There is a contradiction between high processing complexity and limited processing resources when turbo codes are used on the on-board processing(OBP)satellite platform.To solve this problem,this paper proposes a part...There is a contradiction between high processing complexity and limited processing resources when turbo codes are used on the on-board processing(OBP)satellite platform.To solve this problem,this paper proposes a partial iterative decode method for on-board application,in which satellite only carries out limited number of iteration according to the on-board processing resource limitation and the throughput capacity requirements.In this method,the soft information of parity bits,which is not obtained individually in conventional turbo decoder,is encoded and forwarded along with those of information bits.To save downlink transmit power,the soft information is limited and normalized before forwarding.The iteration number and limiter parameters are optimized with the help of EXIT chart and numerical analysis,respectively.Simulation results show that the proposed method can effectively decrease the complexity of onboard processing while achieve most of the decoding gain..展开更多
The uplink of mobile satellite communication(MSC) system with hundreds of spot beams is essentially a multiple-input multiple-output(MIMO) channel. Dual-turbo iterative detection and decoding as a kind of MIMO receive...The uplink of mobile satellite communication(MSC) system with hundreds of spot beams is essentially a multiple-input multiple-output(MIMO) channel. Dual-turbo iterative detection and decoding as a kind of MIMO receiver, which exchanges soft extrinsic information between a soft-in soft-out(SISO) detector and an SISO decoder in an iterative fashion, is an efficient method to reduce the uplink inter-beam-interference(IBI),and so the receiving bit error rate(BER).We propose to replace the linear SISO detector of traditional dual-turbo iterative detection and decoding with the AMP detector for the low-density parity-check(LDPC) coded multibeam MSC uplink. This improvement can reduce the computational complexity and achieve much lower BER.展开更多
This paper proposes a multi-band speech enhancement algorithm exploiting iterative processing for enhancement of single channel speech. In the proposed algorithm, the output of the multi-band spectral subtraction (MBS...This paper proposes a multi-band speech enhancement algorithm exploiting iterative processing for enhancement of single channel speech. In the proposed algorithm, the output of the multi-band spectral subtraction (MBSS) algorithm is used as the input signal again for next iteration process. As after the first MBSS processing step, the additive noise transforms to the remnant noise, the remnant noise needs to be further re-estimated. The proposed algorithm reduces the remnant musical noise further by iterating the enhanced output signal to the input again and performing the operation repeatedly. The newly estimated remnant noise is further used to process the next MBSS step. This procedure is iterated a small number of times. The proposed algorithm estimates noise in each iteration and spectral over-subtraction is executed independently in each band. The experiments are conducted for various types of noises. The performance of the proposed enhancement algorithm is evaluated for various types of noises at different level of SNRs using, 1) objective quality measures: signal-to-noise ratio (SNR), segmental SNR, perceptual evaluation of speech quality (PESQ);and 2) subjective quality measure: mean opinion score (MOS). The results of proposed enhancement algorithm are compared with the popular MBSS algorithm. Experimental results as well as the objective and subjective quality measurement test results confirm that the enhanced speech obtained from the proposed algorithm is more pleasant to listeners than speech enhanced by classical MBSS algorithm.展开更多
We combine the Turbo codes with differential frequency hopping (DFH) technique and propose a new technique called Turbo-DFH coding. The structures of Turbo-DFH encoder and decoder are given. Taking aim at characterist...We combine the Turbo codes with differential frequency hopping (DFH) technique and propose a new technique called Turbo-DFH coding. The structures of Turbo-DFH encoder and decoder are given. Taking aim at characteristic of Turbo-DFH system, the modified Log-MAP algorithm is presented and used for iterative decoding of Turbo-DFH decoder. Simulation results show that because the ideas of random coding and iterative decoding are used, the bit error rate (BER) performance of the Turbo-DFH system is better than that of the conventional DFH system.展开更多
The computationally efficient iterative receiver is investigated for Turbo-BLAST （Bell Labs layered space time） system over frequency selective fading channels. Compared with the conventional receiver based on soft ...The computationally efficient iterative receiver is investigated for Turbo-BLAST （Bell Labs layered space time） system over frequency selective fading channels. Compared with the conventional receiver based on soft interference cancellation（SIC）, an iterative detection scheme based on bit-level cancellation is presented to reduce the complexity of the receiver by decomposing of an M-QAM constellation into a linear Combination of binary constellations. Simulation results demonstrate that compared with the conventional SIC scheme, the proposed scheme based on bit-level cancellation performs almost as well as the SIC scheme after several iterations while proving a lot of saving in computational complexity.展开更多
基金supported by National High Technology Research and Development Program(863 Program,2012AA01A502)National Natural Science Foundation of China (41206031)National Basic Research Program(2012CB316000)
文摘There is a contradiction between high processing complexity and limited processing resources when turbo codes are used on the on-board processing(OBP)satellite platform.To solve this problem,this paper proposes a partial iterative decode method for on-board application,in which satellite only carries out limited number of iteration according to the on-board processing resource limitation and the throughput capacity requirements.In this method,the soft information of parity bits,which is not obtained individually in conventional turbo decoder,is encoded and forwarded along with those of information bits.To save downlink transmit power,the soft information is limited and normalized before forwarding.The iteration number and limiter parameters are optimized with the help of EXIT chart and numerical analysis,respectively.Simulation results show that the proposed method can effectively decrease the complexity of onboard processing while achieve most of the decoding gain..
基金supported by the National Natural Science Foundation of China under Grants 61320106003 and 61401095the Civil Aerospace Technologies Research Project under Grant D010109The Fundamental Research Funds for the Central Universities under Grant YZZ17009
文摘The uplink of mobile satellite communication(MSC) system with hundreds of spot beams is essentially a multiple-input multiple-output(MIMO) channel. Dual-turbo iterative detection and decoding as a kind of MIMO receiver, which exchanges soft extrinsic information between a soft-in soft-out(SISO) detector and an SISO decoder in an iterative fashion, is an efficient method to reduce the uplink inter-beam-interference(IBI),and so the receiving bit error rate(BER).We propose to replace the linear SISO detector of traditional dual-turbo iterative detection and decoding with the AMP detector for the low-density parity-check(LDPC) coded multibeam MSC uplink. This improvement can reduce the computational complexity and achieve much lower BER.
文摘This paper proposes a multi-band speech enhancement algorithm exploiting iterative processing for enhancement of single channel speech. In the proposed algorithm, the output of the multi-band spectral subtraction (MBSS) algorithm is used as the input signal again for next iteration process. As after the first MBSS processing step, the additive noise transforms to the remnant noise, the remnant noise needs to be further re-estimated. The proposed algorithm reduces the remnant musical noise further by iterating the enhanced output signal to the input again and performing the operation repeatedly. The newly estimated remnant noise is further used to process the next MBSS step. This procedure is iterated a small number of times. The proposed algorithm estimates noise in each iteration and spectral over-subtraction is executed independently in each band. The experiments are conducted for various types of noises. The performance of the proposed enhancement algorithm is evaluated for various types of noises at different level of SNRs using, 1) objective quality measures: signal-to-noise ratio (SNR), segmental SNR, perceptual evaluation of speech quality (PESQ);and 2) subjective quality measure: mean opinion score (MOS). The results of proposed enhancement algorithm are compared with the popular MBSS algorithm. Experimental results as well as the objective and subjective quality measurement test results confirm that the enhanced speech obtained from the proposed algorithm is more pleasant to listeners than speech enhanced by classical MBSS algorithm.
文摘We combine the Turbo codes with differential frequency hopping (DFH) technique and propose a new technique called Turbo-DFH coding. The structures of Turbo-DFH encoder and decoder are given. Taking aim at characteristic of Turbo-DFH system, the modified Log-MAP algorithm is presented and used for iterative decoding of Turbo-DFH decoder. Simulation results show that because the ideas of random coding and iterative decoding are used, the bit error rate (BER) performance of the Turbo-DFH system is better than that of the conventional DFH system.
基金The Natural Science Foundation of Jiangsu Province (BK2007192)
文摘The computationally efficient iterative receiver is investigated for Turbo-BLAST （Bell Labs layered space time） system over frequency selective fading channels. Compared with the conventional receiver based on soft interference cancellation（SIC）, an iterative detection scheme based on bit-level cancellation is presented to reduce the complexity of the receiver by decomposing of an M-QAM constellation into a linear Combination of binary constellations. Simulation results demonstrate that compared with the conventional SIC scheme, the proposed scheme based on bit-level cancellation performs almost as well as the SIC scheme after several iterations while proving a lot of saving in computational complexity.
