enables continuous synchronization maintenance in PTM transmission, resolving the contradiction between service efficiency and synchronization reliability.
Solution Approach 2:
The patent applies preliminary actions by establishing synchronization mechanisms before actual data transmission begins. The base station and user equipment perform initial count value alignment and configure synchronization parameters in advance, ensuring reliable packet ordering and integrity verification throughout the PTM transmission process.
2Measurement precision
If PDCP count values are synchronized through dedicated signaling, then synchronization accuracy is improved, but signaling overhead and system complexity increase
Solution Approach 1:
The patent makes the PDCP status report mechanism universal by enabling it to serve multiple functions: not only for synchronization but also for error detection, packet ordering verification, and quality of service monitoring. This multi-functionality reduces the need for separate dedicated synchronization signaling, thereby reducing overall system complexity while maintaining high synchronization accuracy.
Solution Approach 2:
The patent merges the synchronization function with existing PDCP status reporting mechanisms. Instead of creating separate dedicated signaling channels for synchronization, the patent combines synchronization information transmission with the existing status report structure, thereby achieving accurate synchronization without proportionally increasing signaling complexity.
Data Source
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AI summary
In a first aspect, a communication method is a communication method used in a mobile communication system for supporting a multicast and broadcast service (MBS). The communication method includes: managing, by a user equipment having started reception of an MBS session from a base station, a first Packet Data Convergence Protocol (PDCP) variable updated in response to reception of a PDCP packet in the MBS session, the first PDCP variable being managed in a PDCP layer; and performing, by the user equipment, control of synchronizing the first PDCP variable with a second PDCP variable managed by the base station, in response to determining that the reception of the MBS session has been interrupted for a predetermined time.