دانلود مقاله Performance Evaluation of Network Coding in IEEE 802.11 Wireless Ad Hoc Networks - انتشار 2014
Volume 16, May 2014, Pages 131–141
Kyu-Hwan Lee, Sunghyun Cho, Jae-Hyun Kim
Abstract
We evaluate the practical network coding (NC) gain in a wireless ad hoc networks.
First, we introduce how network coding can be applied to IEEE 802.11
ad hoc networks. Next, we find obstructive factors by which the NC gain
may decrease as compared with the theoretical NC gain. Finally, through
the performance evaluation, we analyze why a performance difference occurs
between practical and theoretical NC gains owing to the suggested obstructive
factors. According to the simulated results, even though there is some
overhead caused by the characteristics of the media access control (MAC)
protocol and control signals to apply NC to wireless ad hoc networks, the
practical NC gain is almost the same as the theoretical gain in an ideal environment
for NC. However, in the NC system with the hidden node problem,
the NC gain decreases because of packet collision. In the NC system using
a promiscuous mode where packet overhearing is possible, nodes consume
more power than the conventional system because of overhearing packets.
For instance, when the number of overhearing nodes not related to NC is set
to 15, the power reduction rate is −38.04%. Furthermore, under the network
conditions inappropriate for NC, such as asymmetric flows and scarce coding
structures, the NC gain can be considerably reduced. For example, in
5x5 and 7x7 grid topology networks, the load reduction rate by NC are only
4.12% and 7.01%, respectively. Therefore, research to solve the suggested
obstructive factors is necessary to achieve sufficient NC gain in a practicalwireless network such as an IEEE 802.11 ad hoc networks.
Keywords: Network coding, Wireless ad hoc network, Wireless LAN,
Performance evaluation.
دانلود مقاله All-to-all data dissemination with network coding in dynamic MANETs - انتشار 2014
Contents lists available at ScienceDirect
Computer Networks
Péter Vingelmann a,b
, Janus Heide b
, Morten Videbæk Pedersen b
, Qi Zhang c
,
Frank H.P. Fitzek b
a b s t r a c t
This paper investigates the problem of efficient data dissemination in Mobile Ad hoc NETwork
(MANETs). A testbed is presented; which provides a realistic degree of mobility in
experiments. The testbed consists of ten autonomous robots with mobile phones mounted
on them. The mobile phones form an IEEE 802.11g ad hoc network to communicate with
each other. A dynamic network topology is assumed, where the mobile devices form a
cooperative cluster in order to communicate directly with each other. In the investigated
scenario, the initial state is that each device carries a unique fragment of the full data
set, and the goal is to exchange this data set among all devices. Several alternative strategies
are presented that use UDP broadcast transmissions and Random Linear Network Coding
(RLNC) to facilitate the efficient exchange of information in the wireless network. An
application is introduced; which implements these strategies on Nokia phones. Results collected
during an extensive measurement campaign are presented, and the performance of
several strategies is compared using numerous metrics. We observe that network coding
can substantially reduce the completion time in our scenario, which also leads to significant
energy savings.