UE PDCP Control PDU Transmission via Dynamic Link Selection
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Solution Overview
Problem
In LTE networks with dual connectivity, the transmission of PDCP control PDUs is hindered by delays due to non-ideal backhaul connections and scheduling issues, leading to reduced throughput and reliability in UE communication.
Innovation Solution
A user equipment (UE) configured with an uplink split bearer is equipped with a transmitter and controller to dynamically determine and utilize available UL grants, transmit PDCP control PDUs on either the master or secondary eNB links based on grant availability, and adjust transmission according to DRX cycle states, thereby optimizing PDCP control PDU transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PDCP control PDU is transmitted through secondary eNB link, then transmission can proceed when master eNB UL grant is unavailable, but backhaul transfer delay occurs due to non-ideal backhaul connection
Solution Approach 1:
The patent implements dynamic link selection for PDCP control PDU transmission based on real-time UL grant availability. The UE monitors UL grants from both master eNB and secondary eNB, and adaptively switches transmission paths: using master eNB link when UL grant is available (avoiding backhaul delay), and secondary eNB link when master eNB UL grant is unavailable (maintaining transmission continuity). This dynamic adaptation resolves the contradiction between maintaining transmission productivity and avoiding backhaul transfer delays.
2Reliability
If PDCP control PDU transmission follows standard scheduling, then protocol compliance is maintained, but scheduling delays and handover intermission delays occur
Solution Approach 1:
The patent triggers PDCP control PDU transmission proactively based on buffer status reporting (BSR) thresholds and UL grant availability, rather than waiting for standard scheduling opportunities. When the UE has PDCP control data to transmit and detects UL grant availability on either master or secondary eNB link, it immediately initiates transmission. This preliminary action approach maintains protocol compliance through proper BSR triggering while significantly reducing scheduling delays and handover intermission delays.
3Productivity
If dual connectivity is used for UL split bearer, then UL data rate is enhanced through two link chains, but complexity of grant allocation and link selection increases
Solution Approach 1:
The patent applies different transmission strategies to different link chains based on their specific characteristics. For master eNB link, the UE uses standard scheduling procedures when UL grant is available. For secondary eNB link, the UE uses it specifically as a fallback path when master eNB UL grant is unavailable. This localized quality approach - assigning different roles and selection criteria to each link - simplifies the overall decision-making process while maintaining the UL data rate enhancement benefits of dual connectivity.
Data Source
AI summary
A user equipment (UE) configured with an uplink (UL) split bearer and method for packet data convergence protocol (PDCP) control protocol data unit (PDU) transmission by the UE are provided. The method includes triggering, by the UE, a PDCP control PDU; determining, by the UE, whether a UL grant is available for a master evolved node B (eNB); transmitting, by the UE, the PDCP control PDU on a link associated with the master eNB, if the UL grant is available for the master eNB; and transmitting, by the UE, the PDCP control PDU on a link associated with a secondary eNB, when the UL grant is unavailable for the master eNB.