Wireless internet telephony
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Wireless Internet Telephony. Tom La Porta Director, Networking Techniques Research Department Bell Labs, Lucent Technologies. Outline. Background and Overview Transport mobility management and QoS wireless specific services Signaling and Control mobility management

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Wireless internet telephony

Wireless Internet Telephony

Tom La Porta

Director, Networking Techniques Research Department

Bell Labs, Lucent Technologies


Outline

Outline

  • Background and Overview

  • Transport

    • mobility management and QoS

    • wireless specific services

  • Signaling and Control

    • mobility management

    • call control and interworking


Mobile internet telephony all ip

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


Current cellular networks circuit switched

HLR

BS

BS

BS

MSC/VLR

BSC

BSC

PSTN &

SS7

Current Cellular Networks: Circuit Switched

BS: base station

BSC: BS controller

MSC: Mobile Switching Center

VLR: Visitor Location Register

HLR: Home Location Register

1. 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


Migration to all ip packet core

HLR

Access

PVG

Access

PVG

Egress

PVG

BS

BS

BS

PSTN &

SS7

Migration to All-IP: Packet Core

Software

Controller

Intranet

BS: base station

PVG: Packet-Voice Gateway

HLR: Home Location Register

4. Full Rate

3. Packet Voice

1. Air

2. Backhaul

  • Link 1: Air Interface

    • compressed voice (8Kbps) on “dedicated” channel

  • 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


All ip

HLR

IP-BS

IP-BS

IP-BS

Egress

PVG

IP-BSC

IP-BSC

PSTN &

SS7

All-IP

Software

Controller

Intranet

Internet

5. Packet Voice

4. Full Rate

3. Packet Voice

1. Air

2. Backhaul

  • Link 1: Air Interface

    • compressed voice (8Kbps) on “dedicated” channel

  • 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


Outline1

Outline

  • Background and Overview

  • Transport

    • mobility management and QoS

    • wireless specific services: Soft Handoff and Paging

  • Signaling and Control

    • mobility management

    • call control and interworking


Current telecom based mobile packet networks gprs general packet radio service

SGSN

SGSN

Radio

Access

Networks

MD

Internet

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

Regular routing

Tunneled packets

using special methods

GGSN

Host

Intranet

  • 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


Current internet based mobile packet networks mobile ip

FA

FA

Current Internet-Based Mobile Packet Networks: Mobile IP

Tunneled packets

using IP

HA

Regular routing

Radio

Access

Networks

MD

Host

Internet

  • 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


Hawaii a domain based approach to ip mobility

Internet

Domain

Router

Domain

Router

MD

Local mobility

Local mobility

Mobile IP

R

R

R

R

R

R

R

R

R

R

R

R

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

  • Supportspaging

  • Compatible with Mobile IP


Hawaii local mobility

Internet

Domain

Router

R1

R

R

R

R2

R3

MD

HAWAII: Local Mobility

  • 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


Hawaii overhead

Network Model

Domain Router

...

  • 39 users/sq. miles

  • users moves at 112 Km/hr.

  • base stations cover 7 Km2

Router 1

Router 7

...

BS-R20

BS-R20

BS-R1

BS-R1

HAWAII Overhead

  • 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


Hawaii handoff delay packet loss

HAWAII Handoff Delay: Packet Loss

Audio (160B/20msec)

Video (4KB/33msec)


Hawaii performance handoff delay

HAWAII Performance: Handoff Delay

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

    • packets dropped due to late arrival:

Local Mobile IP

IP network delay

Roaming Mobile IP

HAWAII

Acceptable for voice


Wireless services ip paging

Domain

Router

Domain

Router

MD

R

R

R

R

R

R

R

R

R

R

R

R

Wireless Services: IP-Paging

Paging entry

Internet

Multicast entries

  • 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


Wireless services ip soft handoff

Domain

Router

Domain

Router

MD

R

R

R

R

R

R

R

R

R

R

R

R

Wireless Services: IP Soft Handoff

Internet

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


Outline2

Outline

  • Background and Overview

  • Transport

    • mobility management and QoS

    • wireless specific services

  • Signaling and Control

    • mobility management

    • call control and interworking


Integrated sip registrar and hlr

User/mobile location management

Integrate

HLR/VoIP server

Security control (authentication

center, IP security server)

functions

Service profile DB management

IP security server

Integrated SIP Registrar and HLR

  • Provide enhanced HLR functionality for Internet and wireless network users

Current

HLR

Cellular

VoIP server

Internet (VoIP)

MAP

/ SS7

User

location

manager

Cellular

  • 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)

Protocol

Gateways

Integrated

User

Profile

Database

VoIP / IP

AAA / IP

Internet

Security

manager

Super HLR

Next-Generation


Mobility management terminal and user mobility

Registration and locally assigned number

Information from registrar

Mobile Phone #

SIP URL

Current Location Area

Current Location Area

Home Switch

SIP Server

Calling

party

Calling

party

Terminal

Terminal

Mobility Management: Terminal and User Mobility

  • 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

  • SIP

    • personal URL defines a server

    • registrars and proxies point to devices

    • extra level of indirection of interworking with cellular phone


Mobility management

User

PSTN networks

Tel #2

AMPS / PCS

Wireless

access networks

Mobility Management

  • User mobilityacross 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

Super

HLR

SIP user name (URL)

Tel # 1 (MSISDN)

BS

User

location

manager

Internet

SIP

terminal

GSM

phone

PSTN

phone

Security

manager

User location DB


Preliminary analysis internetworking with super hlr

  • Modified registration

HLR

PSTN/MAP

+

SIP registrar

SIP proxy

Dual registration

Serving

MSC

Call delivery (SIP )

BS

SIP

terminal

SIP

terminal

SIP

terminal

IP stream up to BS

Internet

Super HLR

SIP registrar

+

SIP call proxy

HLR

PSTN

GW

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

  • Super HLR

MAP mobile registration

Routing info. lookup

HLR

+

PSTN/MAP

Home MSC

SIP proxy

Mobile registration

IP

Wireless

Access

Serving

MSC

Call delivery (SIP )

Call delivery (SIP )

BS

BS

IP stream up to BS

IP up to BS

Serving

MSC

Internet

Internet


Call control internetworking among wireless voip and pstn networks

Use called party’s protocol

User

Use calling party’s protocol

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

Super HLR

(2) LOCREQ/SRI

SIP location lookup

SIP user name

DN1 (MSISDN)

(1) IAM / SIP INVITE

(3) Request Location

hMSC /gMSC

SIP proxy

PG 1

(10) locreq/SRI Ack

SIP loc. Lookup rsp

sHLR

User

Location

Server

(9) Request Location RSP

user

profile

(11) IAM / SIP INVITE

(4) DB lookup

(5) Request Route Info

DN2

(6) ROUTEREQ / PRN

Serving MSC

SIP UA

PG 2

(7) routereq / PRN Ack

(8) Request Route Info RSP

SIP

terminal

GSM

phone

PSTN

phone

(12) Call delivery

Core s-HLR

operations

User location DB


Super hlr architecture

AAA / IP

MAP / SS7

VoIP / IP

DB

manager

Security

manager

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’

PG MAP

Super HLR

User location

manger

PG VoIP

Super HLR

Common

operations

Integrated

user profile

Database

PG AAA

  

  

s-HLR core servers


Summary

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


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