25-05-2012, 11:36 AM
Efficient Routing in Intermittently Connected Mobile Networks: The Multiple-Copy Case
Efficient Routing in Intermittently Connected Mobile Networks The Multiple-Copy Case.doc (Size: 34.5 KB / Downloads: 26)
ABSTARCT
Intermittently connected mobile networks are wireless networks where most of the time there does not exist a complete path from the source to the destination. Under such intermittent connectivity many traditional protocols fail (e.g.,TCP, DNS, etc.). It is for this reason that novel networking architectures are being pursued that could provide mobile nodes with better service under such intermittent characteristics. We explore the problem of efficient routing in intermittently connected mobile networks (ICMNs), and describe our proposed solution, Spray routing. Our problem setup consists of a number of nodes moving inside a bounded area according to a stochastic mobility model. Additionally, we assume that the network is disconnected at most times, and that transmissions are faster than node movement (i.e., it takes less time to transmit a message using the wireless medium—ignoring queuing delay—than to move it physically for the same distance using node mobility).
Existing system:
Intermittently connected mobile networks are wireless networks where most of the time there does not exist a complete path from the source to the destination. There are many real networks that follow this model. In this context, conventional routing schemes fail, because they try to establish complete end-to-end paths, before any data is sent. To deal with such networks researchers have suggested to use flooding-based routing schemes. While flooding-based schemes have a high probability of delivery, they waste a lot of energy and suffer from severe contention which can significantly degrade their performance.
Wireless data networks often aim at extending Internet services into the wireless domain. Services like GPRS enable Internet access through the widespread cellular infrastructure, while the deployment of WiFi 802.11 access points provides direct Internet connectivity for wireless users that are within range. Despite these ongoing efforts, wireless access currently seems to give rise to inconvenience and frustration more often than providing the envisioned flexibility to the user. Cellular access is low bandwidth and expensive, while WiFi access is typically only available at a few “hotspots” that the user has to locate and move to, without real “mobile computing”.
The reason for these failures is that many of the assumptions made in the wired world, and which are largely responsible for the success of the Internet, do not hold in the wireless environment. The concept of a connected, stable network over which data can be routed reliably rarely holds there. Wireless signals are subject to multi-path propagation, fading, and interference making wireless links unstable and lossy. Additionally, frequent node mobility (e.g., as in vehicular ad hoc networks—VANETs) significantly reduces the time a “good” link exists, and constantly changes the network connectivity graph. As a result, wireless connectivity is volatile and usually intermittent, as nodes move in and out of range from access points or from each other, and as signal quality fluctuates.
Proposed system:
We propose a family of multi-copy protocols called Spray routing, which can achieve both good delays and low transmissions. Spray routing algorithms generate only a small, carefully chosen number of copies to ensure that the total number of transmissions is small and controlled. Then, an appropriate single-copy algorithm is used to route each of the copies independently. From the perspective of functionality, spray routing can be viewed as a tradeoff between single and multiple copy techniques. Despite this, theory and simulations show that spray routing achieves an order of magnitude reduction in transmissions compared to flooding based schemes, and even fewer transmissions than some single copy end-to-end paths exist most of the time, these protocols fail to deliver any data to all but the few connected nodes.
Modules:
Constructing a Topology
In this module is used to construct the topology. The user gives the number of node used to construct the topology. The node is added to give the name of the node, system number and port address of that node. If the node name and port address is already available means to display the message box “Node already added”, otherwise to display the message box “Node added successfully”.
Finding Possible Path
In this module used to display the possible path from source to destination. The user selects the destination and displays the available path and weight of each path.
N/2 Copy & Transfer the Message
In this module is used to take the fixed number of copies in the same message. The source fixes the number of copies based on the possible path. The source takes the n/2 copies of the same message and also the source chooses the best path. The best path chooses the minimum weight of n/2 best the path. The source sends all the best paths. The intermediate nodes get the message and check the status of the destination, If the destination is connected or not. If the destination is connecting transfer the information to the destination otherwise to display the message “the destination is not connect”. Another intermediate node checks the status, suppose the destination is connecting to check the destination is already receiving the message or not. If the message is not received means to show the message otherwise the destination is already receive the message. The destination is receiving the message send the acknowledgement to the source.
Node Mobility
In this module is used to change the topology structure. The mobile adhoc network is a unstructured network. So the user changes the network topology. The user clicks the node mobility button to display the node mobility frame. In this frame to enter which node to change is the node name and also enter the intermediate node From node and To node and weight of the path. To display the message ”node move successfully”