Resource allocation for throughput improvement for non-orthogonal multiple access system in fifth-generation networks
Non-Orthogonal Multiple Access (NOMA) is a promising technique to improve system capacity and coverage in terms of high data rate and spectral efficiency for Fifth-Generation (5G). The NOMA-power domain multiplexes multiple users simultaneously on the frequency, code, or time, but with different pow...
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| 格式: | Thesis |
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2022
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| 总结: | Non-Orthogonal Multiple Access (NOMA) is a promising technique to improve system capacity and coverage in terms of high data rate and spectral efficiency for Fifth-Generation (5G). The NOMA-power domain multiplexes multiple users simultaneously on the frequency, code, or time, but with different power levels providing a higher data rate than conventional Orthogonal Multiple Access (OMA). The NOMA scheme uses superposition coding (SC) and successive interference cancellation (SIC) techniques. The work focuses on resource allocation in terms of user pairing, subchannel power allocation, and power ratio allocation to maximise throughput in the NOMA system to meet the 5G network requirements, such as high throughput and fairness. The resource allocation is a non-deterministic polynomial (NP), where a NP-hard problem poses challenges to throughput maximisation. To achieve the above-stated objectives of throughput improvement using resource allocation optimisation, the strategy would be, in order of priority. The first strategy was to gain an in-depth understanding of the power allocation and resource allocation schemes and detail the optimisation algorithms applied for resource allocation problems in NOMA based 5G networks. Ant colony optimisation (ACO) is proposed to optimise the power allocation to maximise the throughput for two users in the downlink NOMA system. The results demonstrated that the proposed ACO performs up to 35% better than the existing numerical method for system throughput. Furthermore, a power allocation scheme is proposed with a theoretical and practical framework to illustrate the concept of the power ratio using binary phase-shift keying (BPSK) in the NOMA system under perfect and imperfect SIC. Subsequently, simulated annealing (SA) standalone algorithm is proposed to optimise the power allocation and perform user pairing to maximise throughput for the NOMA system. The proposed SA effectively outperformed by 7% more than the existing numerical algorithm. Moreover, an optimal power allocation solution is provided. Finally, a hybrid resource allocation scheme is designed using integer linear programming (ILP) and particle swarm optimisation (PSO) to achieve trade-offs between throughput maximisation and fairness in the NOMA system. The simulation results showed that the proposed approaches outperformed the conventional approaches by 17% with less computational time in terms of throughput maximisation and had a better fairness rate. |
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