3,290 research outputs found
Non-Orthogonal Multiple Access for mmWave Drones with Multi-Antenna Transmission
Unmanned aerial vehicles (UAVs) can be deployed as aerial base stations (BSs)
for rapid establishment of communication networks during temporary events and
after disasters. Since UAV-BSs are low power nodes, achieving high spectral and
energy efficiency are of paramount importance. In this paper, we introduce
non-orthogonal multiple access (NOMA) transmission for millimeter-wave (mmWave)
drones serving as flying BSs at a large stadium potentially with several
hundreds or thousands of mobile users. In particular, we make use of
multi-antenna techniques specifically taking into consideration the physical
constraints of the antenna array, to generate directional beams. Multiple users
are then served within the same beam employing NOMA transmission. If the UAV
beam can not cover entire region where users are distributed, we introduce beam
scanning to maximize outage sum rates. The simulation results reveal that, with
NOMA transmission the spectral efficiency of the UAV based communication can be
greatly enhanced compared to orthogonal multiple access (OMA) transmission.
Further, the analysis shows that there is an optimum transmit power value for
NOMA beyond which outage sum rates do not improve further
A Novel Network NOMA Scheme for Downlink Coordinated Three-Point Systems
In this paper, we propose a network non-orthogonal multiple access (N-NOMA)
technique for the downlink coordinated multipoint (CoMP) communication scenario
of a cellular network, with randomly deployed users. In the considered N-NOMA
scheme, superposition coding (SC) is employed to serve cell-edge users as well
as users close to base stations (BSs) simultaneously, and distributed analog
beamforming by the BSs to meet the cell-edge user's quality of service (QoS)
requirements. The combination of SC and distributed analog beamforming
significantly complicates the expressions for the
signal-to-interference-plus-noise ratio (SINR) at the reveiver, which makes the
performance analysis particularly challenging. However, by using rational
approximations, insightful analytical results are obtained in order to
characterize the outage performance of the considered N-NOMA scheme. Computer
simulation results are provided to show the superior performance of the
proposed scheme as well as to demonstrate the accuracy of the analytical
results
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