Variable Amplitude Phase Signal Carrier Recovery
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Solution Overview
Problem
Conventional carrier phase recovery methods are limited in their applicability to high-order quadrature amplitude modulation (QAM) signals and are computationally complex, making them unsuitable for flexible modulation formats in optical communications systems.
Innovation Solution
A signal transmission apparatus and method that inserts phase modulation signals with variable amplitudes into data modulation signals to facilitate carrier phase recovery, enabling compatibility with various modulation formats and reducing calculation complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If Viterbi-Viterbi algorithm is used for carrier phase recovery, then calculation complexity is reduced, but it is only applicable to constant modulus modulation signals such as QPSK and cannot be directly applied to high-order QAM signals
Solution Approach 1:
The transmitted signal is segmented into two parts: a phase modulation signal component that carries phase information for carrier phase recovery, and a data modulation signal component that carries the actual data. By separating these functions into different signal components, the phase recovery function can be extracted and processed independently using simple algorithms while the data transmission can utilize high-order modulation formats.
Solution Approach 2:
A phase modulation signal is introduced as an intermediary carrier that embeds the carrier phase information within the data modulation signal. This intermediary signal serves as a reference for phase recovery, enabling the receiver to extract phase information without directly processing the complex high-order QAM signal, thus reducing calculation complexity while maintaining broad applicability.
2Adaptability or versatility
If blind phase search algorithm is used for carrier phase recovery, then applicability to multiple modulation formats is achieved, but calculation complexity becomes high and is hard to be achieved in hardware
Solution Approach 1:
The phase information is extracted from the transmitted signal by inserting a phase modulation signal with variable amplitude into the data modulation signal. This extraction allows the receiver to obtain carrier phase information directly from the signal structure itself, eliminating the need for complex blind search algorithms while maintaining compatibility with various modulation formats.
Solution Approach 2:
The amplitude of the phase modulation signal is varied to encode phase information in a manner that is easily distinguishable and processable. By changing the amplitude parameter of the phase modulation component, the system enables simple threshold-based or correlation-based detection at the receiver, avoiding the need for computationally intensive blind phase search while supporting multiple modulation formats.
3Device complexity
If phase modulation signals with variable amplitudes are inserted into data modulation signals, then carrier phase recovery can be performed efficiently in various modulation formats, but system capacity redundancy increases
Solution Approach 1:
Instead of inserting full-phase modulation signals that would consume significant capacity, only partial phase information is embedded through variable amplitude insertion. The amplitude of the phase modulation signal is adjusted to be just sufficient for reliable phase recovery, avoiding excessive redundancy while ensuring adequate phase information is available for carrier phase recovery in various modulation formats.
Data Source
AI summary
Embodiments of this disclosure provide a signal transmission apparatus, a carrier phase recovery apparatus and method. By inserting phase modulation signals with variable amplitudes into data modulation signals and performing carrier phase recovery on received signals at a receiving end according to the phase modulation signals, the apparatuses and methods are applicable to communications systems of various modulation formats and are compatible with existing communications systems, and calculation complexity is relatively low. Furthermore, as the amplitudes of the inserted phase modulation signals are variable, the phase modulation signals may be flexibly configured in data modulation signals, to lower redundancy and influence on the system capacity is relatively small.