WiMAX core Network
Outline









WiMAX introduction
WiMAXQoS & Flow
Network Working Group (NWG)
Network Reference Model
WiMAX Inter Networking
Key hierarchy
Network Entry
Mobility management
Network QoS Functional Elements
Outline









WiMAX introduction
WiMAXQoS & Flow
Network Working Group (NWG)
Network Reference Model
WiMAX Inter Networking
Key hierarchy
Network Entry
Mobility management
Network QoS Functional Elements
簡介


WiMAX 全名Worldwide Interoperability for
Microwave Access，中文譯名為「微波存取
全球互通」。
具有遠距離、傳輸量大，使用IEEE 802.16的
協定，其傳輸速度最高可達70Mbps，傳輸範
圍最廣可達30英哩，對個人、家庭與企業的行
動化將有很大助益為新一代的無線網路標準。
名詞解釋








BS（Base Station，基地臺），指訊號發射端。
SS（Subscriber Station，接收端），有室內、戶外型，必須轉接
才能連到一般設備。
CPE（Customer Premise Equipment，客戶端接收器），內建在
設備上，不用像SS還要轉接裝置。
RS（Rely Station，中繼器），在802.16j（Mobile Multi-hop Relay
）制定，能延伸BS訊號，能智慧型轉發訊號。
PTP（Point to Point，點對點模式），1臺BS對應1臺SS。
PMP（Point to Multiple，點對多點模式），1臺BS可對應多臺SS
。
License Band及Un-License Band（License-Exempt），前者為特
許營運頻帶，必須有營運執照才能使用，例如2.5GHz及3.5GHz，
後者為非特許營運頻帶，不需執照，一般皆可使用，例如5.8GHz
。
LOS（Line-of-sight）及NLOS（Non-Line-of-sight），前者是指設
備間沒有任何障礙物，視為直視距離，後者則是兩端間有障礙物
，視為非直視距離。
WiMAX特色
1.
2.
3.
4.
5.
包含非直視性(Non-Line-of-Sight，NLOS)及
直視性（Line-of-Sight，LOS）技術、傳輸
距離長、網路涵蓋範圍廣。
高頻譜效率、高傳輸速率。
具彈性的系統容量。
支援語音、影像等服務之服務品質（QoS）
需求。
支援多種工作頻段，可配合不同國家之頻譜
指配。
LOS模式與NLOS模式


NLOS(Non Line of Sight)模式
 速度較慢，穿透力較高，適用於都會環境
 使用2-11GHz頻段，最大傳輸距離為10公里
 當通道頻寬為20MHz時，最高速度約75Mbps
LOS(Line of Sight)模式
 速度較高，穿透力差，適用於空曠的環境
 使用10-66GHz頻段，最大傳輸距離為5公里
 當頻寬為28MHz時，速度最高為134Mbps
應用情境
固接式WiMAX


IEEE 802.16 工作小組，最初是將寬頻點發展
為多點 (PMP) 標準，以作為有線網路基礎架
構的無線擴充。而第一個獲認可的空中介面，
即是建立在分時多工存取 (TMDA) 通訊協定上
。
此一介面支援分時雙工 (TDD) 與分頻雙工
(FDD)。
移動式WiMAX

主要以2.5G頻譜為主，具有行動上網的優勢，
未來汽車也將全面配備WiMAX連網設備，以
便行駛間能接收網路訊息。
協定演進
Uplink nad Downlink

Uplink


From SS to BS
Downlink

From BS to SS
TDD and FDD


Frequency Frequency-Division Duplex (FDD)
 DL & UL on separate RF channels
Time Time-Division Duplex (TDD)
 DL & UL time-share the same RF channel
 SS does not transmit/receive simultaneously
Time Time-Division Duplex (TDD)
實體層定義

WiMAX系統為了因應各種不同使用場景，訂定
了兩個使用頻段：10～66GHz與2～11GHz，及4
種不同的實體層介面規範：WirelessMAN-SC、
WirelessMAN-SCa、WirelessMAN-OFDM及
WirelessMAN-OFDMA，其中WirelessMAN-SC屬
於10～66GHz頻段，而其餘三者屬於2～11GHz
頻段
使用環境

WirelessMAN-SC及WirelessMAN-SCa適用於
直視路線(Line of Sight, LOS)環境，而
WirelessMAN-OFDM及WirelessMANOFDMA適用於非直視路線(Non-Line of Sight,
NLOS)環境
效能提升方法

WirelessMAN-SCa、WirelessMAN-OFDM及
WirelessMAN-OFDMA均可採用「適應性天線
系統」(Adaptive Antenna System, AAS)技術
提升效能；其中Wireless MAN-Sca基本上採
用的是「智慧型天線」波束形成技術，而
WirelessMAN-OFDM及Wireless MANOFDMA則採用MIMO技術
實體層規格
‧WirelessMAN-OFDM

本規範主要訴求在藉由OFDM有效對抗通道多
重路徑效應與提高資料傳輸率。OFDM調變共
有256個次載波，可支援包括QPSK、16-QAM
和64-QAM的適應性調變(adaptive
modulation)，根據各個次載波通道狀況決定其
調變位階。多重接取採用的是分時的TDMA。
為因應多路徑環境之特性，
WirelessMAN-OFDMA

本規範主要訴求在提供移動式應用。調變方式
與WirelessMAN-OFDM相同，但多重接取採
用的是分頻的FDMA，並支援可變(scalable)頻
寬的機制，其功能為根據通道狀況改變系統頻
寬與次載波數
WirelessMAN-OFDMA (cont.)

OFDMA的運作原則是將所有次載波分割成若
干群組，稱為次通道(subchannel)，分配給不
同用戶使用，並根據傳輸環境狀況決定各個次
通道的次載波數。
WirelessMAN-OFDMA (end)
MIMO


多輸入多輸出(Multiple Inputs, Multiple
Outputs, MIMO)
MIMO的核心概念為利用多根發射天線與多根
接收天線所提供之空間自由度提升傳輸速率與
改善通訊品質。
MIMO功能形式

空間多樣(spatial diversity)


利用發射或接收端的多根天線所提供的多重傳輸途
徑來對抗通道衰落(fading)的影響
空間多工(spatial multiplexing)

在發射端利用多根天線傳送不同資料序列，並在接
收端利用多根天線的空間自由度將該組資料序列分
別解出
MIMO優點




系統涵蓋範圍
提升鏈路品質
提高系統容量及頻譜效率
與提高資料傳輸率
Outline









WiMAX introduction
WiMAXQoS & Flow
Network Working Group (NWG)
Network Reference Model
WiMAX Inter Networking
Key hierarchy
Network Entry
Mobility management
Network QoS Functional Elements
Introduction

QoS supporting is a fundamental part of the
WiMAX MAC-layer design.

How does WiMAX support for QoS?
Connections

A connection-oriented MAC architecture


all downlink and uplink connections are controlled
by the serving BS
Each connection is identified by a connection
identifier (CID)
Service flows

A service flow is a unidirectional flow of
packets



with a particular set of QoS parameters
is identified by a service flow identifier (SFID)
The service flow characteristics of the
connection provide the QoS for that packet
Service Flow Creation
Service Flow Management



Dynamic Service Change (DSC)
Dynamic Service Delete (DSD)
Dynamic Service Activate (DSA)
DSD
DSC
NULL
DSA
OPERATIONAL
Classifier

A classifier is a set of matching criteria
applied to each packet




It consists of some protocol-specific packet
matching criteria (destination IP address, for
example)
a classifier priority
a reference to a CID.
Classifiers can be added by dynamic
signaling
Scheduler
Scheduler
Service
Classifier flows
QoS logical
connections
MS1 MAC
Service flow
over
QoS connections
BS MAC
Priority
queues
MS2 MAC
Associate packets into service flow
Define QoS parameter for each service flow
Dynamically establishing QoS-enabled service flows
Associate QoS service flow with logical connections
Quality of Service Support
Scheduling services

Four services are supported in 802.16 802.16-2004





Unsolicited Grant Service (UGS),
Real-time Polling Service (rtPS),
Non-real-time Polling Service (nrtPS), and
Best Effort (BE).
Five services are supported in 802.16e 802.16e2005





UGS (Unsolicited Grant Service)
RT-VR (Real-Time -Variable Rate Service)
NRT-VR (Non-Real Time -Variable Rate service)
BE (Best Efforts)
ERT-VR (Extended Real-Time Variable Rate)
Unsolicited Grant Service (UGS)

support real-time data streams consisting of
fixed-size data packets issued at periodic
intervals

Such as T1/E1 and Voice over IP without silence
suppression
INTERNET
VoIP
Real-time Polling Service (rtPS)

support real-time data streams consisting of
variable-sized data packets that are issued at
periodic intervals

Such as moving pictures experts group (MPEG)
video.
Non-real-time Polling Service (nrtPS)

support delay-tolerant data streams
consisting of variable-sized data packets for
which a minimum data rate is required

such as FTP
Best Effort (BE)

support data streams for which no minimum
service level is required and therefore may be
handled on a space-available basis.
Extended Real-Time Variable Rate
(ERT-VR) service

support real-time applications with variable
data-rates, which require guaranteed data
and delay, for example VoIP with silence
suppression.
Handover

An mobile station (MS) migrates from the airinterface provided by one BS to the air
interface provided by another BS
Handover in WiMAX


Hard Handover
Fast Base Station Switching (FBSS)




Active Set (Diversity set)
Anchor BS
MS  Anchor BS
Macro Diversity Handover (MDHO)



Active Set (Diversity set)
Anchor BS
MS  all BSs in an active set
Outline









WiMAX introduction
WiMAXQoS & Flow
Network Working Group (NWG)
Network Reference Model
WiMAX Inter Networking
Key hierarchy
Network Entry
Mobility management
Network QoS Functional Elements
WiMAX Forum


The WiMAX Forum is a nonprofit organization
formed in 2001 to enhance the compatibility and
interoperability of equipment based on the IEEE
802.16 family of standards
WiMAX Forum_Network Working Group (NWG)
define



Stage 1: use case scenarios and service
requirements and defined along with Service
Provider Working Group
Stage 2: Architecture Tenets, Reference Model and
Reference Points
Stage 3: Detailed Protocols and Procedures
WiMAX Working Group
‧Application Working Group (AWG)
‧Certification Working Group (CWG)
‧Evolutionary Technical Working Group (ETWG)
‧Global Roaming Working Group (GRWG)
‧Marketing Working Group (MWG)
WiMAX Working Group
‧Network Working Group (NWG)
‧Regulatory Working Group (RWG)
‧Service Provider Working Group (SPWG)
‧Technical Working Group (TWG)
Relationship between the scopes
of WiMAX NWG and 802.16

From IEEE 802.16 to WiMAX NWG


build an interoperable broadband wireless
network.
Interoperable networks involve end-to-end service

such as IP connectivity and session management,
security, QoS, and mobility.
Outline









WiMAX introduction
WiMAXQoS & Flow
Network Working Group (NWG)
Network Reference Model
WiMAX Inter Networking
Key hierarchy
Network Entry
Mobility management
Network QoS Functional Elements
WiMAX Network Reference
Model(1/2)
Decomposed ASN into BS and
ASN GW entities
Entities of the WiMAX Network
Reference Model (1/2)

ASN: Access Serving Network

Logical representation of the functions of a NAP, e.g.






802.16 interface network entry and handover
Radio Resource Management & Admission ctrl.
L2 Session/mobility management
QoS and Policy Enforcement
Foreign Agent (FA)
Forwarding to selected CSN
Entities of the WiMAX Network
Reference Model (2/2)

CSN: Connectivity Serving Network

Logical representation of the functions of a NSP, e.g.





Connectivity to the Internet, ASPs
Authentication, authorization and accounting
IP address management
L3 Mobility and roaming between ASNs
Policy & QoS management based on a SLA
Network Reference point (1/2)

R1:


R2:


Reference point between MS and ASN-GW or CSN: logical interface used
for authentication, authorization, IP host configuration and mobility
management.
R3:


Reference point between MS and BS: implements IEEE 802.16e-2005.
Reference point between ASN and CSN: supports AAA, policy enforcement,
and mobility –management capabilities. Implements tunnel between ASN
and CSN.
R4:

Reference point between ASN and ASN: used for MS mobility across ASNs.
Reference point (2/2)

R5:


R6:


Reference point between BS and ASN: implements intraASN tunnels and used for control plane signaling.
R7:


Reference point between CSN and CSN: used for
internetworking between home and visited network.
Reference point between data and control plane in ASNGW: used for coordination between data and control plane
in ASN-GW.
R8:

Reference point between BS and BS: used for fast and
seamless handover.
WiMAX Network Reference
Model(2/2)
Outline









WiMAX introduction
WiMAXQoS & Flow
Network Working Group (NWG)
Network Reference Model
WiMAX Inter Networking
Key hierarchy
Network Entry
Mobility management
Network QoS Functional Elements
ASN Network & GW
ASN-GW Reference model
Internetworking with 3GPP
Scope

WiMAX-3GPP Interworking
refers to the integration of a
WiMAX Access Network to an
existing 3GPP core network.
Internet
Billing Server
PDG
Home Agent
WAG
Home AAA
3GPP Core
Network
GCSN
WiMAX Network
Service Provider
Local AAA
SGSN
RNC
3GPP Access
Network
Loosely-Coupled
Internetworking
WiMAX ASN
WiMAX Base Stations
3GPP
Card
WiMAX
Card
UE
Outline









WiMAX introduction
WiMAXQoS & Flow
Network Working Group (NWG)
Network Reference Model
WiMAX Inter Networking
Key hierarchy
Network Entry
Mobility management
Network QoS Functional Elements
802.16e network entry

In a WiMAX network, a
full network entry
includes four steps:
a. Network Discovery and
Selection
b. Access Authentication
c. Connection Setup
d. Data Transfer
802.16 TDD Frame Structure
Time Slot
Downlink Subframe
Uplink Subframe
Frame Control
Contention Request
Bandwidth Request
DATA
Contention Slot
UCD
DCD
DATA
UL-MAP
DL-MAP
TDD Frame Structure
Outline









WiMAX introduction
WiMAXQoS & Flow
Network Working Group (NWG)
Network Reference Model
WiMAX Inter Networking
Key hierarchy
Network Entry
Mobility management
Network QoS Functional Elements
Network entry


A WiMAX subscriber station has to complete the
network entry process , in order to communicate
on the network.
Steps:









Scan for DL channel and establish synchronization with the BS
Obtain transmit parameters (form UCD message)
Perform initial ranging
Negotiate basic capabilities
Authorize MS and perform key exchange
Establish IP connectivity
Establish time of day
Transfer operational parameters
optional
Set up connections
Network entry


a)Downlink Channel Synchronization:
When an SS wants to communicate on a WiMAX
network, it first scans for available channels in the
defined frequency list. On finding a DL channel, it tries to
synchronize at the PHY level using the periodic frame
preamble. Information on modulation and other DL and
UL parameters is obtained by
observing the DL Channel Descriptor (DCD) and the UL
channel descriptor (UCD) of the DL channel.
Ranging(1/2)



b) Initial Ranging:
An SS starts an Initial ranging process by sending a
ranging request MAC message using the minimum
transmission power. If no response is received from the
BS, the SS resends the message on a subsequent frame
using a higher transmission power. The response either
indicates power and timing corrections that the SS must
make or indicates success.
Purpose:

The process by which the SS and BS maintain the quality of RF
communication link between them.
Ranging(2/2)

Periodic ranging

Allows SS to adjust transmission parameters and
maintain uplink communication with the BS.
Network entry


c) Exchanging Capabilities:
After successful completion of the initial ranging step, the
SS sends capability request message indicating the
supported modulation level, coding scheme and rates
and duplexing methods.
Network entry




d) Authentication:
After capability negotiation, the BS authenticates the SS,
determines the ciphering algorithm to be used, and
sends an authentication response to the SS.
e) Registration:
After authentication, the SS sends a registration request
message to the BS and the BS sends a registration
response.
Network entry


f) IP Connectivity:
After registration, the SS gets the IP address via DHCP.
The SS also downloads other operational parameters
using TFTP.

g) Connection Creation:

After completing the IP connectivity step, transport connections are
created. For preprovisioned service flows, the BS sends a dynamic
service flow addition request message to the SS and SS confirms
the creation of connection. For non-preprovisioned service flows,
connection creation is initiated by the SS by sending a dynamic
service flow addition request message to the BS. The BS responds
with the confirmation.
Network Discovery and Selection




NAP discovery
NSP discovery
NSP Enumeration and selection
ASN attachment based on NSP Selection
NSP Discovery
ASN Attachment based on NSP
Selection
Connection setup

The ASN setup



Access Authentication
Binding of MS flow to intra-ASN DATA PATH
MIP req / resp


PMIP4 / CMIP4 / CMIP6
MIP tunnel
Connection setup procedure
( DHCP proxy )
Connection setup procedure
( CMIPv4 )
Connection Setup Procedure (CMIP6 )
Outline









WiMAX introduction
WiMAXQoS & Flow
Network Working Group (NWG)
Network Reference Model
WiMAX Inter Networking
Key hierarchy
Network Entry
Mobility management
Network QoS Functional Elements
Mobility management

The WiMAX mobility solution consists of two
mobility levels

Intra-ASN mobility


ASN Anchored Mobility
inter-ASN mobility


ASN-anchor (based on profile A & C)
CSN Anchored Mobility
ASN Anchored Mobility
Management(1/4)

ASN Anchored Mobility Management is
defined as mobility of an MS not involving a
CoA update (MIP re-registration)
ASN anchor Mobility (2/4)
ASN anchored mobility (3/4)
CSN Anchor mobility
( R3-mobility )

Re-anchoring of the current FA to a new FA
and the consequent binding updates to
update the upstream and downstream data
forwarding paths.
Authentication, Authorization and
Accounting

The WiMAX AAA framework is based on IETF specifications.
The term AAA is used to refer to the AAA protocols, Radius or
Diameter.

The AAA framework provides the following services to WiMAX:
 Authentication Services


Authorization Services


These include MS, user, or combined MS and user authentication.
These include the delivery of information to configure the session for
access, mobility, QoS and other applications.
Accounting Services

These include the delivery of information for the purpose of billing
(both prepaid and post paid billing) and information that can be used
to audit session activity by both the home NSP and visited NSP.
Accounting Architecture
Outline









WiMAX introduction
WiMAXQoS & Flow
Network Working Group (NWG)
Network Reference Model
WiMAX Inter Networking
Key hierarchy
Network Entry
Mobility management
Network QoS Functional Elements
QOS

IEEE 802.16 MAC is connection oriented. Each
connection, upon establishment, subscribes to one
of the scheduled services

Resource allocation, admission, and scheduling is
controlled the base station
QoS Functional Elements

Service Flow Management (SFM)


Service Flow Authorization (SFA)


e.g., SIP Proxy
PF: Policy Function


Evaluate any service request
against user QoS profile.
AF: Application Function


responsible for the creation,
admission, activation, modification
and deletion of 802.16 service
flows.
Maintained information includes HNSP's general policy rules
LPF: Local Policy Function

enforce admission control based
on available resources
Reference


Wimax forum WiMAX End-to-End Network
Systems Architecture (Stage 3: Detailed
Protocols and Procedures)
Wimax forum WiMAX End-to-End Network
Systems Architecture (Stage 2)