Sparse Code Multiple Access (SCMA) is a potential Non-Orthogonal Multiple Access (NOMA) scheme that is widely employed in 5G wireless networks to address rigid improvisations through system capacity, reduced latency, ...
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Sparse Code Multiple Access (SCMA) is a potential Non-Orthogonal Multiple Access (NOMA) scheme that is widely employed in 5G wireless networks to address rigid improvisations through system capacity, reduced latency, and user-controlled connection. The design of the optimum codebook is critical to the operation of the uplink SCMA-based NOMA system. This paper proposes an optimum parity check polar coding (PCPC)-Probabilistic Shaping(PS)-based uplink SCMA codebook design using a biologically inspired-Hybrid-Firefly-Bat algorithm (HFFBA) for the enhancement of average mutual information (AMI) and a reduction in the bit error rate (BER). The application of optimal PCPC aids in reducing the receiver complexity in the uplink NOMA systems. Furthermore, the diversity gain and process reliability has been improved with the merging of PCPC with SCMA. The proposed system's performance is evaluated over Rayleigh and Additive White Gaussian Noise (AWGN) channels for codebook size of 8 and 16 and aims to improve the performance through AMI and BER. The proposed HFFBA codebook achieved an SNR of 12 dB for AWGN and 18 dB for the Rayleigh channel for M = 4 for a BER of 10(-3). The same was attained at an SNR of 21.4 dB for AWGN and 23.6 dB for the Rayleigh channel for M = 16. The gain in SNR for M = 4 to16 for the AWGN and Rayleigh channels are 9.4 dB and 5.6 dB respectively. The optimized codebooks with such biologically inspired algorithms adapt to the changing wireless network conditions and could achieve an increase in data rate and reduced error rate compared to existing systems.
Non-Orthogonal Multiple Access (NOMA) is an efficient multiple access scheme which augments the capacity and overall throughput in LTE and 5G networks. Tackling the high system throughput and device connectivity of mu...
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Non-Orthogonal Multiple Access (NOMA) is an efficient multiple access scheme which augments the capacity and overall throughput in LTE and 5G networks. Tackling the high system throughput and device connectivity of multiple users with different channel state information is a key challenge at this juncture. The joint detection and decoding using parity check polar coding (PCPC) and the utilization of Sparse Code Multiple Access (SCMA) in Code domain NOMA improves throughput supporting an overloaded number of users. Also, Multiple-Input Multiple-Output (MIMO)-SCMA scheme has potential in providing spectrum and energy efficiency. MIMO-SCMA superimposes multiple users in the code domain and utilizes the channel gain difference between multiplexed users. Hence, this paper aims to propose a proficient code domain NOMA scheme, the PCPC SCMA multiplexed over Orthogonal Frequency Code Division Multiple Access (OFCDMA), implementing a joint detection and decoding with user scheduling. Signals of numerous users are superimposed and transmitted over a channel. At the receiver, Multi-User Detection (MUD) exploiting the Message Passing Algorithm (MPA) is used to identify the desired user. To ensure proper resource utilization of multiple data blocks, the users are scheduled by implementing the Invasive Weed Optimization (IWO) technique along with the MPA. The proposed scheme, which engages an IWO-MPA based MUD scheme, improves the convergence rate, in terms of the number of iterations thereby leading to lower complexity, as well as reduces the Bit Error Rate (BER). Computer simulations reveal that the proposed scheme achieves high spectrum and energy efficiency, higher throughput and overloaded user fairness compared with recent researches.
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