Overview of
Cellular Networks
Mobile Ad hoc Networks
Sensor Networks
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
WIRELINE
Cell
Base Station (BS)
Mobile unit
Wireless Links
Wired Links
Mobile Switching Center (MSC)
NETWORK
Why Mobile Ad hoc Networks?
 Characteristics
- Infrastructure-less
- 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
Mobile Ad hoc Networks
transmission
range
Hybrid Environments
 Use infrastructure when convenient
 Use ad hoc connectivity when necessary or superior
BS1
infrastructure
A
BS2
E
Z
Ad hoc connectivity
X
© 2001 Nitin Vaidya
Variations
• Symmetric environments
• Asymmetric capabilities
• Asymmetric responsibilities
• Traffic characteristics
• May co-exist (and collaborate) with an infrastructure-based
network
• Mobility patterns
• Mobility characteristics
© 2001 Nitin Vaidya
Sensor Networks
 Characteristics
- low-cost, low-power, small in size
- two-ways of deployment: pre-determined and random
- densely deployed
- prone to failures
 Application Areas
- Military
- Environmental
- Health
- Home
 Objectives
- Monitor activities
- Gather and fuse information
- Communicate with global data processing unit
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
Research Problems in Ad hoc and
Sensor Networks
 Medium Access Control Protocols
 Sensor management
 Power conservation/energy consumption
 Data fusion and dissemination of sensor data
 New applications for ad hoc and sensor networks