Effect of Channel Noise on Fractionally Spaced CMA and MMA

This paper analyzes and compares the robustness of the constant modulus algorithm (CMA) and multimodulus algorithm (MMA) in the presence of additive channel noise when the channel satisfies the zero-forcing conditions. A generalized formulation of the relocation of stationary points toward the origin in terms of signal-to-noise ratio (SNR) was developed for both the CMA and the MMA to facilitate the comparison of the sensitivity to channel noise of CMA with that of MMA for various source constellations. Relationships between the relocation of the stationary points for the MMA and CMA were derived. Simulation results appear to confirm the main results of this work, regarding the sensitivity to channel noise when the fractionally spaced CMA (FS-CMA) and fractionally spaced MMA (FS- MMA) criteria were applied with various sources.