QoS Routing in Ad Hoc Networks --Literature Survey

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 Li Cheng, ELG5125

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 Li Cheng, ELG5125

4. MS GMSC HLR 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 OMC AC BSC BTS PSTN MSC BSC BTS VLR BSC MS Ad Hoc wireless network BTS Cellular wireless network Li Cheng, ELG5125

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 <5,4> <4,5> C B A <4,2> <5,3> <2,4> Tuple: <BW,D> QoS requirement: BW≥4 <3,4> E F <3,3> D <2,2> <4,4> Shortest path G QoS Satisfying path Li Cheng, ELG5125

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 Li Cheng, ELG5125

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 Li Cheng, ELG5125

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 Li Cheng, ELG5125

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 Li Cheng, ELG5125

10. RREQ2 (delay=20) Source Node A Node B Traversal_time=30 Node C Traversal_time=50 Dest. Node D Rejected! Delay(B->D)=80 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) Delay(C->D)=50 RREP1 (delay=80) RREP1 (delay=50) RREP1 (delay=0) QAODV example: Delay Requirement Li Cheng, ELG5125

11. B p1(1) p1(1) A C p2(2) p3(1) p4(1) D E p4(1) 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 Li Cheng, ELG5125

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 Li Cheng, ELG5125

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 Li Cheng, ELG5125

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. Li Cheng, ELG5125

15. CEDAR: routing example G A • Core Node • Links that node B aware of H B C D E F S K J Node S informs dominator B G A H B C D E F Links that node E aware of Partial Route constructed by B S J K G A • Disadvantages of CEDAR: • Sub-optimal route • Core nodes being bottleneck H B C D E F S J K Complete, with last 2 nodes determined by E Li Cheng, ELG5125

16. Predicted location (xp, yp) at tp v(tp-t2) (x2, y2) at t2 Direction of motion (x1, y1) at t1 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, (xp,yp) 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 Li Cheng, ELG5125

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 Li Cheng, ELG5125

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 Li Cheng, ELG5125

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. Li Cheng, ELG5125

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 Li Cheng, ELG5125

21. Thanks for your time Any Questions? Li Cheng, ELG5125