Abstract

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.

Highlights

  • As a candidate for the 5G communication, a novel multiple access (MA) technique, named non-orthogonal multiple access (NOMA), has been widely investigated

  • It is proved that NOMA is introduced to address the spectral efficiency improvement compared with traditional multiple access schemes, i.e., orthogonal multiple

  • P hb dbm Remark 1: It is noted that the amount of harvested energy at U1 is higher than that of U 2 because of different distances to the power beacon, which result in better channel power gain

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Summary

INTRODUCTION

As a candidate for the 5G communication, a novel multiple access (MA) technique, named non-orthogonal multiple access (NOMA), has been widely investigated. It is proved that NOMA is introduced to address the spectral efficiency improvement compared with traditional multiple access schemes, i.e., orthogonal multiple. To enhance spectrum efficiency and prolong the lifetime of the system, NOMA networks with energy-limited devices need to employ the efficient integration of energy harvesting with NOMA [19]–[21]. Security of energy harvesting-enabled NOMA systems need to be investigated due to the broadcasting nature of NOMA and RF signals [22]–[25]. Motivated by interesting results in [1], we develop two scenarios of energy harvesting to show different performance improvements in NOMA.

SYSTEM MODEL AND ENERGY HARVESTING POLICIES IN NOMA
First Phase
Second Phase
Outage Performance Analysis in Scheme I
SCHEME II
Pr hb xa 1 ha xa 2
NUMERICAL AND SIMULATION RESULTS
CONCLUSIONS
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