adhoc networs
TRANSCRIPT
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Ad hoc Wireless Networks
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Mobile Ad hoc Networks Ad hoc Networks useful when infrastructure not available, impractical, or expensive
Do not need backbone infrastructure support
Are easy to deploy
military applications, rescue, home networking MANET
Host movement and Topology change frequent
Infrastructure may not be present in a disaster area or war zone
Infrastructure may not be practical for short-range radios; Bluetooth (range ~
10m) No cellular infrastructure. Multi-hop wireless links.
Data must be routed via intermediate nodes.
A
B AB
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MANET-Some Features Temporary network composed of mobile nodes without
preexisting communication infrastructure, such as Access
Point (AP) and Base Station (BS)- Each node plays the role
of router for multi-hop routing Self-organizing network without infrastructure networks
Each node decode-and-forward packets for other nodes
Multi-hop packet forwarding through wireless links
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Mobile Ad hoc Networks Ad Hoc Wireless Networks: multi-hop radio relaying and
without support of infrastructure
Wireless Mesh Networks
Wireless Sensor Networks
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EXAMPLE
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Comparison
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Comparison
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Applications Personal area networking
cell phone, laptop, ear phone, wrist watch
Military environments
soldiers, tanks, planes Civilian environments
taxi cab network
meeting rooms
sports stadiums
boats, small aircraft
Emergency operations
search-and-rescue
policing and fire fighting
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Wireless Mesh Networks An alternate communication infrastructure for mobile or fixed
nodes/users
Provides many alternate paths for a data transfer session
between a source and destination Advantages are High data rate, quick and low cost of
deployment, enhanced services, high scalability, easy
extendability, high availability, and low cost per bit
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Wireless Sensor Networks A collection of a large number of sensor nodes that are
deployed in a particular region
Differences with the ad hoc wireless networks
Mobility of nodes ( not mandatory),
size of network (larger)
density of deployment ( depends on application)
power constraints (more stringent than ad hoc)
data/information fusion ( for reducing delay of packets)
traffic distribution ( traffic pattern varies depends on applictaion)
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Challenges in Mobile Environments
Limitations of the Wireless Network
packet loss due to transmission errors
variable capacity links
frequent disconnections/partitions
limited communication bandwidth Broadcast nature of the communications
Limitations Imposed by Mobility
dynamically changing topologies/routes
lack of mobility awareness by system/applications
Limitations of the Mobile Computer
short battery lifetime
limited capacities
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Issues in Designing MANET
Medium access scheme Distributed operation
Synchronization
Hidden terminals
Exposed terminals
Throughput
Access Delay
Real time traffic support Resource reservation
Ability to measure resource availability
Power control
Use of directional antennas
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Issues in Designing MANET
Routing Mobility
Bandwidth Constraint
Error prone shared medium
Location dependent contention
Other resource constraints
Requirements of a Routing protocol
Minimum route acquisition delay Quick route reconfiguration
Loop free routing
Distributed routing approach
Minimum control overhead Scalability
QoS
Security and privacy
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Issues in Designing MANET
Multicasting
Robustness
Efficiency Control overhead
QoS
Efficient group management Scalability
Security
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Issues in Designing MANET
TPC protocol
Setting up and maintain end to end delivery of
packets, flow control and congestion control Pricing scheme
Non optimal path consumes more resources and
affects throughput, wastes battery power and
energy of nodes
QoS
Per flow, per node per link basis.
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Issues in Designing MANET
Self-organization
Neighbor discovery, topology organization. Topology
reorganization
Security
Denial of service, Information disclosure, Interference
Energy management
Transmission power management
Battery energy management
Processor power management
Device power management
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Issues in Designing MANET
Addressing and service discovery
Scalability
Deployment considerations Low cost of deployment
Incremental deployment
Short deployment time
Reconfigurability
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Effect of mobility on the protocol stack
Application
new applications and adaptations
Transport
congestion and flow control
Network
addressing and routing
Link
media access and handoff
Physical
transmission errors and interference