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VoIP in WLAN‘s

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

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  1. VoIP in WLAN‘s QoS and mobile devices David Jackisch

  2. Outline • Quality of Service • CISCO Solution • Mobil Devices • Scenarios 2 David Jackisch

  3. 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

  4. 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

  5. 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

  6. 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

  7. A A A • Authentification, Authorization, Accounting • Possibilities: use of SIM cards, electronic keys • Different invoices from service provider, internet provider… 7 David Jackisch

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. Thank you. Questions? 14 David Jackisch

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