PSK Carrier Phase Estimation Using Pilot and Data Symbols

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Solution Overview

Problem

Existing communication systems face challenges in accurately estimating carrier phase and amplitude in received signals using phase shift keying modulation schemes, particularly when both pilot and data symbols are present, as existing methods do not effectively incorporate pilot symbols for coherent detection.

Innovation Solution

A method for estimating carrier phase and amplitude in a received signal using M-ary phase shift keying digital modulation schemes, which involves calculating M-ary rounded phase offsets, sorting data symbols, and optimizing a sum of squares objective function with recursive calculation of candidate values to determine the optimum carrier phase and amplitude.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If non-coherent detection with differential encoding is used, then the method works without pilot symbols, but the inclusion of pilot symbols is not effective and accuracy deteriorates in noisy conditions

Engineering Contradiction:

Improveability to work without pilot symbolsVSAvoidcarrier phase and amplitude estimation accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by treating pilot symbols and data symbols differently in the estimation process. Pilot symbols are used to establish a reference phase, while data symbols are processed with differential detection. The estimator selectively applies different processing methods to different portions of the signal based on their nature (pilot vs data), thereby improving overall accuracy while maintaining versatility.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the received symbols into pilot symbols and data symbols, applying different estimation techniques to each segment. The pilot symbols are used to estimate the common phase error, while data symbols are processed using the segmented information to refine the estimation. This segmentation allows effective incorporation of pilot symbols into the detection process.

Inventive Principle:

Principle #1Segmentation

2Reliability

If traditional least squares estimator is used, then the method provides maximum likelihood estimation under Gaussian noise, but it does not effectively incorporate both pilot and data symbols together

Engineering Contradiction:

Improvemaximum likelihood estimation propertyVSAvoidcomplexity of incorporating both pilot and data symbols

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by first estimating the common phase error using only pilot symbols before processing the data symbols. This preliminary estimation step simplifies the subsequent processing of data symbols, as the phase reference is already established. This approach maintains the maximum likelihood property while reducing the complexity of jointly processing all symbols.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary step where the pilot symbols serve as a mediator to establish a phase reference that is then used in processing the data symbols. This intermediary approach allows the system to leverage both pilot and data symbols effectively without requiring complex joint processing, thereby maintaining reliability while managing complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If more pilot symbols are transmitted, then the accuracy of phase estimation improves, but the efficiency of data transmission decreases

Engineering Contradiction:

Improvephase estimation accuracyVSAvoiddata transmission efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent applies partial action by using only a portion of the received symbols as pilot symbols and the remainder as data symbols. The estimator is designed to extract maximum information from the pilot symbols for phase estimation while minimizing their proportion in the overall transmission. This allows achieving sufficient accuracy with a minimal number of pilot symbols, thereby maintaining high data transmission efficiency.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS9491018B2Carrier phase and amplitude estimation for phase shift keying using pilots and data

Publication Date: 2016.11.08 MYRIOTA PTY LTD

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 optimization 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.