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VoIP in WLAN‘s QoS and mobile devices David Jackisch Outline Quality of Service CISCO Solution Mobil Devices Scenarios 2 David Jackisch Quality of Service WLAN is shared medium QoS is important for wireless mobile IP phone calls

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Voip in wlan s l.jpg

VoIP in WLAN‘s

QoS and mobile devices

David Jackisch


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Outline

  • Quality of Service

  • CISCO Solution

  • Mobil Devices

  • Scenarios

2

David Jackisch


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Quality of Service

  • WLAN is shared medium

  • QoS is important for wireless mobile IP phone calls

  • Delay: up to 150ms acceptable for most user applications, above 400ms unacceptable

  • Jitter (75ms), delay, packet loss (3%)

  • Optimising the path of a voice packet

  • Technique: buffers, admission ctrl,

  • Security issues WPA…

3

David Jackisch


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Quality of Service (2)

  • Reliability

  • Availability (data networks 94% ~ 22 days/year)

  • Real-time

  • DiffServ – priority in data traffic, service classes

  • Echo cancellation

  • Some proprietary standards

  • -> 802.11e

4

David Jackisch


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IEEE 802.11e

  • Defines QoS for 802.11 wireless networks

  • Due packet delay/loss and jitter QoS is needed

  • Mechanism for prior data streams

  • EDCF defines 8 traffic categories, software update

  • HCF allocates timeslots, hardware upgrade necessary

  • Implemented 2004

5

David Jackisch


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CISCO Implementations

  • Skinny client control protocol (SCCP) for communicating with Call Manager IP PBX

  • CISCO Aironet WLAN infrastructure is expensive

  • In future: push to talk, WPA, layer-3 roaming, SIP, voice dial…

6

David Jackisch


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A A A

  • Authentification, Authorization, Accounting

  • Possibilities: use of SIM cards, electronic keys

  • Different invoices from service provider, internet provider…

7

David Jackisch


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Mobile Devices

  • Notebook or PDA with soft phone

  • Inexpensive, effective

  • Not comfortable in use

  • UMA (unlicensed mobile access) seamless to WLAN, GSM/GPRS, Bluetooth

8

David Jackisch


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Mobile Devices (2)

WiFi phones

  • ZyXEL P2000W

    • 802.11b WLAN Standard

    • SIP v2

    • G.711 G.729a voice coding

    • 802.11 Ad hoc modus

    • Range 300m/75m

    • 64/128bit WEP encryption

    • QoS TOS/DiffServ

9

David Jackisch


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Mobile Devices (3)

Dual mode phones

  • MOTOROLA CN620

    • GSM and WLAN support

    • MS Windows CE

  • T-Mobile MDA3

    • PDA with GSM

  • NOKIA Communicator 9500

10

David Jackisch


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Scenarios

  • Last mile for telecommunication service providers

  • Connecting new infrastructure with the core network

  • Backup for cellular phone in emergency situations

  • Company telecommunication network, intranet

  • Access from all over the world to corporate network

11

David Jackisch


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Summary

  • Cheaper to operate, maintain and upgrade

  • More powerful, flexible and feature-rich than conventional devices currently in the market

  • One telephone number in every location

  • New markets for hardware producers, service providers and network providers

12

David Jackisch


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Sources

[1] www.google.de

[2] www.networkcomputing.de/cms/fileadmin/ nwc/downloads/pdf/itwissen_ebook_voip.pdf

[3] www.motorola.com

[4] www.siemens.de

[5] www.zdnet.com

[6] www.ivs.tu-berlin.de/Lehre/WS0304/TIA/Material/09-QoS-Teil2.pdf

[7] www.cisco.com

13

David Jackisch


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Thank you. Questions?

14

David Jackisch


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