0 Wireless Internet Telephony Tom La Porta Director, Networking Techniques Research Department Bell...

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Wireless Internet Telephony

Tom La Porta

Director, Networking Techniques Research Department

Bell Labs, Lucent Technologies

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Outline

• Background and Overview

• Transport

– mobility management and QoS

– wireless specific services

• Signaling and Control

– mobility management

– call control and interworking

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Mobile Internet Telephony - All IP

Goal: migrate wireless mobile access networks to IP

– Support the anticipated explosive growth of the wireless Internet• merging of services for wireline and wireless networks• merging of wireless voice and data networks

– Reduced product and operational costs of IP infrastructure• increased efficiency of packet-based networks for combining voice and data

Technical Challenges:

– Transport:• quality of service • real-time mobility management• wireless specific services

– Signaling and Control:• personal and device mobility• call control• interworking with existing telephony systems

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Current Cellular Networks: Circuit Switched

BS

BSC

MSC/VLR

PSTN &SS7

HLR

BS

BS

BSCBS: base stationBSC: BS controllerMSC: Mobile Switching CenterVLR: Visitor Location RegisterHLR: Home Location Register1. Air 2. Backhaul 3. Full Rate 4. Full Rate

• Link 1: Air Interface• compressed voice (8Kbps) on “dedicated” channel

• Link 2: Backhaul• compressed voice multiplexed on sub-rate circuits• BSC performs voice coding to 64 Kbps (one option)• BSC performs soft handoff or frame selection function (one option)

• Link 3-4: Full rate• full rate voice switched at MSC to the PSTN• MSC may perform voice coding and soft handoff

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Migration to All-IP: Packet Core

BS

Access PVG

Software Controller

PSTN &SS7

HLR

BS

BS

BS: base stationPVG: Packet-Voice GatewayHLR: Home Location Register

1. Air 2. Backhaul 3. Packet Voice 4. Full Rate


• Link 2: Backhaul• compressed voice multiplexed on sub-rate circuits• Access PVG performs soft handoff or frame selection function• Access PVG may perform voice coding

• Link 3: Packet Voice• RTP session between Access and Egress PVGs • Egress PVG may perform voice coding

• Link 4• full rate voice switched at Egress PVG to the PSTN

Access PVG

EgressPVG

Intranet

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All-IP

IP-BSC

Software Controller

PSTN &SS7

HLR

IP-BS

1. Air 2. Backhaul 3. Packet Voice 4. Full Rate


• Link 2: Backhaul• aggregated, compressed IP voice• IP-BSC performs soft handoff or frame selection function

• Link 3: Packet Voice• RTP session between Access and Egress PVGs • Egress PVC performs voice coding

• Link 4• full rate voice switched at Egress PVG to the PSTN

• Link 5: Packet voice to Internet

EgressPVG

IntranetIP-BS

IP-BS

IP-BSCInternet

5. Packet Voice

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Outline


Transport – mobility management and QoS

– wireless specific services: Soft Handoff and Paging

• Signaling and Control

– mobility management


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Current Telecom-Based Mobile Packet Networks: GPRSGeneral Packet Radio Service

• Compatible with cellular telecom networks+ may be deployed using existing infrastructure– requires separate advances from the Internet

• Specialized nodes manage mobility and forward packets+ requires no changes to fixed hosts or intermediate routers– results in triangular routing– special failure recovery mechanisms needed

• Packets are tunneled through the Intranet+ intermediate routers are not mobile-aware– difficult to perform QoS

• Inter-SGSN handoffs always managed by GGSN– high update overhead– slow handoffs

IntranetMDSGSN

GGSN

Host

Regular routingTunneled packetsusing special methods

InternetSGSN

RadioAccess

Networks

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Current Internet-Based Mobile Packet Networks: Mobile IP

• Compatible with regular IP networks and hosts+ most Internet advances apply

• Specialized agents manage mobility and forward packets

+ requires no changes to fixed hosts or routers– results in triangular routing– special failure recovery mechanisms needed

• Packets are tunneled through the Internet+ Internet routers are not mobile-aware– difficult to perform QoS

• Handoffs always managed by Home Agent– high update overhead– slow handoffs

• No paging– high update overhead

MD FA

HA

HostInternet

Regular routing

Tunneled packetsusing IP

FA

RadioAccess

Networks

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HAWAII: A Domain Based Approach to IP Mobility

• Distributed control: Enhanced reliability– host-based routing entries in routers on path to mobile

• Localized mobility management: Lower overhead, fast handoffs– updates only reach routers affected by a movement

• Minimized or Eliminated Tunneling: no triangular routing, easy QoS– dynamic, public address assignment to mobile devices

• Supports paging

Compatible with Mobile IP

DomainRouter

RR

R R R R

DomainRouter

RR

R R R R

Local mobility Local mobilityMobile IP

Internet

MD

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HAWAII: Local Mobility

Internet

Domain Router

R2 R3 R R

RR1

MD

• Initial host-based routing entries in routers shaded in yellow (DR, R1, R2)– minimizes number of host-based entries

• Update host-based routing entries in routers shaded in green (R3, R1)– minimizes number of routers processing updates– reduces handoff time

• Address of mobile device remains constant– allows uninterrupted communication– allows QoS entries in unaffected routers (yellow) to remain unchanged

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HAWAII Overhead

Domain Router

Router 1 Router 7...

BS-R1 BS-R20... BS-R1 BS-R20

• 39 users/sq. miles• users moves at 112 Km/hr.• base stations cover 7 Km2

Network Model

Message HAWAII @ DomainRouter

Mobile IP @ HomeAgent

Msg/sec % CPU util Msg/sec % CPU utilHawaii Registration 127.8 1.92 0 0Hawaii Updates 51.3 0.85 0 0M-IP Rgistration 48.4 7.6 574 91.2M-IP Updates 12.7 0.15 127.4 1.5Total 240.2 10.5 701.4 92.7

Comparison of most heavily loaded entities in each network: HAWAII DR processes 34% number of messages as M-IP HA HAWAII DR is utilization is 11% of M-IP HA

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HAWAII Handoff Delay: Packet Loss

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Audio (160B/20msec) Video (4KB/33msec)

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Voice (or other real-time applications): less disruption

–packets dropped due to late arrival:

HAWAII Performance: Handoff Delay

Drops/handoff (average)Protocol

1 level, 75 msecplayout delay



MIP (MIPV6) 9 6.5 7.8

MIP withforwarding

4 1.5 2.8

HAWAII 0.3 - 1.5 0 - 0.3 0.3 - 1

IP network delay

HAWAII

Local Mobile IP Roaming Mobile IP

Acceptable for voice

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Wireless Services: IP-Paging

• Hierarchical scheme – scaleable– allows load balancing between levels of routers

• Uses IP Multicast– no new protocols

• Alternatives– paging from Home Agent– paging from Foreign Agent

• Result: – Domain paging supports ~10% higher load than FA-Paging

DomainRouter

RR

R R R R

DomainRouter

RR

R R R R

Internet

MD

Paging entry

Multicast entries

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Wireless Services: IP Soft Handoff

• Goals– true end-to-end IP networking– leverage IP protocols (e.g., multicasting)– support efficient routing

• Challenges– traffic aggregation– processing overhead– QoS

DomainRouter

RR

R R R R

DomainRouter

RR

R R R R

Internet

MD

IP Soft Handoff

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Outline


• Transport

– mobility management and QoS

– wireless specific services

Signaling and Control– mobility management


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Integrated SIP Registrar and HLR

Integrate 3 key functions of HLR & IP (VoIP) servers

• mobility management

• security

• profile management

Support multiple standard interfaces• Wireless: ANSI 41, GSM / UMTS MAP

• Internet: VoIP (SIP, H.323), AAA (RADIUS)

Provide enhanced HLR functionality for Internet and wireless network users

CurrentIntegrateHLR/VoIP server

functions

MAP / SS7

IntegratedUser

Profile Database

Securitymanager

Pro

toco

lG

atew

ays

User locationmanager

CellularCellular

InternetInternetVoIP / IPAAA / IP

Next-Generation

Internet (VoIP)Internet (VoIP)VoIP server

IP security server

CellularCellular

HLR

User/mobile location managementUser/mobile location management

Security control (authentication Security control (authentication center, IP security server)center, IP security server)

Service profile DB managementService profile DB management

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Mobility Management: Terminal and User Mobility

Current Location Area

TerminalHome Switch Calling

party

Mobile Phone #Registration and locally assigned number

• Current telephone network– mobile phone number points to home network of device– home network points to current location based on registration information and locally assigned temporary phone numbers

Current Location Area

TerminalSIP Server Calling

party

SIP URLInformation from registrar

• SIP– personal URL defines a server– registrars and proxies point to devices– extra level of indirection of interworking with cellular phone

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Mobility Management

User mobility across networks (wireless, Internet) in addition to terminal mobility

• Manage profile information for a ‘user’, not a ‘wireless terminal’

• Call delivery to the current user terminal Unified user location DB

• Global roaming between network types

• Receive the same service anywhere Unified service profile

PSTN networks

Internet

Securitymanager

Userlocationmanager

User location DB

GSMphone

SIPterminal PSTN

phone

User

SIP user name (URL)Tel # 1 (MSISDN)

Tel #2

AMPS / PCSWireless

access networks

BS

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Preliminary Analysis: Internetworking with Super HLR

Call delivery from a SIP terminal to a GSM phone

No dual registration or routing number lookup with super HLR

15~30% less signaling message load

Modified call setup

PSTN/MAP

BS InternetServingMSC

HLR +

Call delivery (SIP )

Mobile registration

IP stream up to BS

SIP proxy

Home MSCRouting info. lookup

Modified registration

PSTN/MAP

BSInternet

ServingMSC

HLR+


Dual registration

IP stream up to BS

SIP registrarSIP proxy

SIPterminal

Super HLR

IPIPWirelessWirelessAccessAccess

BSInternet


MAP mobile registration

IP up to BS

HL

R SIP registrar+

SIP call proxyGW

PSTN

ServingMSC

SIPterminal SIP

terminal

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Call Control: Internetworking among wireless, VoIP, and PSTN networks

Develop general internetworking models and procedures

To avoid different procedures for each internetworking scenario

Call delivery to home/gateway MSC or SIP proxy

Location query to super HLR

Routing information if delivered to wireless mobile terminal

Call delivery to a mobile terminal

Extend the procedures for supplementary services

Use calling party’s protocol

Use called party’s protocol

sHLRUser

LocationServer

user profile

hMSC /gMSCSIP proxyPG 1

(2) LOCREQ/SRISIP location lookup

(10) locreq/SRI AckSIP loc. Lookup rsp

Serving MSCSIP UAPG 2

(6) ROUTEREQ / PRN

(7) routereq / PRN Ack

(3) Request Location(1) IAM / SIP INVITE

(12) Call delivery

(11) IAM / SIP INVITE

(4) DB

lookup

(9) Request Location RSP

(5) Request Route Info

(8) Request Route Info RSP

Core s-HLR operations

GSMphone

SIPterminal

PSTNphone

User

User location DB

SIP user nameDN1 (MSISDN)

DN2

Super HLR

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Super HLR : Architecture

Super HLR core servers

- Common functions across protocols

- Multiple server instances on a cluster of processors for system scalability

- Interworking function between protocols: O(n) versus O(n2) complexity

Super HLR common operations

- Protocol independent

Protocol gateways

- Performs protocol specific control

- Facilitates new protocol introduction

Integrated user profile DB

- Common database for a ‘user’

Super HLR Common

operations

MAP / SS7

VoIP / IP

AAA / IP

PG MAP

PG VoIP

PG AAAIntegrated

user profile Database

DBmanager

User locationmanger

Securitymanager

s-HLR core servers

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Summary

Mobile Internet Telephony requires:

• Transport advancements

– efficient mobility management

– QoS

– wireless services

• Signaling advancements

– additional levels of mobility

– interworking with cellular telephony

• Other Issues

– efficiency of Internet signaling over the air

0 Wireless Internet Telephony Tom La Porta Director, Networking Techniques Research Department Bell...

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