Constant modulus receivers under reduced noise amplification objective

A family of algorithms is presented for the adaptation of a fractionally spaced FIR channel equaliser for binary data. These algorithms incorporate an additive adjustment to the standard constant modulus objective so as to facilitate a reduction in the noise amplification factor. The novel algorithms essentially seek to balance the constant modulus objective of the equalisation with the noise power present in the output. The consequence of such a balance is that many of the local minima are excluded implicitly as, at those points, the noise amplification factor is greater than its value at the global minimum. Thus it is expected that a solution near the global minimum is likely to be attained. Computationally, these algorithms are of the same order as the standard CMA algorithm. Results support the expected behaviour of the algorithm. © IEE, 1999