Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences

COLLEGE OF ENGINEERING

UC Berkeley

   

2008 Research Summary

Analysis of Interference Effects in MB-OFDM UWB Systems

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Yanmei Li, Jan M. Rabaey and Alberto L. Sangiovanni-Vincentelli

The inter-modulation products of interferences introduced by the receiver's nonlinearities could significantly degrade the system performance, and should be properly estimated when determining system design requirements. However, because of the lack of accurate estimation of distortion effects, designers usually set larger design margins to deal with the uncertainty, resulting in over-design with power consumption higher than it would be required if accurate analysis had been performed. The interest in minimizing the power consumption of a robust design implies the need for a thorough investigation of the interference impacts on the receiver's performance.

In this project, our first observation was that the performance estimation is inaccurate if the traditional two-tone test is applied to MB-OFDM UWB systems. We instead proposed an analytical approach to calculate the interference distortion products. By exploring the statistical properties of OFDM signals, accurate analytical expressions of various interference inter-modulations were derived and then validated by simulation. Based on this approach, numerical simulation allows designers to predict the distortion behavior and BER degradation without performing simulation of the entire actual system. In this work, we also provided an approach to accurately determine the adjustment factors of the two-tone test. Consequently, system designers could still utilize the easy-to-use two-tone technique in MB-OFDM UWB systems without sacrificing accuracy.