Time-Frequency Effects in Wireless Communication Systems

nonlinearities;intermodulation;passive filters;amplifier distortion;switching;time division multiplexing;transient response;frequency hop communication;time-frequency analysis;communication system performance;bandpass filters

Mazzaro, Gregory James ; J. Keith Townsend, Committee Member,Mohammed A. Zikry, Committee Member,Kevin G. Gard, Committee Member,Michael B. Steer, Committee Chair,W. Devereux Palmer, Committee Member,Mazzaro, Gregory James ; J. Keith Townsend ; Committee Member ; Mohammed A. Zikry ; Committee Member ; Kevin G. Gard ; Committee Member ; Michael B. Steer ; Committee Chair ; W. Devereux Palmer ; Committee Member

University:North Carolina State University

关键词: nonlinearities;    intermodulation;    passive filters;    amplifier distortion;    switching;    time division multiplexing;    transient response;    frequency hop communication;    time-frequency analysis;    communication system performance;    bandpass filters;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/4523/etd.pdf?sequence=2&isAllowed=y

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【 摘 要 】

Time-frequency effects in wireless communication systems caused by narrowband resonances and coupled with device nonlinearities are revealed as new sources of co-site interference, exploited for the metrology of bandpass circuits, and employed to linearize amplitude-modulated transmissions.The transient properties of bandpass filters are found to last much longer than traditional time/bandwidth rules-of-thumb. The cause of this long-tail behavior is attributed to the coupled-resonator structure of the filter circuit.A solution method which uses lowpass prototyping is developed to reduce, by a factor of two, the complexity of the differential equation set describing a narrowband filter's transient response.Pulse overlap caused by the frequency dependence of long tails produced by filters is shown to cause intersymbol interference and intermodulation distortion in RF front-ends during frequency-hopped communications.The same properties which cause the ISI and IMD are used to develop three new transient methods for measuring resonant circuit parameters and a one-port method for extracting the operating band of a filter.A new signal-processing technique which combines time- and frequency-selectivity, Linear Amplification by Time-Multiplexed Spectrum, is developed to reduce IMD associated with amplitude modulation. Distortion reduction is demonstrated experimentally for multisines up to 20 tones.