Wireless Network Organization Spring 07 CS 527 – Lecture 3

Overview Classification of wireless networks Based on infrastructure Based on mobility Based on size of network Motivating real life examples of ad-hoc networks Networks in action Vehicular network Community wireless network Sensor Network

Wireless Network classification - 1 Based on infrastructure Infrastructure networks Base station/ Access point infrastructure Generally one-hop networks E.g.: Cellular, Wireless LANs, Ad-hoc networks Remote nodes capable of coordinating to form a network Multi-hop wireless links common

Wireless Network classification - 2 Based on Mobility Static wireless networks Why do we need wireless access in such scenarios? Harsh Terrain Cost-effectiveness E.g.: Enabling internet access to a remote village Mobile wireless networks A part of wireless nodes are mobile E.g.: Cellular networks, Mobile Ad-hoc networks (MANETs) Challenges: Sustaining opened connections E.g.: Mobile IP Naming Moving to different network

Wireless Network classification - 3 Based on size of the network Body Area Networks E.g.: Sensors inserted inside the body coordinate Personal Area Networks E.g.: Home Networking, Bluetooth and Zigbee networks Local Area Networks E.g.: Wireless LANs, WiFi Metropolitan Area Networks E.g.: Community wireless networks Wide Area Networks E.g.: Cellular and Satellite networks Figure borrowed from [http://www.cs.mun.ca/~yzchen/teaching/whu_2006/Introduction.pdf]

Overview Classification of wireless networks Based on infrastructure Based on mobility Based on size of network Motivating real life examples of ad-hoc networks Networks in action Vehicular network Community wireless network Sensor Network

Some motivating real-life examples for ad-hoc networks Mesh networks - Community Wireless networks Cost-effective way of enabling network access to remote areas Sensor networks Applications in a variety of fields Habitat monitoring is valuable to biologists Disaster monitoring Vehicular networks Intelligent Transport Systems Body area networks Healthcare

Overview Classification of wireless networks Based on infrastructure Based on mobility Based on size of network Motivating real life examples of ad-hoc networks Networks in action Vehicular network Community wireless network Sensor Network

Vehicular networks Concrete application of Mobile Ad-hoc network (MANET) Applications Automated driving, parking, etc. How is it different from control systems for individual vehicles? Information and warning functions: Incidents, congestion, surface condition, etc. Communication-based longitudinal control Avoiding accidents and platooning vehicles Co-operative assistance systems Blind crossings Highway entries Miscellaneous Location-based services and multiplayer games Figure borrowed from [CarTALK2000]

Vehicular networks - Components Inter-vehicle communication (IVC) Topics discussed in previous slide Road-to-vehicle communication (RVC) Access to fixed networks Issues: High speeds mean lesser time connected to a single access point Access point association, validation, connection initiation in this short period of time Will Mobile IP and variants work? (Hierarchical Mobile IP) Results are not very disappointing More than ten seconds of connectivity even at speeds of 180 km/h. Figure borrowed from [Drive-thru Internet: IEEE 802.11 for "Automobile" users - Infocom '04]

Vehicular networks – Discussion Use WLAN or Cellular networks Cellular is centralized (infrastructured) 802.11 is susceptible to resource reservation drawbacks and multipath Mobility is intrinsic Use of group communication How to group vehicles Set of vehicles Based on a particular location E.g.: Platooning and co-operative driving (4 way stop signs) Advantages: Battery power Dimension of the wireless node Examples: California PATH project, Chauffeur of EU, CarTALK 2000 Fun part! – Watch videos of vehicular networks in action at http://www.path.berkeley.edu/PATH/Publications/Videos/

Overview Classification of wireless networks Based on infrastructure Based on mobility Based on size of network Motivating real life examples of ad-hoc networks Networks in action Vehicular network Community wireless network Sensor Network

Community wireless networks Creation of a broadband wireless Metropolitan Area Network (MAN) E.g: MIT Roofnet, SeattleWireless, CUWireless Characteristics Designed for low mobility Semi-infrastructured backbone network (Mesh) Long distance links common Uses: Large Socio-economic impact Reduces physical infrastructure cost, Encourages unplanned growth of the network Extend Internet access into areas which do not have wired networking infrastructure. Lots of use in developing nations

Community Wireless networks Figure borrowed from paper [Experiences in using WiFi for Rural Internet in India]

Community Wireless Networks Links as long as 37 km (23 miles) Antenna design?

Community Wireless Network Is 802.11 MAC protocol suitable? Timing parameters (E.g.: Waiting for Acknowledgement across long distance links) How about TDMA based links? Such reservation based approach eliminates certain pattern of drops (hidden terminals) in 802.11 which might have a huge effect on long distance links More while discussing MAC layer

Overview Classification of wireless networks Based on infrastructure Based on mobility Based on size of network Motivating real life examples of ad-hoc networks Networks in action Vehicular network Community wireless network Sensor Network

Sensor Network - Zebranet An example for the use of sensor networks in habitat monitoring of zebras at Kenya Brief description: Sensor Nodes are mounted on zebras as "collars" Observer with wireless node collects information when in proximity with a zebra Figure borrowed from [http://www.princeton.edu/~mrm/ZNetASPLOS.pdf]

Zebranet - Challenges Large monitoring area All nodes (zebras and observer) are mobile Harsh environment acting on sensors - Water proof, shock proof, bite-proof No infrastructure Low power sensor nodes Intelligent Data collection mechanisms and storage requirements Infeasible for an observer to contact each zebra for collecting data Data aggregation

Zebranet Figure borrowed from [http://www.princeton.edu/~mrm/ZNetASPLOS.pdf]

Zebranet Interesting data collected Valuable and accurate information to biologists without physical monitoring hassles Example: Zebra movement

Conclusion Various varieties of wireless networks with different network characteristics Lot of open and challenging problems for research Varies widely from wired networking Vast business market in near future!? High-Impact applications