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theses

Owing to the very low duty cycle of impulse like ultra wideband signals, timing acquisition with acceptable accuracy and complexity has been a constant topic of research. Most acquisition techniques can be broadly classified under two categories: Training based algorithms, which require a specific training sequence at the start of communication and - Blind Acquisition, which relies on the correlation between successive data symbols transmitted and cyclostationarity of the transmitted signal. Amidst algorithms which use a clean template or a noiseless reference, a recent class of techniques named 'Timing based on Dirty Templates' (TDT) has been proposed.
These algorithms rely on the correlation of two adjacent portions of the noisy received signal. One portion of the noisy received signal acts as a template for the other, thus improving the synchronization speeds and accuracy by making the acquisition independent of training sequences. A novel blind TDT algorithm, which we refer to as Agrawal Blind Synchronization scheme (ABS), was proposed for IR-UWB signals. Based on the design of the time hopping code, significant improvements in acquisition speeds have been demonstrated using the ABS scheme, compared to existing blind acquisition schemes.
The objective of this thesis is to analyze the performance capabilities of the selfcorrelating ABS scheme in multi-user multipath environments. Adopting the best performing time hopping pattern, we investigate the effect of multiple interferers on absolute timing error, under various SNR scenarios as well as multiple symbols used for timing acquisition. Link performance is evaluated through bit-error-rate (BER) analysis under various system conditions. Since we use differential methods for timing acquisition as well as symbol detection, significant energy capture can be achieved in a dense multipath scenario due to self-Raking. We also propose modifications to conventional differential detectors to avoid self-Raking of interfering pulses. As a comparison to differential detectors, the detection performance of an ideal Rake receiver was tested with the ABS scheme. Our results indicate that the timing error performance the ABS scheme and thus the BER performance of the detection phase deteriorate notably with increase in the number of users in the system. The effective number of interferers is the limiting factor in both absolute timing error and BER performance. In differential detection, the effect of interference is so large it dominates over the effect of timing errors. The use of the ABS scheme is advantageous when Rake receivers are used, since timing error has a drastic effect of degrading the BER performance. The improvements of using ABS scheme in multi-user multi-path environments become more prominent in the case of ideal Rake reception, as compared to differential detection.

M.S.

Includes bibliographical references (p. 63-66).

http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17252

ETD_586

doi:10.7282/T3BV7H0P

ETD graduate

The author owns the copyright to this work.

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