PDCP Duplication Activation for 5G Survival Time Packets
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Solution Overview
Problem
Existing PDCP packet duplication mechanisms in 5G NR are inadequate for quickly responding to survival time scenarios, as they rely on slow RRC and MAC CE activation, which is unsuitable for short survival times, leading to potential packet loss and delayed delivery.
Innovation Solution
Configuring PDCP duplication with discard timers and logical channel prioritization to proactively manage packet transmission, allowing for rapid activation of unused duplication legs and discarding stale packets, enabling quick resource allocation during survival time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP packet duplication is activated using RRC or MAC CE signaling, then reliability is improved through multiple transmission paths, but activation speed deteriorates due to slow signaling procedures
Solution Approach 1:
The patent configures multiple PDCP duplication legs in advance but does not activate them immediately. Instead, the legs are prepared with discard timers and logical channel prioritization settings beforehand, allowing rapid activation when needed without waiting for slow RRC or MAC CE signaling procedures. This preliminary configuration enables the system to switch to duplication mode quickly when survival time scenarios are detected.
Solution Approach 2:
The patent implements dynamic activation of PDCP duplication legs based on real-time network conditions and survival time requirements. The system can selectively enable or disable specific duplication legs without reconfiguring the entire PDCP entity, allowing flexible and rapid adaptation to changing transmission conditions while maintaining high reliability through available duplication paths.
2Loss of energy
If PDCP duplication legs are kept inactive to save resources, then resource efficiency is improved, but response time deteriorates when activation is needed
Solution Approach 1:
The patent performs preliminary configuration of PDCP duplication legs including setting discard timers and logical channel prioritization, but keeps them inactive until needed. This allows the system to maintain resource efficiency while being prepared for rapid activation. The preliminary setup ensures that when activation is required, the legs can be enabled immediately without configuration delays.
Solution Approach 2:
The patent changes the activation state parameter of PDCP duplication legs dynamically based on survival time scenarios. By adjusting the activation parameter rather than reconfiguring the entire duplication structure, the system achieves fast response time while maintaining resource efficiency during inactive periods. The discard timer parameters are also adjusted to match survival time requirements.
3Reliability
If discard timer is set to allow packet retransmission, then reliability is improved, but latency increases for stale packets
Solution Approach 1:
The patent sets the discard timer parameter to be strictly less than the survival time for each PDCP duplication leg. This parameter configuration ensures that packets are discarded before they become stale, preventing unnecessary retransmissions and reducing latency. The timer value is optimized to balance reliability (allowing sufficient time for legitimate retransmissions) with latency (discarding packets that exceed survival time requirements).
Solution Approach 2:
The patent applies different discard timer values to different PDCP duplication legs based on their specific characteristics and survival time requirements. Each duplication leg can have locally optimized timer settings that match its transmission path characteristics, allowing the system to maintain high reliability for time-critical packets while discarding stale packets that would only increase latency.
4Reliability
If multiple secondary RLC entities are configured for PDCP duplication, then reliability is improved through multiple paths, but device complexity increases
Solution Approach 1:
The patent segments the PDCP duplication functionality into multiple independent RLC entities, each handling a specific duplication leg. This segmentation allows the system to manage complexity by treating each RLC entity as a separate, manageable unit with its own configuration parameters. The logical channel prioritization is also segmented across different LCHs, allowing independent control of each transmission path while maintaining overall system reliability.
Solution Approach 2:
The patent designs the secondary RLC entities to be universal components that can serve multiple purposes. Each secondary RLC entity can function as a backup for primary transmission and can be activated for different duplication legs as needed. This multi-functionality reduces overall device complexity by using standardized, reusable RLC entity templates rather than requiring custom configurations for each duplication scenario.
Data Source
AI summary
At least one Packet Data Convergence Protocol (PDCP) packet duplication leg is configured with a logical channel prioritization (LCP) restriction, restricting a logical channel in the duplication leg to which transmission resources are intentionally not available. Stale packets, (not transmitted due to a lack of resources) are discarded, so the current packet is always at the top of the queue. PDCP duplication can then be activated quickly when needed, such as in survival time mode, as it has already been configured, and the current packet is always ready for transmission. The transmission resources can be dynamically allocated by the network by transmitting a DCI command (e.g., the Configured Grant type 2 activation or dynamic grant with a specific PHY-priority-index). Alternatively, the transmission resource can be allocated beforehand, but scarcely, such that it occurs (i.e., is available) every N-th packet, and so there is a duplication for every N-th packet.