An Adaptive Maximally Decimated Channelized UWB Receiver With Cyclic Prefix

摘要

The frequency channelized receiver based on hybrid filter bank is a promising receiver structure for ultra-wideband (UWB) radio because of its relaxed circuit requirements and robustness to interference. The uncertainties in the analog analysis filters and the time varying nature of the propagation channels necessitate adaptive methods in practical frequency channelized receivers. Adaptive synthesis filters, however, suffer from slow convergence speed especially when maximally decimated to reduce the analog-digital converter sampling frequency. To improve the convergence speed, the cyclic prefix is applied to the transmitted data. The propagation channel and the channelizer can then be modeled as a circulant matrix and block CM, respectively. Such matrix representation enables the transmitted data to be recovered by two cascaded one-tap equalizers, one of which corresponds to the channelizer and the other to the propagation channel. The cascaded structure is attractive as it allows the estimation of the propagation channel and the channelizer, which vary at vastly different rates, to be updated separately. Adaptive algorithms for both the fractionally spaced equalizer and the symbol spaced equalizer are derived. After initial convergence during startup, the adaptive performance of the channelized receiver to different propagation channels is similar to that of an ideal full band receiver.