194 research outputs found
Spectrum Sharing Opportunities of Full-Duplex Systems using Improper Gaussian Signaling
Sharing the licensed spectrum of full-duplex (FD) primary users (PU) brings
strict limitations on the underlay cognitive radio operation. Particularly, the
self interference may overwhelm the PU receiver and limit the opportunity of
secondary users (SU) to access the spectrum. Improper Gaussian signaling (IGS)
has demonstrated its superiority in improving the performance of interference
channel systems. Throughout this paper, we assume a FD PU pair that uses proper
Gaussian signaling (PGS), and a half-duplex SU pair that uses IGS. The
objective is to maximize the SU instantaneous achievable rate while meeting the
PU quality-of-service. To this end, we propose a simplified algorithm that
optimizes the SU signal parameters, i.e, the transmit power and the circularity
coefficient, which is a measure of the degree of impropriety of the SU signal,
to achieve the design objective. Numerical results show the merits of adopting
IGS compared with PGS for the SU especially with the existence of week PU
direct channels and/or strong SU interference channels
In-Band Full-Duplex Communications for Cellular Networks with Partial Uplink/Downlink Overlap
In-band full-duplex (FD) communications have been optimistically promoted to
improve the spectrum utilization in cellular networks. However, the explicit
impact of spatial interference, imposed by FD communications, on uplink and
downlink transmissions has been overlooked in the literature. This paper
presents an extensive study of the explicit effect of FD communications on the
uplink and downlink performances. For the sake of rigorous analysis, we develop
a tractable framework based on stochastic geometry toolset. The developed model
accounts for uplink truncated channel inversion power control in FD cellular
networks. The study shows that FD communications improve the downlink
throughput at the expense of significant degradation in the uplink throughput.
Therefore, we propose a novel fine-grained duplexing scheme, denoted as
-duplex scheme, which allows a partial overlap between uplink and
downlink frequency bands. To this end, we show that the amount of the overlap
can be optimized via adjusting to achieve a certain design objective.Comment: To be presented in IEEE Globecom 201
Data Center-Enabled High Altitude Platforms: A Green Computing Alternative
Information technology organizations and companies are seeking greener
alternatives to traditional terrestrial data centers to mitigate global warming
and reduce carbon emissions. Currently, terrestrial data centers consume a
significant amount of energy, estimated at about 1.5% of worldwide electricity
use. Furthermore, the increasing demand for data-intensive applications is
expected to raise energy consumption, making it crucial to consider sustainable
computing paradigms. In this study, we propose a data center-enabled High
Altitude Platform (HAP) system, where a flying data center supports the
operation of terrestrial data centers. We conduct a detailed analytical study
to assess the energy benefits and communication requirements of this approach.
Our findings demonstrate that a data center-enabled HAP is more
energy-efficient than a traditional terrestrial data center, owing to the
naturally low temperature in the stratosphere and the ability to harvest solar
energy. Adopting a data center-HAP can save up to 14% of energy requirements
while overcoming the offloading outage problem and the associated delay
resulting from server distribution. Our study highlights the potential of a
data center-enabled HAP system as a sustainable computing solution to meet the
growing energy demands and reduce carbon footprint
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