Overview of Wireless Networks: Cellular Mobile Ad hoc Sensor

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!)

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

WIRE- LINE NETWORK WIRE- LINE NETWORK Base Station (BS) Cell Wireless Links Wired Links Mobile Switching Center (MSC) Mobile unit 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

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 Mobile Ad hoc Networks

Mobile Ad hoc Networks (MANET) transmission range

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 - 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 - Communicate with global data processing unit Sensor Networks

Application Areas [Akyildiz+ 2002] 1.Military:  Monitoring equipment and ammunition  Battlefield surveillance and damage assessment  Nuclear, biological, chemical attack detection and reconnaissance Sensor Networks 2.Environmental:  Forest fire / flood detection 3.Health:  Tracking and monitoring doctors and patients inside a hospital  Drug administration in hospitals

Sensor Networks 5.Other Commercial Applications:  Environmental control in office buildings  Detecting and monitoring car thefts  Managing inventory control  Vehicle tracking and detection Application Areas [Akyildiz+ 2002] 4.Home:  Home automation  Smart environment

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

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

 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) Current Challenges

 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 data management  Power conservation/energy consumption  Data fusion and dissemination of sensor data  New applications for ad hoc and sensor networks Research Problems in Ad hoc and Sensor Networks

[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 , August References