Approximate Constellation Signaling for Nonlinear QAM Amplifiers
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Solution Overview
Problem
Existing wireless communication systems using quadrature amplitude modulation (QAM) face issues with data recognition errors due to amplifier distortion, particularly when operating in the non-linear region, which limits amplifier capability and reduces data rate.
Innovation Solution
A wireless communication system that provides information on an approximate constellation to the reception device, allowing it to perform correct likelihood calculations even in the non-linear region of the amplifier by using an approximate constellation instead of the actual distorted one, thereby maintaining high data rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmission power is increased to improve SNR, then signal quality is improved, but amplifier distortion increases causing data recognition errors
Solution Approach 1:
The transmission device performs preliminary action by generating distortion compensation information based on the transmitted signal characteristics before transmission. This compensation information is then sent to the reception device, which uses it to pre-correct the received signal, preventing distortion-induced recognition errors before they occur.
Solution Approach 2:
The system implements feedback by having the reception device calculate distortion compensation information based on the received signal and the transmitted signal characteristics. This compensation information is fed back to correct the received signal, creating a closed-loop system that actively counteracts amplifier distortion effects.
2Reliability
If the linear region of the amplifier is used to avoid distortion, then data recognition accuracy is improved, but amplifier capability utilization is reduced
Solution Approach 1:
The reception device calculates distortion compensation information based on feedback from the received signal characteristics and transmits this compensation information back. This enables the system to operate in the non-linear region while maintaining accurate data recognition through active distortion compensation.
Solution Approach 2:
The system changes the operational parameters by allowing transmission power to operate in the non-linear region of the amplifier while dynamically adjusting the reception process using distortion compensation. This transforms the system from a static linear-region operation to a dynamic non-linear region operation with compensation.
3Productivity
If distortion compensation information is transmitted to enable non-linear region operation, then amplifier capability utilization is improved, but communication overhead increases
Solution Approach 1:
The system extracts only the essential distortion compensation information from the full signal characteristics and transmits only this condensed compensation data. This reduces the overhead by taking out only the necessary correction parameters rather than transmitting complete signal characterization data.
Solution Approach 2:
The distortion compensation information is represented in an efficient parameter format that minimizes the data size required for transmission. By changing the representation parameters of the compensation information, the system reduces communication overhead while maintaining the effectiveness of distortion compensation.
Data Source
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AI summary
The present disclosure relates to a wireless communication system using a quadrature amplitude modulation scheme, and an object thereof is to effectively prevent erroneous recognition of data while utilizing a non-linear region of an amplifier. A transmission device includes: a transmission signal amplifier enabled to vary transmission power; a transmission power control unit that controls the transmission power; and an approximate pattern information notification unit that generates pattern information on an approximate constellation. In a case where 64 QAM is used as the modulation scheme, a 64 QAM distortion constellation is generated in the non-linear region of the transmission signal amplifier. In this case, a 64 APSK approximate constellation is generated, and pattern information on the 64 APSK approximate constellation is transmitted to a reception device. The reception device performs likelihood calculation for a reception point indicated by a data signal by using the approximate constellation corresponding to the pattern information.