System Architecture Design for Low-Complexity Downlink Receivers in MU-OFDM Systems

This study introduces a novel resource allocation approach and a simplified receiver design tailored for power- and processing-constrained devices within an orthogonal frequency division multiplexing (OFDM) system accommodating both mobile and static users. Specifically, pilot symbols are selectively allocated to high-mobility users to facilitate frequent updates of channel state information (CSI). In contrast, static users are excluded from regular pilot updates to enhance resource utilization and minimize unnecessary overhead. To further reduce computational load and make the receiver design simple, we implement $N/2$ -point fast Fourier transform (FFT) for processing a large number of subcarriers. This approach effectively addresses the computational limitations associated with traditional OFDM systems. The proposed design significantly reduces processing overhead while maintaining system reliability. Comprehensive simulations demonstrate that the proposed system achieves bit error rate (BER) performance, and spectral efficiency comparable to conventional methods while significantly reducing computational complexity.