دانلود مقاله A comparative study of packet combining based error recovery schemes for wireless networks انتشار 2014

Int. J. Ad Hoc and Ubiquitous Computing, Vol. 16, No. 3, 2014

Sheng-Shih Wang*, Pei-Chun Lee, Kan-Yen Lin
and Tzu-Chang Yeh

Abstract: To provide reliable communications in wireless environments, two fundamental error
control mechanisms, automatic repeat request (ARQ) and forward error correction (FEC) are
proposed. However, the ARQ mechanism may suffer frequent retransmissions and the FEC
mechanism incurs bandwidth overhead. To reduce the number of retransmissions and support
efficient correction, previous studies have proposed numerous packet combining based error recovery
schemes. This study investigates the recovery performance of three packet combining based error
recovery schemes, including the extended ARQ (EARQ), the merge strategy in the simple packet
combining (SPaC-M), and the destination packet (DPC) schemes through the mathematical analysis
and simulations. Results present that the EARQ outperforms the SPaC-M and the DPC in recovery
speed in case of a large packet length and a high bit error rate. However, the EARQ is not suggested
if the space overhead is the major consideration.
Keywords: packet combining; error recovery; ARQ; automatic repeat request; FEC; forward error
correction.

دانلود مقاله AN ANALYSIS OF VARIOUS PARAMETERS IN WIRELESS SENSOR NETWORKS USING ADAPTIVE FEC TECHNIQUE

M.R.Ebenezar jebarani1and T.Jayanthy2

ABSTRACT
In Wireless sensor network, since the media is wireless there will be burst errors which leads to
high bit error rate that affect the throughput. Wireless sensor networks drop the packets due to propagation
errors that lead to retransmission traffic. This paper evaluates the effect of adaptive FEC in Wireless
sensor networks. Adaptive FEC technique improves the throughput by dynamically tuning FEC depending
upon the wireless channel loss. The main aim is to achieve desire throughput with less energy
consumption. If the retransmission traffic decreases, that is error correction performed using adaptive FEC
which maximize the throughput. The other related parameters packet delivery ratio, packet loss, delay,
error rate are also being analyzed. The algorithm reduces the retransmission traffic by using Adaptive
FEC technique thus improving the throughput and reduces the error rate.
KEYWORDS:
Throughput, adaptive FEC, wireless channel, Bit error rate, ARQ
1. INTRODUCTION

دانلود مقاله Multiple Receiver Strategies for Minimizing Packet Loss in Dense Sensor Networks

Bernhard Firner, Chenren Xu, Richard Howard, and Yanyong Zhang

ABSTRACT
A typical wireless sensor network consists of many small sensors
that collect instrument data around their locations and
forward it to a central location for data processing. These
networks can be deployed to monitor livestock and agricultural
assets, products in a store, patients in a hospital, and
so on. In many cases sensors have to be densely deployed,
and collisions or overhead due to collision avoidance will
considerably degrade the system performance below an application’s
required levels. With the decreasing cost of radio
devices the obvious solution to this problem is the use
of multiple receivers on different radio channels. However,
we show that if receivers can be placed in different locations
then increasing the number of receivers on a single
channel will increase the rate of the capture effect and decrease
collision losses, while also increasing the fairness of
the transmitters’ radio links. Not only can this single channel
approach be more effective than using multiple channels,
it is also required for some techniques, such as localization,
where each receiver must be able to detect a transmission
from any transmitter. We also show that the optimal choice
between these two solutions is influenced by the radio attenuation
rate and the number of receivers in the system.
Categories and Subject Descriptors: C.2.1 [Computer-
Communication Networks]:
Network Architecture and Design—Wireless communication
General Terms: Experimentation, Measurement, Performance

Keywords: Scalability, Capture Effect

دانلود مقاله Network Information Flow

IEEE TRANSACTIONS ON INFORMATION THEORY, VOL. 46, NO. 4, JULY 2000

Rudolf Ahlswede, Ning Cai, Shuo-Yen Robert Li, Senior Member, IEEE, and
Raymond W. Yeung, Senior Member, IEEE

Abstract—We introduce a new class of problems called network
information flow which is inspired by computer network applications.
Consider a point-to-point communication network on which
a number of information sources are to be mulitcast to certain sets
of destinations. We assume that the information sources are mutually
independent. The problem is to characterize the admissible
coding rate region. This model subsumes all previously studied
models along the same line. In this paper, we study the problem
with one information source, and we have obtained a simple characterization
of the admissible coding rate region. Our result can be
regarded as the Max-flow Min-cut Theorem for network information
flow. Contrary to one’s intuition, our work reveals that it is in
general not optimal to regard the information to be multicast as a
“fluid” which can simply be routed or replicated. Rather, by employing
coding at the nodes, which we refer to as network coding,
bandwidth can in general be saved. This finding may have significant
impact on future design of switching systems.
Index Terms—Diversity coding, multicast, network coding,
switching, multiterminal source coding.