1

Data in CDMA2000 networks

Pasi Eronen

March 10th, 2004

2

Contents

• CDMA2000 overview

• Basic architecture

• Radio issues

• IP services

• Mobility & handoffs

• Comparison to GPRS/UMTS

3

Cellular market share by technology

GSM

73 %

TDMA 8%

iDen 1%

Analog

1%

PDC 4 %

[3GAmericas.org “World Cellular Subscribers December 2003”]

CDMA 13%(186 M)

4

CDMA subscribers by region

Asia-

Pacific

41 %North

America

40 %

Others

2 %

Latin America 17%

[CDG CDMA2000 World Review December 2003]

KoreaChinaJapanIndia

BrazilMexico

Note: Most countries use other

technologies in addition to CDMA

5

CDMA evolution: radio network

• IS-95/cdmaOne• 60% of CDMA subscribers

• CDMA2000 1X • 40% • Data rates: 60–100 kbps (mobile),

153/307/614 kbps (peak)

• 1X-EV-DO (“data only”)• Currently operational in 9 networks• Data rates: 300–600 kbps (mobile),

980–1200 kbps (fixed), 2.4 Mbps (peak)

• 1X-EV-DV (“data & voice”)• Data rates: 3.1 Mbps (peak)

[CDG CDMA2000 Market Facts February 2004]

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CDMA evolution: packet network

• IS-835-B (September 2002)• Multiple service instances• Diffserv QoS• Fast PDSN-to-PDSN handoff • Dynamic home agent allocation using RADIUS• IP Reachability service (DNS Dynamic Update)• “Always On” support• Remote address based accounting• Simple IPv6

• IS-835-C (August 2003)• Prepaid data• Enhanced compression• Differential flow treatment (QoS, compression)

• IS-835-D (not yet)• Mobile IPv6?

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Basic architecture

AAA server(s)BSC/PCF

MSC/VLR HLR/AC

PDSN

Home Agent

MS

BTS

BTS

A1 (BSAP)

A10/A11

External IP networks

RADIUS

MAP

MIP

Access Network

Circuit Switched Network

PacketNetwork

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Radio overview (1X)

• CDMA2000 can use same 1.25MHz as IS-95/cdmaOne

• Various frequency bands

• 800 MHz

• 1900 MHz

• Dual 800/1900 MHz

• 450 MHz (Russia, Eastern Europe)

• 1700 MHz (Korea)

• Japanese variant of 800 MHz?

• 2100 MHz?

• Improved spectral efficiency due to e.g. better power

control, modulation and smart antennas/transmit

diversity

9

Radio overview (1X)

• Fundamental channel (FCH)

• Low rate (9.6/14.4 kbps)

• Allocated for duration of connection

• Supplemental Channel (SCH)

• Duration decided dynamically (20ms … 5s)

• MS can have 0…2 SCHs

• Variable data rate up to 307 kbps

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IP services

• Basic services

• Simple IPv4

• Simple IPv6

• Mobile IPv4

• IP Reachability Service (DNS dynamic update)

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Service initiation (Simple IPv4)

Origination

A11-Registration <R-P SID, IMSI>

PPP authentication <user@realm>

PPP IPCP <IP address, DNS server addresses>

MSC/VLRMSC/VLR HLR/ACHLR/ACBS/PCFBS/PCFMSMS

PDSNPDSN AAA server(s)AAA server(s)

CM Service Request

RN authentication

Radio link setup

Service connect

PPP LCP negotiation

RADIUS

MAP

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Control plane for Simple IPv4

Phy

MAC

LAC

PPP

Phy

MAC

LAC

L1

L2

IPv4

TCP/UDP

L1

L2

IPv4

TCP/UDP

A9

L1

L2

IPv4

UDP

L1

L2

IPv4

UDP

A11

L1

L2

IPv4

UDP

RADIUSPPP

MS BS PCF PDSN

L1

L2

IPv4

UDP

RADIUS

AAA server

A9 A11

MSC/VLR

Phy

MTP

SCCP

BSAP

HLR/AC

Phy

MTP

SCCP

TCAP

MAP

Phy

MTP

SCCP

TCAP

MAPA1

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User plane for Simple IPv4

Phy

MAC

PPP

Phy

MAC

L1

L2

IPv4

L1

L2

IPv4

A8

L1

L2

IPv4

L1

L2

IPv4

A10

L1

L2

IPv4PPP

MS BS PCF PDSN

A8 A10

IPv4IPv4

TCP/UDPTCP/UDP

App

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PDSN user plane processing (Simple IPv4)

• PDSN state: • MS IP address• PCF address• R-P session ID

• For downlink packets:• PDSN receives IP packet from “outside interface”• Looks up state based on destination IP address• Sends to PCF-Address encapsulated with GRE,

GRE key field set to R-P session ID

• For uplink packets:• PDSN receives GRE packet from PCF• Looks up state based on <PCF address, R-P session ID>• Checks that MS IP address matches (ingress filtering)• Sends packet to “outside interface”

• In both cases, also update accounting• State also contains IMSI, NAI, etc. for accounting messages

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Simple IPv6

• PPP IPCPv6 negotiates only interface identifiers

• Each MS gets an unique /64 using IPv6 Stateless

Autoconfiguration

• PDSN sends Router Advertisements

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Service initiation (Mobile IPv4)

MS

PPP LCP negotiation

MIP Agent Advertisement <PDSN address, challenge>

MIP Registration Request <PDSN addr., user@realm, challenge, response>

RADIUS Access-Request <user@realm>

RADIUS Access-Response <HA address>

MIP RRQ

MIP Registration Reply <home address>

MSMS PDSNPDSN AAA server(s)AAA server(s) Home AgentHome Agent

PDSN storesR-P SID,

home address, home agent address

Home agent stores home address, PDSN address

MIP RRP

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User plane for Mobile IPv4

PPP

L1

L2

IPv4

PPP

MS BS/PCF PDSN

IPv4 IPv4

TCP/UDP

App

L1

L2

Home Agent

TCP/UDP

L1

L2

IP-in-IP/GRE/ESP

IPv4

IP-in-IP/GRE/ESP

IPv4

IPv4

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PDSN user plane processing (Mobile IPv4)

• PDSN state:

• MS IP address

• PCF address

• R-P session ID

• Home Agent address

• For downlink packets:

• PDSN receives tunnelled packet from Home Agent

• Looks up state based on <MS IP IP address, Home Agent addr>

• Sends to PCF-Address encapsulated with GRE

• For uplink packets:

• PDSN receives GRE packet from PCF

• Looks up state

• Checks that MS IP address matches

• Sends tunnelled packet to Home Agent address

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Mobility & handoffs

• Intra-BSC/PCF

• CDMA MS can communicate with multiple BTSs

simultaneously � soft handover possible

• PCF-to-PCF handoff

• PDSN-to-PDSN Mobile IPv4 handoff

• PDSN-to-PDSN fast handoff

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PCF-to-PCF handoff

• Serving and target PCF agree of handoff via MSC/VLR

• Target PCF sends A11-Registration-Request to PDSN

• PDSN updates its state

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PDSN-to-PDSN Mobile IPv4 handoff

• MS re-registers with Home Agent

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PDSN-to-PDSN fast handoff

• PCF—PDSN connection moved to target (new) PDSN

• PPP endpoint stays in serving (old) PDSN

• Tunnel between PDSNs (P-P) interface

• When MS becomes dormant or renegotiates PPP,

tunnel torn down (optionally followed by Mobile

IPv4 re-registration)

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Comparison to GPRS/UMTS

• Various viewpoints

• Basic IP services

• Mobility

• Access to external networks

• Roaming

• Authentication & authorization

• Charging

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Comparison: Basic IP servers

CDMA2000 Simple IPv4

• First hop router is PDSN

• PDSN assigns IP address in PPP

IPCP phase

• “Layer 2 routing” MS—PDSN

• GRE tunnels PDSN—PCF

and PCF—BS

• L2 “routing tables” updated

with A11-Registration-

Request (PDSN—PCF) and

A9 messages (PCF—BS)

GPRS/UMTS

• First hop router is GGSN

• GGSN assigns IP address in PDP

Context Activation

• “Layer 2 routing” MS—GGSN

• GTP-u tunnels GGSN—SGSN

and SGSN—RNC

• L2 “routing tables” updated

with PDP Context Update

(GGSN—SGSN) and LA/RA

Updates (SGSN—RNC)

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Comparison: Mobility

CDMA2000

• Layer 2 mobility: BTS-to-BTS,

PCF-to-PCF, PDSN-to-PDSN fast

handoff

• Layer 3 mobility: Mobile IPv4

(PDSN-to-PDSN)

• Allows mobility to other

networks than CDMA2000

(maybe)

• IP Reachability service

(DNS dynamic updates)

GPRS/UMTS

• Layer 2 mobility: BTS-to-BTS,

BSC-to-BSC, SGSN-to-SGSN

• No Layer 3 mobility in network

• No handoffs to other

networks

• But user can use Mobile IP

without network support

• SIP removes need for DNS

dynamic updates?

• And firewalls prevent

reachability anyway?

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Comparison: Access to external packet networks

CDMA2000

• Single PDSN can provide both Internet access and access to private corporate networks

• MS selects network with NAI (user @ realm)

• Tunneling to corporate network with IP-in-IP set up with Mobile IPv4 (can also doIPsec)

• Tunnel endpoints configured in AAA server(s)

• MS IP address assigned by corporate Home Agent

GPRS/UMTS

• Single GGSN can provide both Internet access and access to private corporate networks

• MS selects network with Access Point Name (APN)

• Tunneling to corporate network with IP-in-IP, IPsec, 802.1q, L2TP, ATM VCs, etc.

• Tunnel endpoints configured in GGSN

• MS IP address assigned by corporate AAA/DHCP/L2TP server

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Comparison: Roaming

CDMA2000

• Basic Internet access:

• PCF and PDSN in visited

network

• Corporate/private access

• PCF and PDSN in visited

network

• Tunnel endpoint (Home

Agent) in corporate net

• Supports AAA brokers (that

don’t participate in user plane)

GPRS/UMTS

• Basic Internet access

• SGSN and GGSN in visited

network

• Corporate/private access

• SGSN in visited network

• GGSN in home network

• Tunnel endpoint in

corporate network

• 2.5/3G operator as AAA broker

(but also in user plane)

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Comparison: Authentication & Authorization

CDMA2000

• RN authentication often

without SIM (R-UIM)

• Access to private networks can

use PAP/CHAP

• PAP/CHAP carried in PPP

between MS and PDSN

• PDSN talks RADIUS to AAA

servers

GPRS/UMTS

• RN authentication uses

SIM/USIM

• Access to private networks can

use PAP/CHAP

• PAP/CHAP carried in PDP

Context Activation messages

between MS and GGSN

• GGSN talks RADIUS to AAA

servers

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Comparison: Charging

CDMA2000

• PCF and PDSN collect data

• A11-Registration-Requests

piggybacks RN accounting

from PCF to PDSN

• PDSN consolidates data and

sends to AAA servers using

RADIUS

GPRS/UMTS

• SGSN and GGSN collect data

• Both send data to Charging

Gateway Functionality (CGF)

using GTP´

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Conclusions

• CDMA2000 offers high data rate IP services

• Many similarities to GPRS/UMTS

• PDSN / GGSN gateway to “outside world”

• IP-based packet network, but does not use IP routing

for user plane (“L2 mobility” instead)

• No real end-to-end IP connectivity to Internet

• CDMA2000 uses Mobile IPv4

• …but are PDSN-to-PDSN handoffs really needed?

• Might be useful for other radio networks (e.g. WLAN)

• Allows better integration with corporate networks—

but big corporations want to manage their own VPNs

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References

• Basavaraj Patil et al.: IP in Wireless Networks

• 3GPP2 specs• A.S0012-A: Interoperability Specification (IOS) for cdma2000 Access Network

Interfaces — Part 2 Transport• A.S0017-A: Interoperability Specification (IOS) for cdma2000 Access Network

Interfaces — Part 7 (A10 and A11 Interfaces)• P.R0001: Wireless IP Architecture Based on IETF Protocols• P.S0001-B: Wireless IP Network Standard• X.S0011-001-C: cdma2000 Wireless IP Network Standard: Introduction• X.S0011-002-C: cdma2000 Wireless IP Network Standard: Simple IP and Mobile

IP Access Services• X.S0011-003-C: cdma2000 Wireless IP Network Standard: Packet Data Mobility

and Resource Management

• Anoop Gupta: 3G CDMA—An Introduction to the Airlink and Data Network, 2003.

• RADCOM Ltd: Introduction to CDMA2000 1x/1x-EV-DO, 2003

• CDG CDMA2000 World Review, December 2003

• CDG CDMA2000 Market Facts, February 2004

• 3GAmericas.org World Cellular Subscribers, December 2003