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 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 Cell Base Station BS Mobile unit Wireless Links Wired Links Mobile Switching Center MSC WIREWIRELINE LINE NETWORK NETWORK 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 Mobile Ad hoc Networks MANET transmission range 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 Sensor Networks Application Areas Akyildiz 2002 1 Military Monitoring equipment and ammunition Battlefield surveillance and damage assessment Nuclear biological chemical attack detection and reconnaissance 2 Environmental Forest fire flood detection 3 Health Tracking and monitoring doctors and patients inside a hospital Drug administration in hospitals Sensor Networks Application Areas Akyildiz 2002 4 Home Home automation Smart environment 5 Other Commercial Applications Environmental control in office buildings Detecting and monitoring car thefts Managing inventory control Vehicle tracking and detection 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 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 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 data management Power conservation energy consumption Data fusion and dissemination of sensor data New applications for ad hoc and sensor networks 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
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