RFFE TDD Path Control for Stable Inter-Band Carrier Aggregation

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Solution Overview

Problem

Existing user equipment (UE) experiences throughput degradation and transmission efficiency issues due to Inter-band Carrier Aggregation (ICA) in Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD) modes, particularly during transitions between TDD uplink and downlink transmissions.

Innovation Solution

Implementing a radio frequency front-end (RFFE) module with controlled Time Division Duplexing (TDD) paths and gain/phase compensation to stabilize phase/gain variations during TDD transitions, preventing throughput degradation by maintaining consistent states during guard symbols.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If Inter-band Carrier Aggregation (ICA) is executed to aggregate multiple carriers from different frequency bands, then data transmission rates and bandwidth are increased, but throughput degradation occurs and transmission efficiency is affected

Engineering Contradiction:
Improvedata transmission rateVSAvoidthroughput stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by controlling the first TDD transmission path to maintain a specific state (either TDD transmitting or receiving state) during the guard symbol period before actual data transmission begins. This advance preparation prevents phase/gain variations that would otherwise occur during state transitions, thereby preventing throughput degradation while maintaining the high data transmission rates enabled by ICA

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements beforehand cushioning by using the guard symbol as a buffer period where the transmission path state is deliberately controlled and stabilized. This cushioning period absorbs potential phase/gain variations and prevents them from affecting the actual data transmission, thus protecting throughput stability while allowing ICA to operate at high data rates

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Adaptability or versatility

If TDD transmission transitions between uplink and downlink modes are executed rapidly, then communication flexibility is improved, but phase/gain variations occur causing throughput degradation

Engineering Contradiction:
Improvecommunication flexibilityVSAvoidphase/gain stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-controlling the transmission path state during the guard symbol period before mode transitions occur. By establishing the desired state in advance during the guard period, the system prevents phase/gain variations during the actual transition, thereby maintaining phase/gain stability while preserving communication flexibility for rapid TDD mode switching

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses the guard symbol as an intermediary element that mediates between uplink and downlink modes. During this intermediary period, the transmission path state is controlled to act as a buffer that absorbs transitions, preventing direct phase/gain variations from occurring during mode switching. This allows flexible mode transitions while maintaining signal stability

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4672623A1User equipment, controlling method and RFFE module thereof
Publication Date: 2025.12.31 MEDIATEK INC
  • EP4672623A1 patent drawingFigure 1
  • EP4672623A1 patent drawingFigure 2A~2B
  • EP4672623A1 patent drawingFigure 3

AI summary

A user equipment, a controlling method and a processing module thereof are provided. The user equipment comprises a radio frequency front-end (RFFE) module and a processing module. The radio frequency front-end module comprises a first transmission path and a second transmission path. The first transmission path is a Time Division Duplexing (TDD) path. The second transmission path is another TDD path or a Frequency Division Duplexing (FDD) path. The processing module is configured to control the RFFE module. A special slot for a TDD transmission on the first transmission path comprises at least one downlink symbol, at least one uplink symbol and at least one guard symbol. During the guard symbol, the first transmission path is controlled to be either a TDD receiving state for executing a TDD downlink transmission or a TDD transmitting state for executing a TDD uplink transmission.