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In this paper, we assess the random coding error exponents (EEs) corresponding to decode-and-forward (DF), compress-and-forward (CF) and quantize-and-forward (QF) relaying strategies for a parallel relay network (PRN), consisting of a single source and two relays. Moreover, through numerical analysis we show that the EEs achieved by using QF relaying along with non-Gaussian signaling (coded modulation,...
A two-stage coding scheme incorporated with a square M-quadrature amplitude modulation (QAM) scheme is proposed to realize multiple non-discrete data rates while reducing the packet error rate (PER) at small packet sizes. Subject to the intended code rate, Turbo-coded parity packets are generated through bit-wise XOR combinations of the source packets to provide additional soft information which can...
We propose a data precoded relay-assisted scheme, for a system cooperating with L relays, each one equipped with a single antenna. The use of relays is of significant interest to allow radio access in situations where either the direct path is not available or has poor quality. However because of the half duplex constraint at the relays, transmission of a data rate that would be possible using a modulation...
We have already proposed a hybrid single-carrier (SC) and multi-carrier (MC) system for next-generation mobile communication system. A SC signal has low peak-to-average power ratio (PAPR), which yields high power output for wide coverage. A MC signal is robust against frequency-selective fading and has high data rate with quadrature amplitude modulation (QAM). By appropriately selecting SC and MC...
This paper presents a link adaptation strategy for non-binary LDPC code over a time-variant frequency-selective channel. The algorithm is based first on the adoption of waterfilling technique to wisely adapt the transmitted power. It is shown that as long as best subchannels are identified with the waterfilling algorithm, an equal power distribution can be applied with performance comparable to the...
Multi-carrier modulation and especially CP-OFDM is widely used nowadays in several radio communications. However, FBMC is a potential alternative to CP-OFDM since it does not require cyclic prefix, and thus, it has a higher spectral efficiency. One of the characteristics of FBMC is that the received data are accompanied by a two dimensional inter-symbol interference term (2D ISI), which complicates...
An exact form of symbol error rate (SER) is derived for zero-forcing decision feedback equalization (ZF-DFE) on fast fading channels. We present an error propagation framework in ZF-DFE, which is dependent on the length of multipath and the size of M-ary quadrature amplitude modulation (M-QAM). By applying the concepts of “error event” and “state” on this framework, we can evaluate the error probability...
In this paper, we propose a non-data-aided (NDA) signal-noise ratio (SNR) estimation algorithm for quadrature amplitude modulation (QAM) signals in additive white Gauss noise (AWGN) channel using Fuzzy logic interface. The NDA SNR estimation algorithm for QAM signals is derived based on a statistical ratio of observables over a block of data. It was shown that SNR can be effectively calculated by...
Estimation of the variance of AWGN is important to the initialization of iterative decoder, such as turbo code and LDPC code. Hence this paper puts forward a low-complexity and effective blind Gaussian variance estimator for MPSK and MQAM. The algorithm is derived from empirical characteristic function and provides a good un-biased estimation despite the knowledge of modulation type, as is proved...
The exact performance analysis of MMSE (minimum-mean-square-error) combining for space diversity reception is studied in the presence of a single and multiple cochannel interference (CCI) sources, and compared to maximum-ratio combining (MRC). This paper considers digital cellular mobile radio systems with quadrature amplitude modulation (QAM) transmission and two diversity antennas in flat and quasi-static...
The paper derives a more accurate upper bound for BER for M-QAM than is currently used in the literature. This allows a more thorough analysis of the power adaptation to fading conditions for optimization of spectral efficiency. By taking into account the effect of error coding gain on power adaptation, a 7-state FSMC model for the implementation of the adaptive modulation and coding scheme in WiMAX...
In the present wireless scenario, transmit diversity has become one of the key contributing technologies. Analytical estimations of bit error rate (BER) can be obtained with space time transmit diversity (STTD). The desired user's BER performance improves as fading of interfering signal decreases. Nakagami-m fading is becoming more prevalent in performance analysis and other studies related to mobile...
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