The combination of non-orthogonal multiple access (NOMA) and multi-input multi-output (MIMO) approaches has been considered as assuring multiple access for the fifth generation technology. In this study, the performan...
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The combination of non-orthogonal multiple access (NOMA) and multi-input multi-output (MIMO) approaches has been considered as assuring multiple access for the fifth generation technology. In this study, the performance of a $2\times 2$2x2 MIMO-NOMA system with low-density parity check (LDPC) codes is investigated. Redundancy with randomly interleaved differential encoding (R-RIDE) is proposed and applied to LDPC encoded messages by two users. LDPC decoding is done using the sum-product algorithm (SPA), which has two types of decoding methods, hard-decision and soft-decision. For hard-decision, bit-flipping decoder is used and for soft-decision, probability domain, log-domain, and simplified log-domain decoders are used. Bit error rate (BER) versus signal-to-noise ratio (SNR) in (dB) and average mutual information (AMI) in (bps/Hz) versus SNR (dB) are evaluated to compare the performance of the proposed and conventional LDPC schemes in NOMA and MIMO-NOMA systems. Simulation results show that both AMI and BER of the proposed LDPC-R-RIDE in MIMO-NOMA system greatly outperforms conventional LDPC coded schemes in NOMA and MIMO-NOMA systems. Moreover, the proposed R-RIDE-LDPC in MIMO-NOMA system outperforms the proposed scheme in the NOMA system. From the simulation results, LDPC-R-RIDE with simplified log-domain decoder has the best AMI result and BER performance compared with other decoding methods.
We propose network coding schemes for a broadcast system where the source packets exhibit a hierarchical structure, such that the successful information retrieval of a packet at a certain layer relies on the correct r...
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We propose network coding schemes for a broadcast system where the source packets exhibit a hierarchical structure, such that the successful information retrieval of a packet at a certain layer relies on the correct receptions of the packets in the previous layers. Assuming the entire transmission consists of two stages, the broadcast stage and the retransmission stage, for progressive packet information decoding, we propose novel source packet combining schemes for retransmission based on networkcoding. The objective is to reduce the number of retransmissions for decoding certain fraction of the source packets. The proposed schemes can be applied to scalable video broadcast systems.
In this article,we introduce a new bi-directional dual-relay selection strategy with its bit error rate(BER)performance *** the first step of the proposed strategy,two relays out of a set of N relay-nodes are selected...
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In this article,we introduce a new bi-directional dual-relay selection strategy with its bit error rate(BER)performance *** the first step of the proposed strategy,two relays out of a set of N relay-nodes are selected in a way to optimize the system performance in terms of BER,based on the suggested algorithm which checks if the selected relays using the maxmin criterion are the best *** the second step,the chosen relay-nodes perform an orthogonal space-time coding scheme using the two-phase relaying protocol to establish a bi-directional communication between the communicating terminals,leading to a significant improvement in the achievable coding and diversity *** further improve the overall system performance,the selected relay-nodes apply also a digital networkcoding ***,this paper discusses the analytical approximation of the BER performance of the proposed strategy,where we prove that the analytical results match almost perfectly the simulated ***,our simulation results show that the proposed strategy outperforms the current state-of-the-art ones.
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