Improved ISR for IEEE 802.11ah Nonlinearity Compensation via Adjustable Constellation Borders

Iterative subcarrier regularization (ISR) has been recently proposed as a receiver-side remedy for orthogonal frequency division multiplexing (OFDM) nonlinearity. It allows the power amplifier of OFDM transmitters to operate at lower input back-off more efficient uplinks. However, compensation ability cannot align with increasing channel quality, because standard quadrature amplitude modulation (QAM) used in ISR may eliminate due erroneous decisions. To solve this issue, an improved version was flexibly adjust constellation borders QAM and numerically optimize it based on IEEE 802.11ah (hereinafter referred 802.11ah) specifications. Simulations show that scheme not only improves converged bit error rate but also accelerates its own convergence, especially high thereby achieving better efficiency Internet Things clients without additional computational complexity.