6,755 research outputs found
Location-Quality-aware Policy Optimisation for Relay Selection in Mobile Networks
Relaying can improve the coverage and performance of wireless access
networks. In presence of a localisation system at the mobile nodes, the use of
such location estimates for relay node selection can be advantageous as such
information can be collected by access points in linear effort with respect to
number of mobile nodes (while the number of links grows quadratically).
However, the localisation error and the chosen update rate of location
information in conjunction with the mobility model affect the performance of
such location-based relay schemes; these parameters also need to be taken into
account in the design of optimal policies. This paper develops a Markov model
that can capture the joint impact of localisation errors and inaccuracies of
location information due to forwarding delays and mobility; the Markov model is
used to develop algorithms to determine optimal location-based relay policies
that take the aforementioned factors into account. The model is subsequently
used to analyse the impact of deployment parameter choices on the performance
of location-based relaying in WLAN scenarios with free-space propagation
conditions and in an measurement-based indoor office scenario.Comment: Accepted for publication in ACM/Springer Wireless Network
Deep Learning for Frame Error Probability Prediction in BICM-OFDM Systems
In the context of wireless communications, we propose a deep learning
approach to learn the mapping from the instantaneous state of a frequency
selective fading channel to the corresponding frame error probability (FEP) for
an arbitrary set of transmission parameters. We propose an abstract model of a
bit interleaved coded modulation (BICM) orthogonal frequency division
multiplexing (OFDM) link chain and show that the maximum likelihood (ML)
estimator of the model parameters estimates the true FEP distribution. Further,
we exploit deep neural networks as a general purpose tool to implement our
model and propose a training scheme for which, even while training with the
binary frame error events (i.e., ACKs / NACKs), the network outputs converge to
the FEP conditioned on the input channel state. We provide simulation results
that demonstrate gains in the FEP prediction accuracy with our approach as
compared to the traditional effective exponential SIR metric (EESM) approach
for a range of channel code rates, and show that these gains can be exploited
to increase the link throughput.Comment: Submitted to 2018 IEEE International Conference on Acoustics, Speech
and Signal Processin
Increasing throughput in IEEE 802.11 by optimal selection of backoff parameters
Engineering and Physical Sciences Research Council. Grant Number: EP/G012628/
Queueing analysis of opportunistic scheduling with spatially correlated channels
International audienc
A Model of the IEEE 802.11 DCF in Presence of Non Ideal Transmission Channel and Capture Effects
In this paper, we provide a throughput analysis of the IEEE 802.11 protocol
at the data link layer in non-saturated traffic conditions taking into account
the impact of both transmission channel and capture effects in Rayleigh fading
environment. Impacts of both non-ideal channel and capture become important in
terms of the actual observed throughput in typical network conditions whereby
traffic is mainly unsaturated, specially in an environment of high
interference.
We extend the multi-dimensional Markovian state transition model
characterizing the behavior at the MAC layer by including transmission states
that account for packet transmission failures due to errors caused by
propagation through the channel, along with a state characterizing the system
when there are no packets to be transmitted in the buffer of a station.Comment: Accepted for oral presentation to IEEE Globecom 2007, Washington
D.C., November 200
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