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
Differential space-time coding was proposed recently in the literature for multi-antenna systems, where neither the transmitter nor the receiver knows the fading coefficients. Among existing schemes, double differenti...Differential space-time coding was proposed recently in the literature for multi-antenna systems, where neither the transmitter nor the receiver knows the fading coefficients. Among existing schemes, double differential space-time (DDST) coding is of special interest because it is applicable to continuous fast time-varying channels. However, it is less effective in fre- quency-selective fading channels. This paper’s authors derived a novel time-frequency double differential space-time (TF-DDST) coding scheme for multi-antenna orthogonal frequency division multiplexing (OFDM) systems in a time-varying fre- quency-selective fading environment, where double differential space-time coding is introduced into both time domain and fre- quency domain. Our proposed TF-DDST-OFDM system has a low-complexity non-coherent decoding scheme and is robust for time- and frequency-selective Rayleigh fading. In this paper, we also propose the use of state-of-the-art low-density parity-check (LDPC) code in serial concatenation with our TF-DDST scheme as a channel code. Simulations revealed that the LDPC based TF-DDST OFDM system has low decoding complexity and relatively better performance.展开更多
This study examined the relation between word concreteness and word translatability. Translatability was operationalized in terms of both lexical and semantic cross-transparency. Two separate scales were used to measu...This study examined the relation between word concreteness and word translatability. Translatability was operationalized in terms of both lexical and semantic cross-transparency. Two separate scales were used to measure the level of concreteness of 123 target English words and their translatability into Chinese. The results of this study showed that word concreteness and translatability are significantly correlated, and that word concreteness determines the extent of semantic closeness between the translation of English and Chinese word pairs. Concreteness might be a variable that influences how translatable a word is between English and Chinese. However, this influence mainly applies to the semantic cross-transparency between the two languages, not the lexical cross-transparency. A link was proposed between the levels of translatability of a translation pair according to concreteness and associated properties. The paper also discusses the implications of the findings for second language learning and teaching, in particular the ＂translation effect＂ and teachers＇ ＂codeswitching＂ behavior.展开更多
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.
基金Project supported by the Hi-Tech Research and Development Pro-gram (863) of China (No. 2003AA123310) and the National Natural Science Foundation of China (No. 60272079)
文摘Differential space-time coding was proposed recently in the literature for multi-antenna systems, where neither the transmitter nor the receiver knows the fading coefficients. Among existing schemes, double differential space-time (DDST) coding is of special interest because it is applicable to continuous fast time-varying channels. However, it is less effective in fre- quency-selective fading channels. This paper’s authors derived a novel time-frequency double differential space-time (TF-DDST) coding scheme for multi-antenna orthogonal frequency division multiplexing (OFDM) systems in a time-varying fre- quency-selective fading environment, where double differential space-time coding is introduced into both time domain and fre- quency domain. Our proposed TF-DDST-OFDM system has a low-complexity non-coherent decoding scheme and is robust for time- and frequency-selective Rayleigh fading. In this paper, we also propose the use of state-of-the-art low-density parity-check (LDPC) code in serial concatenation with our TF-DDST scheme as a channel code. Simulations revealed that the LDPC based TF-DDST OFDM system has low decoding complexity and relatively better performance.
基金supported by the Fundamental Funds for the Central Universities,and the Research Funds of Remin University of China
文摘This study examined the relation between word concreteness and word translatability. Translatability was operationalized in terms of both lexical and semantic cross-transparency. Two separate scales were used to measure the level of concreteness of 123 target English words and their translatability into Chinese. The results of this study showed that word concreteness and translatability are significantly correlated, and that word concreteness determines the extent of semantic closeness between the translation of English and Chinese word pairs. Concreteness might be a variable that influences how translatable a word is between English and Chinese. However, this influence mainly applies to the semantic cross-transparency between the two languages, not the lexical cross-transparency. A link was proposed between the levels of translatability of a translation pair according to concreteness and associated properties. The paper also discusses the implications of the findings for second language learning and teaching, in particular the ＂translation effect＂ and teachers＇ ＂codeswitching＂ behavior.
