Low-complexity receiver structures for impulse radio (IR) UWB systems


The interest in ultra wideband (UWB) systems has grown tremendously in recent years. The UWB systems occupy an instantaneous bandwidth of 500 MHz or fractional bandwidth of 20%. The wide bandwidth, low power spectral density, high multiple access capability and precision location are among the qualities of UWB systems. These qualities of UWB systems make them an attractive choice for both high and low data rate applications. UWB technology is a promising physical layer candidate for high data rate wireless personal area networks (WPANs), while the low data rate applications of UWB include wireless sensor networks.


 The transmission of UWB signal over wireless channel results in multipath components (MPCs) that arrive at the receiver with different delays and attenuation.  The use of RAKE receiver is common to collect the received multipath energy. However, due to wide bandwidth, a large number of multipath components are resolved at the receiver. To collect a significant amount of the received energy, RAKE receiver needs a large number of correlators (fingers), which is not realistic. Thus, alternative low-complexity schemes needs to be investigated to capture sufficient amount of multipath energy. The transmitted reference (TR) is a sub-optimum low-complexity scheme for the demodulation of IR-UWB signals. The TR scheme has gained attention as it does not require the complex task channel estimation and provides a simple receiver structure. However, low-complexity TR scheme also has its drawbacks. First, half of the energy is “wasted” on the reference pulses. Secondly, the receiver performance degrades significantly as the noisy reference pulses are used in the correlator as a template.  It is needed to investigate different techniques to remedy the drawbacks of existing TR schemes.


In this project, the low-complexity schemes for IR-UWB systems are investigated with the aim to improve the performance of conventional schemes. Moreover, the objective is to analyze and evaluate the performance of proposed schemes using measured and standard IEEE multipath channels. The performance of RAKE receiver is evaluated using measured and simulated channels for industrial environments. Further, the recursive and dual-doublet TR schemes has been proposed for performance improvement of the conventional TR schemes. In addition, Kurtosis-based detection scheme is proposed and its performance is compared with existing energy detection scheme using standard IEEE channel model.

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