PRESENTED BY:
Manish.N.kothari

---

[attachment=13165]
SeminarTopic: The study of effectiveness for ad-hoc wireless network
Cellular and Ad Hoc Wireless Networks
The following figure represents different wireless networks.
Infrastructure: cellular wireless networks
Ad hoc: wireless sensor and mesh networks
Hybrid networks
Cellular networks
These are infrastructure based wireless network
It has a Access point whose function is to page link one or more wireless local area network and the existing cable network
The call between any two nodes is only through base station
Cellular network
Hybrid Wireless Networks
Hybrid Wireless Networks
Multi-hop cellular networks (MCNs) allows the transmission through the base stations or multi-hop of mobile nodes.
Integrated cellular ad hoc relay (iCAR) is a system that combines conventional cellular technology with Ad hoc Relay Station (ARS) technology.
Advantages
Higher capacity than cellular networks
Increased flexibility and reliability in routing
Better coverage and connectivity
Ad-hoc networks
These are non-infrastructure based wireless local area network
The principle behind ad hoc networking is multi-hop relaying in which messages are sent from the source to the destination by relaying through the intermediate hops (nodes).
The absence of base station makes routing complex compared to cellular networks
Here the call between two nodes is direct or through intermediate node.
Ad-hoc networks
In multi-hop wireless networks, communication between two end nodes is carried out through a number of intermediate nodes whose function is to relay information from one point to another. A static string topology is an example of such network:
Ad-hoc networks
There is no fixed base station to use as gateway nodes
In these, nodes are free to directly signal to other nodes within the scope of communication
Here nodes are free to move in any direction
However because of mobile node it leads to several disadvantages
Ad-hoc framework
Advantages
Users of internet users in ad-hoc networks does not require any connection line, the wiring needed to save space
It is built in low-cost
The investment required in wireless mesh networks is much less than in the cellular network counterparts
Applications of Ad hoc Wireless Networks
Military applications
Ad hoc wireless networks is useful in establishing communication in a battle field.
Collaborative and Distributed Computing
A group of people in a conference can share data in ad hoc networks.
Streaming of multimedia objects among the participating nodes.
Emergency Operations
Ad hoc wireless networks are useful in emergency operations such as search and rescue, and crowd control.
A Wireless Mesh Network is a mesh network that is built upon wireless communications and allows for continuous connections and reconfiguration around blocked paths by "hopping" from node to node until a connection can be established
Wireless Mesh Networks
Disadvantages of mobile nodes
Signal attenuation
Interference
Most of the mobile communication devices are subject to power constraints
Many other factors that led to disconnection
These disadvantages would lead to development of different routing protocol in order to maintain the best signal transmission
Routing protocols for ad-hoc networks
Table-driven routing protocol
In this routing protocol, every node maintain the network topology information in the form of routing table by periodically exchanging routing information
Routing information is generally flooded in the whole network
Whenever a node requires a path to destination it runs an appropriate path-finding algorithm on the topology information it maintains.
Example:- DSDV, CGSR etc…..
Destination Sequenced Distance Vector (DSDV)
Each Route is tagged with a sequence number originated by destination
Hosts perform periodic & triggered updates, issuing a new sequence number
Sequence number indicates the “freshness” of a route
Routes with more recent sequence numbers are preferred for packet forwarding
If same sequence number, one having smallest metric used
Topology changes
Broken links assigned a metric of ∞
Any route through a hop with a broken page link is also assigned a metric of ∞
“∞ routes” are assigned new sequence numbers by any host and immediately broadcast via a triggered update
If a node has an equal/later sequence number with a finite metric for an “∞ route”, a route update is triggered
DSDV Operation
DSDV Operation
Ad-hoc On DemandDistance Vector (AODV)
On-demand protocol uses an on-demand approach to find routes
Key difference from DSR is that source route is no longer required (data packet carries the complete path)
It floods a RouteRequest packet in the network when a route is not available to destination
Key difference with other on-demand routing protocols is that it uses DestSeqNum to determine an up-to-date path to the destination.
AODV Reverse path setup
Counters : Sequence number, Broadcast id
Reverse Path
Broadcast route request (RREQ) < source_addr, source_sequence-# , broadcast_id, dest_addr, dest_sequence_#, hop_cnt >
RREQ uniquely identified by <source_addr , broadcast_id>
Route reply (RREP) if neighbor is the target, or knows a higher dest_sequence_#
Otherwise setup a pointer to the neighbor from whom RREQ was received
Maintain the reverse path entries based on timeouts i.e a timer is used to delete this entry in case a Routereply is not received before the time expires.
AODV Forward path setup
RREQ arrives at a node that has current route to the destination ( larger/same sequence number)
Unicast request reply (RREP)<source_addr, dest_addr, dest_sequence_#, hop_cnt,lifetime> to neighbor
RREP travels back to the source along reverse path
Each upstream node updates dest_sequence_#, sets up a forward pointer to the neighbor who transmit the RREP
AODV Operation
D-destination S-source
Hybrid routing protocol
Protocol belonging to this category combine the best features of above two protocols.
Nodes within certain distance are said to be within the routing zone of the given node.
For routing within this zone a table-driven approach is used
For nodes that are located beyond this zone,
an on-demand approach is used
METHODOLOGY
Here we use NS2 to simulate and analyze its results, including:
(1) Packet delivery ratio: the source-side generated by the
CBR packets sent reach their destination number and the success ratio of the number of client packets.
(2) The average point-to-packet delay: This includes all of
the possible delay of aggregate, such as found in the path of the
buffer time, MAC layer retransmission time, delivery time, etc...
(3) The first packet received in time: This parameter can be
used to assess the routing table convergence time, if received
earlier, then relatively fast convergence rate, so as to compare is
put the first one to send packets from the client sent to the receiver.
Simulation and Analysis
We will carry out two experiments;
the first time in the simulation there is no mobility, to observe the results of the analysis.
The second factor to join the mobile, so that at any time the node movement, and to compare them with the first difference between a model and analysis discussed
Performance Analysis
The avg point-to-point delay time
The time of the first packet received
CONCLUSION
Here we discussed all the wireless network and the benefits of ad-hoc network compared to other networks.
We also verify the comparability of DSDV and AODV based on performance relationship
Future research will further enhance the goal of the routing.