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This paper presents a multi-bit discrete time sigma-delta converter for orthogonal frequency division multiplexing ultra wide band systems adopted by IEEE 802.15.3a and ECMA368 standard. An intact scheme of timing synchronization algorithm is also proposed for the receiver. The overall sigma-delta converter consists of two modulators. The low and high subbands of signal are operated by using third-order...
A multi-bit discrete time sigma-delta converter for an orthogonal frequency division multiplexing ultrawideband system has been designed. The overall sigma-delta converter consists of two modulators. The low and high subbands of signal are operated by using third-order low pass and fourth-order band pass modulator respectively. A simulation has been designed to realize the system with the converter...
Based on the high peak to average power ratio of orthogonal frequency division multiplexing systems, several methods of reducing the peak to average power ratio were analyzed. Then a method based on Golay complementary sequences was proposed to realize the low peak to average power ratio. The high peak to average power ratio sequences were encoded into Golay complementary sequences, peak to average...
A novel carrier frequency offset tracking scheme for multilevel quadrature amplitude modulation-orthogonal frequency division multiplexing (MQAM-OFDM) systems is proposed using a designed conjugate code composed of MQAM mapping values and their complex conjugates which can also reduce peak-to-average power ratio (PAPR). The peak power is reduced by phase cancellation in the conjugate pairs avoiding...
A new carrier frequency offset estimation scheme in the orthogonal frequency division multiplexing (OFDM) system is proposed. In non-data-aided synchronization systems, maximum likelihood estimation (MLE) is often used for carrier frequency offset acquisition , but it could not correct the accumulated residue frequency offset caused by sampling clock offset and other factors. After simple comparisons...
This paper refers to MIMO-OFDM (multiple input multiple output orthogonal frequency-division multiplexing) system studies in the fourth generation mobile communication. We have designed two schemes, one is two transmit antennas and one receive antenna, and the other is two transmit and two receive antennas. In this system we use MPSK modulation, Alamouti space-time coding, RS coding in channel transmission...
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