Introduction to Ad Hoc Networking

1. Introduction to Ad Hoc Networking Perkin’s book: Ch 1 and Ch 2. Some data collected from the Internet by Prof. Yu-Chee Tseng

2. Model of Operations

3. Assumptions • Symmetric Links: • unidirectional links are difficult to dealt with, and sometimes at the verge of failure • Layer-2 Routing: • Most protocols are presented in layer-3 routing, but can be easily retooled as a layer-2 ones. • Proactive vs. Reactive Protocols • (to be elaborated later)

4. Applications • ad hoc conferencing • home networking • emergency services • personal area network (PAN) • ubiquitous computing • “computers are all around us, constantly performing mundane tasks to make our lives a litter easier” • “Ubiquitous intelligent internetworking devices that detect their environment, interact with each other, and respond to changing environmental condition will create a future that is as challenging to imagine as a science fiction scenario.”

5. Sensor Dust: • a large collection of tiny sensor devices • once situated, the sensors remain stationary • largely homogeneous • power is likely to be a scarce resource, which determines the lifetime of the network • can offer detailed information about terrain or environmental dangerous conditions. • Intelligent Transportation System: • may be integrated with cars, positioning devices, etc.

6. Technical Factors • scalability • power budget vs. latency • protocol deployment and incompatibility standards • “Unless a miracle happens (e.g., the IETF manet working group is able to promulgate a widely deployed ad hoc networking protocol), ad hoc networks will gain momentum only gradually because users will have to load software or take additional steps to ensure interoperability. • wireless data rate • e.g., TCP over multi-hop wireless links • security issues

7. More Extensions (DoD’s Perspective) • could be a group of hosts supported by one or more radios • could across the Internet

8. IEFT MANET Working Group • goal: • to standardize an interdomain unicast routing protocol which provides one or more modes of operation, each mode specialized for efficient operation in a given mobile networking “context”, where a context is a predefined set of network characteristics. • a dozen candidate routing protocols have been proposed.

9. Applications of Ad Hoc Networks

10. No Infrastructure (ad hoc networks): no base stations; no fixed network infrastructure Network Architectures

11. MANET • MANET = Mobile Ad Hoc Networks • multi-hop communication • needs support of dynamic routing protocols

13. Routing = Ants Searching for Food ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?

15. Three Main Issues in Ants’ Life • Route Discovery: • searching for the places with food • Packet Forwarding: • delivering foods back home • Route Maintenance: • when foods move to new place

16. Proactive vs. Reactive Routing • Proactive Routing Protocol: • continuously evaluate the routes • attempt to maintain consistent, up-to-date routing information • when a route is needed, one may be ready immediately • when the network topology changes • the protocol responds by propagating updates throughout the network to maintain a consistent view • Reactive Routing Protocol: • on-demand • Ex: DSR, AODV

17. ON-DEMAND-DRIVEN REACTIVE DSDV CGSR AD-HOC MOBILE ROUTING PROTOCOLS HYBRID TABLE DRIVEN/ PROACTIVE DSR AODV ZRP Ad hoc routing protocols

18. DSDV • Destination Sequenced Distance Vector • Table-driven • Based on the distributed Bellman-Ford routing algorithm • Each node maintains a routing table • Routing hops to each destination • Sequence number

19. DSDV • Problem • A lot of control traffic in the network • Solution • two types of route update packets • Full dump • All available routing information • Incremental • Only information changed since the last full dump

20. C2 C1 M2 C3 Clustering Protocol • Cluster Gateway Switch Routing (CGSR) • Table-driven for inter-cluster routing • Uses DSDV for intra-cluster routing

21. AODV • Ad hoc On-demand Distance Vector • On-demand driven • Nodes that are not on the selected path do not maintain routing information • Route discovery • The source node broadcasts a route request packet (RREQ) • The destination or an intermediate node with “fresh enough” route to the destination replies a route reply packet (RREP)

22. Destination N2 N8 Destination N5 N2 N8 N5 Source N1 N7 N4 Source N1 N7 N4 N3 N6 N3 N6 AODV (a) RREQ (b) RREP

23. AODV • Problem • A node along the route moves • Solution • Upstream neighbor notices the move • Propagates a link failure notification message to each of its active upstream neighbors • The source node receives the message and re-initiate route discovery

24. DSR • Dynamic Source Routing • On-demand driven • Based on the concept of source routing • Required to maintain route caches • Two major phases • Route discovery • Route maintenance • A route error packet

25. N1-N2 N1-N2-N5 N8 N2 N5 N1 N1-N3-N4 N1-N3-N4-N7 N1-N2-N5-N8 N1-N2-N5-N8 N2 N8 N1 N7 N5 N4 N1-N2-N5-N8 N1-N3-N4 N1 N1-N3 N1 N7 N1-N3-N4-N6 N4 N3 N1-N3-N4 N6 N3 N6 DSR

26. ZRP • Zone Routing Protocol • Hybrid protocol • On-demand • Proactive • ZRP has three sub-protocols • Intrazone Routing Protocol (IARP) • Interzone Routing Protocol (IERP) • Bordercast Resolution Protocol (BRP)

27. Zone of Node Y Bordercasting Border Node Zone of Node Y Zone Radius = r Hops Border Node Node X Node Z Zone of Node X Zone of Node Z

28. LAR • Location-Aided Routing • Location information via GPS • Shortcoming • GPS availability is not yet worldwide • Position information come with deviation

29. Request Zone Expected Zone (Xd+R, Yd+R) DEST R (Xd,Yd) SRC (Xs,Ys) LAR

30. N2 N1 SRC DEST + – + – + – + – + – + – N3 N4 PAR • Power-Aware Routing