Power Allocation Evaluation for Downlink Non-Orthogonal Multiple Access (NOMA)

Abstract

Fifth-generation of wireless cellular systems has the potential to increase capacity, spectral efficiency, and fairness among users. The Non-Orthogonal Multiple Access based wireless networks (NOMA) is the next generation multiplexing technique. NOMA breaks the orthogonality of traditional multiple access to allow multiple users to share the same radio resource simultaneously. The main challenge in designing NOMA is the selection of the resource allocation algorithms since user pairing and power allocation are coupled. This paper compares the performance of three power allocation schemes: fixed power allocation, fractional transmit power allocation and full search power allocation. The algorithms are analyzed in different simulation scenarios using three performance metrics of the spectrum efficiency and energy efficiency and sum rate. Additionally, the impact of user pairing algorithms studied through two user pairing schemes: random user pairing and channel state sorting based user pairing. Results indicate the superiority of NOMA to increase the capacity compared to traditional orthogonal multiple access. On the other hand, full search power allocation is the best performance compared to the other power allocation schemes though it is highly complex compared to fractional transmit power that gives a suboptimal performance.

AI-RAN in 6G Networks: State-of-the-Art and Challenges

“…This is especially helpful in congested networks with high user density [106]. NOMA substitutes power-domain multiplexing for conventional orthogonal resource allocation techniques to accomplish this [107]. By lowering latency and increasing data speeds, NOMA can enhance the user experience.…”

Differential Evolution Optimized Non-Orthogonal Multiple Access for Sum Rate Maximization

“…The authors of [7] compare the fixed PA, fractional transmit PA, and full search PA in the NOMA system. The authors of [7] take into account simulated scenarios including spectral and energy efficiencies (EEs) and sum rates.…”

“…The authors of [7] compare the fixed PA, fractional transmit PA, and full search PA in the NOMA system. The authors of [7] take into account simulated scenarios including spectral and energy efficiencies (EEs) and sum rates. Techniques for user matching are investigated, including irregular user grouping and user grouping based on channel gains.…”

Performance Analysis of Novel User Pairing-Based Hybrid NOMA System With Fixed/Optimal Power Allocation Strategy

“…From a list of several renowned works in the literature, it can be affirmed that there exists diverse varieties of UP strategies which relies on several factors like the achievable results, distribution setting, and complexity of execution. Pertaining to the idealistic situation, UP would work in conjunction with the PA method to maximise throughput while trying to minimize computational complexity and guaranteeing user fairness [10]. Some of the conventional UP schemes used in NOMA include random user pairing, virtual user pairing, near far, uniform channel gain difference, hybrid user pairing, genetic algorithm, and adaptive user pairing were presented in [11]- [16].…”