Approximation of recursive least squares equalization

A receiver device comprising:

• a communication interface configured to detect a received signal comprising a degraded version of a transmitted signal, the received signal suffering from degradations incurred over a communication channel;
• and
• circuitry configured to
• apply an adaptive filter to a series of received blocks of a digital representation of the received signal, thereby generating respective filtered blocks, wherein each received block represents 2N frequency bins, and wherein N is a positive integer;
• and
• calculate coefficients for use by the adaptive filter on a jth received block using (i) error estimates associated with a (j−D−1)th filtered block, wherein D is a positive integer representing a number of blocks, and wherein j is a positive integer greater than (D−1);
• and (ii) an inverse of an approximate covariance matrix associated with the (j−D−1)th received block, wherein the approximate covariance matrix is a diagonal matrix of size L×L, and wherein L is a positive integer lower than 2N.