Effects of Quantization in Systolic 2D IIR Beam Filters on UWB Wireless Communications

Ultra-wideband (UWB) wireless beamforming systems may potentially be implemented digitally at multi-gigahertz clock frequencies using low-precision systolic array realizations of two-dimensional (2D) infinite impulse response (IIR) beam plane-wave filters. The finite precision performance of such filters is analyzed in terms of quantization noise. Extensive Monte Carlo simulations are performed using test vectors that are derived from 2D finite-difference time-domain (FDTD) computational electromagnetic models of the UWB channels. The bit error rate (BER) is determined as a function of signal-to-interference ratio (SIR), with and without beamforming, and for various practical combinations of finite internal wordlengths and A/D converter precisions. It is established that 3-bit A/D converters with 3- to 6-bit internal wordlengths are adequate for good performance and that 4-bit A/D converters with 4- to 7-bit internal wordlengths achieve excellent performance.