Least Squares Carrier Phase Estimation Using Pilot Symbols
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Solution Overview
Problem
Existing communication systems face challenges in accurately estimating carrier phase and amplitude in receivers using phase shift keying modulation schemes, particularly when both pilot and data symbols are present, and existing methods do not effectively incorporate pilot symbols for improved estimation.
Innovation Solution
A method employing a least squares estimation algorithm that utilizes pilot symbols to optimize the estimation of carrier phase and amplitude, leveraging the knowledge of pilot symbols to improve the accuracy of phase and amplitude estimation in noisy signals, and extending this approach to multiple modulation schemes for unequal error protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If non-coherent estimation methods are used, then device complexity is reduced, but measurement precision of carrier phase and amplitude deteriorates
Solution Approach 1:
The received signal is segmented into pilot symbols (known to receiver) and data symbols (unknown to receiver). The estimation process is divided into two stages: first estimating carrier phase and amplitude using only pilot symbols, then using these estimates to decode data symbols. This segmentation allows coherent estimation to achieve high precision while keeping the estimation process manageable.
Solution Approach 2:
The carrier phase and amplitude are estimated preliminarily using pilot symbols before data symbol decoding. This preliminary estimation provides the necessary channel state information for subsequent coherent detection of data symbols, enabling accurate recovery of transmitted information while maintaining systematic processing.
2Measurement precision
If pilot symbols are incorporated into estimation, then measurement precision improves, but device complexity increases
Solution Approach 1:
The algorithm segments the signal processing into distinct phases: pilot symbol processing for channel estimation, and data symbol processing for information recovery. By separating known pilot symbols from unknown data symbols, the algorithm achieves coherent estimation precision while maintaining clear computational boundaries that simplify implementation.
Solution Approach 2:
The estimation algorithm uses feedback from pilot symbol processing to inform data symbol decoding. The estimated carrier phase and amplitude obtained from pilot symbols are fed back into the data detection process, enabling coherent detection that achieves high precision while the feedback structure provides a systematic framework for implementation.
3Measurement precision
If coherent detection with pilot symbols is used, then measurement precision improves, but loss of information increases due to pilot overhead
Solution Approach 1:
The system uses a partial amount of pilot symbols (not all symbols are pilots) to achieve sufficient channel estimation accuracy. By using only the necessary number of pilot symbols required for reliable coherent detection, the system achieves high measurement precision while minimizing the overhead and maximizing data transmission efficiency.
Data Source
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AI summary
A least squares estimator of carrier phase and amplitude in a receiver in a communication system using a phase shift keying modulation scheme that uses both known pilot symbols and unknown data symbols is described. That is, the method exploits knowledge of pilot symbols in addition to the unknown data symbols to estimate carrier phase and amplitude. Further, an efficient recursion based estimation method is described that only requires O(L. log L) arithmetic operations where L is the number of received signals. This method uses the M-Ary rounded phase offsets to sort the data symbols and this sorted order is used to recursively calculate candidate values in an optimisation process. Simulation results show that the- estimation methods Using data and pilot symbols outperform estimation methods using only data symbols (ie non-coherent detection methods). Further, the system can be used for systems using multiple M-ary phase shift keying digital modulation schemes.