VoFi standards & deployment models Thenu Kittappa.

VoFi standards & deployment models

Thenu Kittappa

www.voipdeveloper.comAugust 8-10, 2006

Santa Clara, CaliforniaHyatt Regency Santa Clara

Agenda

• Trends in VoWLAN• VoWLAN standards• What makes a good VoWLAN handset?• Different deployment models for Voice over Wi-Fi,

single-mode & FMC



VoWLAN trends 2005-07

Q3 05 Q4 05 Q1 06 Q2 06 Q3 06 Q4 06

FMCA PRD I(UMA)

FMCA PRD II(SIP)

FMCA PRD III(IMS)

FMC Gateway

s

FMC Operator

s

Small SIP PBX

Large SIP PBX

SIP handset

s

WMM handset

sWMM infra

802.11e in CE

SVPQoS

VoIP

FMC

WMM-SA?

Any SIP VoWLAN handset with any SIP

PBX

Fixed-Mobile Systems with handover

Fixed-Mobile Systems Single-number

with no handover

Later Later

FMCAMobileIGNITE

UMAVCC

802.11WFA

SIP (IETF)



Enterprise VoWLAN interfaces

SIP PBXOr softswitch

Voice Telephony Gateway

WLAN to Handset interface• Fast handover• Good QoS• Call Admissions Control• Good battery life• Public access & emergency

WLAN to PBX interface• Emergency call handling• Location• SLA indications• Troubleshooting tools

WLAN • QoS• Seamless coverage• Interference detection• Management tools• Troubleshooting tools

Handset to PBX interface• SIP• SIP++• Presence• Emergency calls



Current 802.11 standards

• Standards activity relevant to voice

– .11i (MAC Security Enhancements) / WPA• All phones will become better at authentication, encryption, by implementing

WPA, WPA2…

– .11e (MAC Enhancements, QoS) / WMM• Phases: WMM, APSD, TSpec sig, WMM-SA improve QoS, battery life

– .11k (Radio Resource Measurement)• Assistance for handoff: opportunistic key caching with knowledge of key scope

– .11r (Fast Roaming)• Aimed at improving secure handoff speeds. Not necessary when .11k neighbor

report is used in conjunction with centralized encryption



1 2 3 4 5Scale of excellence

802.11r

802.11r

How complete is standards support?WMM-SA

802.11k

WMM functionality

802.11k

WMM-SA

Other 802.11 functionality

Centralized architecture & vendor-specific features

QoSJitter

Latency

Packet errors/ drops

(Over wired and wireless)

CAC

HandoverControl/influence decision

Speed of handover

Security of handover

Sleep Control: battery lifeU-APSD

S-APSD

Other featuresCALEA

E911

Coverage

802.11h

802.11h



What makes a good WLAN phone?Function Good Better Best Notes

Call Admissions Control & QoS

802.11e QBSS load element

Tspec signalling

Uplink QoS WMM (EDCA)

Authentication MAC address 802.1x 802.1x & PMK caching

Encryption Static WEP PSK-TKIP, PSK-AES TKIP, AES Aim for WPA2

Handover 802.11k AP channel report element

802.11e QBSS load element

AP channel report & QBSS load & 802.11k neighbor report & PMK caching

Depends also on algorithms in handset

Transmit power control

802.11h TPC

Bandwidth efficiency

802.11b 802.11a/g .11b reduces the cell throughput

Battery life 802.11 power save U-APSD U-APSD & 802.11h TPC & proprietary

Future developments on loosely-associated state



Deployment of Voice in the Mobile Network

• VoIP allows a phone to receive corporate dialtone over the Internet• Incoming, outgoing numbers as PBX extension• Wireless VoIP is more secure than wired VoIP• Wireless requires less reprogramming than wired VoIP (no reconfiguration of

AP or handset)

Corporate IP PBX

LAN Internet

Home officeMain location

WAN

Hotel roomBranch office



Enterprise VoWLAN Deployment Models



Internet

• PBX Extension Mode: Wireless phone is configured as an extension on the PBX

Pros• Easy to configure on the WLAN and the IP-PBX• SIP support on single-mode VoFi phones and IP-PBX allows best-of-breed mix & match• Phone automatically participates in Enterprise numbering plan (4-, 5-digit) and least-cost routing for long-distance calling

Cons• Existing PBX may need upgrading to support SIP extensions• All configuration falls on the Enteprise IT group (or outsourcer)• Single-mode phones will work on Enterprise Wi-Fi network & home locations, but not outside this coverage• Configuration complexity when users roam between sites (unless already covered by a unified PBX network)

LAN core

LAN edge



Enterprise VoWLAN Deployment Models

SIP PBXOr softswitch • Hosted Mode: All call control is from the

Internet

Pros• No end-user configuration• Works with VoIP wired and single-mode wireless phones• Easy to upgrade to a fixed-mobile service (upgrade by the SP) • Easily integrated by the SP with long-distance & international VoIP plans

Cons• Survivability (loss of WAN = loss of service)• QoS (may require a guaranteed-QoS Internet/VPN service)• Single-mode phones will work on Enterprise Wi-Fi network & home locations, but not outside this coverage

LAN edge

LAN core

Internet



Enterprise FMC Deployment ModelsSIP PBXOr softswitch

LAN edge

LAN core

Internet

Cellular Core

FMC Gateway

Cellular Base Station

• Hosted Mode: VoFi side of the phone is homed to the hosted FMC Gateway

– Cellular operator (SP) ‘owns’ the phone number and behaviour

– User experience is closer to cellphone whether in or out of Wi-Fi coverage

Pros• No configuration by the IT group (except for access, see below)• Standards support for this model will ensure good pricing and availability of phones (eventually)• Easy inter-site roaming• Easily extended to commercial hotspots by SP roaming agreemeents

Cons• Configuration of SSIDs, NAT, firewall may be a problem• Access by the SP for troubleshooting may require special firewall, demarc considerations• All calls are seen and possibly charged by the SP



Enterprise FMC Deployment Models

• PBX Extension Mode: VoFi side of the phone is homed to the PBX

– PBX forwards calls to the cellular number when phone is out of Wi-Fi coverage

– Sometimes works with cellular data channel for presence & signalling when in cellular coverage

– User experience is closer to PBX extension whether inside or outside Wi-Fi coverage

Pros• Can be configured by the IT group• Major PBX vendors are adding this functionality• Integrates with PBX numbering plan & features

Cons• Configuration burden falls on the IT group• All calls are anchored on the PBX • No standards, so phones will need custom code updates• Inter-site roaming needs to be carefully configured

LAN edge

LAN core

Internet

Cellular Core

Cellular Base Station





• Thank you

VoFi standards & deployment models Thenu Kittappa.

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