A Lattice triangular expansion matrix is presented based on the classical Hadamard matrices, which is defined over the fields of finite characteristic. Also, the modular Lattice and Pentagon expansion matrices are str...A Lattice triangular expansion matrix is presented based on the classical Hadamard matrices, which is defined over the fields of finite characteristic. Also, the modular Lattice and Pentagon expansion matrices are structured from triangular 7x7 matrix, each of the expansion matrices are modular the sides of the shape p. The issue for the existence (necessary conditions) of odd and even order matrices of that kind is addressed. The modular Lattice code is highly efficient since it requires only additions, multiplications by constant modulo p. The modular 6 Lattice triangular expanded constellation is even possible efficiency to gain advantage from the channel selection and maximum likelihood (ML) decoding in the interference Lattice alignment (IA) system.展开更多
In this paper, an adaptive co-channel interference suppression technique for multi-user MIMO MC DS/CDMA system is envisaged. MC DS/CDMA offers many advantages like flexibility, robustness, low PAPR and spectral effici...In this paper, an adaptive co-channel interference suppression technique for multi-user MIMO MC DS/CDMA system is envisaged. MC DS/CDMA offers many advantages like flexibility, robustness, low PAPR and spectral efficiency. In spite of these advantages, performance of MC DS/CDMA system is greatly impaired by interference. Common interferences, which degrade the performance of the system, are MAI and CCI. Mitigating these interferences can directly increase the capacity of the system. In this work, an adaptive co-channel interference suppression technique based on single-stage and two-stage MMSE IC is considered for multi-user MIMO MC DS/CDMA system. Simulation results show that, at low SNR two-stage MMSE IC outperforms single-stage, while at high SNR, single-stage provides better BER performance. Based on this, a selection criterion has been propounded for improved system performance as a whole in interference limited environment. Also, adaptive selection criterion resulted in better error performance.展开更多
This paper presented a concatenated maximum-likelihood (ML) decoder for space-time/space-frequency block coded orthogonal frequency diversion multiplexing (ST/SFBC-OFDM) systems in double selective fading channels. Th...This paper presented a concatenated maximum-likelihood (ML) decoder for space-time/space-frequency block coded orthogonal frequency diversion multiplexing (ST/SFBC-OFDM) systems in double selective fading channels. The proposed decoder first detects space-time or space-frequency codeword elements separately. Then, according to the coarsely estimated codeword elements, the ML decoding is performed in a smaller constellation element set to searching final codeword. It is proved that the proposed decoder has optimal performances if and only if subchannels are constant during a codeword interval. The simulation results show that the performances of proposed decoder is close to that of the optimal ML decoder in severe Doppler and delay spread channels. However, the complexity of proposed decoder is much lower than that of the optimal ML decoder.展开更多
In this paper, both the high-complexity near-ML list decoding and the low-complexity belief propagation decoding are tested for some well-known regular and irregular LDPC codes. The complexity and performance trade-of...In this paper, both the high-complexity near-ML list decoding and the low-complexity belief propagation decoding are tested for some well-known regular and irregular LDPC codes. The complexity and performance trade-off is shown clearly and demonstrated with the paradigm of hybrid decoding. For regular LDPC code, the SNR-threshold performance and error-floor performance could be improved to the optimal level of ML decoding if the decoding complexity is progressively increased, usually corresponding to the near-ML decoding with progressively increased size of list. For irregular LDPC code, the SNR-threshold performance and error-floor performance could only be improved to a bottle-neck even with unlimited decoding complexity. However, with the technique of CRC-aided hybrid decoding, the ML performance could be greatly improved and approached with reasonable complexity thanks to the improved code-weight distribution from the concatenation of CRC and irregular LDPC code. Finally, CRC-aided 5GNR-LDPC code is evaluated and the capacity-approaching capability is shown.展开更多
Various efficient generalized sphere decoding (GSD) algorithms have been proposed to approach optimal ML performance for underdetermined linear systems, by transforming the original problem into the full-column-rank o...Various efficient generalized sphere decoding (GSD) algorithms have been proposed to approach optimal ML performance for underdetermined linear systems, by transforming the original problem into the full-column-rank one so that standard SD can be fully applied. However, their design parameters are heuristically set based on observation or the possibility of an ill-conditioned transformed matrix can affect their searching efficiency. This paper presents a better transformation to alleviate the ill-conditioned structure and provides a systematic approach to select design parameters for various GSD algorithms in order to high efficiency. Simulation results on the searching performance confirm that the proposed techniques can provide significant improvement.展开更多
An improved list sphere decoder (ILSD) is proposed based on the conventional list sphere decoder (LSD) and the reduced- complexity maximum likelihood sphere-decoding algorithm. Unlike the conventional LSD with fix...An improved list sphere decoder (ILSD) is proposed based on the conventional list sphere decoder (LSD) and the reduced- complexity maximum likelihood sphere-decoding algorithm. Unlike the conventional LSD with fixed initial radius, the ILSD adopts an adaptive radius to accelerate the list cdnstruction. Characterized by low-complexity and radius-insensitivity, the proposed algorithm makes iterative joint detection and decoding more realizable in multiple-antenna systems. Simulation results show that computational savings of ILSD over LSD are more apparent with more transmit antennas or larger constellations, and with no performance degradation. Because the complexity of the ILSD algorithm almost keeps invariant with the increasing of initial radius, the BER performance can be improved by selecting a sufficiently large radius.展开更多
文摘A Lattice triangular expansion matrix is presented based on the classical Hadamard matrices, which is defined over the fields of finite characteristic. Also, the modular Lattice and Pentagon expansion matrices are structured from triangular 7x7 matrix, each of the expansion matrices are modular the sides of the shape p. The issue for the existence (necessary conditions) of odd and even order matrices of that kind is addressed. The modular Lattice code is highly efficient since it requires only additions, multiplications by constant modulo p. The modular 6 Lattice triangular expanded constellation is even possible efficiency to gain advantage from the channel selection and maximum likelihood (ML) decoding in the interference Lattice alignment (IA) system.
文摘In this paper, an adaptive co-channel interference suppression technique for multi-user MIMO MC DS/CDMA system is envisaged. MC DS/CDMA offers many advantages like flexibility, robustness, low PAPR and spectral efficiency. In spite of these advantages, performance of MC DS/CDMA system is greatly impaired by interference. Common interferences, which degrade the performance of the system, are MAI and CCI. Mitigating these interferences can directly increase the capacity of the system. In this work, an adaptive co-channel interference suppression technique based on single-stage and two-stage MMSE IC is considered for multi-user MIMO MC DS/CDMA system. Simulation results show that, at low SNR two-stage MMSE IC outperforms single-stage, while at high SNR, single-stage provides better BER performance. Based on this, a selection criterion has been propounded for improved system performance as a whole in interference limited environment. Also, adaptive selection criterion resulted in better error performance.
文摘This paper presented a concatenated maximum-likelihood (ML) decoder for space-time/space-frequency block coded orthogonal frequency diversion multiplexing (ST/SFBC-OFDM) systems in double selective fading channels. The proposed decoder first detects space-time or space-frequency codeword elements separately. Then, according to the coarsely estimated codeword elements, the ML decoding is performed in a smaller constellation element set to searching final codeword. It is proved that the proposed decoder has optimal performances if and only if subchannels are constant during a codeword interval. The simulation results show that the performances of proposed decoder is close to that of the optimal ML decoder in severe Doppler and delay spread channels. However, the complexity of proposed decoder is much lower than that of the optimal ML decoder.
文摘In this paper, both the high-complexity near-ML list decoding and the low-complexity belief propagation decoding are tested for some well-known regular and irregular LDPC codes. The complexity and performance trade-off is shown clearly and demonstrated with the paradigm of hybrid decoding. For regular LDPC code, the SNR-threshold performance and error-floor performance could be improved to the optimal level of ML decoding if the decoding complexity is progressively increased, usually corresponding to the near-ML decoding with progressively increased size of list. For irregular LDPC code, the SNR-threshold performance and error-floor performance could only be improved to a bottle-neck even with unlimited decoding complexity. However, with the technique of CRC-aided hybrid decoding, the ML performance could be greatly improved and approached with reasonable complexity thanks to the improved code-weight distribution from the concatenation of CRC and irregular LDPC code. Finally, CRC-aided 5GNR-LDPC code is evaluated and the capacity-approaching capability is shown.
文摘Various efficient generalized sphere decoding (GSD) algorithms have been proposed to approach optimal ML performance for underdetermined linear systems, by transforming the original problem into the full-column-rank one so that standard SD can be fully applied. However, their design parameters are heuristically set based on observation or the possibility of an ill-conditioned transformed matrix can affect their searching efficiency. This paper presents a better transformation to alleviate the ill-conditioned structure and provides a systematic approach to select design parameters for various GSD algorithms in order to high efficiency. Simulation results on the searching performance confirm that the proposed techniques can provide significant improvement.
基金The National Natural Science Founda-tion of China ( No 60496316)the National Hi-Tech Re-search and Development Program (863) of China (No2006-AA01Z270)
文摘An improved list sphere decoder (ILSD) is proposed based on the conventional list sphere decoder (LSD) and the reduced- complexity maximum likelihood sphere-decoding algorithm. Unlike the conventional LSD with fixed initial radius, the ILSD adopts an adaptive radius to accelerate the list cdnstruction. Characterized by low-complexity and radius-insensitivity, the proposed algorithm makes iterative joint detection and decoding more realizable in multiple-antenna systems. Simulation results show that computational savings of ILSD over LSD are more apparent with more transmit antennas or larger constellations, and with no performance degradation. Because the complexity of the ILSD algorithm almost keeps invariant with the increasing of initial radius, the BER performance can be improved by selecting a sufficiently large radius.