WiMAX: A Promising Technology
for the Next Generation Wireless
Communications Systems
June 22, 2007
Makoto Yoshida
Senior Researcher
Wireless Systems Engineering Dept.
NGW Project
Fujitsu Laboratories Ltd.
1
Outline
1.
2.
3.
4.
Network and Wireless: What is WiMAX’s role?
Advanced technologies for WiMAX systems
Application systems for digital divide
Standardization activities: IEEE and ITU-R
2
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Outline
1.
2.
3.
4.
Network and Wireless: What is WiMAX’s role?
Advanced technologies for WiMAX systems
Application systems for digital divide
Standardization activities: IEEE and ITU-R
3
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Next Generation Packet-based Network
IP multimedia
Service
Circuit switch
Emulated service
Service
Control /
Management
Resource Control/Mobility Management
AGW
xGSN
xDSL/FTTx
RNC
3G-LTE
BTS
PSTN
Internet
IP Core Network
Transport/Access
3G/3.5G
Streaming service
AGW
AGW
WiFi/WiMAX
HGW
BTS
BTS
BTS: Base station transceiver
RNC: Radio Network Controller
xGSN: Serving/ Gateway GPRS Support Node
BTS
AP
AP
AGW: Access Gateway
AED: Access edge Device
LTE: Long Term Evolution
4
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Circuit Switching
Code1
Code2
Dedicated
channel
Different codes
are used
Keep channel resource during the call
(Code, Bandwidth, etc.)
5
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Packet Switching
Packet
A
A
Code1
A
A
A
B
A
B
B
B
B
B
Code1
Shared
channel
Same code is
shared in time
Share channel resource among users
(Code, Bandwidth, etc.)
6
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Circuit Switch and Packet Switch
Circuit switching
Packet switching
Feature
• Keep channel resource during the
call
• Share channel resource among users
Pros.
• Constant bandwidth during the call
• There is no interruption by other
users after call-setup
• Efficient use of channel resource
• Total capacity will be increased due to
the statistical multiplexing
Cons.
• Keep channel resource even if there is • Bandwidth may not be guaranteed
no data to transmit
• Packet may be lost when channel
• Capacity is limited by the number of
congestion occurred
channels
• Packet order will not guaranteed
7
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Wireless Technology Trend
2->5->10bit/s/Hz
St
at
io
na
ry
Pe
d
es
tr
ia
n
Ve
h
ic
ul
ar
Mobility
WAN/
Cellular 1995
Data rate
increases
7 times
every
5 years.
Data Rates
Spectral Efficiency
(bit/s/Hz)
Radio Access
W-CDMA/HSDPA
O/DV
CDMA2000 EV-D
GSM/PDC/ IS-95
W
WLAN/WIFI
PAN
~40kbps
0.4
TDMA
QPSK
3G-LTE
3.5G
3G
(IMT2000)
2G
1G
(Analog) (Digital)
AMPS
ETACS
NTT
2010
2000
X
A
M
i
/W
N
16.
A
2
0
M
8
2Mbps
.16e
2
0
8
16j
Wireless
Broadband
Systems
2004
2.4GHz
802.11b
Bluetooth
802.15.1
16m
5GHz
802.11a/g
802.11n
ZigBee
802.15.4
14Mbps
0.4
DS-CDMA
MC-CDMA
8
UWB
802.15.3a
54Mbps
100Mbps
2.8
2.7
5
Adaptive
QAM
OFDM/QAM
Adaptive Coding
1Gbps
10
MIMO
Adaptive Array
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Beyond 3G Packet-based Wireless Systems
3.5G
(1x-EVDO Rev.A)
3G-LTE
(3.9G)
(HSDPA,HSUPA)
WiMAX
IMT-Advanced
(4G)
802.16e
802.16m
Access
method
DL：CDMA
UL: CDMA
DL: CDMA
UL: CDMA
DL: OFDMA
UL: SC-FDMA
DL: OFDMA(?)
UL: (?)
DL: SOFDMA
UL: SOFDMA
DL: SOFDMA
UL: SOFDMA
Bandwidth
1.25 MHz
5 MHz
20 MHz
>100 MHz
20 MHz
>20 MHz
Modulation
BPSK,QPSK
8PSK,16QAM
HPSK,QPSK
16QAM
QPSK,16QAM
64QAM,etc.
QPSK,16QAM
64QAM,etc.
QPSK,16QAM
64QAM,etc.
QPSK,16QAM
64QAM,etc.
Data rate
(max.)
DL: 3.1Mbps
UL: 1.8Mbps
DL: 14.4Mbps
UL: 5.7Mbps
DL: 100Mbps
UL: 50Mbps
DL: ~1Gbps
UL: >50Mbps
DL+UL:
75Mbps
DL: >130Mbps
UL: >56Mbps
Service-in
Year 2006
Year 2006
Expected in
2009
Expected in
next decade
Expected in
2007
Expected in
next decade
Features
Enhancement Enhancement
of data rate
of packetised
and QoS
data rate
Great
improvement
of data rate
and latency
Further
improvement
of data rate
and mobility
Great
improvement
of data rate
and latency
Further
improvement
of data rate
and latency
3G-LTE: 3G Long Term Evolution
9
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Wireless MAN History: WiMAX
(Metropolitan Area Network)
„ Wireless MAN was initially developed as
FWA(Fixed Wireless Access) system
z first
• Point to Point Access
• LoS link
z enhanced to support
• Point to Multipoint Access
• NLoS link
LoS :Line of Sight
NLoS :Non 10
Line of Sight
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
802.16 Series Wireless MAN Specifications
Fixed
•
•
•
Simple Mobile/
Full Mobile
Nomadic/Portable
Alternative to ADSL
Business Access
WiFi Backhaul
802.16-2004
Relay /
High speed
Complements Cellular System
P802.16j
802.16e-2005
Relay
Mobile Data
Fixed
Indoor/
Outdoor
Nomadicity/
Portability
WiFi
Backhaul
P802.16m
11
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Main Features of IEEE802.16
9 Provide low-cost solution
(networking, mobile performance)
9 Fit to IP Communication
9 Flexible depending on frequency assignment
9 Various operational parameters are defined
9 Only MAC/PHY layers are specified
(i.e. Core network is out of scope in the 802.16)
12
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Specification of WiMAX
Fixed
(802.16-2004)
Mobile
(802.16e-2005)
802.16m
Frequency band
< 11GHz
< 6GHz
< 6GHz
Bandwidth
1.25～20MHz
1.25～20MHz
1.25～20MHz
Peak Data Rate
75Mbps
(DL+UL)
75Mbps
(DL+UL)
> 130Mbps(DL)
> 56Mbps(UL)
Cell Radius
2-10km （max. 50km)
2-3km
Up to 5km*
Primary (AMC)
BPSK/QPSK/16QAM/64
QAM
QPSK/16QAM/
64QAM
QPSK/16QAM/
64QAM
Secondary
OFDMA
SOFDMA
SOFDMA
Technology for higher data
speed
AAS, STC, MIMO
AAS, STC, MIMO
AAS, STC, MIMO
Mobility
Fix、Nomadic
Max. 120km/h
Max. 350km/h
Freq.
Modulation
AMC: Adaptive Modulation and Coding, SC: Single Carrier,
AAS: Adaptive Antenna System, STC: Space Time Coding
MIMO: Multiple Input Multiple Output
*: some members propose “functionally up to 100km” for rural area application
13
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
OFDM and OFDMA
Transmission by OFDM
Transmission by OFDMA
(Orthogonal Frequency
Division Multiple Access)
(Orthogonal Frequency Division
Multiplexing)
Signal
Amplitude
Signal
Amplitude
Time
Time
Down Link
Burst #n
Frequency
Sub-Carrier
Sub-Carrier CH
• Sub carriers are flexibly allocated to one or
more users depending to their radio
condition.
• All sub carriers are allocated to one user.
• Used in 802.16-2004
• Used in 802.16e-2005 and 802.16m
14
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Outline
1.
2.
3.
4.
Network and Wireless: What is WiMAX’s role?
Advanced technologies for WiMAX systems
Application systems for digital divide
Standardization activities: IEEE and ITU-R
15
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Scalable OFDMA (S-OFDMA)
OFDMA:802.16-2004
SOFDMA:802.16e-2005
•
•
Allocate the FFT size according to
available frequency bandwidth
•
Interval of sub-carriers is fixed.
•
•
FFT size is fixed to 2048
for all bandwidth
Interval of the sub-carriers becomes
narrower as available bandwidth.
More difficult to keep performance
2048/20MHz
2048/20MHz
2048/10MHz
1024/10MHz
16
512/5MHz
128/1.25MHz
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Multi-Antennas for Higher Capacity
¾AAA
(Adaptive Array Antennas)
• Space division to reduce interference at
both terminal and base station
• Optimal antenna directivity is best
calculated on real-time basis.
Desired signal
Desired user
Interference
Interferer
Interferer
¾MIMO
(Multi Input Multi Output)
• Space Division Multiplexing in the same space
using the same frequency band
• Expected capacity increase of number-ofantenna-fold
• Adaptive signal processing required to
establish each independent channel
17
Four-times channel capacity using
the same frequency band
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
MIMO: Multiple Input Multiple Output
r1 = h11 s1 + h21 s2 + n1
r1
h11
s1
h21
s1
h12
s2
r2
h22
H=
s2
MIMO Signal
Processing
h11 h21
h12 h22
r2 = h12 s1 + h22 s2 + n2
MIMO Spatial Multiplexing
Multiple data streams are transmitted through multiple antennas
Ö Data rate can be increased proportional to the number of antennas
(min. of Tx and Rx)
18
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
MIMO Signal Processing Schemes
S1
S2
h11
h21
h12
h22
r1
r2
r1 = h11 s1 + h21 s2
r2 = h12 s1 + h22 s2
ZF:
h22r1 = h22h11 s1 + h22h21 s2
h21r2 = h21h12 s1 + h21h22 s2
r1
S1
r2 = H S2
Matrix Inverse
r1
S1
-1
=H r
2
S2
h22r1 – h21r2 = (h22h11 – h21h12) s1
h22r1 – h21r2
s1 =
h22h11 – h21h12
h12r1 – h11r2
s2 =
h12h21 – h11h22
Other schemes
• MMSE: Wiener Filter
• BLAST: Serial Interference Canceller
• MLD: Maximum Likelihood Detection
• Eigen-mode precoding: with feedback
19
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Quadrature Amplitude Modulation
„Modulation Phase and Amplitude
QPSK
16QAM
i1
i2
10
11
q2
00
10
i2
1011
1001
0001
0011
1010
1000
0000
0010
1110
1100
0100
0110
1111
1101
0101
0111
q1
q2
Same amount
of noise
2 bits per symbol
Robust
4 bits per symbol
Requires high S/N
20
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Radio Channel Quality
Adaptive Modulation and Coding (AMC)
Modulation &
Coding
Channel Quality Indicator
(CQI)
QPSK
16 QAM
time (mS)
„Use high level modulation and coding rate when channel condition is good
Data Throughput can be increased
2007/6/18
21
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Adaptive Modulation and Coding (AMC)
Throughput (bits/sec)
„Throughput Performance
64-QAM 3/4
16-QAM 3/4
16-QAM 1/2
QPSK 1/2
Single path
Rayleigh Fading
Fd = 5.555 Hz
(dB)
IˆS/N
or/Ioc
22
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Hybrid ARQ
discarded
<Conventional ARQ>
ＢＴＳ
zDiscard error packet
zRetry
Data
Parity1
retry
Data
Parity1
NAK
ＭＳ
Data
Parity1
Packet1’
Ｅｒｒｏｒ
<Hybrid ARQ>
„Chase Combining (CC)
zStore
zResend
zCombine
ＢＴＳ
Data Parity1
Data
Parity1
NAK
ＭＳ
Data
＋
Parity1
Ｅｒｒｏｒ
„Incremental Redundancy (IR)
zStore
zSend
Additional redundant bits
ARQ: Automatic Repeat Request
MRC: Maximum Ratio Combining
ＢＴＳ
OK?
Error?
Weighted and Combined
Like MRC diversity
Data
Data
Send additional redundant bits
Data
Parity1
Parity2
Decode
as low rate coding
NAK
Data
Data
Parity1
Parity2
Data
Ｅｒｒｏｒ
23
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Critical Problems to Solve
„Single Frequency Network (SFN) operation
z Fractional Frequency Reuse (FFR)
z Antenna diversity (STC)
z Other-cell interference mitigation: Scheduling algorithm
„Peak-to-Average Power Ratio (PAPR) in Uplink (UL)
z Linearization for terminal: high-linearity PA, Digital PreDistortion (DPD)
z 3G-LTE employs Single-Carrier (SC) approach
„Control channel quality in Time Division Duplex
(TDD): Data/C-ch mixed frame structure
z Circular-Shifted Transmit Diversity (CSTD) for 2-Tx
antennas
z Repetition Coding
24
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Fractional Frequency Reuse (FFR)
BS
FRF =3 Zone
BW
(Ex. 10MHz)
FRF = 1
FRF: Frequency Reuse Factor
BW/3
FRF =1 Zone
(Ex. 3.3MHz)
FRF = 3
25
1 ≦ FRF ≦ 3
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Circular-Shifted Transmit Diversity (CSTD)
Δ0
CP
s( Nfft - 1 ), …, s( 1 ), s( 0 )
s( 1 )
Δ1
CP
s( 0 ), s( Nfft - 1 ), …, s( 1 )
P/S
IFFT
s( 0 )
s( Nfft - 1 ), …, s( 1 ), s( 0 )
s( Nfft - 1 )
ΔM-1
CP
s( Nfft - 1 ), …, s( n )
s( n - 1 ), …, s( 0 )
„Transmitter
-Transmit circular-shifted OFDM symbols by Δ-circular operator
at each antenna
Δ0 = 0
Δ1 ＜ Δ2 ＜ … ＜ ΔM-1
Æ Available delay path more than Cyclic Prefix (CP)
26
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Circular-Shifted Transmit Diversity (CSTD)
OFDM Symbol
4
3
2
CP
1
4
Frequency Response
Tx Antenna 1
Rx Antenna
Add
GI
OFDM
Symbol
f
Tx Antenna 2
Δ1
Add
GI
OFDM Symbol
4
1
3
4
2
3
1
2
CP
4
1
27
Impulse Response
τ(t)
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Outline
1.
2.
3.
4.
Network and Wireless: What is WiMAX’s role?
Advanced technologies for WiMAX systems
Application systems for digital divide
Standardization activities: IEEE and ITU-R
28
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Multi-hop Relay (802.16j)
„Add
the repeater function:
-Wider coverage without backhaul line
-Higher throughput
„Two
Relay modes:
•Transparent relay
•Two hop simple relay
•Centralized scheduling
•Non-transparent relay
•Multiple Relay
•For expanding coverage
•Centralized/Distributed scheduling
Sample Application
Passengers in a train
Train/vehicles in a tunnel
29
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Fixed Wireless Access (FWA)
„802.16e
usage according to application:
-FWA for digital divide area
-MWA for dense urban area
Digital Divide Area
Urban Area
Village
FWA(802.16e)
MWA
(802.16e)
MWA: Mobile Wireless Access
30
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Coexistence FWA and MWA
„MIC
of Japan studied the possibility of coexistence FWA/MWA:
-Antenna directivity for FWA SS should be considered
-Site engineering between MWA/FWA should be considered
Co-channel interference
Fixed use
MWA
SS
10km (assumption)
MIC: The Ministry of Internal Affairs and Communications
31
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Outline
1.
2.
3.
4.
Network and Wireless: What is WiMAX’s role?
Advanced technologies for WiMAX systems
Application systems for digital divide
Standardization activities: IEEE and ITU-R
32
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
IEEE802.16 Standard Family
802.16 Rev2
802.16-2004 ( Oct 2004 )
IEEE Std 802.16
•10-66 GHz PHY
Apr 2002
802.16e-2005 ( Jan 2006 )
802.16c
Profiles
Jan 2003
802.16-2004/ Cor1
802.16e-2005
•Mobile Amendment
802.16a
•2-11 GHz PHY
Jan 2003
802.16-REVd
802.16-2004/ Cor2
• <11 GHz NLos PHY
• MIB for fixed operation
Jun 2004
802.16/Conformance
01,02,03,04
802.16.2 Coexistence
802.16h
•License Exempt Band
Supporting Specification
802.16f-2005
Sep 2005
802.16g
•Management Plane
802.16j
• Mobile Relay
802.16i
• Mobile MIB
802.16m
• IMT-Advanced
802.16k
:Active
• Media Access Control Bridge
33
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
WiMAX Forum
„Non profitable organization
„Established in 2001 to promote Broadband
Wireless Access
„Objectives
z Promotion of IEEE802.16 based products
z Define system profiles
z Create end to end network specification
z Conduct interoperability test
z Give the certificate logo allowance
„Members
z Increase about 100 per year:
about 100(June 2004), more than 420 now
z Fujitsu is a board member from the beginning
34
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
WiMAX System Structure
Web
Service
Service//
Application
Applicationcont
cont
QoS
Streaming
Call
Network
Network
Middleware
Middleware
PTT
Authentication
Mobility
/Charge
WiMAX
WiMAX
Network
Network
IP
IPCore
CoreTransport
Transport
Layer
Layer22Access
Access
PHY
PHY//MAC
MAC
WiMAX
WiMAX
Client
Client
AGW
（BRAS)
FTTH
AGW
(ASN-GW)
AGW
WiMAX
3G/LTE
AGW
WiFi
PC Card
Indoor CPE
35
Outdoor
CPE
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
Mobile WiMAX System
3GSM World Congress
2007/2/13 – 2/16, Barcelona, Spain
Video Streaming
MPEG2
MP@ML/HL
Video Server
BS
Data Speed
18Mbps
MS SoC board
64QAM
Constellation
PC Card
36
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
802.16j Time Line
2005
2006
MMR SG
2005/05
Proposal of MMR（Mobile
Multihop Relay）
2005/09
MMR SG
2007
2008
Relay TG
2006/05
Relay TG
2007/05
Draft1 Letter ballot start
Deferred
2007/09
2006/09
Sponsor ballot start
Supporting Doc finalized
2008/01
Call for proposal
Sponsor ballot finalize
2006/11
2008/03
Deliberations on main
SA approval
body
2-month delay?
37
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
802.16m Time Line Plan
38
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
ITU-R: IMT-2000
•
IMT-2000
–
–
•
3G mobile communications systems
Aimed at the global standard for up to 2Mbps (in stationary)
in 2000
IMT-2000 terrestrial family (2000/05) defined in ITU-R
M.1457
1.
2.
3.
4.
5.
•
CDMA direct spread … WCDMA
CDMA multicarrier
….CDMA-2000
CDMA TDD
… TD-SCDMA
TDMA single carrier … EDGE
FDMA/TDMA
….DECT
IMT-2000 frequency band
–
–
–
–
–
806-960 MHz
1710 – 1885 MHz
1885 – 2025 MHz
2110 – 2220 MHz
2500 – 2690 MHz
39
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
IP-OFDM for IMT-2000
• The 6th air interface for IMT-2000
– IP-OFDMA
… 802.16e OFDMA
– Submit M.1457 amendment to ITU-R WP8F at the
Cameroon meeting in 2006/11
– 9 Evaluation groups
TIA(USA), TTA(Korea), CEG(Canada),
ChEG(China), ATIS(USA), IEG(Israel),
WCA(USA), ARIB-EG(Japan), Anatel(Brazil)
– 22nd WP8F meeting (held in Kyoto) in 2007/05
→ Failed to reach consensus concerning the
decision on IP-OFDMA as the 6th member of IMT2000 (Forward the decision to SG8)
40
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007
41
All Rights Reserved, Copyright © Fujitsu Laboratories Ltd. 2007