2,058 research outputs found
Reliable Energy-Efficient Routing Algorithm for Vehicle-Assisted Wireless Ad-Hoc Networks
We investigate the design of the optimal routing path in a moving vehicles
involved the internet of things (IoT). In our model, jammers exist that may
interfere with the information exchange between wireless nodes, leading to
worsened quality of service (QoS) in communications. In addition, the transmit
power of each battery-equipped node is constrained to save energy. We propose a
three-step optimal routing path algorithm for reliable and energy-efficient
communications. Moreover, results show that with the assistance of moving
vehicles, the total energy consumed can be reduced to a large extend. We also
study the impact on the optimal routing path design and energy consumption
which is caused by path loss, maximum transmit power constrain, QoS
requirement, etc.Comment: 6 pages, 5 figures, rejected by IEEE Globecom 2017,resubmit to IEEE
WCNC 201
A New Cell Association Scheme In Heterogeneous Networks
Cell association scheme determines which base station (BS) and mobile user
(MU) should be associated with and also plays a significant role in determining
the average data rate a MU can achieve in heterogeneous networks. However, the
explosion of digital devices and the scarcity of spectra collectively force us
to carefully re-design cell association scheme which was kind of taken for
granted before. To address this, we develop a new cell association scheme in
heterogeneous networks based on joint consideration of the
signal-to-interference-plus-noise ratio (SINR) which a MU experiences and the
traffic load of candidate BSs1. MUs and BSs in each tier are modeled as several
independent Poisson point processes (PPPs) and all channels experience
independently and identically distributed ( i.i.d.) Rayleigh fading. Data rate
ratio and traffic load ratio distributions are derived to obtain the tier
association probability and the average ergodic MU data rate. Through numerical
results, We find that our proposed cell association scheme outperforms cell
range expansion (CRE) association scheme. Moreover, results indicate that
allocating small sized and high-density BSs will improve spectral efficiency if
using our proposed cell association scheme in heterogeneous networks.Comment: Accepted by IEEE ICC 2015 - Next Generation Networking Symposiu
Downlink Small-cell Base Station Cooperation Strategy in Fractal Small-cell Networks
Coordinated multipoint (CoMP) communications are considered for the
fifth-generation (5G) small-cell networks as a tool to improve the high data
rates and the cell-edge throughput. The average achievable rates of the
small-cell base stations (SBS) cooperation strategies with distance and
received signal power constraints are respectively derived for the fractal
small-cell networks based on the anisotropic path loss model. Simulation
results are presented to show that the average achievable rate with the
received signal power constraint is larger than the rate with a distance
constraint considering the same number of cooperative SBSs. The average
achievable rate with distance constraint decreases with the increase of the
intensity of SBSs when the anisotropic path loss model is considered. What's
more, the network energy efficiency of fractal smallcell networks adopting the
SBS cooperation strategy with the received signal power constraint is analyzed.
The network energy efficiency decreases with the increase of the intensity of
SBSs which indicates a challenge on the deployment design for fractal
small-cell networks.Comment: 5 figures. Accepted by Globecom 201
Strong cosmic censorship for the massless Dirac field in the Reissner-Nordstrom-de Sitter spacetime
We present the Fermi story of strong cosmic censorship in the near-extremal
Reissner-Nordstrom-de Sitter black hole. To this end, we first derive from
scratch the criterion for the quasi-normal modes of Dirac field to violate
strong cosmic censorship in such a background, which turns out to be exactly
the same as those for Bose fields, although the involved energy momentum tensor
is qualitatively different from that for Bose fields. Then to extract the
low-lying quasi-normal modes by Prony method, we apply Crank-Nicolson method to
evolve our Dirac field in the double null coordinates. As a result, it shows
that for a fixed near-extremal black hole, strong cosmic censorship can be
recovered by the black hole family mode once the charge of our
Dirac field is greater than some critical value, which is increased as one
approaches the extremal black hole.Comment: JHEP published versio
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