Selective PDCP Duplication for TSN Flow Reliability
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Solution Overview
Problem
In wireless communication systems, the existing mechanism for activating and deactivating PDCP duplication by MAC CE signaling from the network is not fast enough to meet the latency and reliability requirements of new radio (NR) industrial internet of things (IIoT) applications, leading to potential transmission failures and survival time expiry in time-sensitive network (TSN) flows.
Innovation Solution
Allowing user equipment (UE) to autonomously enable PDCP duplication for selected packets based on transmission errors indicated by a new field in the downlink control information (DCI), skipping HARQ retransmissions when necessary, and configuring whether HARQ retransmissions are supported for uplink grants to enhance transmission reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP duplication is activated by MAC CE signaling from the network, then transmission reliability is improved, but the activation speed is too slow to meet latency requirements of TSN flows
Solution Approach 1:
The UE is empowered to autonomously activate and deactivate PDCP duplication based on transmission failure detection, without requiring network control. When the UE detects a transmission failure (e.g., through HARQ feedback or timeout), it automatically switches to the duplication mode, and when successful transmission is achieved, it switches back to normal mode. This self-service mechanism eliminates network signaling delay and enables rapid adaptation to transmission conditions.
Solution Approach 2:
The system pre-configures multiple transmission paths (primary and duplicate PDCP entities) in advance, so that when a transmission failure occurs, the UE can immediately switch to the pre-configured duplicate path without requiring time for path establishment. This preliminary preparation of alternative paths ensures rapid response to transmission failures while meeting latency requirements.
2Reliability
If HARQ retransmission is performed for failed TB transmission, then transmission reliability is improved, but latency increases for time-sensitive TSN flows
Solution Approach 1:
The system dynamically adjusts the transmission strategy based on the type of data being transmitted. For TSN flow data, the UE disables HARQ retransmission and relies on PDCP duplication for reliability, while for non-TSN data, conventional HARQ retransmission is maintained. This dynamic adaptation allows the system to optimize between reliability and latency based on traffic requirements.
Solution Approach 2:
The system segments the transmission mechanism into two independent paths: one using HARQ retransmission for reliability and another using PDCP duplication for low-latency reliability. For TSN flows, the UE selectively uses the duplication path and skips HARQ retransmission, thereby avoiding the latency penalty while maintaining transmission reliability through the duplicate path.
3Reliability
If PDCP duplication is continuously activated for all packets, then transmission reliability is maximized, but resource consumption and device complexity increase
Solution Approach 1:
Instead of uniformly applying PDCP duplication to all packets, the system applies duplication selectively only to TSN flow packets that require high reliability and low latency. The UE identifies TSN packets through appropriate indicators and activates duplication only for these specific packets, while non-TSN packets use conventional transmission. This localized application reduces overall resource consumption and simplifies duplication management.
Solution Approach 2:
The system changes the operational parameters of PDCP duplication dynamically based on packet type and transmission status. For TSN packets, duplication is activated with specific parameters optimized for low latency; for other packets, duplication is deactivated or configured with different parameters. This parameter adaptation allows the system to manage duplication complexity while maintaining high reliability where needed.
Data Source
AI summary
Various aspects of the present disclosure relate to selective duplication for TSN flows. One apparatus includes at least one memory and at least one processor that is configured to transmit a transport block (“TB”), receive, in response to the TB, downlink control information (“DCI”), the DCI comprising a new data indicator (“NDI”) field and a control field, the NDI field comprising a value that indicates that the transmission of the TB was unsuccessful and the control field comprising a value that indicates not to perform a retransmission of the TB, and triggers at least one action to increase a transmission reliability for a subsequent TB.