Performance of bit-interleaved coded modulation with iterative decoding based multiple-access relay cooperative systems
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Using network coding, multiple-access relay channel makes a breakthrough at its performance. In order to further improve the performance of the uplink, a bit-interleaved coded modulation scheme with iterative decoding (BICM-ID) using joint coding differential modulation is designed. Specifically, it uses DE-16QAM of gray mapping mode matched with convolution code. Research has proved that in terms of quadrature amplitude modulation, modified set partitioning (MSP) mapping is optimal in iterative decoding scheme with convolution code. Yet when using joint coding differential modulation, the system has better reliability. The simulation results also show that the proposed scheme obtained dramatic performance gains by using joint coding differential modulation.Keywords:
Differential coding
Coding gain
Convolutional code
QAM
Configuration and error ratio performance of M‐QAM whose number of signal points is not a power of 2
Abstract This study examines the practicality of M ‐quadrature amplitude modulation ( M ‐QAM) where the number of signal points M is not a power of two. A practical problem is the complexity of the configuration because one symbol in an M ‐QAM signal does not correspond to an integer number of bits, and the symbol error does not simply convert to the bit error. Therefore, from the perspective of simplifying the configuration and minimizing bit error rate (BER) properties, multidimensional encoding (binary/ M ‐ary conversion) for converting a binary sequence to correlated symbols is proposed and the theoretical formulas of the symbol error rate (SER) and the bit error rate (BER) are clarified. SER properties of 40QAM, 44QAM, 48QAM, 56QAM, and 60QAM fall between 32QAM and 64QAM. The configuration of a QAM scheme where the number of signal points becomes 3 × 2 p −1 where p is an integer greater than or equal to 3 is shown, as are theoretical values for the SER properties of 12QAM and 24QAM in particular. Also shown are the theoretical values of the BER properties with and without differential encoding; these are verified with a computer simulation. A discussion based on these results concerns the effectiveness of M ‐QAM in the sense of expanding decision branches for adaptive modulation. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(2): 46–57, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/ecja.20269
QAM
Differential coding
Symbol rate
Modulation (music)
Coding gain
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This paper studies non-integer power of two-ary quadrature amplitude modulation (QAM) for long-haul optical fiber transmission systems.Numerical simulations show that 12-QAM and 24-QAM provide intermediate solutions on reachable transmission distances among traditional M-QAM such as C8-QAM, 16-QAM, and 32-QAM.In addition, short block length probabilistic shaping of 24-QAM not only provides an intermediate solution with nonlinear tolerance, but also yields greater transmission distances than 16-QAM for the same information data rates.
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The denoise-and-forward (DNF) method of physical-layer network coding (PNC) is a promising approach for wireless relaying networks. In this paper, we consider DNF-based PNC with M-ary quadrature amplitude modulation (M-QAM) and propose a mapping scheme that maps the superposed M-QAM signal to coded symbols. The mapping scheme supports both square and non-square M-QAM modulations, with various original constellation mappings (e.g. binary-coded or Gray-coded). Subsequently, we evaluate the symbol error rate and bit error rate (BER) of M-QAM modulated PNC that uses the proposed mapping scheme. Afterwards, as an application, a rate adaptation scheme for the DNF method of PNC is proposed. Simulation results show that the rate-adaptive PNC is advantageous in various scenarios.
QAM
Differential coding
Constellation diagram
Modulation (music)
Coding gain
Link adaptation
Linear network coding
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The 16-ary quadrature amplitude modulation(16QAM)is a high spectral efficient scheme for high-speed transmission systems. To remove the phase ambiguity in the coherent detection system, differential-encoded 16QAM(DE-16QAM) is usually used, however, it will cause performance degradation about 3 d B as compared to the conventional 16 QAM. To overcome the performance loss, a serial concatenated system with outer low density parity check(LDPC) codes and inner DE-16 QAM is proposed. At the receiver, joint iterative differential demodulation and decoding(ID) is carried out to approach the maximum likelihood performance. Moreover, a genetic evolution algorithm based on the extrinsic information transfer chart is proposed to optimize the degree distribution of the outer LDPC codes. Both theoretical analyses and simulation results indicate that this algorithm not only compensates the performance loss, but also obtains a significant performance gain, which is up to 1 d B as compared to the conventional non-DE-16 QAM.
Differential coding
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Differential modulation techniques are being employed in future access networks. Differential Amplitude Phase Shift Keying (DAPSK) is a differential modulation technique that combines the features of Differential Phase Shift Keying (DPSK) and Quadrature Amplitude Modulation (QAM). The basic fundamentals and the system design considerations of DAPSK are discussed. A detailed analysis of the QAM and DAPSK modulation techniques carried out reveals that DAPSK is spectrally efficient and hence more suitable for the access network.
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The new philosophy of realizing high-order modulation schemes directly in the RF domain enables the generation of spectrally efficient $4^{M}$ quadrature-amplitude-modulated $(4^{M}$ QAM) symbols using the vectorial summation of $M$ quadrature phase-shift keying (QPSK) signals. As will be shown in this paper, this approach, called RF-QAM, leads to several remarkable advantages in power amplification and signal formation in terms of both performance and power consumption. This paper presents a study of the RF-QAM transmitter (TX) and a comparison with the conventional architecture, as well as analytical studies and simulations to verify the superior performance of the RF-QAM transmitter compared to the conventional counterpart.
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The propose differential space time block codes (STBC) using quadrature amplitude modulation (QAM), which can not be utilized in the conventional differential STBC. Since QAM constellations have a larger minimum distance compared with phase shift keying (PSK), the proposed method has the advantage of SNR gain compared with conventional differential STBC. The QAM signals are encoded in a manner similar to that of conventional differential STBCs. To decode QAM signals, the signals received are normalized by the channel power estimated forgoing training symbols, and then decoded with a conventional QAM decoder. When the transmission rate is more than 3 bits/channel use in time varying channels, the simulation results demonstrate that the proposed method with the channel power estimation outperforms the conventional differential STBC.
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Recent theoretical studies of physical-layer network coding (PNC) show much interest on high-level modulation, such as M-ary quadrature amplitude modulation (M-QAM), and most related works are based on the assumption of phase synchrony. The possible presence of synchronization error and channel estimation error highlight the demand of analyzing the symbol error rate (SER) performance of PNC under different phase errors. Assuming synchronization and a general constellation mapping method, which maps the superposed signal into a set of M coded symbols, in this paper, we analytically derive the SER for M-QAM modulated PNC under different phase errors. We obtain an approximation of SER for general M-QAM modulations, as well as exact SER for quadrature phase-shift keying (QPSK), i.e. 4-QAM. Afterwards, theoretical results are verified by Monte Carlo simulations. The results in this paper can be used as benchmarks for designing practical systems supporting PNC.
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Differential coding
Coding gain
Linear network coding
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It is well-known that the performance of turbo codes can be improved by allocating different energies per code symbol. In this paper, based on this observation, we propose a joint encoding and modulation scheme for quadrature amplitude modulated turbo code systems. In the proposed scheme, the amount of energy difference between the turbo coded symbols is optimized by optimizing the constellation of quadrature amplitude modulation (QAM). The proposed scheme offers better coding gain compared to the conventional combination of binary turbo code and QAM at the bit error rate of 10??.
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In this paper, we propose a noncoherently non-catastrophic trellis-coded modulation scheme, in which the transmitter includes a differential encoder, a rotator, an inverse signal mapper, a convolutional encoder and a signal mapper. We present examples of the proposed scheme including MPSK (M-ary phase shift keying), QAM (quadrature-amplitude modulation), and TAPSK (twisted amplitude and phase shift keying). For trellis-coded QAM, a differential encoder with which the complexity of the proposed scheme can be reduced is proposed. Simulation results demonstrate that for noncoherent decoding, the proposed trellis-coded QAM has much better error performance than conventional trellis-coded QAM, and the proposed trellis-coded 16APSK outperforms trellis-coded 16QAM for short observation length.
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Differential coding
Trellis modulation
Convolutional code
Space–time trellis code
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