PDCP Mapping Table for URLLC Radio Resource Optimization
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Solution Overview
Problem
The existing PDCP duplication feature in 5G NR technology for URLLC services in Dual Connectivity (DC) leads to increased overhead and resource consumption due to unnecessary HARQ retransmissions, as each carrier treats duplicate packets separately, causing redundant retransmissions even if one carrier successfully receives the packet.
Innovation Solution
Implementing a PDCP sequence number to CBG mapping table at the UE, which allows the UE to internally manage and update information about successfully received packets, enabling it to send ACK signals instead of NACK when the other RAT has received the data, thereby reducing HARQ retransmissions and optimizing radio resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCP duplication is activated to send packets over multiple carriers, then reliability is improved, but overhead increases and spectrum efficiency decreases
Solution Approach 1:
The invention implements a feedback mechanism where the receiving end (UE) sends ACK/NACK information back to the transmitting end (gNB) to indicate whether packets were successfully received. The gNB uses this feedback to determine whether retransmission is necessary, thereby avoiding unnecessary retransmissions and reducing overhead while maintaining reliability
Solution Approach 2:
The system enables self-service by allowing the receiving end to autonomously determine packet reception status and provide feedback, which automatically controls whether the transmitting end performs retransmission, eliminating the need for manual intervention or complex centralized control
2Reliability
If packets are sent over multiple carriers with PDCP duplication, then reliability is improved, but HARQ retransmissions increase due to separate packet treatment
Solution Approach 1:
The invention merges the packet status information from multiple carriers by implementing a mapping table that tracks PDCP sequence numbers across different carriers. When a packet is successfully received on one carrier, the system consolidates this information and uses it to prevent redundant retransmissions on other carriers, thereby reducing energy consumption while maintaining reliability
3Adaptability or versatility
If each carrier treats duplicate packets separately, then carrier independence is maintained, but unnecessary HARQ retransmissions occur
Solution Approach 1:
The invention introduces a mapping table as an intermediary structure that connects packet status information across different carriers. This intermediary enables the system to maintain carrier independence while still allowing information sharing about packet reception status, thereby preventing unnecessary retransmissions and improving overall radio resource efficiency
Data Source
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AI summary
Provided is a method for optimizing radio resource for Ultra-Reliable Low Latency Communication services in a Dual Connectivity technology. The method includes: receiving DownLink (DL) data by a UE using a first Radio Access Technology (RAT) from a base station; transmitting a first Acknowledgement (ACK) signal using the first RAT to the base station based on the DL data being successfully received; updating a Mapping Table Sequence Number of the DL data in a Mapping Table by the UE, based on the DL data being successfully received by the UE using the first RAT; checking the Mapping Table by the UE upon detecting an error in the received DL data using a second RAT; and sending a second ACK signal to the base station using the second RAT of the UE based on the Mapping Table Sequence Number of the DL data being found in the Mapping Table.