Adaptive Modulation Coding for Low-PAPR Wireless Signals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High peak to average power ratio (PAPR) in quadrature amplitude modulation (QAM) leads to signal distortion and reduced signal coverage, necessitating a reduction in average power which compromises power amplifier efficiency and coverage area, while increasing subcarriers to reduce PAPR consumes more frequency resources and reduces spectral efficiency.
Innovation Solution
A coding scheme determining method that dynamically sets thresholds for parameters like modulation order, bandwidth extension, spectral efficiency, and code rate to introduce offset QAM (OQAM) signals with low PAPR, ensuring backward compatibility by maintaining or modifying only specific conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If QAM modulation is used, then spectral efficiency is improved, but PAPR becomes excessively high causing signal distortion
Solution Approach 1:
The patent changes the modulation scheme parameter from conventional QAM to OQAM (Offset Quadrature Amplitude Modulation) specifically for low-order modulations (QPSK, 16QAM, 64QAM). This parameter change maintains the spectral efficiency benefits of QAM while reducing PAPR through the offset structure of OQAM, thereby resolving the contradiction between spectral efficiency and signal quality
Solution Approach 2:
The patent dynamically selects between OQAM and QAM modulation schemes based on the modulation order. For modulation orders ≤ 6 (QPSK, 16QAM, 64QAM), OQAM is used to reduce PAPR; for higher modulation orders, conventional QAM is used. This dynamic adaptation allows the system to optimize both spectral efficiency and signal quality under different operating conditions
2Reliability
If average power is reduced to lower PAPR, then signal coverage is improved, but power amplifier efficiency decreases
Solution Approach 1:
By changing the modulation parameter to OQAM for low-order modulations, the patent achieves lower PAPR inherently through the offset structure. This allows the power amplifier to operate at higher average power levels without causing signal distortion, thereby improving both signal coverage and power amplifier efficiency simultaneously
3Reliability
If quantity of transmitted subcarriers is increased to reduce PAPR, then signal quality is improved, but frequency resources are consumed and spectral efficiency decreases
Solution Approach 1:
The patent changes the modulation parameter to OQAM which inherently provides lower PAPR without requiring an increase in the number of transmitted subcarriers. This resolves the contradiction by achieving signal quality improvement through modulation scheme optimization rather than through resource consumption
Data Source
Figure 1~2
Figure 3~4
Figure 5(a)~5(b)
AI summary
This application provides a coding scheme determining method and a communication apparatus. The method includes: determining a modulation scheme, where the modulation scheme is related to a threshold of a first parameter, and the first parameter includes at least one of the following: a modulation order, bandwidth extension, scheduled bandwidth, spectral efficiency, a modulation and coding scheme MCS index, and a code rate; and sending first indication information to a terminal device, where the first indication information indicates the modulation scheme. According to the method provided in this application, a network device can dynamically determine a signal modulation scheme based on at least one of a specified threshold of the modulation order, a specified threshold of the bandwidth extension, a specified threshold of the scheduled bandwidth, a specified threshold of the spectral efficiency, a specified threshold of the modulation and coding scheme MCS index, and a specified threshold of the code rate, so that more OQAMs can be introduced, to generate signals with a low PAPR.