OFDM bit error rate simulation based on MATLAB wavelet packet
OFDM (Orthogonal Frequency Division Multiplexing) is a commonly used modulation technology widely used in wireless communication systems. In OFDM systems, the bit error rate is one of the important indicators for evaluating system performance. This article will introduce how to use MATLAB to implement an OFDM system based on wavelet packets and simulate the bit error rate.
Wavelet packet is a multi-resolution analysis tool that can perform time-frequency analysis of signals and has good time-frequency localization characteristics. In OFDM systems, wavelet packets can be used for modulation and demodulation of subcarriers to improve the anti-interference performance of the system.
First, we need to define the parameters of the OFDM system. Suppose we use N subcarriers for transmission, and the number of symbols on each subcarrier is M. We can define the modulation order, for example, the QAM modulation order is 16. Additionally, we need to define the channel model and noise power.
Next, we generate random baseband data and modulate it. We can use the randi function in MATLAB to generate random integers and then map the integers to the corresponding modulation symbols. For example, for 16-QAM modulation, we can use the qammod function in MATLAB for mapping.
Then, we transform the modulated symbols into wavelet packets. MATLAB provides a wealth of wavelet packet functions, which can easily perform transformation and inverse transformation. We can choose the appropriate wavelet packet basis function and use the waverec and waverec2 functions to perform the transformation and inverse transformation.
Based on the wavelet packet transform, we perform OFDM modulation. The wavelet packet coefficients are allocated to each subcarrier, and IFFT (Inverse Fast Fourier Transform) is performed to obtain the time domain signal. Then, a cyclic prefix is added to the time domain signal and transmitted in parallel between various subcarriers.
At the receiving end, we first remove the cyclic prefix and perform FFT transformation to obtain the frequency domain signal. Then, the frequency domain signal is inversely modulated by wavelet packets and demodulated to obtain baseband data. Finally, we calculate the bit error rate and analyze it.
The following is an example of MATLAB code: