Pilot-Channel-Assisted Log-Likelihood-Ratio Selective Combining for Low-Rate DS-UWB Communications

In this paper, we propose a pilot-channel-assisted log-likelihood-ratio selective combining (PCA-LLR-SC) scheme for Rake receivers that will be used in long-range low-rate UWB communications targeted by the IEEE 802.15.4a specification. The pilot and data channels are constructed using quadrature sinusoidal bursts that have the same Gaussian envelope. The system parameters are optimized through jointly minimizing the channel estimation mean square error and maximizing the receiver output signal-to-noise ratio. Simulation results show that the proposed PCA-LLR-SC scheme is able to provide robust low-rate UWB communications in fast-fading multipath channels.