26 research outputs found
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
Energy-Efficient NOMA Enabled Heterogeneous Cloud Radio Access Networks
Heterogeneous cloud radio access networks (H-CRANs) are envisioned to be
promising in the fifth generation (5G) wireless networks. H-CRANs enable users
to enjoy diverse services with high energy efficiency, high spectral
efficiency, and low-cost operation, which are achieved by using cloud computing
and virtualization techniques. However, H-CRANs face many technical challenges
due to massive user connectivity, increasingly severe spectrum scarcity and
energy-constrained devices. These challenges may significantly decrease the
quality of service of users if not properly tackled. Non-orthogonal multiple
access (NOMA) schemes exploit non-orthogonal resources to provide services for
multiple users and are receiving increasing attention for their potential of
improving spectral and energy efficiency in 5G networks. In this article a
framework for energy-efficient NOMA H-CRANs is presented. The enabling
technologies for NOMA H-CRANs are surveyed. Challenges to implement these
technologies and open issues are discussed. This article also presents the
performance evaluation on energy efficiency of H-CRANs with NOMA.Comment: This work has been accepted by IEEE Network. Pages 18, Figure
A novel spectrum sharing scheme assisted by secondary NOMA relay
In this letter, a two-slot secondary non-orthogonal multiple access (NOMA) relay is used to assist spectrum sharing, where the primary transceivers with long distance communicate through the relay. First, the information for the primary receiver (PR) and secondary receivers (SRs) is transmitted via the NOMA relay. Then, the information for PR is re-transmitted to it through a selected SR to improve its quality of service using maximal-ratio combining, while the next data for PR is sent from the primary transmitter (PT) to the NOMA relay simultaneously. The power allocation solution is derived for the NOMA relay. Simulation results have shown the effectiveness of the proposed scheme
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
PERFORMANCE ANALYSIS IN WIRELESS POWERED D2D- AIDED NON-ORTHOGONAL MULTIPLE ACCESS NETWORKS
This paper examine how to integrate energy harvesting (EH) to non-orthogonal multiple access (NOMA) networks. Recently, device-to-device (D2D) underlaying licensed network is introduced as novel transmission mode to perform two nearby user equipment units (UEs) communicating directly without signal processing through the nearest base station (BS). By wireless power transfer, they can be further operational to D2D communications in which a UE may harvest energy from RF signal of dedicated power beacons (PB) to help EH assisted UEs communicate with each other or assist these UEs to communicate with the BS. In particular, we investigate outage and throughput performance in a scenario of D2D communications powered by RF signal where one UE may help other two UEs to exchange information with optimal throughput
Enhancement of outage probability for down link cooperative non-orthogonal multiple access in fifth-generation network
Future wireless networks are expected to face several issues, but cooperative non-orthogonal multiple access (C-NOMA) is a promising technology that could help solve them by providing unprecedented levels of connection and system capacity. In this regard, the influence of the power location coefficient (PLC) for remote users adopting multiple-input-multiple-output (MIMO) and massive MIMO has been explored to provide effective performance. The goal of this study is to design fifth-generation (5G) downlink (DL) NOMA power domain (PD) networks with a variety of distances and PLCs for remote users and then to compare their outage probability (OP) performance versus signal to noise ratio (SNR). As a novel approach to improving OP performance rate and mitigating the influence of the PLC for remote users, DL C-NOMA is combined with 16×16, 32×23, and 64×64 MIMO and 128×128, 256×256, and 512×512 massive MIMO. The results were obtained that the 64×64 MIMO improves the OP for the remote user by 65.0E-03, while the 512×512 massive MIMO achieved an improvement that reaches 1.0E-06 for the PLC of 0.8 at SNR of 14 dB. The Rayleigh fading channels and MATLAB simulation tools were utilized to carry out the study work