Wireless Routing Protocols Mobile Ad hoc NETwork MANET

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Wireless Routing Protocols--- Mobile Ad hoc
NETwork (MANET)

• Prof. Gao
• ECE697J Spring 2005
• Advanced Computer Networks

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Outline

• MANET overview
• Routing in MANET
• Routing with constraints
• Open issues and future directions

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Point-to-multipoint networks

• Cellular networks
• IEEE 802.11

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Mobile Ad Hoc Networks

• Formed by wireless autonomous hosts
• Without (necessarily) using a pre-existing
  infrastructure
• Routes between hosts may potentially contain
  multiple hops
• Host mobility causes route changes
• Shared wireless channel

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Why Ad Hoc Networks ?

• Ease of deployment
• Speed of deployment
• Decreased dependence on infrastructure
• User flexibility

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Application areas

• Military environments
• Battle field sensors, soldiers, vehicles
• Emergency operations
• search-and-rescue
• policing and fire fighting
• Civilian environments
• conference halls
• sports stadiums, Library, etc.
• Personal area networking
• laptop, PDA, cell phone, ear phone, wrist watch

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Challenges

• Lack of centralized entity
• Shared unreliable wireless medium
• Low bandwidth
• Hidden/exposure node effect
• Ease of snooping on wireless transmissions
• Mobility-induced route changes/packet losses
• Battery constraints
• Asymmetric Capabilities
• transmission ranges
• battery life
• processing capacity
• Speed/pattern of movement

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Routing in MANET

• Host mobility
• link failure/repair due to mobility
• different characteristics than those due to other
  causes
• Rate of link failure/repair may be high when
  nodes move fast
• New performance criteria may be used
• Route stability despite mobility
• Packet delivery ratio
• Routing overhead

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Ad hoc Routing Protocols

• Proactive protocols (DSDV)
• Reactive protocols (AODV, DSR)
• Hybrid protocols (OLSR, ZRP, CEDAR)
• Which approach achieves a better trade-off
  depends on the traffic and mobility patterns

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Proactive Protocols

• Destination-Sequenced Distance-Vector (DSDV)
• Features
• Traditional distributed shortest path routing
  protocols
• distance-vector protocol
• Continuously update the reachability
  information at all the network nodes
• Lower route request latency and higher overhead

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Reactive Protocols

• Ad hoc On Demand Distance Vector Protocol (AODV)
• Dynamic Source Routing Protocol (DSR)
• Features
• Maintain routes only if needed
• Flooding of control message
• higher latency and lower overhead
• Source routing/hop-by-hop routing

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Hybrid Protocols

• Optimized Link State Routing Protocol (OLSR)
• Zone Routing Protocol (ZRP)
• Core-Extraction Distributed Ad hoc Routing
  (CEDAR)
• Features
• Constrained link state maintenance
• Route established on-demand

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Other Constraints

• Power
• Security
• QoS

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Power-Aware Routing

• Define optimization criteria as a function of
  energy consumption.
• Examples
• Minimize energy consumed per packet
• Minimize time to network partition due to energy
  depletion
• Maximize time to a node failure due to energy
  depletion

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Power-Aware Routing approach

• Assign a weight to each link
• Weight of a link may be a function of
• energy consumed when transmitting a packet on
  that link
• residual energy level
• Prefer a route with the smallest aggregate weight

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Security Issues in Mobile Ad Hoc Networks

• Ad hoc network based on peer cooperation
• Can you trust your peer?
• Wireless medium is easy to snoop on
• Trace the path of active routes
• Easier for intruders to insert themselves into
  the network
• Everybody is a router
• inject erroneous routing information
• divert network traffic, or
• make routing inefficient

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Open Problems

• Address assignment problem
• Stationary or auto-configuration?
• Cross layer design
• Might need feedback from MAC to detect link
  status
• Position information from higher layer
• Integration with Internet
• Existing ad hoc routing with infrastructure nodes
• Heterogeneous networks