Wireless Sensor Networks (WSN) have applications in many different areas of life, such as health care, environmental monitoring, and military and economic areas and in industrial automation and many other applications.
The development of these net
works and the improvement of their performance occupy an important place of interest in research centers and specialized scientific institutes. The interest in these structures as a way to improve the performance of these networks leads to good results in this area. The cluster structure is one of the most important structures that have received increasing attention over recent years.
This research suggested a modification of the structure of the cluster tree WSN dividing clusters into sub-groups, and each group of these sub-groups operates like a tree from a small amount of nodes. The results that have been obtained by means of simulation indicate a significant improvement in terms of reducing energy consumption and thus an increase in the lifetime of the network, as compared to traditional cluster tree WSN. But that was at the expense of slightly lower rates of transmission and delivery ratio in the nodes of these networks. This leads us to recommend using this method to build the networks used to monitor protected agriculture and other networks with low transmission rates.
Network coding isone of the important researches in multi-hop wireless networks domain
and it widely participates in improving the performance of these networks, since it benefits from
the broadcasting nature of transmission processes to transmit m
ore than single packet in one
broadcasting transmission. So it achieves double use of the available bandwidth, which can
increase the throughput of the network and reduce the congestion.Our aim in this research is to
verify the improvement that network coding presents to theperformance of multi-hops wireless
Ad-hoc networks, and to study the accelerating of research process for coding chances through
constructing a virtual queues according to the packets flows that pass the node, and applying
affective manner to manage this queues.
Although the fact that VPN provide a safe and reliable transfer of customers’ data,
but the basic configurations on which they depend VPN and transport networks of
asynchronous (ATM) and Frame Relay networks (FR).Link, that depend on them these
te
chniques are relatively slow and cause a delay in time
With the rapid growth of the Internet and increase the load on the network in terms
of users and providers of service to look for ways of effective and fast routing packets of
data while ensuring quality of service began(QoS)and class of service(Cos)and secure
management and engineering movement(traffic) on the network and appeared the multiswitch
tags of the Protocol(MPLS)standard modern technique verify the previous
requirement safter she was initially way to improve the transmission speed routers.
This paper presents an analytical study on improving the performance of virtual
private networks using multi-protocol label switching( MPLS_VPN), by improving routing
operations on the third level, minimizing the delays and complexity resulting from the
routing on full internal routers in the traditional technical protocols settings and limited to
Edge routers in networks MPLS_VPN.
OPNET was used simulation software to get the results of the analysis and
simulation of new technology and compare it with the old technology.
Ad-hoc networks has opened a new dimension in wireless networks. It allows
wireless communication in the absence of central support of the contract. In these
networks, there are no fixed infrastructure because the mobile nodes are continuously
mak
ing continuous and dynamic change in the topology.
Routing protocols of mobile ad-hoc networks differ from the existing internet
protocols which are designed for the fixed structure based wireless networks. MANET
protocols have to face high challenges due to dynamically changing of topologies, low
transmission power and asymmetric links. Due to link instability, node mobility and
frequently changing topologies routing becomes one of the core issues in MANETs.
Currently existent routing protocols provide routing solutions up to a certain level
and most of them are designed and implemented in small areas. Many researchers are still
working on the developments of MANET routing protocols.
With the increase in the types of routing protocols used in mobile network it has
become necessary to study the effectiveness of each type of protocols In this papper we
compared between the most famous species (proactive, Reactive, hybrid) and choose a
protocol to be representative of all species previously mentioned and the network
performance assessment each type in terms of Throughput, dynamic routing routing, load,
delay and determine which of these protocols appropriate for each case.
In last decade, many of researches have proposed to study materials with periodic
structures,These structures can be engineered to realize novel electromagnetic properties
and to achieve behaviors that are not found in naturally materials. These ma
terials have
negative permittivity and permeability .Those are called meta-material or Left Hand
Material (LHM), They are fabricated, studied and analyzed within different applications of
microwave and optical communication. Recently, the microwave engineering applications
of artificial metamaterials have been widely discussed and various novel microwave
components were achevid for example, filters, antennas and fiber optic. This paper studys
and analyzes the reflection from fractal distribution of MMs layers in RHM medium, using
the recursive method, and applies it in the design of microwave narrow band filters.
Antennas have become an indispensable basic need, especially in the area of wireless
networks, and have developed in the past few decades in a very large way in terms of profit
and resistance, bandwidth, bandwidth, radiation pattern, etc. in line w
ith new and
increasing requirements.
In this study, we are interested in studying a broad band antenna where this antenna is very
important in systems that operate on a set of frequencies rather than at a fixed frequency.
The traditional antennas that are designed at a specific frequency change their response
significantly if used on a wide bandwidth around the designed frequency
In this study, the LPDA (Log periodic dipole Array) antenna was designed and studied in a
broadband field and compared to the antenna reference of wire antennas. It is a halfwavelength
antenna λ/2. The study of the effect of frequency change in the antenna
radiation pattern and the radiation beam Half-power level and front-to-back ratio (F/B).
