Target Access Node Packet Duplication Check During Handover

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Solution Overview

Problem

Current handover solutions in wireless communication networks, such as Make-Before-Break (MBB) in LTE Rel-14, suffer from increased application data latency and wastage of radio transmission resources due to packet duplication and delayed data transfer during handovers, especially for UEs with single Tx/Rx chains, where there is no clear mechanism to handle simultaneous data transfer without interruption.

Innovation Solution

Implementing a method where the target access node performs a data packet duplication check based on a status report from the UE about the last received data packet from the source access node, ensuring that only unreceived data packets are sent to the UE during handover, thereby avoiding packet duplication and reducing latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Make-Before-Break handover is implemented, then handover continuity is improved, but data latency increases and radio resources are wasted due to packet duplication

Engineering Contradiction:

Improvehandover continuityVSAvoiddata latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The target access node performs preliminary actions by checking for duplicate packets before transmitting data to the UE during handover. The status report mechanism allows the target node to identify which packets have already been received from the source node, enabling it to send only unique packets and avoid duplication delays

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A feedback mechanism is implemented where the UE sends a status report to the target access node indicating which data packets have been received from the source access node. This feedback enables the target node to adjust its transmission strategy and avoid sending duplicate packets, thereby reducing latency

Inventive Principle:

Principle #23Feedback

2Reliability

If packet duplication is used during handover, then reliability is improved, but radio transmission resources are wasted

Engineering Contradiction:

Improvedata delivery reliabilityVSAvoidradio transmission resources

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The status report feedback mechanism informs the target access node about packets already received from the source node, enabling it to transmit only non-duplicate packets. This eliminates redundant radio transmissions while maintaining reliable data delivery during handover

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system discards duplicate packets at the target access node based on status report information, preventing wasteful retransmissions. By identifying and discarding packets that have already been successfully delivered, the system recovers radio resources for transmitting only necessary unique packets

Inventive Principle:

Principle #34Discarding and recovering

Data Source

PatentUS11818615B2User equipment, source access node, target access node, and methods in a wireless communications network for handling data packets in a handover

Publication Date: 2023.11.14 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method performed by a target access node for handling data packets in a handover of a User Equipment, UE, from a source cell served by a source access node, to a target cell, served by the target access node in a wireless communications network is provided. The target access node receives a status report of last received data packet in the UE from the source access node. The target access node performs a data packet duplication check based on the information comprised in the status report. The target access node then sends to the UE, only data packets which have not already been received by the UE from the source access node, based on the outcome of the duplication check.