A-PSK Pilot Symbols for Phase Error Compensation
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Solution Overview
Problem
Existing methods for coherent demodulation of high-order QAM signal constellations in phase noise environments result in long error bursts and reduced traffic throughput due to the limitations in phase error tracking and the need for additional pilot symbols.
Innovation Solution
The use of Amplitude and Phase-Shift Keying (A-PSK) pilot symbols that carry data and are optimized for phase tracking, allowing them to serve dual purposes while maintaining robustness for phase error correction, thereby improving traffic throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional N-QAM pilot symbols are used for phase tracking, then phase error tracking can be performed, but long error bursts occur and decision errors increase
Solution Approach 1:
The patent changes the fundamental parameter of the pilot symbol configuration from traditional N-QAM to A-PSK with specifically arranged signal points. This parameter change transforms the pilot symbols into a more robust configuration that is inherently less susceptible to phase errors, thereby improving phase tracking reliability without introducing long error bursts
Solution Approach 2:
The patent applies local quality by creating different signal point arrangements for different parts of the constellation. The A-PSK pilot symbols have a specific local configuration optimized for phase tracking, while maintaining overall N-QAM modulation for data transmission. This localized optimization improves phase measurement precision without affecting the overall system throughput
2Reliability
If more pilot symbols are inserted for better phase tracking, then phase error determination improves, but payload capacity decreases due to scavenging
Solution Approach 1:
The patent applies universality by designing A-PSK pilot symbols that serve dual functions: they provide robust phase tracking information and simultaneously carry payload data. This multi-functionality eliminates the need for additional dedicated pilot symbols, maintaining traffic throughput while improving phase error determination reliability
Solution Approach 2:
The patent merges the functions of pilot symbols and data-carrying symbols into a single unified structure. The A-PSK configured symbols perform both phase tracking and payload transmission, combining what were previously separate functions into one efficient mechanism that improves reliability without sacrificing productivity
Data Source
AI summary
A method of compensating phase error of a received signal is disclosed. The signal comprises a symbol set comprising a plurality of symbols of a first type having an N-Quadrature Amplitude Modulation, N-QAM, signal configuration, where N is an integer larger than 4, and at least one symbol of a second type having an Amplitude and Phase-Shift Keying, A-PSK, signal configuration, wherein both the symbols of the first type and of the second type carries data and wherein the symbols of the second type also are arranged as pilot symbols for determination of phase rotation determination. A receiver and transmitter, as well as a communication system, employing the symbol set are disclosed.