394 research outputs found
Optimization of Free Space Optical Wireless Network for Cellular Backhauling
With densification of nodes in cellular networks, free space optic (FSO)
connections are becoming an appealing low cost and high rate alternative to
copper and fiber as the backhaul solution for wireless communication systems.
To ensure a reliable cellular backhaul, provisions for redundant, disjoint
paths between the nodes must be made in the design phase. This paper aims at
finding a cost-effective solution to upgrade the cellular backhaul with
pre-deployed optical fibers using FSO links and mirror components. Since the
quality of the FSO links depends on several factors, such as transmission
distance, power, and weather conditions, we adopt an elaborate formulation to
calculate link reliability. We present a novel integer linear programming model
to approach optimal FSO backhaul design, guaranteeing -disjoint paths
connecting each node pair. Next, we derive a column generation method to a
path-oriented mathematical formulation. Applying the method in a sequential
manner enables high computational scalability. We use realistic scenarios to
demonstrate our approaches efficiently provide optimal or near-optimal
solutions, and thereby allow for accurately dealing with the trade-off between
cost and reliability
Non-Orthogonal Multiple Access for FSO Backhauling
We consider a free space optical (FSO) backhauling system which consists of
two base stations (BSs) and one central unit (CU). We propose to employ
non-orthogonal multiple access (NOMA) for FSO backhauling where both BSs
transmit at the same time and in the same frequency band to the same
photodetector at the CU. We develop a dynamic NOMA scheme which determines the
optimal decoding order as a function of the channel state information at the CU
and the quality of service requirements of the BSs, such that the outage
probabilities of both BSs are jointly minimized. Moreover, we analyze the
performance of the proposed NOMA scheme in terms of the outage probability over
Gamma-Gamma FSO turbulence channels. We further derive closed-form expressions
for the outage probability for the high signal-to-noise ratio regime. Our
simulation results confirm the analytical derivations and reveal that the
proposed dynamic NOMA scheme significantly outperforms orthogonal transmission
and existing NOMA schemes.Comment: This paper has been submitted to IEEE WCNC 201
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