Superimposed training on redundant precoding for low-complexity recovery of block transmissions

The adoption of orthogonal frequency-division multiplexing (OFDM) by wireless local area networks and audio/video broadcasting standards testifies to the importance of recovering block precoded transmissions propagating through frequency-selective FIR channels. Existing block transmission standards invoke bandwidth-consuming error control codes to mitigate channel fades and training sequences to identify the FIR channels. For low-complexity block-by-block processing, redundant precoders with cyclic prefix (CP) along with superimposed training sequence are optimally designed to enable least squares estimation of time-varying FIR channels and symbol recovery regardless of the underlying FIR frequency-selective multipath channel. Numerical results are also presented to access the performance of the proposed affine precoders.