Polar coded sparse code multiple access(SCMA) system is conceived in this paper. A simple but new iterative multiuser detection framework is proposed, which consists of a message passing algorithm(MPA) based multiuser...Polar coded sparse code multiple access(SCMA) system is conceived in this paper. A simple but new iterative multiuser detection framework is proposed, which consists of a message passing algorithm(MPA) based multiuser detector and a soft-input soft-output(SISO) successive cancellation(SC) polar decoder. In particular, the SISO polar decoding process is realized by a specifically designed soft re-encoder, which is concatenated to the original SC decoder. This soft re-encoder is capable of reconstructing the soft information of the entire polar codeword based on previously detected log-likelihood ratios(LLRs) of information bits. Benefiting from the soft re-encoding algorithm, the resultant iterative detection strategy is able to obtain a salient coding gain. Our simulation results demonstrate that significant improvement in error performance is achieved by the proposed polar-coded SCMA in additive white Gaussian noise(AWGN) channels, where the performance of the conventional SISO belief propagation(BP) polar decoder aided SCMA, the turbo coded SCMA and the low-density parity-check(LDPC) coded SCMA are employed as benchmarks.展开更多
We investigate an adaptive cooperative protocol in a Two-Hop-Relay (THR) wireless system that combines the following: (1) adaptive relaying based on repetition coding; (2) single or two transmit antennas and one recei...We investigate an adaptive cooperative protocol in a Two-Hop-Relay (THR) wireless system that combines the following: (1) adaptive relaying based on repetition coding; (2) single or two transmit antennas and one receive antenna configurations for all nodes, each using high order constellation; (3) Bit-Interleaved Coded Modulation (BICM). We focus on a simple decoded relaying (i.e. no error correcting at a relay node) and simple signal quality thresholds for relaying. Then the impact of the two simple thresholds on the system performance is studied. Our results suggest that compared with the traditional scheme for direct transmission, the proposed scheme can increase average throughput in high spectral efficiency region with low implementa-tion-cost at the relay.展开更多
The encoding/decoding scheme based on Fiber Bragg Grating (FBG) for Optical Code Division Multiple Access (OCDMA) system is analyzed and the whole process from transmitting end to receiving end is researched in detail...The encoding/decoding scheme based on Fiber Bragg Grating (FBG) for Optical Code Division Multiple Access (OCDMA) system is analyzed and the whole process from transmitting end to receiving end is researched in detail. The mathematical mode including signal transmission, summing, receiving and recovering are established respectively. One of the main sources of Bit Error Rate (BER) of OCDMA system based on FBGs is the unevenness of signal power spectrum, which leads to the chip powers unequal with each other. The Signal to Interfere Ratio (SIR) and BER performance of the system are studied and simulated at the case with uneven distribution of chips' powers.展开更多
We consider an iterative phase synchronization scheme based on maximum a posteriori probability algorithm.In classical approaches,the phase noise estimation model considers one sample per symbol at the channel and rec...We consider an iterative phase synchronization scheme based on maximum a posteriori probability algorithm.In classical approaches,the phase noise estimation model considers one sample per symbol at the channel and receiver.However,information theoretic studies suggested use of more than one sample per symbol at the channel and receiver for achieving higher performance.In this article,a soft-information aided iterative receiver is derived,which uses off-the-shelf blocks for detection and demodulation by keeping the complexity of the receiver acceptable.We consider here two samples per symbols at the channel and receiver in a pragmatic paradigm.It is shown that phase noise estimation can be significantly improved at the expense of modest processing overhead.Simulation results are presented for low-density parity check coded quadrature amplitude modulations.Our results show a significant performance improvement for strong phase noise values compared to classical receiver approaches.展开更多
To maximize the throughput of frequency-selective multicast channel, the minimum-phase Finite Impulse Response (FIR) precoder design is investigated in this paper. This problem can be solved in two steps. Firstly, we ...To maximize the throughput of frequency-selective multicast channel, the minimum-phase Finite Impulse Response (FIR) precoder design is investigated in this paper. This problem can be solved in two steps. Firstly, we focus on designing a nonminimum-phase FIR precoder under the criterion of maximizing the throughput, and develop two efficient algorithms for the FIR precoder design from perspectives of frequency domain and time domain. In the second step, based on the theory of spectral factorization, the nonminimum-phase FIR precoder is transformed into the corresponding minimum-phase FIR precoder by a classic iterative algorithm without affecting the throughput. Numerical results indicate that the achievable rate of the proposed design has remarkable improvement over that of existing schemes, moreover, the group delay introduced by the FIR precoder is minimized.展开更多
A new neural network based method for solving the problem of congestion control arising at the user network interface (UNI) of ATM networks is proposed in this paper. Unlike the previous methods where the coding rate ...A new neural network based method for solving the problem of congestion control arising at the user network interface (UNI) of ATM networks is proposed in this paper. Unlike the previous methods where the coding rate for all traffic sources as controller output signals is tuned in a body, the proposed method adjusts the coding rate for only a part of the traffic sources while the remainder sources send the cells in the previous coding rate in case of occurrence of congestion. The controller output signals include the source coding rate and the percentage of the sources that send cells at the corresponding coding rate. The control methods not only minimize the cell loss rate but also guarantee the quality of information (such as voice sources) fed into the multiplexer buffer. Simulations with 150 ADPCM voice sources fed into the multiplexer buffer showed that the proposed methods have advantage over the previous methods in the aspect of the performance indices such as cell loss rate (CLR) and voice quality.展开更多
The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Option 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Persona...The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Option 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Personal Communications Systems). This paper investigated the combination of turbo codes with Unequal Error Protection (UEP) and 16-QAM modulation for EVRC codec of Rate 1 to get power and bandwidth efficient coding scheme. The results show that the UEP system outperforms the Equal Error Protection (EEP) one by 1.45 dB at BER of 10 -5.展开更多
In this paper, the operation principle of laser rotary encoders is expounded and the optical quadruple frequency technology used in laser rotary encoders is explained, and the design idea of optical system in φ66 mm ...In this paper, the operation principle of laser rotary encoders is expounded and the optical quadruple frequency technology used in laser rotary encoders is explained, and the design idea of optical system in φ66 mm laser rotary encoder is mainly introduced, as well as the choice of principal devices.展开更多
基金supported in part by National Natural Science Foundation of China (no. 61571373, no. 61501383, no. U1734209, no. U1709219)in part by Key International Cooperation Project of Sichuan Province (no. 2017HH0002)+2 种基金in part by Marie Curie Fellowship (no. 792406)in part by the National Science and Technology Major Project under Grant 2016ZX03001018-002in part by NSFC China-Swedish project (no. 6161101297)
文摘Polar coded sparse code multiple access(SCMA) system is conceived in this paper. A simple but new iterative multiuser detection framework is proposed, which consists of a message passing algorithm(MPA) based multiuser detector and a soft-input soft-output(SISO) successive cancellation(SC) polar decoder. In particular, the SISO polar decoding process is realized by a specifically designed soft re-encoder, which is concatenated to the original SC decoder. This soft re-encoder is capable of reconstructing the soft information of the entire polar codeword based on previously detected log-likelihood ratios(LLRs) of information bits. Benefiting from the soft re-encoding algorithm, the resultant iterative detection strategy is able to obtain a salient coding gain. Our simulation results demonstrate that significant improvement in error performance is achieved by the proposed polar-coded SCMA in additive white Gaussian noise(AWGN) channels, where the performance of the conventional SISO belief propagation(BP) polar decoder aided SCMA, the turbo coded SCMA and the low-density parity-check(LDPC) coded SCMA are employed as benchmarks.
基金Supported by the National Natural Science Foundation of China (No.60496311) and partially supported by the B3G project (2003AA123310).
文摘We investigate an adaptive cooperative protocol in a Two-Hop-Relay (THR) wireless system that combines the following: (1) adaptive relaying based on repetition coding; (2) single or two transmit antennas and one receive antenna configurations for all nodes, each using high order constellation; (3) Bit-Interleaved Coded Modulation (BICM). We focus on a simple decoded relaying (i.e. no error correcting at a relay node) and simple signal quality thresholds for relaying. Then the impact of the two simple thresholds on the system performance is studied. Our results suggest that compared with the traditional scheme for direct transmission, the proposed scheme can increase average throughput in high spectral efficiency region with low implementa-tion-cost at the relay.
基金Supported by the Natural Science Research Foundation of Jiangsu Higher-Learning Insti-tution (No.04jkb510057).
文摘The encoding/decoding scheme based on Fiber Bragg Grating (FBG) for Optical Code Division Multiple Access (OCDMA) system is analyzed and the whole process from transmitting end to receiving end is researched in detail. The mathematical mode including signal transmission, summing, receiving and recovering are established respectively. One of the main sources of Bit Error Rate (BER) of OCDMA system based on FBGs is the unevenness of signal power spectrum, which leads to the chip powers unequal with each other. The Signal to Interfere Ratio (SIR) and BER performance of the system are studied and simulated at the case with uneven distribution of chips' powers.
文摘We consider an iterative phase synchronization scheme based on maximum a posteriori probability algorithm.In classical approaches,the phase noise estimation model considers one sample per symbol at the channel and receiver.However,information theoretic studies suggested use of more than one sample per symbol at the channel and receiver for achieving higher performance.In this article,a soft-information aided iterative receiver is derived,which uses off-the-shelf blocks for detection and demodulation by keeping the complexity of the receiver acceptable.We consider here two samples per symbols at the channel and receiver in a pragmatic paradigm.It is shown that phase noise estimation can be significantly improved at the expense of modest processing overhead.Simulation results are presented for low-density parity check coded quadrature amplitude modulations.Our results show a significant performance improvement for strong phase noise values compared to classical receiver approaches.
基金Supported by the National Natural Science Foundation of China (No. 61271272)the National Science and Technology Special Projects of China (No. 2012ZX03001007002)the National High Technology Research and Development Program of China (863 Program) (No. 2012AA01A502)
文摘To maximize the throughput of frequency-selective multicast channel, the minimum-phase Finite Impulse Response (FIR) precoder design is investigated in this paper. This problem can be solved in two steps. Firstly, we focus on designing a nonminimum-phase FIR precoder under the criterion of maximizing the throughput, and develop two efficient algorithms for the FIR precoder design from perspectives of frequency domain and time domain. In the second step, based on the theory of spectral factorization, the nonminimum-phase FIR precoder is transformed into the corresponding minimum-phase FIR precoder by a classic iterative algorithm without affecting the throughput. Numerical results indicate that the achievable rate of the proposed design has remarkable improvement over that of existing schemes, moreover, the group delay introduced by the FIR precoder is minimized.
文摘A new neural network based method for solving the problem of congestion control arising at the user network interface (UNI) of ATM networks is proposed in this paper. Unlike the previous methods where the coding rate for all traffic sources as controller output signals is tuned in a body, the proposed method adjusts the coding rate for only a part of the traffic sources while the remainder sources send the cells in the previous coding rate in case of occurrence of congestion. The controller output signals include the source coding rate and the percentage of the sources that send cells at the corresponding coding rate. The control methods not only minimize the cell loss rate but also guarantee the quality of information (such as voice sources) fed into the multiplexer buffer. Simulations with 150 ADPCM voice sources fed into the multiplexer buffer showed that the proposed methods have advantage over the previous methods in the aspect of the performance indices such as cell loss rate (CLR) and voice quality.
基金National Natural Science Foundation ofChina( No.6972 5 0 0 1)
文摘The Enhanced Variable Rate Codec (EVRC) is a standard for the Speech Service Option 3 for Wideband Spread Spectrum Digital System, which has been employed in both IS-95 cellular systems and ANSI J-STC-008 PCS (Personal Communications Systems). This paper investigated the combination of turbo codes with Unequal Error Protection (UEP) and 16-QAM modulation for EVRC codec of Rate 1 to get power and bandwidth efficient coding scheme. The results show that the UEP system outperforms the Equal Error Protection (EEP) one by 1.45 dB at BER of 10 -5.
文摘In this paper, the operation principle of laser rotary encoders is expounded and the optical quadruple frequency technology used in laser rotary encoders is explained, and the design idea of optical system in φ66 mm laser rotary encoder is mainly introduced, as well as the choice of principal devices.
