Master-Slave Carrier Frequency Error Correction

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Solution Overview

Problem

Existing multi-carrier wireless systems face challenges in efficiently tracking and correcting frequency and time errors across multiple radio frequency carriers without increasing receiver complexity and power consumption, particularly in non-contiguous spectrum usage scenarios.

Innovation Solution

The solution involves designating a master carrier signal and a slave carrier signal, where frequency and timing errors are estimated and corrected for the master carrier, and then used to derive corresponding errors for the slave carrier signals, reducing the need for continuous measurements across all carriers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If continuous measurements are performed on all component carriers to track frequency and timing errors, then measurement precision is improved, but device complexity and power consumption increase

Engineering Contradiction:
Improvefrequency and timing error tracking accuracyVSAvoidreceiver complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the multiple component carriers into two groups: a first set of component carriers where frequency and timing errors are directly measured and estimated, and a second set of component carriers where errors are derived from the first set. This segmentation allows the receiver to perform continuous measurements only on a subset of carriers while still maintaining accurate error tracking for all carriers, thereby reducing device complexity and power consumption while preserving measurement precision.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If continuous measurements are performed on all component carriers to track frequency and timing errors, then measurement precision is improved, but use of energy increases

Engineering Contradiction:
Improvefrequency and timing error tracking accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent segments the component carriers into measurement carriers (first set) and non-measurement carriers (second set). Frequency and timing errors are continuously measured only on the measurement carriers, while errors for non-measurement carriers are mathematically derived from the measurement results. This approach maintains high measurement precision for all carriers while significantly reducing the energy required for continuous measurements across the entire multi-carrier system.

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If separate frequency error estimation is performed for each component carrier, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvefrequency error estimation accuracyVSAvoidreceiver design complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses a mathematical relationship as an intermediary to transfer frequency and timing error information from measured component carriers to non-measured component carriers. Instead of performing separate measurements on all carriers, the system measures errors on a subset of carriers and uses these measurements as intermediaries to derive errors for the remaining carriers, thereby reducing receiver design complexity while maintaining measurement precision.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If frequency error correction is applied independently to each component carrier, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improvefrequency and timing error correction reliabilityVSAvoidreceiver design complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the error correction process into two stages: (1) direct frequency and timing error correction for component carriers in the first set based on measured errors, and (2) derived frequency and timing error correction for component carriers in the second set based on errors propagated from the first set. This segmented approach ensures reliable error correction for all carriers while avoiding the complexity of implementing independent measurement and correction systems for each carrier.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2286561B1Time-error and frequency-error correction in a multi-carrier wireless communications system
Publication Date: 2018.01.03 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP2286561B1 patent drawingFigure 1~2
  • EP2286561B1 patent drawingFigure 3
  • EP2286561B1 patent drawingFigure 4~5

AI summary

Methods and apparatus for automatic frequency control in wireless receivers configured to simultaneously receive multiple carrier signals at distinct radio frequencies are disclosed. An exemplary wireless device comprises at least first and second radio front-end circuits configured to receive first and second wireless communication signals transmitted via first and second radio-frequency carriers at distinct first and second radio frequencies, respectively, a control processor configured to designate a master carrier signal and a slave carrier signal from among the received wireless communication signals, and a frequency error estimation circuit configured to estimate a first receiver frequency error using the received master carrier signal. The control processor is further configured to calculate a second receiver frequency error from the first receiver frequency error, for use in compensating one or more receiver processes performed on the slave carrier signal.