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Qo S Routing In Ad Hoc Networks
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Qo S Routing In Ad Hoc Networks



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  • 1. QoS Routing in Ad Hoc Networks --Literature Survey Presented by: Li Cheng Supervisor: Prof. Gregor v. Bochmann
  • 2. Outline
    • QoS routing overview: targets and challenges
    • Classification of QoS routing protocols
    • Typical QoS routing protocols
    • Conclusion and Open Issues
    Video frame without QoS Support Video frame with QoS Support
  • 3. Features of MANET
    • Mobile Ad-hoc Network
    • Definition: a self-configuring network of mobile routers (and associated hosts) connected by wireless links—the union of which form an arbitrary topology ( www.wikipedia.org )
    • Features
      • Dynamic and frequently changed topology
      • Self-organizing
      • Nodes behaving as routers
      • Minimal configuration and quick deployment
      • Limited resources
  • 4. Ad Hoc vs. Cellular Networks
    • Multi-hop route vs. One-hop route
      • In an Ad Hoc network, every nodes has to behave as a router
    • Self-administration vs. Centralized Administration
      • Ad hoc networks are self-creating , self-organizing , and self-administering
    PSTN MSC OMC AC VLR BSC BSC BSC BTS BTS BTS MS Cellular wireless network Ad Hoc wireless network GMSC HLR MS
  • 5. Target of QoS Routing
    • To find a feasible path between source and destination, which
      • satisfies the QoS requirements for each admitted connection and
      • Optimizes the use of network resources
    A B C D E F G <2,4> <3,3> <4,5> Tuple: <BW,D> QoS requirement: BW≥4 <2,2> <5,4> <4,4> <5,3> <4,2> <3,4> Shortest path QoS Satisfying path
  • 6. Challenges of QoS Routing in Ad Hoc Networks
    • Dynamic varying network topology
    • Imprecise state information
    • Scare resources
    • Absence of communication infrastructure
    • Lack of centralized control
    • Power limitations
    • Heterogeneous nodes and networks
    • Error-prone shared radio channel
    • Hidden terminal problem
    • Insecure medium
    • Other layers
  • 7. Criteria of QoS Routing Classification
    • Routing information update mechanism
      • Proactive/table-driven: QOLSR, EAR
      • Reactive/On-demand: QoSAODV, PLBQR, TBP
      • Hybrid: CEDAR
    • Use of information for routing
      • Information of past history: QOLSR, QoSAODV, TBP
      • Prediction: PLBQR
    • State maintenance
      • Local: PLBQR, CEDAR
      • Global: TDMA_AODV, TBP
    • Routing topology
      • Flat: QOLSR, QoSAODV, PLBQR, TBP
      • Hierarchical: CEDAR
    • Interaction with MAC layers
      • Independent: PLBQR, QoSAODV, TBP
      • Dependent: CEDAR, PAR
    • Number of Path Discovered
      • Single path: QoSAODV , CEDAR, PLBQR
      • Multiple paths: TDMA_AODV, TBP
    • Utilization of Specific Resources
      • Power aware routing: PAR, EAR
      • Geographical information assisted routing: PLBQR
  • 8. Typical Routing Mechanism
    • Proactive routing: QOLSR
    • Reactive routing: QoSAODV
    • Ticket-based Routing: TBP
    • Hierarchical Routing: CEDAR
    • Predictive & Location-based routing: PLQBR
    • Power aware routing
  • 9. Proactive QoS Routing: QOLSR
    • Optimized Link State Routing [RFC3626]
    • Aiming at large and dense MANETs with lower mobility
    • Only selected nodes as multi-point relays (MPRs) forwards broadcasting messages to reduce overhead of flooding
    • MPR nodes periodically broadcast its selector list
    • QoS extensions
      • QOLSR [IETF Draft] : Hello messages and routing tables are extended with parameters of maximum delay and minimum bandwidth , and maybe more QoS parameters
    • Advantage: ease of integration
    • in Internet infrastructure
    • Disadvantages: Overhead to keep
    • tables up to date
    Black nodes: MPRs
  • 10. Reactive QoS Routing: QoS Enabled AODV
    • AODV: Ad-hoc On-demand Distance Vector routing [RFC3561]
    • Best effort routing protocol
    • On need of a route, source node broadcasts route request(RREQ) packet
    • Destination, or an intermediate node with valid route to destination, responses with a route reply(RREP) packet.
    • QoS extensions [IETF Draft] : maximum delay and minimum bandwidth are appended in RREQ, RREP and routing table entry
    • Disadvantages
      • No resource reservation, which unable to guarantee QoS
        • Improved with bandwidth reservation: TDMA_AODV [7]
      • Traversal time is only part of delay
    RREQ1 (delay=100) RREQ1 (delay=70) RREQ1 (delay=20) RREP1 (delay=0) RREP1 (delay=50) RREP1 (delay=80) Delay(C->D)=50 QAODV example: Delay Requirement Source Node A Node B Traversal_time=30 Delay(B->D)=80 Node C Traversal_time=50 Dest. Node D RREQ2 (delay=20) Rejected!
  • 11. Ticket-based Probing [5] : Features
    • Objective: To find delay/bandwidth-constrained least-cost paths
    • Source-initiated path discovery, with limited tickets in probe packets to decrease overhead
    • Based on imprecise end-to-end state information
    • QoS metrics: Delay and bandwidth
    • Redundancy routes for fault tolerance during path break
    • Destination initiated Resource Reservation
    A B C D E p 1 (1) p 2 (2) p 3 (1) p 4 (1) p 4 (1) p 1 (1)
  • 12. Tickets-relative Issues
    • Colored tickets: yellow ones for smallest delay paths, green ones for least cost paths
    • For source node, how many tickets shall be issued?
      • more tickets are issued for the connections with tighter or higher requirements
    • For intermediate nodes, how to distribute and forward tickets?
      • the link with less delay or cost gets more tickets
    • How to dynamically maintain the multiple paths?
      • the techniques of re-routing, path redundancy, and path repairing are used
  • 13. Disadvantages and Enhancement of TBP
    • Enhanced TBP Algorithm [13]
      • Color-based ticket Distribution
      • Ticket optimization using historical probing results
    • Disadvantages
      • Based on assumption of relatively stable topologies
      • Global state information maintenance with distance vector protocol incurs huge control overhead
      • Queuing delay and processing delay of nodes are not taken into consideration
    Ticket blocking Color-based ticket distribution
  • 14. Hierarchical Routing: CEDAR [6]
    • Core Extraction Distributed Ad Hoc Routing
    • Oriented to small and middle size networks
    • Core extraction: A set of nodes is distributivedly and dynamically selected to form the core, which maintains local topology and performs route calculations
    • Link state propagation: propagating bandwidth availability information of stable high bandwidth links to all core nodes, while information of dynamic links or low bandwidth is kept local
    • QoS Route Computation:
      • A core path is established first from dominator (neighboring core node) of source to dominator of destination
      • Using up-to-date local topology, dominator of source finds a path satisfying the requested QoS from source to furthest possible core node
      • This furthest core node then becomes the source of next iteration.
      • The above process repeats until destination is reached or the computation fails to find a feasible path.
  • 15. CEDAR: routing example G H D B F K E J C A S G H D B F K E J C A S G H D B F K E J C A S Links that node E aware of Partial Route constructed by B
    • Core Node
    • Links that node B aware of
    Complete, with last 2 nodes determined by E Node S informs dominator B
    • Disadvantages of CEDAR:
      • Sub-optimal route
      • Core nodes being bottleneck
  • 16. Predictive Location-based QoS Routing: PLBQR [8]
    • Motivation: to predict a future physical location based on previous location updates, which in turn to predict future routes
    • Update protocol: each node broadcasts its geographical update and resource information periodically and in case of considerable change
    • Location and delay prediction:
      • Using similarity of triangles and
      • Pythagoras’ theorem,
      • (x p ,y p ) can be calculated
      • End-to-end delay from S to D
      • is predicted to be same as delay of latest update from D to S
    • QoS routing
      • Neighbor discovery with location-delay prediction
      • Depth-first search to find candidate routes satisfied QoS requirements
      • Geographically shortest route is chosen
      • Route is contained in data packets sent by source
    • Disadvantages
      • No resource reservation
      • Inaccuracy in delay prediction
    Direction of motion Predicted location (x 2 , y 2 ) at t 2 (x 1 , y 1 ) at t 1 (x p , y p ) at t p v(t p -t 2 )
  • 17. Power-aware QoS Routing
    • Objective:
      • to evenly distribute power consumption of each node
      • to minimize overall transmission power for each connection
      • to maximize the lifetime of all nodes
    • Power-Aware Routing [9] : using power-aware metrics in shortest-cost routing
      • Minimize cost per packet, with cost as functions of remaining battery power
      • Minimize max node cost of the path to delay node failure
    • Maximum battery life routing [10] : Conditional Max-Min Battery Capacity Routing (CMMBCR)
      • To choose shortest path if nodes in possible routes have sufficient battery
      • Avoiding routes going though nodes whose battery capacity is below threshold
    • Energy Aware Routing [11] : selecting path according to its probability, which is inversely proportional to energy consumption, using sub-optimal paths to increase network survivability
  • 18. Conclusion
    • QoS routing is key issue in provision of QoS in Ad Hoc networks
    • Number of QoS routing approaches have been proposed in literature, focusing on different QoS metrics
    • No particular protocol provides overall solution
    • Some Open Issues
      • QoS metric selection and cost function design
      • Multi-class traffic
      • Scheduling mechanism at source
      • Packet prioritization for control messages
      • QoS routing that allows preemption
      • Integration/coordination with MAC layer
      • Heterogeneous networks
  • 19. Primary References
    • [1] T.Clausen, P.Jacquet, Optimized Link State Routing Protocol(OLSR), IETF RFC3626 , Oct.2993.
    • [2] H.Badis, K.Agha, Quality of Service for Ad hoc Optimized Link State Routing Protocol (QOLSR), IETF Draft , Oct.2005
    • [3] C.Perkins, E. Royer and S. Das, Ad hoc On-Demand Distance Vector (AODV) Routing, IETF RFC3561 , Oct.2993.
    • [4] C.Perkins, E. Royer and S. Das, Quality of Service for Ad hoc On-Demand Distance Vector Routing, IETF Draft , Jul.2000.
    • [5] S.Chen,K.Nahrstedt, Distributed Quality-of-Service Routing in Ad Hoc Network, IEEE Journal on Selected Areas in Commun, Aug 1999.
    • [6] R.Sivakumar, P.Sinda and V. Bharghavan, CEDAR: A Core-Extraction Distributed Ad Hoc Routing Algorithm, IEEE Journal on Selected Areas in Commun, Aug 1999 .
    • [7] C.Zhu, M.Corson, QoS routing for mobile ad hoc networks, IEEE Infocom 2002.
    • [8] S.Shah, K.Nahrstedt, Predictive Location-Based QoS Routing in Ad Hoc Networks, IEEE ICC 2002 .
    • [9] S. Singh, M.Woo and C.Raghavendra, Power-aware Routing in Mobile Ad Hoc Networks, MOBICOM’98 .
    • [10] C. Toh, Maximum Battery Life Routing to Support Ubiquitous Mobile Computing in Wireless Ad Hoc Networks, IEEE commun, Magazine , Jun 2001.
    • [11] R Shah, J.Rabaey, Energy Aware Routing for Low Energy Ad Hoc Sensor Networks, IEEE WCNC 2002.
  • 20. Secondary References
    • [12] S.Chen,K.Nahrstedt, Distributed QoS Routing with Imprecise State Information, IEEE ICCCN’98.
    • [13] L.Xiao,J.Wang and K.Nahrstedt, The Enhanced Ticket-based Routing Algorithm, IEEE ICC , 2002
    • [14] C.Murthy, B.Manoj, Ad Hoc Wireless Networks, Pentice Hall , 2004
    • [15] M.Ilyas, I.Mahgoub, Mobile Computing Handbook, Auerbach Publications , 2005
    • [16] S.Chakrabarti, A.Mishra, QoS Issues in Ad Hoc Wireless Networks, IEEE Commun. Magzine, Feb. 2001
  • 21. Thanks for your time Any Questions?