Overview of Wireless Networks:

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Overview of Wireless Networks Cellular Mobile
Ad hoc Sensor
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Wireless networking

• Digital connection through radio waves
• Justification
• Convenience
• Cost!
• It is always more efficient to go wired
  (especially optical)
• No interference
• You need more bandwidth just add a bunch more of
  fibers!
• As fiber is cheaper than digging and resurfacing
  streets, many companies put in more fiber than
  they would ever need (dark fiber look it up!)

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Wireless networking types

• Cellular
• With a big emphasis on voice communication
• Satelite
• WiFi
• Local networks over wireless, with infrastructure
• 801.11a,b,g,n
• Thrash frequencies
• WiMAX
• Internet provider last mile replacement
• Ad Hoc Networking
• Local networks over wireless, without
  infrastructure
• Sensor networks
• RFID

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Cellular Architecture
- Infrastructure-based networks - All units are
fixed in location except mobile units - BS and
MSC are connected via wirelines - Communication
between BS and mobile unit is wireless
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Mobile Ad hoc Networks
Characteristics- Infrastructureless- All nodes
are potentially mobile- Network topology is
dynamic- All nodes act as individual
routers Examples - Disaster recovery
situations - Battle field communications - Law
enforcement operations - Civilian applications
Objectives- Maintain connectivity between
mobile devices- Provide congestion-free routing
for multimedia traffic- Support scalability-
Minimize memory, bandwidth and energy consumption
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Mobile Ad hoc Networks (MANET)
transmission range
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Sensor Networks

• Wireless sensor networks consists of group of
  sensor nodes
• to perform distributed sensing task using
  wireless medium.
• Characteristics- low-cost, low-power,
  lightweight
• - densely deployed
• - prone to failures
• - two ways of deployment randomly,
  pre-determined or engineered
• Objectives- Monitor activities- Gather and fuse
  information
• - Communicate with global data processing
  unit

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Sensor Networks

• Application Areas Akyildiz 2002
• Military
• Monitoring equipment and ammunition
• Battlefield surveillance and damage assessment
• Nuclear, biological, chemical attack detection
  and reconnaissance

• Environmental
• Forest fire / flood detection

• Health
• Tracking and monitoring doctors and patients
  inside a hospital
• Drug administration in hospitals

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Sensor Networks

• Application Areas Akyildiz 2002
• Home
• Home automation
• Smart environment

• Other Commercial Applications
• Environmental control in office buildings
• Detecting and monitoring car thefts
• Managing inventory control
• Vehicle tracking and detection

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Sensor Networks vs. Traditional Wireless
Networks (Cellular, MANET)

• Higher number of sensor nodes (several orders of
  magnitude)
• Dense deployment
• Prone to failures
• Limited in power, computation and memory
• May not have global identification (ID) due to
  high overhead and the total number of sensors
• Optimization on the energy consumption vs. QoS
  and high bandwidth constraints
• Stationary vs. mobile
• Data flow unidirectional vs. bi-directional
• Date rates

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Sensor Networks Preliminaries

• For large scale environment monitoring
  applications, dense sensor networks are mainly
  used
• Sensing capabilities should be distributed and
  coordinated amongst the sensor nodes
• Algorithms deployed should be localized since
  transmissions between large distances are
  expensive and lowers networks life time
• These networks should be self-configuring,
  scalable, redundant and robust during topology
  changes

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Current Challenges

• Limited wireless transmission range
• Broadcast nature of the wireless medium
• Packet losses due to transmission errors
• Mobility-induced route changes
• Mobility-induced packet losses
• Battery constraints
• Potentially frequent network partitions
• Ease of snooping on wireless transmissions
  (security hazard)

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Research Problems in Ad hoc and Sensor Networks

• Clustering
• Partitioning of the network
• Identification of vital nodes (clusterheads)
• Routing
• Discovering routes from source to destination
• Maintaining the routes
• Rediscovery and repair of routes
• Topology management
• Maintain the links
• Minimize the changes in underlying graph
• Security

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Research Problems in Ad hoc and Sensor Networks

• Medium Access Control Protocols
• Sensor data management
• Power conservation/energy consumption
• Data fusion and dissemination of sensor data
• New applications for ad hoc and sensor networks

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References

• Akyildiz 2002 I. F. Akyildiz, W. Su, Y.
  Sankarasubramaniam, and E. Cayirci, A Survey on
  Sensor Networks, IEEE Communications Magazine,
  Vol. 40, No. 8, pp. 102-114, August 2002.