Research on Anti-Interference Techniques for Wireless Channels in OFDM Systems with MATLAB Implementation

OFDM (Orthogonal Frequency Division Multiplexing) systems, as an efficient multi-carrier modulation technique, are widely applied in wireless communications. The core principle involves dividing high-speed data streams into multiple orthogonal subcarriers for transmission, effectively combating inter-symbol interference caused by multipath effects. However, in practical wireless channels, the system still faces challenges such as frequency-selective fading, inter-carrier interference (ICI), and additive noise.

To address the critical issue of channel anti-interference, modern communication systems typically employ the following technical combinations: Pilot-assisted channel estimation techniques enable receivers to estimate channel frequency responses by inserting known pilot symbols into specific subcarriers; while adding cyclic prefix (CP) sacrifices some spectral efficiency, it effectively eliminates inter-symbol interference caused by multipath propagation; additionally, equalizers based on MMSE (Minimum Mean Square Error) or LS (Least Squares) algorithms can compensate for channel distortion, and adaptive modulation techniques dynamically adjust modulation schemes according to channel conditions.

At the MATLAB simulation level, complete implementation requires constructing the following modules: The transmitter performs QAM modulation, pilot insertion, and IFFT transformation; the channel model needs to simulate multipath delay and Doppler effects; the receiver converts signals back to the frequency domain through FFT, then uses interpolation algorithms to recover full-band channel responses. By comparing bit error rate curves under different signal-to-noise ratio conditions, the effectiveness of anti-interference techniques can be visually evaluated.

This research provides reference value for the design of high-frequency band communication systems like 5G. Future work could further explore the potential of novel channel estimation methods such as compressed sensing in reducing pilot overhead.