5G Fast Handover Using Radio Bearer and Security Key Reuse

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Solution Overview

Problem

Existing handover procedures in wireless communication systems, particularly in 5G networks, suffer from inefficiencies such as user plane reset and security key updates, leading to increased latency and hinder fast handovers due to frequent cell changes in high-frequency bands.

Innovation Solution

Implementing a method for terminals and base stations to perform fast handovers by reusing user plane protocols and security keys during inter-cell handovers, minimizing protocol resets and key updates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional handover procedures are used in 5G networks, then security is maintained through key updates, but handover latency increases and handover speed decreases

Engineering Contradiction:
ImprovesecurityVSAvoidhandover latency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-configuring security keys and user plane protocol parameters in the target base station before handover occurs. The source base station transfers necessary security context and protocol configuration information to the target base station in advance, allowing the target to be ready for immediate service continuity without waiting for post-handover key derivation and protocol setup.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter state of security keys and protocol configurations by maintaining their validity across handovers rather than resetting them. Specifically, the patent preserves PDCP sequence numbers and reuses security keys when conditions allow, transforming the traditional approach of parameter reset into parameter preservation to reduce handover latency.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If security keys are updated during every handover, then security is strengthened, but handover performance deteriorates due to increased processing time

Engineering Contradiction:
ImprovesecurityVSAvoidhandover speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies partial action by selectively updating security keys only when necessary rather than performing full key updates in every handover scenario. The patent determines whether key update is needed based on specific conditions such as handover distance, security policies, and network configuration, allowing partial reuse of existing keys to improve handover speed while maintaining adequate security.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The patent changes the state of security key parameters from mandatory update to conditional update. By modifying the key management policy from always-update to selective-update based on handover characteristics, the patent improves handover performance while maintaining security through context-aware key management decisions.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If user plane protocols are reset during handover, then protocol consistency is ensured, but handover latency increases

Engineering Contradiction:
Improveprotocol consistencyVSAvoidhandover latency
Core Design Contradiction:
Stability of the object's compositionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-synchronizing PDCP sequence numbers and configuring user plane protocol parameters in the target base station before handover. The source base station transfers the current PDCP sequence number state to the target, allowing the protocol to continue seamlessly without reset, thus reducing handover latency while maintaining consistency.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies continuity of useful action by maintaining the user plane protocol state across handovers rather than resetting it. By preserving PDCP sequence numbers and protocol configurations, the patent ensures continuous data flow and protocol operation throughout the handover process, eliminating interruptions and reducing latency.

Inventive Principle:
Principle #20Continuity of useful action

4Adaptability or versatility

If frequent cell changes are supported in high-frequency bands, then network flexibility improves, but handover efficiency decreases due to repeated protocol resets

Engineering Contradiction:
Improvenetwork flexibilityVSAvoidhandover efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent applies universality by creating a handover mechanism that works across multiple scenarios and frequency bands with a unified approach. The patent establishes universal security key management and user plane protocol configuration that can be applied consistently whether the terminal moves between cells in high-frequency 5G bands or lower-frequency bands, enabling flexible network adaptation without scenario-specific complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the state of handover parameters from reset-based to preservation-based, allowing frequent cell changes to occur without repeated protocol resets. By maintaining protocol state and security parameters across handovers, the patent enables high network flexibility for frequent cell changes in high-frequency bands while avoiding the efficiency penalty of repeated resets.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3454603B1Method and apparatus for executing handover in wireless communication system
Publication Date: 2026.04.22 SAMSUNG ELECTRONICS CO LTD
  • EP3454603B1 patent drawingFigure 1
  • EP3454603B1 patent drawingFigure 2
  • EP3454603B1 patent drawingFigure 3

AI summary

The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE). A handover method for a terminal according to one embodiment of the present disclosure may include: receiving, from a source cell, a message including information on one or more target cells for performing a fast handover; and performing a fast handover by reusing a radio bearer based on the received information.