QAM Transmission Power Control With Approximate Constellation Decoding
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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 in the non-linear region, limiting power usage and requiring excessive capital investment to stay in the linear region.
Innovation Solution
A wireless communication system that includes a transmission device with a transmission power control unit and an approximate pattern information notification unit to generate and transmit pattern information on an approximate constellation, allowing the reception device to perform likelihood calculations using either a normal or approximate constellation based on the amplifier's region, thereby reducing data recognition errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmission power is increased to improve signal-to-noise ratio, then communication reliability is improved, but amplifier distortion increases causing data recognition errors
Solution Approach 1:
The transmission device performs preliminary action by generating approximate constellation information based on the transmission power level before actual data transmission. This pre-calculated constellation information is then transmitted to the reception device, which uses it to perform likelihood calculations and correct for amplifier distortion effects, thereby preventing data recognition errors that would otherwise occur at high power levels.
2Reliability
If transmission power is limited to the linear region to avoid distortion, then data recognition accuracy is maintained, but amplifier capability is not sufficiently utilized and capital investment increases
Solution Approach 1:
The invention changes the parameter of constellation representation from the traditional fixed normal constellation to a dynamic approximate constellation that varies with transmission power level. By adjusting the constellation parameters based on the actual power level (whether in linear or non-linear region), the system maintains data recognition accuracy while enabling full utilization of amplifier power capability.
3Device complexity
If normal constellation is used for likelihood calculation in non-linear region, then calculation complexity is low, but data recognition errors occur due to constellation collapse
Solution Approach 1:
The invention introduces dynamics into the constellation used for likelihood calculation. Instead of using a static normal constellation, the system dynamically selects or generates an approximate constellation that matches the actual transmission conditions (power level and amplifier operating region). This dynamic adaptation maintains calculation simplicity while significantly improving data recognition accuracy in non-linear regions.
Data Source
AI summary
The present disclosure relates to a wireless communication system using a quadrature amplitude modulation scheme. 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.