41 research outputs found
Cooperative underlay cognitive radio assisted NOMA: secondary network improvement and outage performance
In this paper, a downlink scenario of a non-orthogonal multiple access (NOMA) scheme with power constraint via spectrum sensing is considered. Such network provides improved outage performance and new scheme of NOMA-based cognitive radio (CR-NOMA) network are introduced. The different power allocation factors are examined subject to performance gap among these secondary NOMA users. To evaluate system performance, the exact outage probability expressions of secondary users are derived. Finally, the dissimilar performance problem in term of secondary users is illustrated via simulation, in which a power allocation scheme and the threshold rates are considered as main impacts of varying system performance. The simulation results show that the performance of CR-NOMA network can be improved significantly
Outage performance analysis of cell-center/edge users under two policies of energy harvesting
In this paper, two energy harvesting policies deploying in cooperative non-orthogonal multiple access (NOMA) systems are considered. After period of wireless power transfer, the NOMA users including cell-edge and cell-center users simultaneously transmit the superposition coded symbols to the base station (BS). In the last time slot, the BS decodes to achieve its signal based on superposition coded symbol with corresponding power allocation factors. This paper provides exact expressions of outage probability in two schemes. Performance gap of two NOMA users can be raised by providing different power allocation factors. It is confirmed by numerical result. Distance and data rate are main factors affecting outage performance. Scheme I exhibit scenario where power beacon transmits energy signal to NOMA user while the BS feeds energy to NOMA user in Scheme II. It is shown that outage performance of Scheme I is better than that of Scheme II.Web of Science254807
Enhancing PHY Security of MISO NOMA SWIPT Systems With a Practical Non-Linear EH Model
Non-orthogonal multiple-access (NOMA) and simultaneous wireless information
and power transfer (SWIPT) are promising techniques to improve spectral
efficiency and energy efficiency. However, the security of NOMA SWIPT systems
has not received much attention in the literature. In this paper, an artificial
noise-aided beamforming design problem is studied to enhance the security of a
multiple-input single-output NOMA SWIPT system where a practical non-linear
energy harvesting model is adopted. The problem is non-convex and challenging
to solve. Two algorithms are proposed to tackle this problem based on
semidefinite relaxation (SDR) and successive convex approximation. Simulation
results show that a performance gain can be obtained by using NOMA compared to
the conventional orthogonal multiple access. It is also shown that the
performance of the algorithm using a cost function is better than the algorithm
using SDR at the cost of a higher computation complexity.Comment: This paper has been accepted by ICC 2018 worksho