Browsing by Author "Liu, DZ"

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A digital timing recovery scheme for TDMA digital mobile radio
(1996)
Liu, DZ
;
Wei, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Asynchronous symbol timing recovery with adaptive interpolation filter for high data-rate digital mobile radio
(2000)
Liu, DZ
;
Wei, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An asynchronous symbol timing recovery with adaptive interpolation filter is investigated far high data-rate digital mobile radio. The timing error estimation employing a general type of nonlinearity is used to estimate the timing error by the discrete-time spectral method. An adaptive interpolation filter is adopted to mitigate both the timing error and inter-symbol interference (ISI) due to multipath fading. Computer simulations are employed to evaluate the performance of the symbol timing recovery over the environment with additive Gaussian noise (AWGN), carrier frequency offset and Rayleigh fading. The proposed timing synchronizer is well suited for burst mode, narrow-band, high data-rate digital mobile radio.
Channel estimation and compensation for preamble-assisted DAPSK transmission in digital mobile radio system
(2001-03-01)
Liu, DZ
;
Wei, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents a novel channel estimation and compensation technique, combining fading estimation and frequency offset estimation, for preamble-assisted differentially encoded amplitude- and phase-shift keying (DAPSK) transmission in the digital mobile radio system. The received preamble symbols are used to estimate the combined distortions caused by multipath fading and frequency offset. The detected data symbols as well as preamble symbols are used to enhance the accuracy of the estimation process. The combined distortions can be compensated in the data symbols at the same time. The storage-delay time of the estimation process is only several symbols long. A series of computer simulations have been carried out to investigate the bit error rate performances of the preamble-assisted 16-DAPSK signals with uncertain frequency offset in the frequency-nonselective and frequency-selective Rayleigh fading channels.
Combined carrier phase tracking and equalization for pi/4-DQPSK signals in mobile radio
(1999)
Chen, TS
;
Liu, DZ
;
Wei, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The digital sinlock loop (DSL) is a nonuniform-sampling digital phase-locked loop (DPLL), whose phase error detector using the arcsine function with the quadrature samples of incoming signal, has a linear characteristics with a period of 2 pi. The phase equalizer using the decision-feedback phase tracking method operates only on the phase information to avoid the multiplication operations required in conventional equalization algorithms. In this paper, combined carrier phase tracking and phase equalization is investigated for pi/4-DQPSK signals in the mobile radio system.
Synchronization scheme in non-coherent demodulator for TDMA digital mobile radio system
(1999)
Liu, DZ
;
Wei, CH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Symbol timing recovery, frame synchronization and frequency offset compensation are essential synchronization circuits in noncoherent demodulator for TDMA digital mobile radio system. In this paper, we present a synchronization scheme, combined with a nonlinear symbol timing recovery using Gardner's timing error detector, a baseband feedback frequency offset compensation, and a simple frame synchronization using a code-matched correlator and a peak detector with a suitable threshold.