Parallel architectures for decision-directed RLS-equalization

Parallel architectures for decision-directed adaptive recursive least-squares (RLS) equalizers based on a QR-decomposition (QRD) using square-root free Givens-rotations are derived that allow very high throughput for broadband applications. We apply an algorithmic optimization that leads to the use of additional fast adder trees together with a re-timing of the required arithmetic components to maximize throughput. A hybrid RLS/least-mean-squares equalizer is further proposed allowing even higher throughput. The complexity of the resulting equalizer structures is compared for an eight-tap decision-feedback equalizer in terms of an equivalent NAND gate count.