25-03-2011, 02:45 PM
Presented By
B VANITHA
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ABSTRACT
A MANET is a collection of wireless nodes that can dynamically form a network to exchange information without using any pre-existing fixed network infrastructure.
A mobile ad hoc network is a collection of wireless nodes that can dynamically be set up anywhere and anytime without using any pre existing network infrastructure.
It is an autonomous system in which mobile hosts connected by wireless links are free to move randomly and often act as routers at the same time.
INTRODUCTION
Wireless Mobile Networks
Infrastructured.
- mobile devices communicate with access points like base stations connected to the fixed network infrastructure.
Typical examples of this kind of wireless networks are GSM, UMTS, WLL, WLAN, etc.
Wireless Mobile Networks
Infrastructureless
- mobile wireless network is commonly known as a mobile ad hoc network (MANET).
In many contexts information exchange
between mobile units cannot rely on any fixed network infrastructure, but on rapid configuration of a wireless connections on-the-fly.
WIRELESS MOBILE NETWORKING
CHARACTERISTICS OF
MOBILE AD HOC NETWORKS(MANETs)
Dynamic network of autonomous mobile nodes
Uses wireless links without existing infrastructure
Does not use centralized administration
Dynamic network leads to high rate of topology changes
Topology changes occur both rapidly and unexpectedly
MANETs are often referred to as multihop wireless
ad hoc networks
High expectations of future capabilities
Capable of extending network service to areas without existing infrastructure
MANET EXTENDING INFRASTRUCTURE
KEY ELEMENTS OF MANETs
Formed dynamically through the cooperation of independent nodes
Nodes do not have any pre-specified roles
Nodes make decision independently based on the current network situation
Nodes are expected to behave as routers
As routers, nodes must assist in discovery and maintenance of network routes
FORMATION OF A MANET
Mobile Ad Network – HOME
MANET DESIGN COMPLEXITIES & CONSTRAINTS
Infrastructureless with distributed management
Frequent and unpredictable topology changes
Physical layer limitation
Limited page link bandwidth and quality
Variation in node capabilities
Routing
Internetworking
Network reliability
Network security
Network scalability
Quality of service
Power consumption
MANET TOPOLOGY
Topology changes occur with every move of a mobile node
Every topology change results in route changes
Route changes lead to network partitions and in most instances some packet losses
COLLISION RISK & PACKET LOSS
Limited wireless range and shared frequency space leads to specific mobile ad hoc problem
- High risk of collisions and packet losses
MANET BANDWIDTH CONSTRAINTS
Bandwidth used by MANETs has a wide range of capacity levels.
Wireless bandwidth in general is more error-prone than wired links.
Wireless bandwidth in general is more insecure than wired links.
These factors lead to lower capacity throughput than equivalent wired links.
The lower capacity wireless links lead to higher congestion problems.
MANET NODE VARIABILITY
Nodes may have one or more radio interfaces of varying transmission capabilities
Node radios may operate in different frequency bands
Node radio capabilities may result in asymmetric links
Node hardware and software configurations can affect processing capabilities
MANET NODE VARIABILITY
MANET APPLICATIONS
Military communications and operations control in battlefield environments.
Sensor Networks – Collection of embedded sensor devices used to collect real-time data to automate everyday functions.
Weather monitoring
Earth activities
Manufacturing Equipment automation
Emergency Services – Search-and rescue operations as well as disaster recovery and medical needs.
Patient records retrieval at point of contact
Loss of infrastructure due to catastrophic disaster
MANET APPLICATIONS
Commercial Environments – electronic commerce
Make and receive payments from anywhere
Access customer records from the field
Vehicular access of road conditions, weather, or local news
Home and Enterprise Networking -
Anywhere access for PDA
Personal area networks
Educational Applications – virtual classrooms or conference rooms for use during conferences, meetings or lectures.. etc……
CONCLUSION
Ad hoc wireless networks eliminate the constraints of infrastructure and enable devices to create and join networks on the fly – any time, anywhere – for virtually any application.
The most attractive property of an mobile ad hoc networking model is perhaps its independence from centralized control
Ease of use and flexibility are fueling the demand for ad hoc operation.