Radio Node Carrier Type Switching for Legacy UE Access

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Solution Overview

Problem

In cellular networks, the transition from Legacy Carrier Type (LCT) to New Carrier Type (NCT) is hindered by the inability of legacy UEs to access NCT, which limits network performance and prevents the benefits of NCT, such as reduced interference and overhead, from being realized when legacy UEs are present.

Innovation Solution

A radio node switches between applying NCT and LCT on a second frequency to allow legacy UEs to measure and receive signals, using indicators to determine data channel mappings and resource element usage, enabling flexible and rapid switching between carrier types to support both legacy and new UEs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the radio node applies NCT on the second frequency to improve network performance and reduce interference, then network performance and throughput are improved, but legacy UEs cannot access the second frequency

Engineering Contradiction:
Improvenetwork throughputVSAvoidlegacy UE access capability
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The radio node dynamically switches between NCT and LCT on the second frequency based on whether legacy UEs need to access it. When legacy UEs are present, the node switches to LCT to maintain their access capability; when legacy UEs are absent, the node switches to NCT to improve network performance and reduce interference. This dynamic adaptation resolves the contradiction between throughput improvement and legacy UE access.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The radio node changes the carrier type parameter (from NCT to LCT or vice versa) on the second frequency based on the presence of legacy UEs. This parameter change allows the system to toggle between two operational modes: one optimized for performance (NCT) and one ensuring compatibility (LCT), thereby resolving the contradiction between throughput and access capability.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the radio node switches between NCT and LCT on the second frequency to support both legacy and new UEs, then adaptability is improved, but device complexity increases

Engineering Contradiction:
Improvecarrier type switching capabilityVSAvoidradio node complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The radio node uses feedback from UE capability indications to determine whether to apply NCT or LCT on the second frequency. When a legacy UE is detected, the node receives feedback indicating LCT capability and switches to LCT; when only new UEs are present, the node applies NCT. This feedback mechanism enables automatic adaptation without complex manual configuration, resolving the contradiction between adaptability and device complexity.

Inventive Principle:
Principle #23Feedback

3Adaptability or versatility

If the radio node applies LCT on the second frequency to allow legacy UE access, then legacy UE access capability is improved, but network performance and throughput are reduced

Engineering Contradiction:
Improvelegacy UE access capabilityVSAvoidnetwork throughput
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The radio node dynamically switches between LCT and NCT on the second frequency based on the presence of legacy UEs. When legacy UEs are present, the node applies LCT to ensure their access capability; when legacy UEs are absent, the node switches to NCT to maximize network throughput and performance. This dynamic switching resolves the contradiction between access capability and throughput by applying the appropriate carrier type at the appropriate time.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The radio node periodically evaluates whether legacy UEs are present on the second frequency and switches carrier types accordingly. This periodic assessment allows the system to transition between LCT and NCT modes, ensuring that legacy UE access is maintained when needed while maximizing throughput when legacy UEs are absent, thereby resolving the contradiction between access capability and network performance.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP2997783B1Method and radio node for transmitting downlink signals
Publication Date: 2020.01.01 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP2997783B1 patent drawingFigure 1~2
  • EP2997783B1 patent drawingFigure 3~4b
  • EP2997783B1 patent drawingFigure 5~6

AI summary

A method and radio node(600) for radio communication of data with a User Equipment, UE, (602) wherein a first carrier type A is applicable for serving both legacy UEs and new UEs and a second carrier type B is applicable only for serving new UEs, and wherein the UE (602) is configured to support both the first and second carrier types A,B. The radio node (600) applies the first carrier type A for downlink signals on a first frequency (F1), and switches between the second and first carrier types B,A for downlink signals on a second frequency (F2) in order to allow the legacy UEs to measure and/or be served on the second frequency (F2). The radio node (600) further transmits to the UE (602) an indicator (604) in a downlink assignment for data on a data channel,the indicator (604) indicating to the UE (602) whether Cell-specific Reference Signal,CRS, resource elements are used for transmitting the data to the UE. Thereby the UE (602) is enabled to determine a mapping for the data channel depending on the indicator (604).