-
[show abstract]
[hide abstract]
ABSTRACT: An efficient RS encoder for a parity replacer circuit of ATSC M/H mobile DTV receiver is presented. First, we derive the non-systematic RS encoder architecture which requires the well-known Forney algorithm to evaluate the parity symbol values located at arbitrary positions. We notice that only at most three information symbols corresponding to the trellis initialization symbol determine the RS parity symbols to be replaced in the parity replacer circuit. So we derive another form of the Forney algorithm to represent the parity symbol value as a linear combination of the input information symbols. With the new form, efficient architecture for implementing the RS encoder of a parity replacer is presented.
IEEE Transactions on Consumer Electronics 09/2010; · 0.94 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An estimation of ultrasound attenuation in soft tissues is critical in the quantitative ultrasound analysis since it is not only related to the estimations of other ultrasound parameters, such as speed of sound, integrated scatterers, or scatterer size, but also provides pathological information of the scanned tissue. However, estimation performances of ultrasound attenuation are intimately tied to the accurate extraction of spectral information from the backscattered radiofrequency (RF) signals. In this paper, we propose two novel techniques for calculating a block power spectrum from the backscattered ultrasound signals. These are based on the phase-compensation of each RF segment using the normalized cross-correlation to minimize estimation errors due to phase variations, and the weighted averaging technique to maximize the signal-to-noise ratio (SNR). The simulation results with uniform numerical phantoms demonstrate that the proposed method estimates local attenuation coefficients within 1.57% of the actual values while the conventional methods estimate those within 2.96%. The proposed method is especially effective when we deal with the signal reflected from the deeper depth where the SNR level is lower or when the gated window contains a small number of signal samples. Experimental results, performed at 5MHz, were obtained with a one-dimensional 128 elements array, using the tissue-mimicking phantoms also show that the proposed method provides better estimation results (within 3.04% of the actual value) with smaller estimation variances compared to the conventional methods (within 5.93%) for all cases considered.
Ultrasonics 05/2010; 50(6):592-9. · 1.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this paper, we first analyze the performance loss due to the waveform shaping filter specified by the 3GPP2. Analysis and simulation results show that there is significant SNR penalty which was not usually considered in the previous system. Then we propose the MMSE receiver filter which is designed to eliminate remaining interference and satisfy the FCC mask rule at the same time. Both the analysis and simulation results show that most of the SNR penalty can be eliminated.
Vehicular Technology Conference, 2003. VTC 2003-Spring. The 57th IEEE Semiannual; 05/2003
-
[show abstract]
[hide abstract]
ABSTRACT: By design, IS-95 filter generates remaining ICI (interchip interference) after matched filtering in the receiver side. To keep the backward compatibility, IS-95 filter is recommended as a chip waveform shaping filter in all sequels of international standard from the 3GPP2. The performance degradation by the filter was not significant in a conventional QPSK modulation scheme but not negligible in the recently proposed system where multi-level modulation scheme is adopted. In this paper, we investigate the performance degradation caused by the ICI of the IS-95 filter and propose MMSE receiver filter to compensate for the performance loss. We apply the proposed receiver to CDMA1xEV-DV system where multi-level modulation is used.
Wireless Communications and Networking, 2003. WCNC 2003. 2003 IEEE; 04/2003
