Wireless Communication Adaptive Modulation to Avoid Amplifier Distortion
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Solution Overview
Problem
Conventional wireless communication systems experience nonlinear distortion degradation of amplifier waveforms when wireless terminal devices are located far from the base station due to the need for large transmission power, particularly with fixed secondary modulation schemes like OFDM.
Innovation Solution
Adaptive modulation techniques are employed to select MCS indexes based on reception quality, incorporating nonlinear distortion degradation amounts and fading margin values, allowing for optimal modulation and coding schemes to be chosen, including single carrier schemes as secondary modulation, to avoid amplifier distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If large transmission power is used by wireless terminal devices located far from the base station, then the transmission distance is extended, but nonlinear distortion degradation of the amplifier occurs
Solution Approach 1:
The patent applies adaptive modulation where the modulation scheme is dynamically adjusted based on the SINR (Signal-to-Interference plus Noise power Ratio) measured at the receiver. The system switches between different modulation orders (e.g., QPSK, 16-QAM, 64-QAM) depending on channel conditions, allowing the terminal to maintain appropriate transmission power levels without causing amplifier nonlinear distortion while still achieving the required transmission distance.
Solution Approach 2:
The patent changes the modulation order parameter adaptively based on channel conditions. By adjusting the modulation scheme from lower order (more robust) to higher order (higher data rate) depending on the SINR threshold, the system optimizes the balance between transmission power, data rate, and distortion levels, preventing amplifier nonlinear distortion while maintaining communication effectiveness.
2Device complexity
If fixed secondary modulation scheme like OFDM is used, then the system is simple to implement, but PAPR characteristics cause amplifier distortion when transmission power is high
Solution Approach 1:
The patent transitions from fixed modulation schemes to dynamic adaptive modulation. The system continuously monitors SINR at the receiver and adjusts the modulation order accordingly, switching between different modulation types (including single-carrier and multi-carrier schemes) to optimize the balance between implementation simplicity and distortion prevention at high transmission powers.
Solution Approach 2:
The patent introduces adaptive changes in modulation order as a key parameter. By adjusting the modulation scheme based on SINR thresholds, the system can select appropriate modulation types that have favorable PAPR characteristics for the given transmission power level, thereby reducing amplifier distortion while maintaining reasonable system complexity.
Data Source
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AI summary
The present disclosure relates to a wireless communication system pertaining to an adaptive modulation technique that changes a modulation method of a wireless signal according to communication quality of wireless communication, and an object of the present disclosure is to provide a wireless communication system in which, even when a wireless terminal device located far from a wireless base station transmits a wireless signal, a transmitted waveform of a wireless signal is not accompanied by nonlinear distortion degradation of an amplifier. In the wireless communication system according to the present disclosure, MCS indexes include a single carrier modulation scheme as a secondary modulation scheme. A transmitter is configured to execute: processing of selecting one of the MCS indexes by comparing a reception quality notified by a receiver and a required reception quality specified for each of the MCS indexes with each other; processing of modulating and coding a transmission signal; and processing of transmitting the transmission signal to the receiver. The receiver is configured to execute: processing of calculating the reception quality based on average transmission power and a nonlinear distortion degradation amount notified by the transmitter; and processing of transmitting the reception quality to the transmitter.