Patent ID: 7061977

Claim:
In a digital communication system an apparatus for calculating adaptive equalizer coefficients comprising: means for using an algorithm that exploits sparsities in target weight vectors in an adaptive channel equalizer to increase a convergence rate of at least one adaptive equalizer coefficient, wherein said means for using said algorithm further includes any one of; means for providing a sparse least mean square algorithm of the form w k + 1 i = w k i + μ ⁢ ( y k - y ^ k ) ⁢ x k i ⁢ (  w k i  + ɛ ) where w k i is the i th weight vector at time k, and where w k+1 i is the i th weight vector at time k+1, and where μ is the stepsize, and where ŷ k is a received signal at time k after passing through filter w, and where (ŷ k −c) is a calculated error at time k, and where x k i is the i th value of received signal at time k, and where (|w k i | α +εw) is a measure of sparsity contribution specified by a cost function: means for providing a sparse constant modulus algorithm of the form w k + 1 i = w k i - μ ⁢ y ^ k ⁢ ( y ^ k - c ) ⁢ x k i ⁡ (  w k i  α + ɛ ⁢ ⁢ w ) where w k i is the i th is the weight vector at time k, and where w k+1 i is the i th weight vector at time k+1, and where μ is the stepsize, and where ŷ k is a received signal at time k after passing through filter w, and where (ŷ k −c) is a calculated error at time k, and where x k i is the i th value of received signal at time k, and where (|w k i | α +εw) is a measure of sparsity contribution specified by a cost function; and means for providing a sparse decision directed algorithm of the form w k + 1 i = w k i - μ ⁡ ( Q ⁡ ( y ^ k ) - y ^ k ) ⁢ x k i ⁡ ( | w k i ⁢ | α ⁢ + ɛ ) where w k i is the i th weight vector at time k, and where w k+1 i is the i th weight vector at time k+1, and where μ is the stepsize, and where ŷ k is a received signal at time k after passing through filter w, and where Q(ŷ k ) is a quantization of ŷ k , and where (Q(ŷ k )−ŷ k ) is a calculated error at time k, and where x k i is the i th value of received signal at time k, and where (|w k i | α +ε) is a measure of sparsity contribution specified by a cost function.