Orthogonal frequency division multiplexing (OFDM) is emerging as preferred modulation scheme in modern high data rate wireless communication systems. A well known problem of OFDM system is sensitivity to frequency offset between the transmitted and received signals, which may be caused by Doppler shift in the channel or by the difference between the transmitter and receiver local oscillator fre...

This paper reports on a fully-integrated CMOS switchable directconversion receiver for 2GHz and 5GHz. Switchable low noise amplifier is proposed for suiting for multiband (2GHz, 5GHz). Sub-harmonic mixing is used for down-conversion to minimize the DC-offset due to LO-leakage. The residual DC-offset is cancelled by a digital-to-analog converter at the output of mixer. For quadrature down-conver...

Orthogonal frequency division multiplexing (OFDM) is emerging as preferred modulation scheme in modern high data rate wireless communication systems. A well known problem of OFDM system is sensitivity to frequency offset between the transmitted and received signals, which may be caused by Doppler shift in the channel or by the difference between the transmitter and receiver local oscillator fre...

In mobile radio communication, the fading channels generally exhibit both time-selectivity and frequencyselectivity. Orthogonal frequency division multiplexing has been proposed to combat the frequency-selectivity, but its performance is also affected by the timeselectivity. In this paper, we investigate how various parameters, such as the number of carriers, the guard time length and the sampl...

Zadoff-Chu (ZC) sequences have been used as synchronization sequences in modern wireless communication systems, replacing the conventional pseudo-random noise (PN) sequences due to their perfect autocorrelation properties. We first study the ambiguity problem between a timing offset and a frequency offset when a ZC sequence is used as a synchronization signal. We show how a frequency offset can...

In mobile radio communication, the fading channels generally exhibit both time-selectivity and frequency-selectivity. Orthogonal frequency-division multiplexing has been proposed to combat the frequency-selectivity, but its performance is also affected by the time-selectivity. In this paper, we investigate how various parameters, such as the number of carriers, the guard time length, and the sa...

The unbiased FIR filter is investigated to estimate the time interval error (TIE) K-D polynomial model of a local clock in GPS-based timekeeping in the presence of uniformly distributed sawtooth noise. An estimation algorithm is proposed and applied to the GPS-based TIE measurements of a crystal clock without using the sawtooth correction. Based upon this, we show that the TIE estimates fit act...

This paper presents a technique for frequency offset estimation for polynomial cancellation coded orthogonal frequency division multiplexing with symbols overlapped in the time domain (overlap PCC-OFDM) in the presence of phase noise. The frequency offset estimator is designed based on the subcarrier pair imbalance (SPI) caused by frequency offset. The estimation is performed in the frequency d...

A new Turbo iterative receiver structure is proposed for the uplink multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA) systems. The space-alternating generalized expectation-maximization (SAGE) algorithm is naturally embedded in the framework of iterative receiver to perform synchronization and detection using the Turbo detector outputs. In each iteration,...