Split Bearer Retransmission Diversity for 5G Dual Connectivity
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Solution Overview
Problem
In 5G networks with dual connectivity, achieving a balance between throughput and reliability of packet delivery is challenging due to poor link quality, which can result in dropped packets, especially when the master node is congested and the secondary node's radio link is overloaded, leading to inadequate throughput and reliability.
Innovation Solution
A dynamic mechanism for higher-layer re-transmissions is implemented, where the master network node receives quality of service measurements from the user equipment, determines relative network conditions, and selects a redundancy retransmission mode to wirelessly retransmit packets to the user equipment over a split radio bearer, using multiple redundancy retransmission modes that define different protocols for increasing packet delivery reliability and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packets are transmitted via multiple base stations with split bearer, then reliability of packet delivery is improved, but device complexity increases due to multiple redundancy retransmission modes
Solution Approach 1:
The patent implements dynamic selection among multiple redundancy retransmission modes (Mode 1: PDCP retransmission, Mode 2: RLC retransmission, Mode 3: HARQ retransmission) based on real-time QoS measurements and network conditions. The master network node adapts the retransmission strategy by evaluating packet error rates, throughput, and latency requirements, allowing the system to switch between different reliability mechanisms optimally rather than using a fixed complex structure
Solution Approach 2:
The system changes operational parameters (retransmission mode selection) based on measured QoS conditions such as packet error rate thresholds and throughput requirements. By monitoring network conditions and adjusting the retransmission strategy dynamically, the system manages complexity through parameter adaptation rather than structural complexity
2Reliability
If redundancy retransmission modes are used to improve reliability, then packet delivery reliability improves, but loss of time increases due to additional retransmission overhead
Solution Approach 1:
The system dynamically selects among different retransmission modes based on real-time QoS measurements and network conditions. By evaluating packet error rates, throughput requirements, and latency constraints, the system adapts the retransmission strategy to minimize time loss while maintaining required reliability levels
Solution Approach 2:
The system changes retransmission parameters (mode selection, timing, and resource allocation) based on measured network conditions. By monitoring QoS metrics and adjusting retransmission behavior dynamically, the system optimizes the trade-off between reliability improvement and time overhead
3Productivity
If split bearer is used across multiple nodes, then throughput is improved through multi-connectivity, but reliability deteriorates due to poor link quality and node congestion
Solution Approach 1:
The system implements feedback mechanisms where the user equipment measures QoS parameters (packet error rate, throughput, latency) and reports them to the master network node. Based on this feedback, the master node dynamically adjusts the redundancy retransmission strategy, selecting appropriate modes to compensate for poor link quality while maintaining high throughput through multi-connectivity
Solution Approach 2:
The system dynamically adapts the retransmission strategy based on real-time QoS measurements from the split bearer transmission. By monitoring network conditions and adjusting retransmission behavior, the system maintains reliability despite the challenges of multi-node transmission
Data Source
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AI summary
When a radio bearer for sending packets to a UE is split between master and secondary network nodes, then based on relative network conditions (such as relative link quality in view of latency targets or other conditions that reflect user-plane loading) between that master and secondary network nodes a redundancy retransmission mode may be selected from among multiple redundancy retransmission modes. Each of these redundancy retransmission modes define a different protocol for retransmitting multiple copies of selected ones of the packets to the UE over the split radio bearer. These multiple copies are then wirelessly retransmitted to the UE over the split radio bearer according to the selected redundancy retransmission mode. In one example there are 4 possible modes and different modes retransmit PDCP PDUs versus RLC PDUs; in one mode the master and secondary network nodes both perform retransmissions of the identical selected packets.