Image Fusion is one of the most important methods used in image processing, especially in networks with limited resources such as networks of wireless sensors supporting multimedia. It is classified into technologies operating in spatial domain and o
thers in the frequency domain. In this research, Fusion techniques in frequency domain are manipulated to benefit from its advantages. Discrete Cosine Tansform is used because it fits the characteristics of this type of networking where it is simple, easy to implement and requires low memory.
Three methods based on this transformation, DCTav, DCTma and DCTah, have been investigated and applied to three different sets of images. The evaluation of simulation results, with different parameters, showed that the DCTma was the most appropriate method to integrate the imagery taken from sensory nodes supporting multimedia.
Recent researches consecrate their efforts to overcome multicast network problems by moving all the multicast functions and responsibilities from network layer (routers) to application layer ( terminal nodes (Users)).
Most of Application-Level Multi
cast (ALM)protocols rely on the idea that when a parent node leaves the overlay tree, all itspredecessors should re-join the tree again,which cause several re-organization operations in addition to the interruption of communication frequently. Membership Duration Aware ALM (MDA-ALM) protocol was suggested to solve this problem, it depends on the announcement of the expected membership duration for each new user in order to build a stable and efficient tree.
Although the performance of MD-ALM protocol is good, but it is based on membership duration parameter and this makes it more sensitive for the cheating and non-cooperative nodes. The main goal for the cheating nodes is to improve its position in the tree by trying to get the nearest position to the source node and to avoid having any children’s in order to relieve its load by manipulating the membership duration information.
Our research aims to find the best solution to detect the cheating nodes and cancel its affects in order to improve the performance of MDA against cheating. The simulation results improve that the proposed method detects effectively the cheating nodes.
Overlay multicast (Application-Level Multicast (ALM)) constructs a multicast delivery tree among end hosts. Unlike traditional IP multicast where the internal tree nodes are dedicated routers which are relatively stable and do not leave the multicast
tree voluntarily, the non-leaf nodes in the overlay tree are free end hosts which can join/leave the overlay at will, or even crash without notification. So, the leaving node can leave suddenly and cannot give its descendants (and the Rendez-vous Point (RP)) the time to prepare the recovering (the reconnection) of the overlay tree, and so there is a need to trigger a rearrangement process in which each one of its descendants should rejoin the overlay tree. In this case, all of its downstream nodes are partitioned from the overlay tree and cannot get the multicast data any more. These dynamic characteristics cause the instability of the overlay tree, which can significantly impact the user.
A key challenge in constructing an efficient and resilient ALM protocol is to provide fast data recovery when overlay node failures partition the data delivery paths. In this paper, we analyze the performance of the ALM tree recovery solutions using different metrics.
Application-Level Multicast (ALM) has been proposed as an alternative solution to
overcome the lack of deployment of the IP Multicast group communication model. It
builds an overlay tree consisting of end-to-end unicast connections between end-host
s
based on the collaboration of group members with each other. The efficiency of the
constructed overlay tree depends entirely on the honesty and on the cooperation of all
participating members. However such behaviour can not be guaranteed and some selfish
and non-cooperative nodes may take profit from the honesty of other members in the
overlay.
Recently, many researchers have been investigating the impact of selfishness of
nodes in the overlay multicast. Our contribution in this paper is to describe in detail the
basic algorithms used to construct the overlay tree, and evaluate the impact of cheating
nodes on the stability and on the performance of constructed overlay tree using these
algorithms.
Wireless sensor networks (WSNs) are often deployed by random bestrewing
(airplane bestrewing for example). A majority of nodes cannot obtain their coordinate
beforehand. Therefore, how to obtain the position information of unknown nodes, which is
called localization problem, has become a hot topic in WSN.
Without position information, WSN cannot work properly. Global Position System
(GPS) is the most extensive and mature position system at present. But because the nodes
usually have the shortcoming of high expenditure, large volume, high cost and require
settled basal establishment, therefore, the GPS is inapplicable for the low-cost selfconfigure
sensor networks, and also it is impossible to install GPS for each sensor node. In
this paper, we will study localization mechanisms (which is not based on GPS) used in
WSN, and will test the effectiveness of using MUSIC algorithm in determining the signal
arrival angel depending on the SDMA- technology and ESPAR antenna.
A lot of research directed its concern to the reliability of Wireless Sensor Networks
(WSNs) used in various applications, especially in early detection of forest fires to ensure
the reliability of warning alarms sent by sensors and reduce the aver
age of false warnings.
In this research we have tried to evaluate the reliability of WSN used in early
detection of fires in Fir and cedar preserve, mainly. By designing hybrid WSN network,
similar to the terrains of the preserve and modeling it using program Opnet14.5. We have
studied several scenarios, to allow increasing malfunction of the network resulting from
fire break out and spreading: starting in allowance of 0% and comparing its results the
results of mathematical equations of reliability according to the same scenarios. In
addition, we have calculated the final availability through suggesting a mechanism to
improve WSN reliability using the redundancy, i.e add sensitive spare nodes, which
replace the damaged ones as the result of fire. The results have proved the remarkable
increasing of reliability. Also, it has been predicted of the reliability of the network
designed according to reliability of different values of the nodes used by using one of the
reliability devices "the Block Diagram".
Wireless Sensor Networks (WSNs) are deployed in adversarial environments and
used for critical applications such as battle field surveillance and medical monitoring, then
security weaknesses become a big concern. The severe resource constraints of
WSNs give
rise to the need for resource bound security solutions.
The Implicit Geographic Forwarding Protocol (IGF) is considered stateless, which
means that it does not contain any routing tables and does not depend on the knowledge of
the network topology, or on the presence or absence of the node in WSN. This protocol is
developed to provide a range of mechanisms that increase security in IGF. Thus it keeps
the dynamic connectivity features and provides effective defenses against potential attacks.
These mechanisms supported the security against several attacks as Black hole, Sybil and
Retransmission attacks, but the problem was the inability of mechanisms to deal with
physical attack.
This research deals with a detailed study of the SIGF-2 protocol and proposes an
improvement for it, in which we use the concept of deployment knowledge from random
key pool algorithm of keys management to defend against physical attack . The evaluation
of simulation results, with different parameters, proved that our proposal had improved the
studied protocol.
Application-Level Multicast Networks are easy to deployment, it does not require
any change in the network layer, where data is sent to the network via the built-up
coverage of the tree using a single-contact transmission of the final contract, who
are the
hosts are free can join / leave whenever they want it, or even to leave without telling any
node so. Causing the separation of the children of the leaved node from the tree, and the
request for rejoin, in other words, these nodes will be separated from the overlay tree and
cannot get the data even rejoin. This causes the distortion of the constructed tree, and the
loss of several packets which can significantly impact the user.
One of the key challenges in building a multi-efficiently and effectively overlay
multicast protocol is to provide a robust mechanism to overcome the sudden departure of a
node from the overlay tree without a significant impact on the performance of the
constructed tree. In this research, we propose a new protocol to solve problems presented
previously.
Telehealth is a promising technology in its effectiveness, accuracy and prevalence, and given the importance of medical care and monitoring in areas that lack adequate medical staff or are difficult to access on the one hand, and as a result of the h
igh costs of medical treatment, especially for the elderly on the other hand. Wireless body sensor networks (WBAN) has received a lot of attention from research and development, especially as a result of the tremendous development in wireless sensor networks and modern electronics that have caused smart small size sensors that can be positioned inside or on the body. In our research, we will discuss the use of these modern networks in the medical field, in particular patient monitoring in hospitals, as continuous monitoring and control of vital parameters here are of great importance to patients' lives. The basic idea is to publish a group of sensor devices with a specific formation on the patient’s body, and these devices have several functions to perform the integrated work of measuring and sensing important parameters, and send them as information to a coordinated node that collects these data and sends them to a main station that processes this information and makes decision. Then, it sends a message of this decision to the deployed agencies that translate this decision in order to adjust the parameters again.
Wireless sensor network simulation programs provide representation for an actual system, without needing to deploy real testbed which is highly constrained by the available budget, and the direct operations inside physical layer in most of these prog
rams are hidden and work implicitly. This is what motivated us to build a kernel for a virtual simulation platform to be able to simulate protocol operations and algorithms at the node processing unit level, The proposed system aims to observe the execution of operations at the low level of the wireless sensor physical infrastructure with the ability to modify at this level. Since secure routing is considered one of the most challenges in WSN field, so we apply in this paper one of the secure routing algorithms inside the GUI of the proposed system to observe execution at the low level of processor operations, which give us the ability to discover the weakness of algorithms and improve them. Three scenarios were applied to evaluate the performance of the proposed simulation platform. The results demonstrate a high flexibility and effectiveness of this platform in tracing the progress of operations performed within the wireless sensor nodes at the Assembly language level.
