Pre-configuring Target TRPs for 5G NR Handover Latency Reduction

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Solution Overview

Problem

The hierarchical architecture of 5G new radio (NR) introduces significant latency due to long backhaul delays between transmission reception points (TRPs) of different central units (CUs), leading to increased handover (HO) latency and failure rates, especially for fast-moving user equipment (UEs), which cannot meet the Ultra-Reliable Low-Latency Communications (URLLC) requirements.

Innovation Solution

Pre-configuring target TRPs based on UE trip route information before the UE enters the coverage border area, minimizing signaling delays and HO failures by allocating dedicated access resources and monitoring opportunities, and triggering activation notifications through the UE path to bypass backhaul delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional handover procedures are used in hierarchical NR architecture, then signaling exchanges occur between source and target nodes over backhaul, but this introduces large latency and HO failure rates due to long backhaul delays

Engineering Contradiction:

Improvehandover reliabilityVSAvoidhandover latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-configuring target TRPs with UE-specific parameters and resources before the UE actually needs to handover. The source TRP prepares the target TRP in advance with all necessary configuration information, so when handover is triggered, the target is already ready to immediately serve the UE without waiting for backhaul signaling exchanges.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent extracts the time-critical signaling exchanges from the handover execution path by performing them in advance during the preparation phase. The configuration signaling is separated from the actual handover execution, allowing the handover to proceed rapidly without being blocked by backhaul latency.

Inventive Principle:

Principle #2Taking out (Extraction)

2Manufacturing precision

If signaling exchanges are performed over backhaul during handover, then target TRP can be configured, but this causes accumulated latency that degrades link quality between UE and source TRP

Engineering Contradiction:

Improvelink qualityVSAvoidsignaling delay

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The source TRP performs preliminary configuration of the target TRP before the UE enters the handover execution phase. This includes pre-configuring UE-specific parameters, resource allocations, and monitoring opportunities at the target TRP, so that when handover occurs, no additional signaling delays are introduced that would degrade link quality.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If fast-moving UEs perform handover with traditional procedures, then connection can be maintained, but HO failure rate increases due to excessive latency

Engineering Contradiction:

Improvehandover success rateVSAvoidUE mobility speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

For fast-moving UEs, the source TRP initiates preliminary configuration of target TRPs earlier in the mobility trajectory. The target TRP is pre-prepared with all necessary UE context and configuration, enabling rapid handover execution that keeps pace with the UE's high mobility without causing connection failures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The source TRP acts as an intermediary that prepares the target TRP in advance before the UE arrives. This intermediary preparation eliminates the need for real-time signaling exchanges during the critical handover moment, ensuring reliable connection maintenance even at high UE speeds.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Loss of time

If pre-configuration of target TRP is performed, then signaling is moved out of time-critical path, but additional initial configuration signaling is required

Engineering Contradiction:

Improvehandover latencyVSAvoidconfiguration complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent merges the preparation of target TRP configuration with the existing handover decision process. The source TRP combines multiple configuration elements (UE context, resource allocations, monitoring parameters) into a single pre-configuration message sent to the target TRP, reducing the overall complexity despite the additional preparatory step.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP3711362B1Methods for mobility latency reduction in a hierarchical NR architecture

Publication Date: 2023.01.25 HUAWEI TECH CO LTD

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AI summary

A method and system for mobility latency reduction in a hierarchical NR architecture is provided. In an embodiment, a method in a network component for handover of a UE includes configuring, by the network component, at least one TRP determined according to UE mobility information. The configuring the at least one target TRP is performed prior to the UE moving into a border area between the at least one target TRP and a first serving TRP. Configuring the at least one target TRP results in the at least one target TRP being configured to act as a secondary serving TRP to the UE. The method also includes configuring at least one target TRP and the UE with corresponding dedicated access resource and monitoring opportunities. The method also includes activating a connection and data communication between the UE and the at least one pre-configured secondary serving TRP.