5,903 research outputs found
Scaling Laws for Infrastructure Single and Multihop Wireless Networks in Wideband Regimes
With millimeter wave bands emerging as a strong candidate for 5G cellular
networks, next-generation systems may be in a unique position where spectrum is
plentiful. To assess the potential value of this spectrum, this paper derives
scaling laws on the per mobile downlink feasible rate with large bandwidth and
number of nodes, for both Infrastructure Single Hop (ISH) and Infrastructure
Multi-Hop (IMH) architectures. It is shown that, for both cases, there exist
\emph{critical bandwidth scalings} above which increasing the bandwidth no
longer increases the feasible rate per node. These critical thresholds coincide
exactly with the bandwidths where, for each architecture, the network
transitions from being degrees-of-freedom-limited to power-limited. For ISH,
this critical bandwidth threshold is lower than IMH when the number of users
per base station grows with network size. This result suggests that multi-hop
transmissions may be necessary to fully exploit large bandwidth degrees of
freedom in deployments with growing number of users per cell.Comment: 5 pages, 3 figure
Dimension Reduction of Large AND-NOT Network Models
Boolean networks have been used successfully in modeling biological networks
and provide a good framework for theoretical analysis. However, the analysis of
large networks is not trivial. In order to simplify the analysis of such
networks, several model reduction algorithms have been proposed; however, it is
not clear if such algorithms scale well with respect to the number of nodes.
The goal of this paper is to propose and implement an algorithm for the
reduction of AND-NOT network models for the purpose of steady state
computation. Our method of network reduction is the use of "steady state
approximations" that do not change the number of steady states. Our algorithm
is designed to work at the wiring diagram level without the need to evaluate or
simplify Boolean functions. Also, our implementation of the algorithm takes
advantage of the sparsity typical of discrete models of biological systems. The
main features of our algorithm are that it works at the wiring diagram level,
it runs in polynomial time, and it preserves the number of steady states. We
used our results to study AND-NOT network models of gene networks and showed
that our algorithm greatly simplifies steady state analysis. Furthermore, our
algorithm can handle sparse AND-NOT networks with up to 1000000 nodes
Improving Third-Party Relaying for LTE-A: A Realistic Simulation Approach
In this article we propose solutions to diverse conflicts that result from
the deployment of the (still immature) relay node (RN) technology in LTE-A
networks. These conflicts and their possible solutions have been observed by
implementing standard-compliant relay functionalities on the Vienna simulator.
As an original experimental approach, we model realistic RN operation, taking
into account that transmitters are not active all the time due to half-duplex
RN operation. We have rearranged existing elements in the simulator in a manner
that emulates RN behavior, rather than implementing a standalone brand-new
component for the simulator. We also study analytically some of the issues
observed in the interaction between the network and the RNs, to draw
conclusions beyond simulation observation.
The main observations of this paper are that: ) Additional time-varying
interference management steps are needed, because the LTE-A standard employs a
fixed time division between eNB-RN and RN-UE transmissions (typical relay
capacity or throughput research models balance them optimally, which is
unrealistic nowadays); ) There is a trade-off between the time-division
constraints of relaying and multi-user diversity; the stricter the constraints
on relay scheduling are, the less flexibility schedulers have to exploit
channel variation; and ) Thee standard contains a variety of parameters
for relaying configuration, but not all cases of interest are covered.Comment: 17 one-column pages, 9 figures, accepted for publication in IEEE ICC
2014 MW
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