An Improved EPA-Based Receiver Design for Uplink LDPC Coded SCMA System

Sparse code multiple access (SCMA) is an emerging paradigm for efficient enabling of massive connectivity in future machine-type communications (MTC). In this letter, we conceive the uplink transmissions of the low-density parity check (LDPC) coded SCMA system. Traditional receiver design of LDPC-SCMA system, which is based on message passing algorithm (MPA) for multiuser detection followed by individual LDPC decoding, may suffer from the drawback of the high complexity and large decoding latency, especially when the system has large codebook size and/or high overloading factor. To address this problem, we introduce a novel receiver design by applying the expectation propagation algorithm (EPA) to the joint detection and decoding (JDD) involving an aggregated factor graph of LDPC code and sparse codebooks. Our numerical results demonstrate the superiority of the proposed EPA based JDD receiver over the conventional Turbo receiver in terms of both significantly lower complexity and faster convergence rate without noticeable error rate performance degradation

A simple butterfly-shaped chaotic system

In this paper, we proposed a multi-wing chaotic system based on the Sprott-B system with the nonlinear feedback method. The novel system can simultaneously generate attractors with one-wing, butterfly-shaped double-wing, and butterfly-shaped four-wing. Comparatively, the novel system is simple, which includes two quadratically nonlinear terms. In the novel system, the period-doubling bifurcation process was observed with the bifurcation diagram, and the period and chaos were confirmed with power spectra. Especially, the novel system was asymmetric about any axis and can generate asymmetric coexisting attractors. The chaotic sequences generated by the novel system had good pseudo-randomness which was confirmed by the NIST test. In addition, the feasibility of the novel system was confirmed by the hardware circuit. The novel system would be able to be widely applied in the field of secure communication

An Improved EPA based Receiver Design for Uplink LDPC Coded SCMA System

Sparse code multiple access (SCMA) is an emerging paradigm for efficient enabling of massive connectivity in future machine-type communications (MTC). In this letter, we conceive the uplink transmissions of the low-density parity check (LDPC) coded SCMA system. Traditional receiver design of LDPC-SCMA system, which is based on message passing algorithm (MPA) for multiuser detection followed by individual LDPC decoding, may suffer from the drawback of the high complexity and large decoding latency, especially when the system has large codebook size and/or high overloading factor. To address this problem, we introduce a novel receiver design by applying the expectation propagation algorithm (EPA) to the joint detection and decoding (JDD) involving an aggregated factor graph of LDPC code and sparse codebooks. Our numerical results demonstrate the superiority of the proposed EPA based JDD receiver over the conventional Turbo receiver in terms of both significantly lower complexity and faster convergence rate without noticeable error rate performance degradation

DataSheet1_A new experimental method to measure and calculate the tensile strength of concrete.docx

Introduction: A new method is introduced to test the tensile strength of concrete: the cylinder transverse splitting test. Compared with the cylinder splitting (or Brazilian) test, the cylinder transverse splitting test involves different load positions and offers the advantages of doubling the data volume with the same number of specimens and improving the detection accuracy.Methods: Finite element analysis software was used to simulate the concrete cylinder transverse splitting test and the stress distribution on the failure surface was determined.Results and Discussion: The results show that the fracture of a cylinder is mainly determined by tensile stress. The splitting strength of normal concrete and crumb rubber concrete, a new environmentally friendly concrete material that has gathered considerable attention in recent years, was obtained by cylinder transverse and cube splitting tests. The cylinder transverse splitting test data show a stable correlation with the cube splitting test data and well characterize the concrete strength. The relationship between the cylinder nominal transverse splitting strength (f2) and cube splitting strength (f1) was established on the basis of linear analysis of the test data: f1 = 0.51f2. The calculated cube splitting strength is in good agreement with the test values.</p