Abstract
In this paper, we study two transmission scenarios for the base station (BS) in cellular networks to serve the far user, who is located at the cell-edge area in such a network. In particular, we show that wireless-powered non-orthogonal multiple access (NOMA) and the cell-center user in such a model can harvest energy from the BS. To overcome disadvantages of the cell-edge user due to its weak received signal, we fabricate a far NOMA user with multiple antennas to achieve performance improvement. In addition, the first scenario only considers a relay link deployed to forward signals to a far NOMA user, while both direct links and relay links are generally enabled to serve a far user in the second scenario. These situations, together with their outage performance, are analyzed and compared to provide insights in the design of a real-multiple-antenna NOMA network, in which the BS is also required to equip multiple antennas for robust quality of transmission. Higher complexity in computations is already known in consideration of outage metrics with respect to performance analysis, since the system model employs multiple antennas. To this end, we employ a transmit antenna selection (TAS) policy to formulate closed-form expressions of outage probability that satisfies the quality-of-service (QoS) requirements in the NOMA network. Our simulation results reveal that the performance of the considered system will be improved in cases of higher quantity of transmit antennas in dedicated devices. Finally, the proposed design in such a NOMA system cannot only ensure a downlink with higher quality to serve a far NOMA user, but also provide significant system performance improvement compared to a traditional NOMA networks using a single antenna.
Highlights
IntroductionTo deploy the generation of wireless networks, one of the potential technologies referred to as a promising application in 5G is Non-Orthogonal Multiple Access (NOMA) [1,2,3]
To deploy the generation of wireless networks, one of the potential technologies referred to as a promising application in 5G is Non-Orthogonal Multiple Access (NOMA) [1,2,3].With more advantages compared to Orthogonal Multiple-Access (OMA) schemes, NOMA allows a superior number of users to be connected to a wireless network concurrently [4]
It is assumed that the base station (BS), the near NOMA user, and the far NOMA user are located in approximate a straight line
Summary
To deploy the generation of wireless networks, one of the potential technologies referred to as a promising application in 5G is Non-Orthogonal Multiple Access (NOMA) [1,2,3]. In [30], to consider the weighted system throughput in single-antenna MC-NOMA systems, the authors developed a sub-optimal sub-carrier and power allocation algorithm. It is important to study outage performance regarding the multi-antenna NOMA user in cooperative NOMA networks. Extending our previous work in terms of single-input single-output (SISO) NOMA strategy [17], we introduce a realistic scenario with multiple antennas which is equipped at the far NOMA user in the considered NOMA. Our findings reveal that a higher number of transmit antennas at the BS provides a superior outage probability for both the near and far users compared to the traditional model. Comparing the proposed multiple-antenna NOMA system with different locations of the user and energy-harvesting time, we provide detailed guidelines for the design of real cooperative NOMA, achieving better outage performance. En (.) stands for the exponential integrals function, Γ (.) is the gamma function
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