تحقیق و بررسی Packet Trace CISCO

اختصاصی از فی بوو تحقیق و بررسی Packet Trace CISCO دانلود با لینک مستقیم و پر سرعت .

اسلاید آموزشی مباحثی از packet tracer و دستور ping

اختصاصی از فی بوو اسلاید آموزشی مباحثی از packet tracer و دستور ping دانلود با لینک مستقیم و پر سرعت .

این اسلاید آموزشی شامل دو بخش می باشد که بخش اول آن به تشریح کامل سوئیچ های مختلف دستور ping و نمایش آنها به صورت عملی پرداخته و بخش دوم آن محیط Cisco packet tracer را به همراه ویژگی های آن  تشریح می کند.

دانلود مقاله A packet error recovery scheme for vertical handovers mobility management protocols

اختصاصی از فی بوو دانلود مقاله A packet error recovery scheme for vertical handovers mobility management protocols دانلود با لینک مستقیم و پر سرعت .

A packet error recovery scheme for vertical
handovers mobility management protocols
Pierre-Ugo Tournoux1,2, Emmanuel Lochin1,2, Henrik Petander3, J´erˆome
Lacan4
1 CNRS ; LAAS ; 7 avenue du colonel Roche, F-31077 Toulouse, France
2 Universit´e de Toulouse ; UPS, INSA, INP, ISAE ; LAAS ; F-31077 Toulouse, France
3 NICTA, Australian Technology Park, Eveleigh, NSW, Australia
4 ISAE ; 10 av. Edouard Belin - BP 54032 - 31055 Toulouse Cedex 4, France

Abstract. Mobile devices are connecting to the Internet through an
increasingly heterogeneous network environment. This connectivity via
multiple types of wireless networks allows the mobile devices to take
advantage of the high speed and the low cost of wireless local area net-
works and the large coverage of wireless wide area networks. In this
context, we propose a new handoff framework for switching seamlessly
between the different network technologies by taking advantage of the
temporary availability of both the old and the new network technology
through the use of an “on the fly” erasure coding method. The goal is
to demonstrate that our framework, based on a real implementation of
such coding scheme, 1) allows the application to achieve higher goodput
rate compared to existing bicasting proposals and other erasure coding
schemes; 2) is easy to configure and as a result 3) is a perfect candidate
to ensure the reliability of vertical handovers mobility management pro-
tocols. In this paper, we present the implementation of such framework
and show that our proposal allows to maintain the TCP goodput (with
a negligible transmission overhead) while providing in a timely manner
a full reliability in challenged conditions.

دانلود مقاله PPR: Partial Packet Recovery for Wireless Networks

اختصاصی از فی بوو دانلود مقاله PPR: Partial Packet Recovery for Wireless Networks دانلود با لینک مستقیم و پر سرعت .

PPR: Partial Packet Recovery for Wireless Networks
Kyle Jamieson and Hari Balakrishnan
MIT Computer Science and Artificial Intelligence Lab
{jamieson, hari}@csail.mit.edu

Abstract
Bit errors occur over wireless channels when the signal isn’t strong enough to
overcome the effects of interference and noise. Current wireless protocols may use
forward error correction (FEC) to correct for some (small) number of bit errors,
but generally retransmit the whole packet if the FEC is insufficient. We observe
that current wireless mesh network protocols retransmit a number of packets and
that most of these retransmissions end up sending bits that have already been received
multiple times, wasting network capacity. To overcome this inefficiency, we
develop, implement, and evaluate a partial packet recovery (PPR) system.
PPR incorporates three new ideas: (1) SoftPHY, an expanded physical layer
(PHY) interface to provide hints to the higher layers about how “close” the actual
received symbol was to the one decoded, (2) a postamble scheme to recover data
even when a packet’s preamble is corrupted and not decodable at the receiver,
and (3) PP-ARQ, an asynchronous link-layer retransmission protocol that allows a
receiver to compactly encode and request for retransmission only those portions of
a packet that are likely in error.
Our experimental results from a 27-node 802.15.4 testbed that includes Telos
motes with 2.4 GHz Chipcon radios and GNU Radio nodes implementing the
Zigbee standard (802.15.4) show that PPR increases the frame delivery rate by a
factor of 2× under moderate load, and 7× under heavy load when many links have
marginal quality.