MATLAB Implementation of OOK Modulation with RLS Algorithm

OOK (On-Off Keying) is a straightforward digital modulation technique that represents binary data by controlling the presence or absence of a carrier signal. Implementing OOK in MATLAB typically involves generating modulated signals, adding noise, and demodulating to recover original data. When combined with Recursive Least Squares (RLS) algorithm, signal processing effectiveness can be significantly improved, particularly in dynamic channel environments. ### Implementation of OOK Modulation The OOK modulation process is intuitive, typically using a sinusoidal wave as the carrier signal. When input data is 1, the carrier signal remains active; when input data is 0, the carrier signal is turned off. In MATLAB, this can be implemented using basic signal generation functions like sin() combined with logical operations to control carrier switching. The implementation involves creating a time vector, generating the carrier wave, and applying data-dependent amplitude modulation. ### Application of Recursive Least Squares Recursive Least Squares is an adaptive filtering algorithm suitable for parameter estimation in time-varying systems. In OOK communication systems, RLS can be used for channel equalization or noise suppression to improve demodulation accuracy. Unlike traditional fixed filtering methods, RLS dynamically adjusts filter weights based on received signals, adapting to channel variations and optimizing demodulation performance. The MATLAB implementation typically uses the dsp.RLSFilter system object or custom RLS update equations with forgetting factor parameter tuning. ### Implementation Approach Generate OOK modulated signal: Control carrier signal switching based on input bit stream using logical indexing and element-wise multiplication operations. Add channel noise: Simulate realistic communication environments using AWGN (Additive White Gaussian Noise) with the awgn() function or manual noise addition. RLS adaptive filtering: Apply RLS algorithm at the receiver using recursive weight updates to minimize error between desired and actual signals. Demodulate and recover data: Restore original bit stream through threshold detection (using comparison operators) or coherent demodulation methods with correlation techniques. By combining OOK and RLS, system interference resistance can be enhanced, making it suitable for low-complexity, high-efficiency communication scenarios such as short-range wireless transmission or optical communication systems. The implementation demonstrates practical MATLAB coding techniques including signal generation, filter design, and bit error rate analysis.