sparse code multiple access (SCMA) is a research hotspot in recent years. In this paper, we proposed a joint SCMA detection and Turbo decoding (JDD) scheme for the SCMA system. The proposed method integrates the messa...
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ISBN:
(纸本)9781509024834
sparse code multiple access (SCMA) is a research hotspot in recent years. In this paper, we proposed a joint SCMA detection and Turbo decoding (JDD) scheme for the SCMA system. The proposed method integrates the message passing between SCMA detector and turbo decoder into the factor graph of the SCMA detector to construct a joint factor graph. Simulation results show the JDD scheme has 1.6 dB performance gain compared to the iterative detection and decoding (IDD) scheme. Moreover, it has only 0.2 dB performance loss compared to the single user QPSK system. To further reduce the computational complexity of the JDD scheme, we implement the JDD scheme in the logarithm domain (LOG-JDD) with the same performance compared with the IDD scheme. A technology that can improve the convergence is used to improve the bit error rate (BER) performance. Simulation results show that a suitable damping factor can obtain about ldB performance gain compared with the IDD scheme.
sparse code multiple access (SCMA) is a promising multiplexing approach to achieve high system capacity. In this paper, we develop a novel iterative detection and decoding scheme for SCMA systems combined with Low-den...
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ISBN:
(纸本)9781467376884
sparse code multiple access (SCMA) is a promising multiplexing approach to achieve high system capacity. In this paper, we develop a novel iterative detection and decoding scheme for SCMA systems combined with Low-density Parity-check (LDPC) decoding. In particular, we decompose the output of the message passing algorithm (MPA) based SCMA multiuser detection into intrinsic part and prior part. Then we design a joint detection and decoding scheme which iteratively exchanges the intrinsic information between the detector and the decoder, yielding a satisfied performance gain. Moreover, the proposed scheme has almost the same complexity compared with the traditional receiver for LDPC-coded SCMA systems. As numerical results demonstrate, the proposed scheme has a substantial gain over the traditional SCMA receiver on AWGN channels and Rayleigh fading channels.
In this paper, we investigated error probability bounds for sparse code multiple access (SCMA) signals. SCMA is one of proposed non-orthogonal multipleaccess schemes for Fifth generation (5G) wireless communication s...
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ISBN:
(纸本)9781509048663
In this paper, we investigated error probability bounds for sparse code multiple access (SCMA) signals. SCMA is one of proposed non-orthogonal multipleaccess schemes for Fifth generation (5G) wireless communication standard. This scheme allows to increase the number of active users inside a given time-frequency resource. For AWGN and Rayleigh (without diversity) channels, we calculated union bounds for symbol and bit error probability. Asymptotic bound based on minimal distance between signals is also calculated. Analytical bounds are compared with simulations results (Maximum Likelihood (ML) Algorithm and Message Passing Algorithm (MPA) were used for signal reception). For AWGN channel, the results show that analytical bounds (symbol and bit error probabilities) are tight in the high-SNR region. For Rayleigh channel, analytical bound for symbol error probability are pessimistic with the gap of approximately 0.7 dB in the medium- and high-SNR regions.
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