Receiver-Side Frequency Offset Tracking for Distributed MIMO
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Solution Overview
Problem
In distributed MIMO systems, frequency offsets caused by differences in local oscillator devices across antennas lead to deteriorated decoding performance and effective data transmission, as existing methods require inserting known sequences and intermittent CFO parameter calculation.
Innovation Solution
A method and apparatus for correcting frequency offsets by receiving and processing signals to acquire center tap coefficients and phases, estimating frequency offsets, and performing dynamic frequency offset correction without relying on known sequences, allowing for continuous and efficient data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If known sequences are inserted in transmission data for CFO estimation, then frequency offset correction can be implemented, but effective data transmission is affected and the process becomes intermittent without dynamic tracing
Solution Approach 1:
The patent extracts the frequency offset estimation function from the data transmission stream by using dedicated pilot signals instead of inserting known sequences within data. This separation allows continuous data transmission without interruption for CFO estimation, resolving the contradiction between measurement precision and productivity
Solution Approach 2:
The patent introduces pilot signals as an intermediary element that carries frequency offset information without interfering with data transmission. These pilot signals serve as a mediator between the transmission channel and the CFO estimation process, enabling continuous monitoring and correction without affecting data throughput
2Reliability
If known sequences are used for CFO calculation, then frequency offset can be obtained, but the calculation process is complex and lacks continuous dynamic tracing capability
Solution Approach 1:
The patent replaces complex intermittent CFO calculation mechanisms with a continuous phase-locked loop based tracking system. This substitution transforms the mechanical/computational process of periodic estimation into a continuous electronic tracking mechanism, reducing complexity while improving reliability
Solution Approach 2:
The patent transitions from static intermittent CFO estimation to dynamic continuous tracking using phase-locked loops. The system continuously adapts to frequency offset changes in real-time, providing dynamic tracing capability that maintains decoding performance without complex calculations
3Measurement precision
If intermittent CFO estimation is used with known sequences, then frequency offset correction is possible, but the system lacks continuous dynamic tracing and requires more hardware restrictions
Solution Approach 1:
The patent ensures continuous useful action by implementing continuous CFO estimation and correction through phase-locked loops. The system maintains constant frequency offset tracking without interruption, enabling dynamic tracing capability while preserving measurement precision through uninterrupted monitoring
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables effective frequency offset correction, reducing operation complexity and system complexity, ensuring stable decoding and efficient data transmission by estimating and compensating frequency offsets at the receiving end, rather than relying on feedback compensation at the sending end.
Implementation Method 1
acquiring n first output phases of a phase-locked loop phase detector that corresponds to the n channels of first corrected signals, and a second output phase of a phase-locked loop phase detector that corresponds to a superposed signal
Data Source
AI summary
A method and an apparatus for correcting a frequency offset are provided. The method includes: receiving n channels of first signals; performing frequency offset correction processing on the n channels of first signals to obtain n channels of first corrected signals; acquiring n center tap coefficients of a space time equalizer, n first output phases of a phase-locked loop phase detector, and a second output phase of a phase-locked loop phase detector; acquiring n first estimated frequency offset values according to the n center tap coefficients and the n first output phases; acquiring a second estimated frequency offset value according to the second output phase; and receiving n channels of second signals, and performing frequency offset correction on the n channels of second signals according to the n first estimated frequency offset values and the second estimated frequency offset value.