45,141 research outputs found

    Iterative Detection of Diagonal Block Space Time Trellis Codes, TCM and Reversible Variable Length Codes for Transmission over Rayleigh Fading Channels

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    Iterative detection of Diagonal Block Space Time Trellis Codes (DBSTTCs), Trellis Coded Modulation (TCM) and Reversible Variable Length Codes (RVLCs) is proposed. With the aid of efficient iterative decoding, the proposed scheme is capable of providing full transmit diversity and a near channel capacity performance. The performance of the proposed scheme was evaluated when communicating over uncorrelated Rayleigh fading channels. Explicitly, significant iteration gains were achieved by the proposed scheme, which was capable of performing within 2~dB from the channel capacity

    Recent progress in random metric theory and its applications to conditional risk measures

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    The purpose of this paper is to give a selective survey on recent progress in random metric theory and its applications to conditional risk measures. This paper includes eight sections. Section 1 is a longer introduction, which gives a brief introduction to random metric theory, risk measures and conditional risk measures. Section 2 gives the central framework in random metric theory, topological structures, important examples, the notions of a random conjugate space and the Hahn-Banach theorems for random linear functionals. Section 3 gives several important representation theorems for random conjugate spaces. Section 4 gives characterizations for a complete random normed module to be random reflexive. Section 5 gives hyperplane separation theorems currently available in random locally convex modules. Section 6 gives the theory of random duality with respect to the locally L0L^{0}-convex topology and in particular a characterization for a locally L0L^{0}-convex module to be L0L^{0}-pre-barreled. Section 7 gives some basic results on L0L^{0}-convex analysis together with some applications to conditional risk measures. Finally, Section 8 is devoted to extensions of conditional convex risk measures, which shows that every representable LL^{\infty}-type of conditional convex risk measure and every continuous LpL^{p}-type of convex conditional risk measure (1p<+1\leq p<+\infty) can be extended to an LF(E)L^{\infty}_{\cal F}({\cal E})-type of σϵ,λ(LF(E),LF1(E))\sigma_{\epsilon,\lambda}(L^{\infty}_{\cal F}({\cal E}), L^{1}_{\cal F}({\cal E}))-lower semicontinuous conditional convex risk measure and an LFp(E)L^{p}_{\cal F}({\cal E})-type of Tϵ,λ{\cal T}_{\epsilon,\lambda}-continuous conditional convex risk measure (1p<+1\leq p<+\infty), respectively.Comment: 37 page

    \Lambda_b \to \Lambda_c P(V) Nonleptonic Weak Decays

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    The two-body nonleptonic weak decays of \Lambda_b \to \Lambda_c P(V) (P and V represent pseudoscalar and vector mesons respectively) are analyzed in two models, one is the Bethe-Salpeter (B-S) model and the other is the hadronic wave function model. The calculations are carried out in the factorization approach. The obtained results are compared with other model calculations.Comment: 18 pages, Late

    A Purely Symbol-Based Precoded and LDPC-Coded Iterative-Detection Assisted Sphere-Packing Modulated Space-Time Coding Scheme

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    In this contribution, we propose a purely symbol-based LDPC-coded scheme based on a Space-Time Block Coding (STBC) signal construction method that combines orthogonal design with sphere packing, referred to here as (STBCSP). We demonstrate that useful performance improvements may be attained when sphere packing aided modulation is concatenated with non-binary LDPC especially, when performing purely symbol-based turbo detection by exchanging extrinsic information between the non-binary LDPC decoder and a rate-1 non-binary inner precoder. We also investigate the convergence behaviour of this symbol-based concatenated scheme with the aid of novel non-binary Extrinsic Information Transfer (EXIT) Charts. The proposed symbol-based turbo-detected STBC-SP scheme exhibits a 'turbo-cliff' at Eb/N0 = 5.0 dB and achieves an Eb/N0 gain of 19.2dB at a BER of 10-5 over Alamouti’s scheme

    The common nodulation genes of Astragalus sinicus rhizobia are conserved despite chromosomal diversity

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    The nodulation genes of Mesorhizobium sp. (Astragalus sinicus) strain 7653R were cloned by functional complementation of Sinorhizobium meliloti nod mutants. The common nod genes, nodD, nodA, and nodBC, were identified by heterologous hybridization and sequence analysis. The nodA gene was found to be separated from nodBC by approximately 22 kb and was divergently transcribed. The 2.0-kb nodDBC region was amplified by PCR from 24 rhizobial strains nodulating A. sinicus, which represented different chromosomal genotypes and geographic origins. No polymorphism was found in the size of PCR products, suggesting that the separation of nodA from nodBC is a common feature of A. sinicus rhizobia. Sequence analysis of the PCR-amplified nodA gene indicated that seven strains representing different 16S and 23S ribosomal DNA genotypes had identical nodA sequences. These data indicate that, whereas microsymbionts of A. sinicus exhibit chromosomal diversity, their nodulation genes are conserved, supporting the hypothesis of horizontal transfer of nod genes among diverse recipient bacteria

    A Turbo-Detection Aided Serially Concatenated MPEG-4/TCM Videophone Transceiver

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    A Turbo-detection aided serially concatenated inner Trellis Coded Modulation (TCM) scheme is combined with four different outer codes, namely with a Reversible Variable Length Code (RVLC), a Non-Systematic Convolutional (NSC) code a Recursive Systematic Convolutional (RSC) code or a Low Density Parity Check (LDPC) code. These four outer constituent codes are comparatively studied in the context of an MPEG4 videophone transceiver. These serially concatenated schemes are also compared to a stand-alone LDPC coded MPEG4 videophone system at the same effective overall coding rate. The performance of the proposed schemes is evaluated when communicating over uncorrelated Rayleigh fading channels. It was found that the serially concatenated TCM-NSC scheme was the most attractive one in terms of coding gain and decoding complexity among all the schemes considered in the context of the MPEG4 videophone transceiver. By contrast, the serially concatenated TCM-RSC scheme was found to attain the highest iteration gain among the schemes considered

    Plasmon assisted transmission of high dimensional orbital angular momentum entangled state

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    We present an experimental evidence that high dimensional orbital angular momentum entanglement of a pair of photons can be survived after a photon-plasmon-photon conversion. The information of spatial modes can be coherently transmitted by surface plasmons. This experiment primarily studies the high dimensional entangled systems based on surface plasmon with subwavelength structures. It maybe useful in the investigation of spatial mode properties of surface plasmon assisted transmission through subwavelength hole arrays.Comment: 7 pages,6 figure
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