Samir N. Hulyalkar

Blended CMA: smooth, adaptive transfer from CMA to DD-LMS

A common technique in a blind equalization communication system is to use the constant modulus algorithm (CMA) to open the channel eye and then to switch to decision-directed LMS once the error rate has dropped to a sufficiently low level. The propose a new algorithm, blended CMA, which dynamically selects to use either the CMA or DD-LMS update term when adapting the equalizer taps. The decision rule governing this selection is also adaptive. Simulation results presented in this paper demonstrate how the algorithm performs when equalizing 64-QAM over real-world channels and highlights the performance gain over using traditional transfer methods.

Low-complexity and low-latency implementation of the Godard/CMA update

This paper discusses methods for calculating and implementing the update error term for the popular blind equalization algorithm known as Godards (1980) algorithm, or the constant modulus algorithm (CMA), without the use of multipliers so that chip area and signal latency are both substantially reduced. One approach uses a decision-directed CMA update term, and another uses region-based quantization. The quantized error term can be calculated using a look-up table in place of costly multipliers and adders. Baseband and passband implementations are discussed, and computer simulations verify our methods.

A decision-directed constant modulus algorithm for higher-order source constellations

This paper discusses methods for calculating and implementing the update error term for the popular blind equalization algorithm known as Godards (1980) algorithm, or the constant modulus algorithm (CMA), without the use of multipliers so that the chip area and signal latency are both substantially reduced. A decision-directed CMA update term is derived for higher-order (non-constant modulus) source alphabets. The modified update error term can be calculated using a look-up table in place of costly multipliers and adders. Baseband and passband implementations for one-dimensional and two-dimensional signaling are discussed.