8,812 research outputs found
Atmospheric channel effects on terrestrial free space optical communication links
Abstract. This paper illustrates the challenges imposed by the atmospheric channel on the design of a terrestrial laser communication link. The power loss due to scattering effect is described using the Kim/Kruse scattering model while the effect and the penalty imposed by atmospheric turbulence is highlighted by considering the bit error rate (BER) of an On-Off Keying modulated link in an optical Poisson channel. The power loss due to thick fog can measure over 100 dB/km while snow and rain result in much lower attenuation. We show that non-uniformity in the atmospheric temperature also contributes to performance deterioration due to scintillation effect. At a BER of 10-4, for a channel with a turbulence strength of>0.1, the penalty imposed by turbulence induced fading is over 20 photoelectron counts in order to achieve the same level of performance as a channel with no fading. The work reported here is part of the EU COST actions and EU projects.
Spatial Performance Analysis and Design Principles for Wireless Peer Discovery
In wireless peer-to-peer networks that serve various proximity-based
applications, peer discovery is the key to identifying other peers with which a
peer can communicate and an understanding of its performance is fundamental to
the design of an efficient discovery operation. This paper analyzes the
performance of wireless peer discovery through comprehensively considering the
wireless channel, spatial distribution of peers, and discovery operation
parameters. The average numbers of successfully discovered peers are expressed
in closed forms for two widely used channel models, i.e., the interference
limited Nakagami-m fading model and the Rayleigh fading model with nonzero
noise, when peers are spatially distributed according to a homogeneous Poisson
point process. These insightful expressions lead to the design principles for
the key operation parameters including the transmission probability, required
amount of wireless resources, level of modulation and coding scheme (MCS), and
transmit power. Furthermore, the impact of shadowing on the spatial performance
and suggested design principles is evaluated using mathematical analysis and
simulations.Comment: 12 pages (double columns), 10 figures, 1 table, to appear in the IEEE
Transactions on Wireless Communication
Interference and Outage in Clustered Wireless Ad Hoc Networks
In the analysis of large random wireless networks, the underlying node
distribution is almost ubiquitously assumed to be the homogeneous Poisson point
process. In this paper, the node locations are assumed to form a Poisson
clustered process on the plane. We derive the distributional properties of the
interference and provide upper and lower bounds for its CCDF. We consider the
probability of successful transmission in an interference limited channel when
fading is modeled as Rayleigh. We provide a numerically integrable expression
for the outage probability and closed-form upper and lower bounds.We show that
when the transmitter-receiver distance is large, the success probability is
greater than that of a Poisson arrangement. These results characterize the
performance of the system under geographical or MAC-induced clustering. We
obtain the maximum intensity of transmitting nodes for a given outage
constraint, i.e., the transmission capacity (of this spatial arrangement) and
show that it is equal to that of a Poisson arrangement of nodes. For the
analysis, techniques from stochastic geometry are used, in particular the
probability generating functional of Poisson cluster processes, the Palm
characterization of Poisson cluster processes and the Campbell-Mecke theorem.Comment: Submitted to IEEE Transactions on Information Theor
Energy-delay bounds analysis in wireless multi-hop networks with unreliable radio links
Energy efficiency and transmission delay are very important parameters for
wireless multi-hop networks. Previous works that study energy efficiency and
delay are based on the assumption of reliable links. However, the unreliability
of the channel is inevitable in wireless multi-hop networks. This paper
investigates the trade-off between the energy consumption and the end-to-end
delay of multi-hop communications in a wireless network using an unreliable
link model. It provides a closed form expression of the lower bound on the
energy-delay trade-off for different channel models (AWGN, Raleigh flat fading
and Nakagami block-fading) in a linear network. These analytical results are
also verified in 2-dimensional Poisson networks using simulations. The main
contribution of this work is the use of a probabilistic link model to define
the energy efficiency of the system and capture the energy-delay trade-offs.
Hence, it provides a more realistic lower bound on both the energy efficiency
and the energy-delay trade-off since it does not restrict the study to the set
of perfect links as proposed in earlier works
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