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From Ad Hoc to ICEBERG: differences in two wireless network environments. Zhigang Gong [email protected] August 9, 2002. Computer Science and Engineering Department University of Minnesota Wireless Networking Seminar. Outline. Ad Hoc What is ad hoc network? Why ad hoc network?

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From ad hoc to iceberg differences in two wireless network environments l.jpg

From Ad Hoc to ICEBERG: differences in two wireless network environments

Zhigang Gong

[email protected]

August 9, 2002

Computer Science and Engineering Department

University of Minnesota

Wireless Networking Seminar

Outline l.jpg
Outline environments

  • Ad Hoc

    • What is ad hoc network?

    • Why ad hoc network?

    • What are the interesting research topics?


    • What is ICEBERG?

    • Why study ICEBERG?

    • How can we take it further?

What are ad hoc networks l.jpg
What are Ad Hoc Networks environments

  • In Latin, ad hoc means "for this," further meaning "for this purpose only.”

  • An ad-hoc network is a LAN or other small network, especially one with wireless connections, in which some of the network devices are part of the network only for the duration of a communications session or, in the case of mobile or portable devices, while in some close proximity to the rest of the network.

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Definition for Mobile Ad-hoc environments

  • A "mobile ad hoc network" (MANET) is an autonomous system of mobile routers (and associated hosts) connected by wireless links--the union of which form an arbitrary graph. The routers are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet. -------- IETF

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Characteristics of ad hoc wireless network environments

  • Autonomous (no infrastructure !);

  • Wireless link based; (bandwidth constraint)

  • Dynamic topology; (Due to movement or entering sleep mode);

  • Rely on batteries for energy; (Power-constraint)

  • Limited physical security;

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Why ad hoc wireless networking? environments

  • Technical side:

    • wireless devices need to be connected;

    • increased performance/cost ratio on devices

    • Internet compatible standards-based wireless systems;

  • Market side:

    • mobile computing; wearable computing; military applications; disaster recovery; robot data acquisition

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Research Challenges (I) environments

  • MAC layer problems:

    • Link layer reliability

    • QoS at MAC layer

    • Power conservation

  • Network layer problems: Mobile IP

    • Routing;

    • QoS

    • Power conserving

    • Multicast

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Research Challenges (II) environments

  • Transport layer problems: (TCP over Ad hoc)

    • End-to-end reliability?

    • Congestion control?

    • QoS?

  • Application layer:

    • Security?

    • QoS?

  • Inter-layer interactions;

  • Internetworking with internet;

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Main problem: Routing environments

  • Standard (Mobile) IP needs an infrastructure

    • Home Agent/Foreign Agent in the fixed network

    • DNS, routing etc. are not designed for mobility

  • No infrastructure in Ad hoc networks

  • Main topic: routing

    • no default router available

    • every host (node) should be able to forward packets

Routing in an ad hoc network l.jpg
Routing in an ad-hoc network environments











good link

weak link

time = t1

time = t2

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Traditional routing algorithms environments

  • Distance Vector

    • periodic exchange of messages with all physical neighbors that contain information about who can be reached at what distance

    • selection of the shortest path if several paths available

  • Link State

    • periodic notification of all routers about the current state of all physical links

    • router get a complete picture of the network

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Problems of traditional routing algorithms environments

  • Dynamic of the topology

    • frequent changes of connections, connection quality, participants

  • Limited performance of mobile systems

    • periodic updates of routing tables need energy without contributing to the transmission of user data, sleep modes difficult to realize

    • limited bandwidth of the system is reduced even more due to the exchange of routing information

  • Problem: protocols have been designed for fixed networks with infrequent changes and typically assume symmetric links

Routing unicast l.jpg
Routing (Unicast) environments

  • Table Driven: DSDV, WRP, etc

  • On-demand Driven: AODV, TORA, DSR, ABR, SSR, ……

  • Zone Routing Protocol (ZRP)

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DSDV (Destination Sequenced Distance Vector) environments

  • Expansion of distance vector routing

  • Sequence numbers for all routing updates

    • assures in-order execution of all updates

    • avoids loops and inconsistencies

  • Decrease of update frequency

    • store time between first and best announcement of a path

    • inhibit update if it seems to be unstable (based on the stored time values)

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Dynamic source routing (DSR) environments

  • Split routing into discovering a path and maintaining a path

  • Discover a path

    • only if a path for sending packets to a certain destination is needed and no path is currently available

  • Maintaining a path

    • only while the path is in use one has to make sure that it can be used continuously

  • No periodic updates needed!

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Dynamic Source Routing environments – Internet-Draft

  • Characteristics:

    • On-demand

    • Unidirectional links and asymmetric routes are supported

  • Route Discovery:

    • S-D route is included in the header of each packet.

    • Nodes forwarding or overhearing data packets may cache multiple routes for any D for future use (uni-directional?)

  • Route Maintenance: on-demand

    • Link failure detection: MAC layer (802.11) or Passive ACK or clear request for ACK

    • Link ERR is propagated to source

    • Use an cached new route or rediscover

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Dynamic Load-Aware Routing environments

  • On-demand, backward learning

    • S floods REQ, D choose route by-- Total buffered packets, Average buffered packets, or Least number of congested routers

    • D detects over-loaded route dynamically and initiates route-setup procedure to S.

      • Load information in I is piggybacked periodically on data packets

    • When link failure, the upstream I sends ERR to S and removes its entry. S initiates new route setup procedure.

    • I does not reply REP even it knows a route to D

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Mitigating routing misbehavior environments

  • It is impossible to build a perfect network

    • Routing denial of service

    • Unexpected events, bugs, etc.

  • Incorporate tools within the network to detect and report on misbehavior

    • Route only through trusted nodes

      • Requires a trust relationship

      • Requires key distribution

      • Trusted nodes may still be overloaded or broken or compromised

      • Untrusted nodes might perform well

    • Detect and isolate misbehaving nodes

      • Watchdog detects the nodes

      • Pathrateravoids routing packets through these nodes

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Routing (Multicast) environments

  • Multicast is still a hot topic even in Internet;

  • In Ad Hoc, besides of those problems in traditional Internet, such as congestion control, routing for multicast is another big problem;

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Other researches on Routing environments

  • QoS support routing;

  • Power conserving routing;

Iceberg l.jpg
ICEBERG environments


  • ICEBERG: Internet-based core for CEllular networks BEyond the thiRd Generation

  • Internet-based integration of telephony and data services spanning diverse access networks

    • Leverage Internet’s low cost of entry for service creation, provision, deployment and integration

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Why ICEBERG environments

  • 3G+ will enable many communication devices and networks – diversity

  • Mobility for transparent information access

  • New applications: audio, video, multimedia

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Design Goals environments

  • Potentially Any Network Services (PANS):

    • Network and device independent

  • Personal Mobility:

    • person as communication endpoint; requires a single identity for an individual - iUID

  • Service Mobility:

    • seamless mobility across different devices in the middle of a service session

  • Easy Service Creation and Customization

  • Scalability, Availability and Fault Tolerance

  • Operation in the Wide Area

  • Security, Authentication and Privacy

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PSTN environments




















ICEBERG Architecture Overview

Access Network





Clearing House

ISP Plane




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ICEBERG Components environments

  • ICEBERG Access Point (IAP):

    • A gateway serves as a bridge

  • Call Agent (CA):

    • call setup and control

  • Name Mapping Service (NMS):

    • mapping between communication endpoint and the iUID

  • Preference Registry (PR):

    • stores user profile

  • Personal Activity Coordinator (PAC):

    • tracks dynamic info of a person that is of her interest

  • Automatic Path Creation Service (APC):

    • establishes and manipulates data flow

Ipop on cluster computing platforms l.jpg
iPOP on Cluster Computing environmentsPlatforms

  • Ninja Base and Active Service Platform (AS1)

  • Clusters of commodity PCs interconnected by a high-speed SAN, acting as a single L-S computer

  • mask away cluster management problems

    • Load balancing, availability, failure management

  • Ninja: highly available service initiation

    • Redirector stub

    • Good for long running services such as web servers

  • AS1: fault tolerant service session

    • Client heartbeat with session state

    • Good for session-based services such as video conferencing

An illustration l.jpg

4 environments










An Illustration










Clearing House

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What’s their difference? environments

  • ICEBERG is an integrated service architecture to link any digital network with the Internet.

  • Ad Hoc is in the wireless network domain.

  • Put them together, some amazing application may be available.