Mobile Ad Hoc Networking

Mobile Ad Hoc Networking, MESH Networking, Wi-MAX Mobile Ad Hoc Networks (MANETs)       Dynamic network of autonomous mobile nodes Uses wireless links without existing infrastructure Does not use centralized administration Dynamic network leads to high rate of topology changes Topology changes occur both rapidly and unexpectedly MANETs are often referred to as multihop wireless ad hoc networks MANETs  Capable of extending network service to areas without existing infrastructure  High expectations of future capabilities  Large volume of existing research  Expected to be a key element of 4G wireless network architecture  MANET capabilities are expected to be an overall driving force for nextgeneration wireless functionalities MANET Extending the Infrastructure Key Elements of MANETs  Formed dynamically through the cooperation of independent nodes  Nodes do not have any pre-specified roles  Nodes make decision independently based on the current network situation  Nodes are expected to behave as routers  As routers, nodes must assist in discovery and maintenance of network routes Formation of a MANET B A C Mobile Ad Network – HOME MANET Design complexities & Constraints           Infrastructureless with distributed management Frequent and unpredictable topology changes Physical layer limitation Limited link bandwidth and quality Variation in node capabilities Energy Considerations Network reliability Network security Network scalability Quality of service MANET Management    Multihop network – each device must carry burden of routing packets from source to destination Each Node handles part of the management of the network Fault detection is extremely difficult because of the distributed design MANAET Distributed Management MANET Topology B A C  Topology changes occur with every move of a mobile node  Every topology change results in route changes  Route changes lead to network partitions and in most instances some packet losses MANET Physical Layer  Limited wireless range and shared frequency space leads to specific mobile ad hoc problems  High risk of collisions and packet losses  Hidden terminal problems  Exposed terminal problem Collision Risk and Packet Loss A B C  Node A and Node B simultaneously try to communicate with Node C. Their traffic collides and both packets are lost at Node C. Hidden Terminal Exposed Terminal MANET Congestion Control Adapted Ready-to-Send (RTS)/Clear-to-Send (CTS) protocols are the current resolutions to MANET congestion control, hidden terminal and exposed terminal problems. MANET Bandwidth Constraints  Bandwidth used by MANETs has a wide range of capacity levels.  Wireless bandwidth in general is more error-prone than wired links.  Wireless bandwidth in general is more insecure than wired links.  These factors lead to lower capacity throughput than equivalent wired links.  The lower capacity wireless links lead to higher congestion problems. MANET Node Variability  Nodes may have one or more radio interfaces of varying transmission capabilities  Node radios may operate in different frequency bands  Node radio capabilities may result in asymmetric links  Node hardware and software configurations can affect processing capabilities MANET Node Variability MANET Energy Constraints  Link Distance  Controlled through topology management  Goal is to reduce overall network power consumption as much as possible through assignment of per node transmit power levels  Routing Protocols  Minimizing routing paths reduces power needed to send a packet end-to-end  Transmit power levels can greatly affect the ability of the network to control congestion  Hidden terminal problems arise MANET Power Considerations MANET Reliability  Reliability occurs by routing and forwarding packets  Network overload  Misbehaving nodes  Broken links  No centralized management makes these problems difficult to detect and isolate  Reliability thus must rely on properly designed protocols MANET Security  Mobile networks are physically insecure  Distributed management means overall security is dependent on individual node security  MANET security considerations  Confidentiality – prevent eavesdropping  Access control – protecting the wireless infrastructure  Data integrity – preventing tampering of traffic  Denial of service Wireless Eavesdropping A B C  Wireless eavesdropping can be performed by anyone who has a radio receiver that is compatible with the signaling used by the Ad Hoc network MANET Scalability  Scalability is critical to the successful deployment of a MANET  Factors affecting MANET scalability        Addressing Routing Location management Configuration management Interoperability Security High-capacity wireless technologies MANET Service Quality  Quality of Service is of key importance to all a networks  MANETs makes the task of maintaining QoS more difficult MANET Applications   Tactical Networks – Military communications and operations control in battlefield environments. Sensor Networks – Collection of embedded sensor devices used to collect real-time data to automate everyday functions.  Weather monitoring  Earth activities  Manufacturing Equipment automation Emergency Services – Search-and rescue operations as well as disaster recovery and medical needs.  Patient records retrieval at point of contact  Loss of infrastructure due to catastrophic disaster Commercial Environments – electronic commerce  Make and receive payments from anywhere  Access customer records from the field  Vehicular access of road conditions, weather, or local news Home and Enterprise Networking  Anywhere access for PDA  Personal area networks Educational Applications – virtual classrooms or conference rooms for use during conferences, meetings or lectures. Entertainment – Multiuser games, robotic pets, and outdoor Internet access. Location-aware Services – Follow-on services  Call forwarding anywhere  Transmission of actual workspace to current location  Advertise location specific services  Location specific travel guides  Service availability information       Mobile Ad Hoc Networks Ad hoc wireless networks eliminate the constraints of infrastructure and enable devices to create and join networks on the fly – any time, anywhere – for virtually any application. MANETs and MESH Networks  Combining two point-to-point or point-to-multipoint MANETs begins the basic design of a MESH network.  MESH networks are semi-mobile. The network nodes may change but the overall coverage is somewhat constant.  MESH networks have dedicated routing nodes where every node in an MANET is a routing node.  MANETs slowly develop into MESH networks as the number of nodes increases.  MESH nodes normally are connected to every other node within range creating a mesh of coverage paths. MESH Network Characteristics  Robust network routing  Routing addresses congestion concerns  Routing addresses line of sight concerns  Node density increases network throughput  Purely dynamic mesh is not suitable for large scale deployment at this time.  Development of protocols for the dynamic nature are still needed  Development of protocols for address assignment in a mobile environment are still needed.  MESH networks are usually designed to cover large geographic regions than MANETs. MESH Network Example A B Route Discovery      (a) Range of A's broadcast. (b) After B and D have received A's broadcast. (c) After C, F, and G have received A's broadcast. (d) After E, H, and I have received A's broadcast. Shaded nodes are new recipients. Arrows show possible reverse routes. Route Discovery (2) Format of a ROUTE REQUEST packet. When a route request arrive (B and D)  Source address and ID is looked up : no duplicate  If route is known then Route Reply, else next step  Increment hop count and rebroadcast the Route Request Route Discovery (3) Format of a ROUTE REPLY packet. Route Maintenance B 3 F F 3 (a) D's routing table before G goes down. (b) The graph after G has gone down. Use periodic Hello MANET and MESH Differences Logical MANET Network Logical MESH Network Large Scale MESH Networks  Large Scale deployments are possible with the proper design in place to provide routing nodes connected to wireline networks.  Current large scale projects include research into Providing Metropolitan Area Network service across a MESH topology. WiMAX  Worldwide Interoperability for Microwave Access  Telecommunications technology providing wireless data over long distances in a variety of ways  FROM Point-to-Point links TO full mobile cellular type access Current devices  The list is growing every day! Advantages  Carrier Class, High-Speed, Wireless Broadband  Lower cost that cellular  Greater range than WiFi, Up to 3000 square miles! Frequency  Non line of site uses 2 Ghz to 11 Ghz. (Similar to WiFi)  Line of site as high as 66 Ghz. WiMAX Forum  WiMAX was created by WiMAX Forum in June 2001.  Industry-led, not-forprofit corporation  Dedicated to certifying the interoperability of WiMAX Products WiMAX Forum Certified  Products and marketing materials pass conformance and interoperability testing  Display certification Forum WiMAX Description A standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL. www.wimaxforum.org WiMAX versus WiFi  Long range system covering kilometers  Similar to Cell phone  Quality Service mechanism between Base Station and user device  Highly scaleabe  Shorter range system covering hundreds of meters  Similar to Cordless Phone  Quality Service mechanism similar to fixed Ethernet Different Providers     Cellular Operators Wireline Carriers Cable Operators MSO-multiple system operators Main WiMAX Competitors  Nortel  Intel  Sprint Nextel WirelessMAN  WirelessMAN is based on IEEE 802.16 standard.  WiMAX allows user to browse internet from laptop computer without wall jack. IEEE Standards  Fixed WiMAX-systems built using 802.16e-2004(802.16d) air interface technology  Mobile WiMAX – systems built using 802.16e-2005 air interface technology Key Value  Guaranteed interoperability between networks and devices from multiple vendors  A Key Value that ensures a competitive and dynamic industry References  http://wi-fitechnology.com/papers+reqshowcontent-ie-7-page-2.html  http://www.sigcomm.org/sigcomm2006/?tutori als  http://www.commsdesign.com/showArticle.jht ml;jsessionid=2FYCYRNWG2MY0QSNDLRCKH0 CJUNN2JVN?articleID=160911814  Basagni, Stefani, Conti, Marco, Giordano, Silva, Stojmenovic, Ivan (2004). Mobile Ad Hoc Networking. Wiley & Sons, Inc, New Your. References Cont      www://intel.com www://nortel.com www://youtube.com www.apertonet.com http://www.wimaxforum.org/home/