OFDM Channel Estimation with 16QAM Modulation and Demodulation

In this paper, we implemented OFDM channel estimation employing 16QAM modulation and demodulation techniques. The implementation involved generating 16QAM symbols using quadrant-based constellation mapping, where each 4-bit symbol is mapped to one of 16 complex constellation points. For channel estimation, we utilized pilot-based methods with LS (Least Squares) or MMSE (Minimum Mean Square Error) algorithms to estimate channel frequency responses. We calculated bit error rate (BER) performance curves across varying signal-to-noise ratio (SNR) conditions, implementing Monte Carlo simulations with additive white Gaussian noise (AWGN) channel models. The BER calculation incorporated digital demodulation using maximum likelihood detection and hard decision decoding. Corresponding performance graphs were plotted using MATLAB's plotting functions (plot() or semilogy()) to visualize the SNR-BER relationship. Furthermore, we analyzed curve trends and characteristics, including the waterfall curve effect and error floor observations. These analyses provide deeper insights into channel performance characteristics and serve as valuable references for subsequent research and system optimization, particularly for adaptive modulation schemes and channel equalization improvements.