Fractional order constant modulus blind algorithms with application to channel equalisation
Syed Muslim Shah, Raza Samar, Syed Mohsen Naqvi, Jonathon A. Chambers · Electronics Letters · 2014
A novel methodology is developed for blind equalisation where the output of the linear filter is passed through a nonlinear fractional update term derived from the cost function using fractional calculus. The final weights update is a combination of the conventional constant modulus algorithm (CMA) weights and a fractional update part. As an improvement over the traditional approach, the new fractional strategy helps capture the parameters of the model at a faster rate while keeping the error small. The algorithm is applied for the blind equalisation of flat and frequency‐selective channels. To assess the suitability of the proposed technique, different fractional orders and step sizes are used; the performance metric considered is the mean squared error for a quadrature phase shift keying transmission scheme. The simulation results show that the proposed technique outperforms the conventional CMA, exhibits faster convergence and yields an improved steady‐state response.