WiMAX System Architecture

1 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials

Company Confidential

WiMAX Overview WiMAX System Architecture

14th November 2006

Esa Viitanen



WiMAX Introduction



Nokia WiMAX Program High-level Direction

• Lightweight, high-speed wireless, personal access to Internet with portability

• Main, initial use case:

• Laptop and

• Tablet Internet access,

• Walking between cells without loosing session (IP address) and/or VPN connection

• Substantially lower cost of ownership than 3G

• Hide system complexity from user and operator through automated operability, moving towards plug-and-play

• Usage of non-cellular licensed spectrum



WiMAX Terminals

• Operators start first with fixed and nomadic terminals• CPE boxes

• Ethernet and POTS interfaces• Indoor or outdoor antenna• Applications:

• Broadband Wireless - DSL replacement• Wireless Local Loop

• PCMCIA cards• For laptops

• WiMAX radio integrated in laptops• Intel WiMAX chipset coming to laptops in 2008

• And continue later with true mobile terminals• PDAs• Mobile handsets

• Starting from high-end business phones

• Cameras, … , with WiMAX radio



WiMAX, Quick Overview on the Air Interface 802.16e• WiMAX is a TDD system

• With various carrier bandwidths: 3.5, 5, 10 MHz

• Frequency bands for WiMAX:• 2.5 GHz (licensed)• 3.5 GHz (licensed)• 5.8 GHz (unlicensed)

• Amount of spectrum needed:• Min. 10 MHz, typically 15 – 30 MHz

• Typical cell ranges @ 2.5 GHz:• 500 – 1500 m, for suburban and urban areas with indoor coverage• 5 – 10 km with outdoor antenna

• Estimated aggregate data rates per sector:• 4 Mbps per sector UL for a 10 MHz carrier• 13 Mbps per sector DL in case of 3x 10 MHz carrier used

• Network architecture:• IP based



WiMAX, Standards

• IEEE 802.16d-2004• Fixed WiMAX air interface standard

• Nokia does not implement this

• IEEE 802.16e-2005• Mobile WiMAX air interface standard

• Nokia WiMAX is based on this, both for fixed and mobile WiMAX applications

• PHY and MAC layers

• WiMAX Forum recommendations• End-to-End Network Systems Architecture, reference model for

• ASN, Access Service Network and

• CSN, Core Service Network

• WiMAX Forum refers to a number of IETF RFCs



WiMAX Networks



WiMAX Network Architecture

• There are two basic applications for WiMAX networks• Fixed/nomadic WiMAX

• Broadband Wireless access to Internet and Wireless Local Loop• In developing countries, rural areas, where copper cables do not exist• Providing DSL type access

• Mobile WiMAX• Mobile access to Internet• Complementary to current cellular networks - data overlay networks

• Nokia has two different WiMAX Network Reference Architectures• Fixed WiMAX Reference Architecture for DSL operators

• Provides Ethernet transport to the terminals - like DSL access• Mobile evolution adds local mobility (local handovers)

• Mobile WiMAX Reference Architecture for Mobile Operators• Adds wide area mobility• Provides IP transport to the terminals



Fixed WiMAX Reference Architecture for DSL operators

BS

BS

BRAS ASP / NSP Network infra (AAA, DHCP, billing, subscriber db, …)

V

A10

DS

LA

MxDSL V

ETH

R1

.16e-2005

DS

LA

MxDSLCPE

TE

TE

. . .

CPE

TE

TE

. . .

T

CPE

TE

TE

. . .T

Laptop PCWiMAX i/f

OMSBS O&M

BTSOM



Mobile WiMAX Evolution for DSL Operators

BS

BS

R1

R6 ASN GW

BRAS ASP / NSP Network infra (AAA, DHCP, billing, subscriber db, …)V

A10

ETH

R3aaa

xDSL VCPE

TE

TE

. . .

DS

LA

M

CPE

TE

TE

. . .

MSS

T

T

OMSBS O&MASN GW O&M

BTSOM

R1

Laptop PCWiMAX i/f CSN P&CF

AAA



Fixed WiMAX – DSL Network, Physical Architecture

AAA

DHCP/DNS

DSL CPE

FWNAPT

Fiber core

Copper access

Microwave access

BS

O&MNetAct

GPS

LDAPSubs. DB

Internet

DSLAM

BRAS

MW IU

ADSL2+VDSL2

ASN CSN

OMS



Mobile WiMAX Reference Architecture for Mobile Operators

MSS

BS

ASN GW

BSR1

R6

R2

ASN GW

CSNHA

CSN P&CFAAA

R3aaaRadius

R4

R3mipMIP

Network Management System(NetAct)

OMSNWI3

PostpaidCG

BS O&MASN GW O&M

X7

Internet

Subs. DBHLR/ HSS

FW/NAPT

LIGBS

DHCP/DNS

R1

CPE

TE

TE

. . .

. . .

T

X2

LIG

. . .

BTSOM

Laptop PCWiMAX i/f

R1



Mobile WiMAX Network, Physical Architecture

HA

AAA

3xASN GW

OMSCore

DHCP/DNS

DSL NT

FWNAPT

Fiber core

Copper access

Microwave access

BS

AccessDHCP/DNS

LIG

NetAct (OSS)

GPS

Subs. DB

Internet

DSLAM BRAS

MW IU

ASN CSN



WiMAX Network Elements



WiMAX Network Elements

• Nokia WiMAX Network Elements• BS Base Station• ASN GW Access Service Network GateWay• OMS Operation and Maintenance Server

• Commercial Network Elements• HA Mobile IP Home Agent• AAA Authentication, Authorization and Accounting Server

• Supplementary Elements• NetAct Network Management System• LIG Legal Intercept Gateway• IP transport elements Routers, Switches, DHCP/DNS, FW/NAPT• BS transport elementsMicrowave radios, xDSL NT, …



Mobile WiMAX rel 1 – Flexi Base Station

• Based on the WCDMA Ariel BTS platform

• Outdoor, 19” 3U module

• Ethernet interface to network

• OBSAI RP3-01 optical interface to RF

• Separate RF head• 2TX/2RX, MRC, external antenna

• RF and BB MIMO capable

• TX power 36dBm, ~ 4 W

• Scalable bandwidth up to 10MHz

• 2.5GHz and 3.5GHz RF and antenna options

• PUSC (incl all SC)

• GPS based synchronization

RF Module

Antenna

OBSAI RP3-01 optical



Frequency Allocation

f1f1

f1

sector #2 uses 1/3 of all

subcarriers


subcarriers


subcarriers

f1f2

f3

all sectorsuse all

subcarriers

f1

cell uses allsubcarriers

1+1+1

Single carrier

(Omni-directional)

PUSC,Partially Used SubCarriers

e.g. 10 MHz bandwidth

FUSC, Fully Used SubCarriers

e.g. 3 x 10 MHz bandwidth



ASN GateWay• Indoor network element

• 19” wide 1 U high

• Main functionalities• Mobility control (Handovers) between

Base stations

• Mobile IP Foreign Agent

• Authenticator

• Security key distribution

• Rate Limiting (Downlink)

• Paging

• Scalable element• Scalable by adding additional GWs

• Traffic routing and tunneling capacity• 2Gbits per box Downlink + 1Gbits Uplink

• Control plane capacity• 200 WiMAX Base station Cells

• Resiliency at network level



AAA - Authentication, Authorization, and Accounting Main functionalities:

• Authentication algorithms/methods

• Optionally allocates IP addresses for terminals at authentication phase

• Fetches the subscriber profiles from the subscriber and subscription databases

• Distributes QoS profiles to ASN GW

• Reports CDRs to the billing system



HA - Mobile IP Home Agent

Main functionalities:• Interfaces WiMAX User plane to the Internet, to other IP networks and to services• Optionally allocates IP HoA addresses for terminals• Performs handovers between ASN GWs• Needed only in large networks, for example for mobility between cities• Used also for roaming between other networks



OMS - Operation and Management Server

• Main functionalities:• WiMAX RAN mediator for NetAct

• Mediates BSs and ASN GWs



Main WiMAX Interfaces

• R1• Encrypted WiMAX air interface • Between Base Station and Terminal

• R6• Interface between the BS and ASN GW• GRE tunneling in user plane and IPSec in control plane

• R3• User plane interface between ASN GW and Home Agent - Standard Mobile IP protocol • Control plane interface between ASN GW and AAA Server - Standard Radius protocol

• V interface• Interface between BS and BRAS (BRAS = Broadband Remote Access Server)• Ethernet based interface, according to TR-101, uses 1:1 and 1:N VLAN mappings• Needs case by case configuring, to interface with the operator’s existing DSL network

• AAA i/f• LDAP interface to operators Subscriber database, also a MAP interface to 2G/3G HLR/HSS• Typically FTP interface for collecting CDRs to operators postpaid billing system• AAA interfaces vary according to operator’s infrastructure and need an integration project



WiMAX BS Transport



WiMAX BS Site Transport

• Three sector 1+1+1 WiMAX BS average capacity is 8 … 24 Mbit/sec• Current GSM or WCDMA backhaul transport is too thin - not applicable for WiMAX

• Build a new transport to the WiMAX BS site

• WiMAX Transport solutions• Microwave radio links

• Ethernet leased lines (fiber or copper, possibly xDSL lines)

• A number of E1/T1 lines (initial solution only)

• WiMAX BS transport interfaces• Ethernet 100Base-TX

• Gigabit Ethernet 1000Base-SX/LX optical

• FlexBus with Ethernet transport, in Rel 2

• 8 x E1/T1, in Rel 2



BS Site Transport Options

BS

ASN GW

Router

Ethernet Switch

Ethernet (Leased)

Line

DSLAM

DSL NT

MWR-IU

BS Chaining

Ethernet

E1/T1

other

BS

E1/T1 (Leased)

Lines



WiMAX System Features



WiMAX Authentication

• Mobile WiMAX uses EAP Authentication methods• Subscriber authentication, protocol run between the Terminal and AAA server

• Several EAP methods available• EAP-AKA for USIM

• EAP-TTLS for shared secret

• . . .

• WiMAX DSL interworking architecture uses the DSL Authentication methods available in BRAS

• DHCP Option 82 authentication, based on MAC address of the terminal

• PPP, user name / password authentication



WiMAX User QoS

• Air interface QoS• Nokia Release 1 has three air interface QoS classes

• UGS - Unsolicited Grant Service, for continuous fixed bit-rate data streams

• ertPS - extended real time Polling Service, for VoIP traffic

• BE - Best Effort, for other traffic like browsing

• Implementation in BS scheduler

• Access Transport Network QoS• Two priorities in Nokia Release 1:

• “VoIP”

• “BE”

• Based on DiffServ

• User Data rate limiting • For traffic between the Terminal and ASN GW

• At subscriber service flow level



WiMAX Mobility

• Fixed / Nomadic Mobility• The usage is stationary• Moving without a connection

• Portable / Full Mobility• Handovers

• R6 mobility – tunnel switching between Base Stations (Inter BS handover)• R4 mobility – extending a tunnel through the next ASN GW (Inter ASN GW

handover)

• Network resource optimization• R3 mobility – Mobile IP (Inter ASN GW handover)• This is not exactly a handover, but network resource optimization after a number of

handovers• Small networks may not implement R3 handover, they may not have a Home Agent

• Idle mode and Paging• Implemented for saving the battery life in mobile devices• Paging is needed mainly for incoming VoIP calls (SIP calls)



Mobility Cases: R6, R4 and R3 Mobility

ASN (NAP-A)

CSN (NSP-B)ASN Gateway (FA)

ASN Gateway (FA)

HA

R6

R4

1

2

3

0

R3

Network

Network



WiMAX Overview WiMAX System Architecture

Thank You

Documents

WiMAX System Architecture