Backhaul Error Handling in Dual Connectivity

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Solution Overview

Problem

In wireless communication systems, particularly in LTE-Advanced networks, packet loss between master and secondary base stations can lead to prolonged intervals where data is not delivered to user equipment, affecting TCP performance due to the lack of efficient mechanisms for acknowledging non-received protocol data units (PDUs) and retransmitting missing packets.

Innovation Solution

The method involves determining non-received data packets at a secondary base station and sending an indication of sequence numbers to a master base station, allowing for comparison and retransmission of missing PDUs, thereby ensuring data integrity and reducing packet loss by using ACK/NACK feedback mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If data is transmitted between master and secondary base stations in dual connectivity, then data delivery speed is improved, but packet loss occurs leading to TCP performance degradation

Engineering Contradiction:
Improvedata delivery speedVSAvoiddata delivery reliability
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent implements an ACK/NACK feedback mechanism where the secondary base station sends acknowledgment messages back to the master base station indicating whether data packets were successfully received. This feedback loop enables the master base station to identify and retransmit lost packets, thereby maintaining high data delivery speed while improving reliability by correcting transmission errors.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent employs sequence numbers to pre-identify data packets before transmission. By numbering packets in advance, the system can efficiently track which packets were received and which were lost, enabling rapid retransmission without waiting for complex error detection procedures. This preliminary identification mechanism prevents packet loss from degrading TCP performance.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If packet loss detection mechanisms are implemented, then data integrity is improved, but system complexity increases

Engineering Contradiction:
Improvedata integrityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The ACK/NACK feedback mechanism provides a simple yet effective way to detect packet loss. The secondary base station merely needs to compare received sequence numbers against expected sequence numbers and send a single acknowledgment message, avoiding complex error detection algorithms while maintaining high data integrity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The sequence number mechanism enables the system to automatically track and identify lost packets without external intervention. The master base station uses the feedback information to autonomously determine which packets need retransmission, reducing the need for complex manual error handling procedures.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4181440A1Backhaul errors in dual connectivity
Publication Date: 2023.05.17 NOKIA SOLUTIONS & NETWORKS OY
  • EP4181440A1 patent drawingFigure 1
  • EP4181440A1 patent drawingFigure 2~3
  • EP4181440A1 patent drawingFigure 4

AI summary

A method comprising: determining, at a first node, that an event has occurred; in response to said determination sending, to a second node, an indication of at least one endpoint of a range of sequence numbers associated with non-received data.