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UWB Communications Systems: a Comprehensive Overview

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... It is well known that narrowband MIMO performance is limited by Rayleigh fading and by antenna/channel correlations. It has been recently shown on the other hand that UWB signals were much more easily decorrelated [2] [3], and also much less prone to fading. These two features make UWB very attractive for SM [4]. ...
... In a dense channel where the amplitudes of the L selected paths in the rake combiners have the same variance (assuming L<<K), the coherent term basically grows linearly with L, while the incoherent one grows as L , resulting in a ratio of coherent output energy to incoherent one varying as L. The correlation coefficient between the output signals of two rake stages connected with the same antenna is here written as: [3], because of the incoherence of the interfering terms. This property is the basis of the SM capability of MIMO UWB [4]: the ICI signal is very small as soon as the antennas are spatially separated, so that we can expect an excellent performance of this scheme with moderate processing complexity. ...
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... GHz spectrum in compliance to Federal Communication Commission (FCC) Part 15 [2]. In addition, emerging standards for wireless personal area network (WPAN) in IEEE 802.15.3a [3] and ECMA-368 [4] demands very high data rate ranging from 100Mbps to 500Mbps [5]. Hence, the range is expected to be further reduced with higher data rate. ...
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... N recent years, ultra-wideband (UWB) spread spectrum techniques have gained increasing interest [1], [2], [3], [4]. UWB systems are often defined as systems that have a relative bandwidth larger than 20% and/or absolute bandwidth of more than 500 MHz [5]. ...
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