The problem of soft-input so,output （ SISO ） detection for time-varying frequency-selec- tive fading channels is considered. Based on a suitably-designed factor graph and the sum-product al- gorithm, a low-complexit...The problem of soft-input so,output （ SISO ） detection for time-varying frequency-selec- tive fading channels is considered. Based on a suitably-designed factor graph and the sum-product al- gorithm, a low-complexity iterative message passing scheme is proposed for joint channel estima- tion, equalization and decoding. Two kinds of schedules （parallel and serial） are adopted in message updates to produce two algorithms with different latency. The computational complexity per iteration of the proposed algorithms grows only linearly with the channel length, which is a significantly de- crease compared to the optimal maximum a posteriori （MAP） detection with the exponential com- plexity. Computer simulations demonstrate the effectiveness of the proposed schemes in terms of bit error rate performance.展开更多
In this paper, A Belief Propagation concatenated Orderd-Statistic Decoder (BP-OSD) based on accumulated Log-Likelihood Ratio (LLR) is proposed for medium and short lengths Low Density Parity-Check (LDPC) codes coded B...In this paper, A Belief Propagation concatenated Orderd-Statistic Decoder (BP-OSD) based on accumulated Log-Likelihood Ratio (LLR) is proposed for medium and short lengths Low Density Parity-Check (LDPC) codes coded Bit-Interleaved Coded Modulation (BICM) systems. The accumulated soft output values delivered by every BP iteration are used as reliability values of Soft-Input Soft-Output OSD (SISO-OSD) decoder and the soft output of SISO-OSD is used as a priori probabilities of the demodulator for the next iteration. Simulation results show that this improved algorithm achieves noticeable performance gain with only modest increase in computation complexity.展开更多
为了降低Turbo均衡中均衡器的复杂度,该文提出了符号方差反馈均衡算法(SVFE)。该算法是对精确的线性最小均方误差估计值(LMMSE)进行Taylor展开得到的。在该算法中,先利用时不变均衡器得到初步符号估计值,再根据先验符号方差对估计值加权...为了降低Turbo均衡中均衡器的复杂度,该文提出了符号方差反馈均衡算法(SVFE)。该算法是对精确的线性最小均方误差估计值(LMMSE)进行Taylor展开得到的。在该算法中,先利用时不变均衡器得到初步符号估计值,再根据先验符号方差对估计值加权,最后进行时不变滤波得到更佳的符号估计值。由于用到了时变的先验符号方差信息,其性能更接近精确的LMMSE均衡器。将所提算法用于Proakis C信道下的Turbo均衡处理,和时不变均衡算法进行仿真对比,所提算法将信噪比损失从0.83 d B降到了0.17 d B,并且仍可通过快速傅里叶变换降低为对数复杂度。展开更多
Relay transmission technique can be utilized to increase coverage or enhance throughput for conventional cellular communication systems. There are two typical relaying schemes： amplify-and- forward （AF） and decode-...Relay transmission technique can be utilized to increase coverage or enhance throughput for conventional cellular communication systems. There are two typical relaying schemes： amplify-and- forward （AF） and decode-and-forward （DF）. This paper presents a new scheme named soft symbol Estimation and Forward （SEF） , which holds the advantages of both AF and DF, i.e. keeping soft information and obtaining decoding gain. This scheme has similar operations as DF except that the operations are performed in a soft-input-soft-output （SISO） fashion. The relay performs SISO deco- ding, SISO re-encoding and key point soft symbol estimation, which is derived based on the maxi- mum likelihood （ML） criteria. Simulation results prove that the proposed SEF scheme much outper- forms both AF and DF.展开更多
基金Supported by the National Natural Science Foundation of China(61201181)Specialized Research Fund for the Doctoral Program of Higher Education(20121101120020)the Co-innovation Laboratory of Aerospace Broadband Network Technology
文摘The problem of soft-input so,output （ SISO ） detection for time-varying frequency-selec- tive fading channels is considered. Based on a suitably-designed factor graph and the sum-product al- gorithm, a low-complexity iterative message passing scheme is proposed for joint channel estima- tion, equalization and decoding. Two kinds of schedules （parallel and serial） are adopted in message updates to produce two algorithms with different latency. The computational complexity per iteration of the proposed algorithms grows only linearly with the channel length, which is a significantly de- crease compared to the optimal maximum a posteriori （MAP） detection with the exponential com- plexity. Computer simulations demonstrate the effectiveness of the proposed schemes in terms of bit error rate performance.
基金Supported by the National Natural Science Foundation of China (No: 60496311)
文摘In this paper, A Belief Propagation concatenated Orderd-Statistic Decoder (BP-OSD) based on accumulated Log-Likelihood Ratio (LLR) is proposed for medium and short lengths Low Density Parity-Check (LDPC) codes coded Bit-Interleaved Coded Modulation (BICM) systems. The accumulated soft output values delivered by every BP iteration are used as reliability values of Soft-Input Soft-Output OSD (SISO-OSD) decoder and the soft output of SISO-OSD is used as a priori probabilities of the demodulator for the next iteration. Simulation results show that this improved algorithm achieves noticeable performance gain with only modest increase in computation complexity.
文摘为了降低Turbo均衡中均衡器的复杂度,该文提出了符号方差反馈均衡算法(SVFE)。该算法是对精确的线性最小均方误差估计值(LMMSE)进行Taylor展开得到的。在该算法中,先利用时不变均衡器得到初步符号估计值,再根据先验符号方差对估计值加权,最后进行时不变滤波得到更佳的符号估计值。由于用到了时变的先验符号方差信息,其性能更接近精确的LMMSE均衡器。将所提算法用于Proakis C信道下的Turbo均衡处理,和时不变均衡算法进行仿真对比,所提算法将信噪比损失从0.83 d B降到了0.17 d B,并且仍可通过快速傅里叶变换降低为对数复杂度。
文摘Relay transmission technique can be utilized to increase coverage or enhance throughput for conventional cellular communication systems. There are two typical relaying schemes： amplify-and- forward （AF） and decode-and-forward （DF）. This paper presents a new scheme named soft symbol Estimation and Forward （SEF） , which holds the advantages of both AF and DF, i.e. keeping soft information and obtaining decoding gain. This scheme has similar operations as DF except that the operations are performed in a soft-input-soft-output （SISO） fashion. The relay performs SISO deco- ding, SISO re-encoding and key point soft symbol estimation, which is derived based on the maxi- mum likelihood （ML） criteria. Simulation results prove that the proposed SEF scheme much outper- forms both AF and DF.
