Frequency Offset Estimation Using Residual Phase Differences
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Solution Overview
Problem
Existing methods for frequency offset estimation in Narrow Band-Internet of Things (NB-IoT) face challenges in accuracy and range due to the long interval between Demodulation Reference Signals (DMRS) symbols and the limited number of DMRS symbols available for estimation.
Innovation Solution
A method and receiver for frequency offset estimation that calculates phase differences between pairs of symbols, removes phase differences due to information carried in the symbols, and estimates frequency offset based on residual phase differences, allowing for increased accuracy and range by utilizing multiple pairs of symbols, including DMRS and data symbols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency offset estimation is based on DMRS symbols, then the estimation process is simple, but the accuracy and estimation range are limited due to long interval and small number of DMRS symbols
Solution Approach 1:
The patent combines DMRS symbols and data symbols into a unified frequency offset estimation process. By merging these two types of symbols, the system increases the number of available samples for estimation while maintaining a manageable process complexity through standardized phase difference calculation procedures.
Solution Approach 2:
The patent makes data symbols serve the dual function of carrying information and providing samples for frequency offset estimation. This multi-functionality approach increases the number of available samples without adding dedicated estimation symbols, thereby improving accuracy while controlling complexity.
2Adaptability or versatility
If the interval between estimation symbols is shortened, then the estimation range increases, but the number of available DMRS symbols decreases
Solution Approach 1:
The patent changes the parameter of symbol selection by including both DMRS and data symbols in the estimation process. This parameter change allows the system to use symbols with shorter intervals while maintaining sufficient sample quantity, thereby expanding the estimation range without sacrificing the number of available symbols.
3Measurement precision
If more symbol samples are used for estimation, then the accuracy improves, but the processing complexity increases
Solution Approach 1:
The patent segments the estimation process into standardized steps (phase difference calculation, information component removal, residual phase extraction, frequency offset computation) that can be systematically applied to each symbol pair. This segmentation makes the processing of multiple symbols more manageable and less complex.
Solution Approach 2:
The patent establishes a continuous estimation process that can operate on multiple symbol pairs in sequence. By creating a reusable calculation framework, the system can process additional symbols without proportionally increasing complexity, as the same methodology is applied repeatedly.
Data Source
AI summary
The present disclosure provides a method in a receiver for frequency offset estimation. The method includes: for each of two or more pairs of symbols in a set of symbols from a transmitter: calculating a phase difference between a first symbol and a second symbol in the pair; and removing from the calculated phase difference a phase difference component due to a difference between information carried in the first symbol and information carried in the second symbol, to obtain a residual phase difference component. The method further includes: estimating a frequency offset between the receiver and the transmitter as a function of the respective residual phase difference components obtained for the two or more pairs.