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Title: A study in optimising a multicarrier demultiplexer demodulator (MCDD) for on-board processing (OBP) satellites
Author: Danesfahani, Gholam Reza
ISNI:       0000 0001 3403 2383
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1995
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For mobile satellite communication systems substantial gains in performance can be achieved by having a multicarrier demultiplexer demodulator (MCDD) on-board the satellite. Fundamental operations in the demodulator are the carrier and bit timing recovery. The aim of this project was to study ways to improve the performance of the MCDD. The results of this study are as follows: 1. An efficient optimum recursive (IIR) demultiplexer (DMUX) has been designed and evaluated for use in OBP satellites [Dan94a, Dan94b]. Comparisons with a typical non-recursive demultiplexer [Goc88, Qi 92] show that the IIR approach: - requires about 80% less arithmetic operations; - has about 50% less delay; - has a superior noise performance for 5 bits filter coefficient quantisation; - is more attractive for ASIC implementation; - enables more optimum spectral utilisation. 2. A survey of timing error detectors (TEDs) has led to a choice between the Gardner [Gar86] and the modified Mueller & Muller (mM&M) [Moe88] algorithms. Although the mM&M algorithm has a larger self-noise, it requires only one sample per symbol to operate. An improvement has been made to the mM&M TED to cancel the self noise. Due to this optimisation, the new algorithm has fewer cycle slips and acquires the timing error in approximately 15 symbols [Dan95]. 3. A study of different frequency error detectors (FEDs) has lead to a new FED which works using preambles. A low hardware and algorithmic complexity, a fast acquisition time and a good noise performance in medium to high signal-to-noise ratio (SNR) are the features of the detector developed. 4. A survey of phase error detectors has led to the choice of the decision directed maximum-likelihood feed forward algorithm because of its fast acquisition which is important in mobile applications [Jes91]. An optimisation has been made to this algorithm to improve its noise performance without increasing the acquisition time. The noise performance of the new algorithm approaches the Cramer-Rao bound at medium to high SNR.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: PostDoctoral
EThOS ID:  DOI: Not available
Keywords: Satellite communication