Tone Reservation Via Clipping Implementation Code

Tone Reservation Via Clipping is a technique used to reduce the Peak-to-Average Power Ratio (PAPR) in OFDM (Orthogonal Frequency Division Multiplexing) signals. In OFDM systems, high PAPR causes nonlinear distortion in power amplifiers. The Tone Reservation method optimizes signals by reserving certain subcarriers (called reserved tones) to reduce peak power.

Basic Principles: Reserved Tone Selection: In the OFDM frequency domain signal, select a portion of subcarriers as reserved tones. These subcarriers are not used for data transmission but are dedicated to PAPR optimization. Peak Clipping: Perform clipping on the time-domain signal by limiting the peak amplitude to reduce PAPR. Iterative Optimization: Through multiple iterations, adjust the values of reserved tones to minimize distortion after clipping while ensuring data subcarriers remain unaffected.

MATLAB Implementation Approach: OFDM Signal Generation: Generate random QAM-modulated data and transform it to the time domain using IFFT. Code typically involves creating QAM symbols and applying ifft() function with proper scaling. Reserved Subcarrier Configuration: Select specific subcarrier indices as reserved tones and set data values to zero at these positions. Implementation requires careful indexing of subcarrier arrays. Clipping Process: Detect signal peaks using max() or peak detection algorithms, then apply clipping threshold using conditional statements like x(x>threshold) = threshold. Frequency Domain Correction: After clipping, convert back to frequency domain using FFT, then adjust reserved tone values using optimization algorithms (e.g., gradient descent or projection methods). Iterative Optimization: Implement while/for loops to repeat clipping and correction processes until PAPR meets acceptable thresholds or maximum iterations are reached. Monitoring convergence through PAPR calculation at each iteration.

Tone Reservation Via Clipping has significant applications in communication systems like 5G and Wi-Fi, effectively improving signal transmission efficiency and reducing power amplifier requirements.