286 research outputs found
Hybrid Radio/Free-Space Optical Design for Next Generation Backhaul Systems
The deluge of date rate in today's networks imposes a cost burden on the
backhaul network design. Developing cost efficient backhaul solutions becomes
an exciting, yet challenging, problem. Traditional technologies for backhaul
networks include either radio-frequency backhauls (RF) or optical fibers (OF).
While RF is a cost-effective solution as compared to OF, it supports lower data
rate requirements. Another promising backhaul solution is the free-space optics
(FSO) as it offers both a high data rate and a relatively low cost. FSO,
however, is sensitive to nature conditions, e.g., rain, fog, line-of-sight.
This paper combines both RF and FSO advantages and proposes a hybrid RF/FSO
backhaul solution. It considers the problem of minimizing the cost of the
backhaul network by choosing either OF or hybrid RF/FSO backhaul links between
the base-stations (BS) so as to satisfy data rate, connectivity, and
reliability constraints. It shows that under a specified realistic assumption
about the cost of OF and hybrid RF/FSO links, the problem is equivalent to a
maximum weight clique problem, which can be solved with moderate complexity.
Simulation results show that the proposed solution shows a close-to-optimal
performance, especially for practical prices of the hybrid RF/FSO links
Resilient Backhaul Network Design Using Hybrid Radio/Free-Space Optical Technology
The radio-frequency (RF) technology is a scalable solution for the backhaul
planning. However, its performance is limited in terms of data rate and
latency. Free Space Optical (FSO) backhaul, on the other hand, offers a higher
data rate but is sensitive to weather conditions. To combine the advantages of
RF and FSO backhauls, this paper proposes a cost-efficient backhaul network
using the hybrid RF/FSO technology. To ensure a resilient backhaul, the paper
imposes a given degree of redundancy by connecting each node through
link-disjoint paths so as to cope with potential link failures. Hence, the
network planning problem considered in this paper is the one of minimizing the
total deployment cost by choosing the appropriate link type, i.e., either
hybrid RF/FSO or optical fiber (OF), between each couple of base-stations while
guaranteeing link-disjoint connections, a data rate target, and a
reliability threshold. The paper solves the problem using graph theory
techniques. It reformulates the problem as a maximum weight clique problem in
the planning graph, under a specified realistic assumption about the cost of OF
and hybrid RF/FSO links. Simulation results show the cost of the different
planning and suggest that the proposed heuristic solution has a
close-to-optimal performance for a significant gain in computation complexity
Integration of optical and satellite communication technologies to improve the cache filling time in future 5G edge networks
© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Caching is an enabler to avoid congestion and delay in the backhaul links of future 5G networks. The basic idea behind this concept consists in estimating the content that would be most likely requested by the end users served by each edge node and, after that, make a pro-active placement of those files during the traffic off-peak hours. Optical wired/wireless terrestrial links support a high point-to-point data rate but, when the same content needs to reach different destinations, parallel unicast transmissions are needed. On the other hand, satellite systems provide a lower link-level data rate but can easily implement a multicast transmission due to their wide-area coverage. In this paper, a resource allocation strategy that determines the most convenient way to transport the different content using both terrestrial (optical) and satellite (radio) technologies is proposed. Simulation results show that the placement time can be notably reduced in a hybrid terrestrial-satellite backhaul network, particularly in case of bad weather that impacts the data rate of the wireless optical links. The effect of the file popularity distribution and the number of 5G edge nodes on the delivery time is also studied in detail.Peer ReviewedPostprint (author's final draft
A Software-Defined Multi-Element VLC Architecture
In the modern era of radio frequency (RF) spectrum crunch, visible light
communication (VLC) is a recent and promising alternative technology that
operates at the visible light spectrum. Thanks to its unlicensed and large
bandwidth, VLC can deliver high throughput, better energy efficiency, and low
cost data communications. In this article, a hybrid RF/VLC architecture is
considered that can simultaneously provide light- ing and communication
coverage across a room. Considered architecture involves a novel multi-element
hemispherical bulb design, which can transmit multiple data streams over light
emitting diode (LED) modules. Simulations considering various VLC transmitter
configurations and topologies show that good link quality and high spatial
reuse can be maintained in typical indoor communication scenarios
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