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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

  • Ad Hoc

    • What is ad hoc network?

    • Why ad hoc network?

    • What are the interesting research topics?

  • ICEBERG

    • What is ICEBERG?

    • Why study ICEBERG?

    • How can we take it further?


What are ad hoc networks l.jpg

What are Ad Hoc Networks

  • 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.


Definition for mobile ad hoc l.jpg

Definition for Mobile Ad-hoc

  • 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


Characteristics of ad hoc wireless network l.jpg

Characteristics of ad hoc wireless network

  • 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;


Why ad hoc wireless networking l.jpg

Why ad hoc wireless networking?

  • 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


Research challenges i l.jpg

Research Challenges (I)

  • MAC layer problems:

    • Link layer reliability

    • QoS at MAC layer

    • Power conservation

  • Network layer problems: Mobile IP

    • Routing;

    • QoS

    • Power conserving

    • Multicast


Research challenges ii l.jpg

Research Challenges (II)

  • Transport layer problems: (TCP over Ad hoc)

    • End-to-end reliability?

    • Congestion control?

    • QoS?

  • Application layer:

    • Security?

    • QoS?

  • Inter-layer interactions;

  • Internetworking with internet;


Main problem routing l.jpg

Main problem: Routing

  • 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

N1

N1

N2

N3

N2

N3

N4

N4

N5

N5

good link

weak link

time = t1

time = t2


Traditional routing algorithms l.jpg

Traditional routing algorithms

  • 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


Problems of traditional routing algorithms l.jpg

Problems of traditional routing algorithms

  • 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)

  • Table Driven: DSDV, WRP, etc

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

  • Zone Routing Protocol (ZRP)


Dsdv destination sequenced distance vector l.jpg

DSDV (Destination Sequenced Distance Vector)

  • 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)


Dynamic source routing dsr l.jpg

Dynamic source routing (DSR)

  • 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!


Dynamic source routing internet draft l.jpg

Dynamic Source Routing – 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


Dynamic load aware routing l.jpg

Dynamic Load-Aware Routing

  • 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


Mitigating routing misbehavior l.jpg

Mitigating routing misbehavior

  • 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


Routing multicast l.jpg

Routing (Multicast)

  • 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;


Other researches on routing l.jpg

Other researches on Routing

  • QoS support routing;

  • Power conserving routing;


Iceberg l.jpg

ICEBERG

  • http://iceberg.cs.berkeley.edu/

  • 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


Why iceberg l.jpg

Why ICEBERG

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

  • Mobility for transparent information access

  • New applications: audio, video, multimedia


Design goals l.jpg

Design Goals

  • 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


Iceberg architecture overview l.jpg

PSTN

GSM

Pager

A

NY iPOP

IAP

IAP

IAP

IAP

IAP

SF iPOP

IAP

B

NY iPOP

CA

SF iPOP

PR

PAC

APC

NMS

ICEBERG Architecture Overview

Access Network

Plane

ICEBERG

Network

Plane

Clearing House

ISP Plane

ISP1

ISP2

ISP3


Iceberg components l.jpg

ICEBERG Components

  • 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 Platforms

  • 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

Call

Agent

Call

Agent

7

3

5

8

1

An Illustration

Bob

Alice

2

PR

NMS

PR

NMS

IAP

IAP

Clearing House


What s their difference l.jpg

What’s their difference?

  • 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.


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