Design of RAKE receivers for ultra-wideband binary block-coded PPM in dense multipath channels

RAKE receivers for ultra-wideband communications employing binary block-coded pulse-position-modulation (PPM) are considered in dense multipath channels corrupted by additive white Gaussian noise (AWGN). Optimum and suboptimum designs are investigated with various finger selection and combining criteria such as the maximum energy capture (MEC), the maximum signal-to-noise ratio (MSNR), and the minimum bit-error-rate (mBER) criteria. The combining weights for the MEC, the MSNR, and the mBER criteria are derived and shown to be distinct in general. Conditions for MSNR and/or MEC receivers to perform comparably to the mBER receiver are also derived. Numerical results well confirm the predictions made by the analytical results.