Parallel adaptive decision feedback equalizers

Achieving high speed in decision feedback equalizers (DFEs) is difficult because of the nonlinear decision directed adaptation. Recently, parallel DFE and extended LMS DFE algorithms were proposed for parallel implementation of DFEs. A new double-row DFE algorithm which outperforms the previous approaches is presented. Under the no error propagation assumption, this algorithm performs exactly like a serial DFE. The above three algorithms degrade drastically at high speeds and are more computationally expensive. Three additional novel parallel implementations of the DFE which lead to considerable hardware savings and avoid the coding loss of the former approaches are proposed. These new algorithms are referred to as the direct parallel, double-row DFE without weight correction, and improved block techniques. The first two algorithms give performance that is only slightly degraded as compared to the earlier methods. The improved block technique provides the best performance at higher speed.