WiMAX and Mobile WiMAX
802.16-2004 (d), 802.16-2005(e)
Presentation Overview
• Standard Overview
• WiMAX Family
– WiMAX, Mobile WiMAX Specification Overview
• Algorithm descriptions
– PHY, MAC
• Mobile WiMAX performance
– Link, System, Comparative
• WiMAX Availability/Deployments
• Further amendments
– 802.16h, 802.16j, 802.16m
Specification Overview
802.16 Family (WiMAX)
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802.16 LOS 10-66 GHz
802.16a 2-11 GHz (superceded by 802.16-2004)
802.16c 2-11 GHz (superceded by 802.16-2004)
802.16d Combined 802.16, 802.16a, 802.16c into 802.16-2004
802.16e Approved Dec 7 2005
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802.16f Network Management Information Base (MIB)
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•
•
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Draft Feb 2006
802.16h Coexistence with license-exempt 802.16 protocols
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Published Dec 1, 2005
802.16g Network management plane
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Published Feb 2006
Draft
802.16i Mobile Management Information Base (explicitly to
handle updates from 802.16e) – Just accepted contributions
802.16j Mobile Multihop Relay (More later in presentation)
802.16k Network Management/Bridging
802.16m 4G WiMAX
– Just started
http://grouper.ieee.org/groups/802/16/milestones_active.html
IEEE 802.16 Standards
Source: www.wimaxforum.org/news/events/wimax_day_agenda/Gordon_Member_IEEE_802.16.pdf
WiMAX Schedules
WiMAX Forum (2006): Mobile WiMAX – Part I: A Technical Overview and Performance Evaluation.
Available at www.wimaxforum.org
Relationship Between Players
www.wimaxforum.org
802.16 Standard and Usage
Model Mapping
Source: www.wimaxforum.org/news/events/wimax_day_agenda/Gordon_Member_IEEE_802.16.pdf
802.16-2004
• Actually a suite of PHY protocols
High Speed Unlicensed MAN
Source: www.wimaxforum.org/news/events/wimax_day_agenda/Gordon_Member_IEEE_802.16.pdf
WirelessMAN-SC
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•
•
•
Single Carrier
Licensed operation
LOS only, >10 GHz
FEC = Reed-Solomon, optional Block Turbo Codes, Convolutional
Turbo Codes
• Power Control
• Directional antennas at subscriber units
• Channel quality measurements
– RSSI
– CINR
Source: www.wimaxforum.org/news/events/wimax_day_agenda/Gordon_Member_IEEE_802.16.pdf
WirelessMAN-SCa
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•
•
•
•
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Licensed operation
< 11 GHz
TDD and FDD duplex
TDMA uplink
Single Carrier
Variable bandwidths
Reed-Solomon and trellis
coded modulation
• Optional block and
convolutional Turbo
codes
• Framing for equalization,
channel performance
• Robust modes for low
SINR
• Space time coding
transmit diversity option
• Block adaptive
modulation
WirelessMAN OFDM
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•
•
•
Licensed operation
NLOS, < 11 GHz, TDD, FDD
TDMA
OFDM modulation, 256 point
FFT
– BPSK, QPSK, 16-QAM, 64QAM
• Uplink power control
• Optional space time coding
– 2 Tx (BS), 1 RX (SS)
• RSSI, CINR measurements
– Adaptive modulation
• Includes Mesh Frame (optional)
• Reed Solomon, Optional BTC,
CTC
From IEEE Std 802.16-2004
Subcarriers: 192 Data, 8 Pilot, 28 Low Guard Band, 27 High Guard Band
WirelessMAN OFDMA
• Licensed operation
• NLOS, < 11 GHz, TDD, FDD
• Channel Bandwidths > 1.0 MHz, 2nxregulatory bandwidth
• OFDM modulation, 256 point FFT
– BPSK, QPSK, 16-QAM, 64-QAM
• Subchannelization
– OFDM FDMA = OFDMA
– Gives flexibiltiy in channel
assignment in time and frequency
• Convolutional code, Optional BTC,
CTC
• Uplink power control
• Optional space time coding
– 2 Tx (BS), 1 RX (SS)
• RSSI, CINR measurements
– Adaptive modulation
From IEEE Std 802.16-2004
Wireless HUMAN
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•
•
•
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Unlicensed operation
NLOS, < 11 GHz, TDD
Supports all PHY but 802.11SC
Adds DFS to the MAC
Defines center frequencies at 5 GHz
– 5000 + 5 nch (MHz)
From IEEE Std 802.16-2004
802.16e (Mobile WiMAX, 802.162005)
• Ideally, 802.16 + mobility
– Really intended for nomadic or low mobility
– Not backwards compatible with 802.16-2004
• http://www.unstrung.com/document.asp?doc_i
d=76862
• Approved Dec 7 2005
– Published Feb 2006
– http://www.ieee802.org/16/tge/schedule.html
• Direct competitor to 3G, 4G, 802.20 though
WiMAX Forum says otherwise
• Receiving significant attention
• Not intended for compatibility with 802.162004
Scalable
OFDMA
• PHY for 802.16e
• Modifies OFDMA so
FFT size varies with
channel bandwidth
– Keeps carrier spacing
constant
• Channel update rate
of 1 KHz
– Channel estimation,
equalization
WiMAX Forum (2006): Mobile WiMAX – Part I: A Technical
Overview and Performance Evaluation. Available at
www.wimaxforum.org
H. Yaghoobi, “Scalable OFDMA Physical Layer in IEEE 802.16 WirelessMAN,” Intel Technology Journal, Volume 8, Issue 3, 2004.
Available online: ftp://download.intel.com/technology/itj/2004/volume08issue03/art03_scalableofdma/vol8_art03.pdf
Mobile WiMAX Peak Rates
• Block Turbo Code
and Low Density
Parity Check Code
(LDPC) are
optional
• Convolutional
Codes (CC) and
Convolutional
Turbo Codes must
be supported
WiMAX Forum (2006): Mobile WiMAX – Part I: A Technical Overview and
Performance Evaluation. Available at www.wimaxforum.org
Optional Antenna Array Support
• MIMO-STC (defined
in Matrix A)
• MIMO-Spatial
Multiplexing (defined
by Matrix C)
• Beamforming
• Operation defined by
three classes
matrices for antenna
different number of
antennas (2x2 STC is
Alamouti)
• Support for switching
between approaches
• Not being deployed
initially, but more later
WiMAX Forum (2006): Mobile WiMAX – Part I: A Technical Overview and
Performance Evaluation. Available at www.wimaxforum.org
Peak Data Rates
MAC/Mobility Features
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Frame-by-frame resource allocation
Hybrid Automatic Repeat Request (HARQ)
UL and DL Scheduling
Variable QoS
Three handoff methods
– A traditional Hard Handoff (HHO)
– Fast Base Station Switching (FBSS)
• A list of reachable base stations is maintained by
mobile and base stations, but base stations discard
packets if not the active BS
– Macro Diversity (MDHO)
• Same list is maintained, but all base stations in the list
can participate in the reception and transmission of
packets.
WiBro
•
Korean version of 802.16e
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Korean spectrum allocated 2002
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2.3 GHz (100 MHz)
Harmonization 802.16e/WiBro agreed Nov 2004
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Phase 1 standardized by TTA of Korea (2004)
Phase 2 standardized in 2005
Samsung joined WiMAX Forum Dec 2004
May indicate Samsung’s guess on 4G direction
Plans for Nationwide Korean deployment
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KT & SK Telecom launched June 30, 2006 in Seoul
http://kt.co.kr/kthome/kt_info/pr/news_center/news_view.jsp?pa
ge=1&no=397&gubun=1
KT and Hanaro Telecom to jointly deploy outside of Seoul and 6
other cities
http://times.hankooki.com/lpage/tech/200501/kt2005011117243
611810.htm
How does WiBRO relate to
802.16e?
•
WiMAX Forum:
(http://www.wimaxforum.org/news/press_releases/WiBro_and_Mobile_WiMAX_Bac
kgrounder.pdf)
– “WiBro is the service name for Mobile WiMAX in Korea. WiBro uses the Mobile
WiMAX System Profile. The system profile contains a comprehensive list of features that
the equipment is required or allowed to support, and, as a result, WiBro offers the same
capabilities and features of Mobile WiMAX.”
– It’s Mobile WiMAX, just with a different profile (frequency, bandwidth…)
•
Vendors: WiBRO is compatible with 802.16e, but there’s more to Mobile WiMAX
than just 802.16e compatibility and many choices in WiBRO are different from what
is mandatory in 802.16e
– From (http://www.nortel.com/solutions/wimax/collateral/wimax_wibro_white_paper.pdf)
•
Some more important differences from white paper
– Mandatory Handoff
• 802.16e = HHO
• WiBRO = FBSS
– HARQ
• 80.16e = Chase combine HARQ
• WiBRO = Incremental redundancy HARQ
– Likely (though unclear) network layer differences
Reality on compatibility
• All of these different profiles would be quite
difficult for a hardware radio to support (as
the white paper points out), but…
• 802.16 is likely the first SDR standard
• Leading implementation approaches appear
to be using specialized processors
• Further, there exists a certification body for
interoperability (WiMAX Forum) with the first
certified Mobile WiMAX products expected
for the end of 2006 or the first quarter of
2007
• And a Global Roaming Alliance
Algorithm Descriptions
PHY, MAC, Security
Mandatory Convolutional Encoder
in 802.16e
• Constraint length 7
• Rate ½
• Initialization
Encoder
– OFDM mode:
• Zeros encoder
• Blocks padded with byte
0x00 at end
– OFDMA
• Tailbiting
• 6 bits appended to front,
output from last six bits of
previous block discarded
– Tailbiting is slightly more
bandwidth efficient (and
mandatory), but much more
computationally intensive
J. Andrews, A. Ghosh, R. Muhamed,
Fundamentals of WiMAX, Prentice Hall,
2007
Supported Data Rates
Optional Codes
802.16-e Turbo Encoder
• Optional codes:
– block turbo codes,
– convolutional turbo
codes,
– low density parity
check (LDPC)
codes
• Significant
performance gains
over mandatory
convolutional
codes without a lot
of added
Andrews, A. Ghosh, R. Muhamed,
complexity J.Fundamentals
of WiMAX, Prentice Hall,
2007
Code performance
Subcarrier Permutations
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•
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Subcarrier permutation – how subcarriers
are allocated across subchannels
Burst profile – predefined combinations of
modulation, code rate and FEC type
Full Usage of Subcarriers (FUSC)
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Downlink Partial Usage of Subcarriers
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Subcarriers divided into tiles (4 subcarriers
over 3 symbols)
8 data, 4 pilot
Good for high Doppler spread
Tile Usage of Subcarriers (TUSC)
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Subcarriers “randomized”
Supports segmentation and frequency
reuse factors of 1
Uplink Partial Usage of Subcarriers
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Pilots independent, data subcarriers evenly
spread out
Downlink version of uplink PUSC
Band Adaptive Modulation and Coding
(AMC)
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All subcarriers are adjacent
•
•
Hurts frequency diversity, but simplifies
multiuser divserity
“Bins” defined as 8 data symbols plus 1 pilot
(in center of data)
•J. Andrews, A. Ghosh, R. Muhamed, Fundamentals of
WiMAX, Prentice Hall, 2007
Specified PHY Information
• Channel Quality
Measurements
– Used to adapt transmission
parameters
• Modulation, coding, burst
profiles, power
– Received signal strength
indicator
• Mean, standard deviation
– SINR
• Mean, standard deviation
• Requires demodulation
• Power Control
– Only directly supported on
uplink
– 30 dB/s fluctuations
– Should account for PAPR
– MS maintains same
transmit power density
(power/subcarrier)
– Maximum MS power for
various modulations
(backoff can vary to control
PAPR)
Open Loop MIMO
• Transmit diversity/space time coding
– Numerous optional schemes for 2,3,4 antennas
– Most common:
• Spatial Multiplexing
• Alamouti
• Frequency Hopped Diversity Code
– Optional mode
– First antenna transmits without modification
– Second encodes over two consecutive subchannels
J. Andrews, A. Ghosh, R. Muhamed, Fundamentals of
WiMAX, Prentice Hall, 2007
Closed Loop MIMO
• Feedback mechanisms
–Antenna selection. The MS indicates to the BS which transmit antenna(s) should be used
• Useful at highspeeds
–Antenna grouping. The MS indicates to the BS the optimum permutation of the order of the various
antennas to be used with the current space/time encoding matrix
–Codebook based feedback. The MS indicates to the BS the optimum precoding matrix to be used,
based on the entries of a predefined codebook.
• Sum capacity and MMSE most popular
–Quantized channel feedback. The MS quantizes the MIMO channel and sends this information to
the BS, using the MIMO_FEEDBACK message.
• High bandwidth, but usable in low speed environments
–Channel sounding. The BS obtains exact information about the CSI of the MS by using a dedicated
and predetermined signal intended for channel sounding.
• Maximum (theoretical) capacity, maximum required bandwidth
J. Andrews, A. Ghosh, R. Muhamed, Fundamentals
of WiMAX, Prentice Hall, 2007
Hybrid ARQ
• HARQ – ARQ, but receiver can
use previous failed transmissions
to improve estimates
• Type I HARQ
Type II HARQ
– Chase combining
– Retransmits until receiver gets
the packet right of failure
propagates up to the network
layer
• Type II HARQ
– Incremental redundancy
– Retransmits with successively
lower rate codes until receiver
gets the packet right of failure
propagates up to the network
layer
J. Andrews, A. Ghosh, R. Muhamed, Fundamentals of WiMAX,
Prentice Hall, 2007
MAC Convergence Sublayers
• Supported Networking protocols
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ATM CS
Packet CS IPv4
Packet CS IPv6
Packet CS 802.3 (Ethernet)
Packet CS 802.1/Q VLAN
Packet CS IPv4 over 802.3
Packet CS IPv6 over 802.3
Packet CS IPv4 over 802.1/Q VLAN
Packet CS IPv6 over 802.1/Q VLAN
Packet CS 802.3 with optional VLAN tags and ROHC header
compression
– Packet CS 802.3 with optional VLAN tags and ERTCP header
compression
– Packet IPv4 with ROHC header compression
– Packet IPv6 with ROHC header compression
Scheduling/QoS
• Actual algorithms vendor specific, but 802.16e
assumes MS requests performance based off of
a number of messages which the BS may or
may not be able (or willing) to accommodate.
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Max data flow per stream
Requested minimum data rate
Request for MBS
Maximum latency
Retransmission policy
Traffic priority (8 classes)
Tolerated Jitter
Mobile WiMAX MAC QoS Classes
WiMAX Forum (2006): Mobile WiMAX – Part I: A Technical Overview and Performance Evaluation.
Available at www.wimaxforum.org
Network Entry Process
Network Entry Steps
Negotiated Parameters
J. Andrews, A. Ghosh, R. Muhamed, Fundamentals of WiMAX, Prentice Hall, 2007
Other Services
• Network discovery
– WiMAX supports either manual or automatic selection of networks
based on user preference
– Defines protocols to support this
• IP address management
– Note: packet transmission in WiMAX is based on connection identifiers
instead of MAC addresses, so multicasting in IPv6 needs work
• Radio Resource Management
– Mostly information management in standard, vendors can do different
things with information
– Activities
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•
•
•
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Controlling measurements by BSs and MSs
Delivering measurements to required databases
maintaining RRM databases
exchanging information between these databases within or across ASNs,
making radio resource information available to other functional entities, such
as HO control and QoS management.
802.16-2004 Security
Vulnerabilities
• Replay Attack
•
•
•
•
Nonetheless, Boom writes:
– Resend detected valid messages
“In the author’s opinion, the
– Intention is to induce BS to send SS a reset
standard is an excellent starting
message
point for the basis of a military
AP Spoof
tactical network. Given that the
– Subscribers are authenticated, but not
above recommendations have
access point
been applied, there would remain
MAC Address Spoof
changes required to create a
RNG-RSP Denial of Service
military wireless network.
– Weaknesses in ranging (not encrypted,
Because of the unique military
automatic acceptance of adaptations by SS)
environment and requirement for
Auth Invalid Attack
very high availability, DoD should
– “Auth Invalid” (possibly spoofed) puts
adopt an appropriately robust
subscriber in a vulnerable state
spread spectrum physical layer to
– Followed with a “Permanent Auth Reject”
message prevents all future communications improve conventional jamming
until MAC reset
resistance. Second, DoD should
continue to use higher layer
encryption to protect end-to-end
transmissions.”
Based on D. Boom, “Denial of Service Vulnerabilities in IEEE 802.16 Wireless Networks,” Thesis, Naval Post
Graduate School, Sep 2004. Available online: http://www.ieee802.org/16/tge/contrib/C80216e-04_406.pdf
802.16e Security
• Multiple layers
of security
• Many aspects
added to
address
WiMAX
problems
D. Pang, L. Tian, J. Hu, J. Zhou, J. Shi,
“Overview and Analysis of IEEE 802.16e
Security,” Available online:
http://hdl.handle.net/2100/172
Security Improvements in 802.16e
• Authentication
– BS identity now verified in
PKMv2
• Authorization
– RSA-based authorization
and EAP
– PKMv1 (2004) AAA in
application layer, but in
PKMv2 (802.16e) in
different hierarchy
• Data confidentiality
– Many more crypto
algorithms
• Data authenticity
– AES CCM-Mode
• Replay attack
– Some added protection,
but still vulnerable
• Handoff support
– Possibly problematic
– 802.16e suggests, but
does not define, preauthorization
– Leads to key sharing
between BS
D. Pang, L. Tian, J. Hu, J. Zhou, J. Shi, “Overview and Analysis of IEEE 802.16e Security,” Available online:
http://hdl.handle.net/2100/172
Mobile WiMAX Performance
Effect of varying parameters on
link and system performance
Link Simulation Parameters
• From Chapt 11 of J.
Andrews, A. Ghosh,
R. Muhamed,
Fundamentals of
WiMAX, Prentice
Hall, 2007
• Scenarios:
– AMC vs PUSC
– Effect of HARQ
– MIMO + Fading +
AMC
– Open loop vs closed
loop
– Common nonlinear
receiver structures
SISO AMC vs PUSC, Pedestrian
AMC vs PUSC: QPSK, Ped B
10-0
10-0
R1/2
R1/2
R3/4
R3/4
PUSC
AMC
PUSC
AMC
R1/2
R1/2
R3/4
R3/4
10-1
PUSC
AMC
PUSC
AMC
BER
BER
10-1
10-2
10-2
10-3
10-4
0
AMC vs PUSC: 16QAM, Ped B
10-3
5
10
15
20
25
30
SNR
AMC vs PUSC: QPSK, Ped A
10-4
0
5
10
15
20
25
30
SNR
AMC vs PUSC: 16QAM, Ped A
10-0
10-0
R1/2
R1/2
R3/4
R3/4
R1/2
R1/2
R3/4
R3/4
PUSC
AMC
PUSC
AMC
PUSC
AMC
PUSC
AMC
10-1
BER
BER
10-1
10-2
10-2
10-3
10-3
10-4
0
10-4
0
5
10
15
SNR
20
25
30
5
10
15
SNR
20
25
30
SISO AMC vs PUSC, Vehicular
AMC vs PUSC: QPSK, VehA30
AMC vs PUSC: QPSK, VehA120
10-0
10-0
R1/2
R1/2
R3/4
R3/4
R1/2
R1/2
R3/4
R3/4
PUSC
AMC
PUSC
AMC
PUSC
AMC
PUSC
AMC
10-1
BER
BER
10-1
10-2
10-2
10-3
10-3
10-4
0
10-4
0
5
10
15
SNR
20
25
30
5
10
15
SNR
20
25
30
SISO AMC vs PUSC, Summary
• AMC (modulation adaptation)
outperforms PUSC (carrier adaptation) at
slow speeds
• PUSC outperforms AMC at high speeds
• Why?
– At Pedestrian (3 kph) coherence time is 150
ms
– At 120 kph channel coherence time
reduced to 3 ms
– Feedback duration (5 ms)
– At high speeds channel feedback needed
for AMC is poor predictor
• Moving from Pedestrian to Vehicular 120
causes drop in link performance
–QPSK ~1-1.5 dB
–16-QAM ~ 2-2.5 QAM
• Why?
–OFDM sensitive to frequency offsets
(Doppler)
–Higher order modulations more sensitive to
channel estimations
• Insights:
–Channel state information very important to
performance
–Value to adjusting adaptation schemes
based on Doppler
Effect of Channel Estimation
(PUSC)
QPSK Real vs Perfect
10-0
R1/2
R1/2
R3/4
R3/4
R1/2
R3/4
10-0
Veh A30
Veh A120
Veh A30
Veh A120
Perfect
Perfect
10-1
BER
BER
10-1
16-QAM Real vs Perfect
10-2
10-2
10-3
10-3
10-4
0
10-4
0
5
10
15
SNR
20
25
30
R1/2
R1/2
R3/4
R3/4
R1/2
R3/4
5
Veh A30
Veh A120
Veh A30
Veh A120
Perfect
Perfect
10
15
20
25
30
SNR
• Channel estimation via frequency domain linear minimum mean
square error + partial information about channel covariance (from
RMS delay spread)
• At low SNR, noise dominates
• At high SNR, estimation imperfections dominate
• Higher order modulation more sensitive to estimation imperfections
Effect of Hybrid-ARQ
HARQ, QPSK
HARQ, 16-QAM
4
R1/2
R1/2
R1/2
R3/4
R3/4
R3/4
3
No HARQ
HARQ I
HARQ II
No HARQ
HARQ I
HARQ II
Transmissions
Transmissions
4
2
1
0
0
3
6
9
12
15
18
21
R1/2
R1/2
R1/2
R3/4
R3/4
R3/4
3
No HARQ
HARQ I
HARQ II
No HARQ
HARQ I
HARQ II
2
1
0
6
9
12 15
SNR
18 21
24
SNR
• Type I HARQ = Chase Combining
– All retransmissions identical to first transmission
• Type II HARQ = Incremental Redundancy
– Puncture patterns vary by retransmission
27 30
Hybrid ARQ Summary
• Benefit of HARQ is at low SINR
• No Benefit at high SINR
• Type II HARQ gives highest gain due to
reducing code rates
SIMO Performance and Correlation
R1/2 Ped B Varying Correlation
R3/4 Ped B Varying Correlation
• QPSK, MMSE receiver, AMC
SIMO Correlation Summary
• Performance gain
– 1x2 yields 3 dB gain (low SINR)
– 1x4 yields 6 dB gain (low SINR)
– Even more at high SINR
Effect of Correlation
AMC, R 1/2, Ped B
AMC, R 3/4, Ped B
Complex
correlation,
=0.5
PUSC, R1/2 Ped B
PUSC, R3/4 Ped B
Correlated/Uncorrelated Fading Summary
Gain versus SISO with AMC
•
•
•
•
•
•
At low SNR, correlation has little effect
At higher SNR, however, the multiantenna gain is reduced by 1dB to 0.5dB, owing to the correlation in the fading
waveform.
Lower code rates are more sensitive to this correlation than are higher code rates.
Figure 11.20 and Figure 11.21 provide link-level results for various possible open-loop and closed-loop transmit
diversity schemes in WiMAX. The open-loop diversity considered here is the 2 x 2 Alamouti pace/time block cde
(STBC).
For AMC subcarrier permutation, STBC’s benefit is marginal, especially with correlated fading because STBC
hardens the channel variation that band AMC is designed to exploit. On the other hand
PUSC subcarrier permutation, as shown in Figure 11.22 and Figure 11.23 benefits significantly from 2 x 2 STBC
Open Loop MIMO with Multiple
Streams
AMC QPSK R1/2 in Ped B
Dual Stream, Matrix B
AMC QPSK R3/4 in Ped B
Open Loop Diversity Summary
Open Loop Gains over 2x2, AMC, Ped B, Dual Streams
• Greater benefit for higher rates
• Why?
– More sensitive to fades and added diversity
reduces fades
Closed Loop Scenarios
AMC, QPSK, R1/2 Ped B
•
AMC, QPSK, R3/4 Ped B
Antenna selection feedback (1/frame)
– 3-bits specify antenna pair for each subchannel
•
Codebook feedback (1/frame)
– 6-bits that specify code for linear precoding for each subchannel
– Code minimizes postdetection mean square error of both streams
•
Quantized channel feedback
– MS quantizes channels; BS chooses code as above
•
Per subcarrier SVD
– Optimal precoding
Open versus Closed Summary
• Closed loop reasonably close (~1-2 dB) to
each other
• However, closed loop techniques can add
5 dB in link gain over open loop
techniques
Effect of Receiver Structures
PUSC, QPSK, R1/2 Ped B
PUSC, QPSK, R3/4 Ped B
• Ordered Successive Interference Cancellation (O-SIC)
– SIC from highest SINR to lowest
• Maximum Likelihood Detection (MLD)
– Search for most likely combination of transmitted symbols
– Simplified by using MMSE followed by sphere-decoding
– Optimum noniterative algorithm for MIMO receivers
Receiver Structure Summary
Gain over MMSE receiver at 10-4 BER 2x2 PUSC, Ped B
• An iterative MAP will outperform MLD
• QRM-MLD is suboptimal (and “low-complexity”) but
performs within a dB of MLD
– K. Kim, J. Yue, “Joint channel estimation and detection
algorithms for MIMO OFDM,” Proceedings of Asilomar
Conference of Signals, Systems, and Computers, Nov 02.
Link Performance Summary
• Adaptive modulation lets WiMAX approach at low SINR
– High SINR limited by discrete modulation set
• Turbo codes yield significant performance gain over
mandatory convolutional codes
• AMC is better at low speeds, PUSC at high speeds
• HARQ most effective at low SINR,
– HARQ II better than HARQ I in terms of BER
• Closed-loop gives > 5 dB gain over open-loop at low
speeds (not practical at high speeds)
• Advanced MIMO structures can give another 5 dB gain
System Level Performance
Simulation Parameters
• From Chapt 12 of J.
Andrews, A. Ghosh,
R. Muhamed,
Fundamentals of
WiMAX, Prentice
Hall, 2007
System Configurations
•
•
•
•
Basic assumes the BS is able to separate the two MSs using the two
receive antennas.
Enhanced configuration 1 increases the number of receive antennas in the
DL from two to four thus providing higher order receive diversity in the DL,
but is otherwise the same
Enhanced configuration 2 increases the number of transmit antennas in the
UL and DL
Enhanced configuration 3 uses 4 x 2 closed-loop MIMO in the DL with
antenna selection and quantized channel-feedback-based closed loop
MIMO . Feedback once every 10 ms over two bands.
Basic Configuration
Ped B
• Handheld
assumes omnidirectional
antennas
• Desktop device
has low-gain
(3dBi-6dBi)
directional
antennas
• Desktop
implements
selection diversity
from 6-8 antenna
Average Throughput, Ped B
Ped A
Average Throughput, Ped A
Basic Configuration Summary
• Directionality does better, but limited benefit when already sectored
• (1,1,3) is more spectrally efficient, but has poor cell-edge
performance
• General tradeoff between reliability and spectral efficiency
Effect of Scheduling and Subcarrier permutations (Handheld)
PUSC vs AMC
PF vs Round Robin
• (1,1,3) configuration
• Without precoding, AMC offers limited benefit
(though still non-negligible ~14-18%)
• Proportional fairness scheduler has slightly more
flexibility in exploiting multi-user diversity so
sees better performance in capacity (~25%)
Effect of MIMO Configurations
Downlink
Uplink
Note: Same uplink used for basic and enhanced 1 configurations
Enhanced Profile Summary
Total Throughput per Cell, Ped B, (1,1,3), 30 MHz
• Both receive diversity and transmit diversity improve the average
throughput of a WiMAX network.
• By increasing the number of transmit antennas from two to four, the
per sector throughput improves by 50 percent.
• Similarly, by increasing the number of receive antennas from two to
four, the per sector throughput is increased by 80 percent
• UL throughput results do not account for the fact that a part of the
UL bandwidth is used by the closed-loop MIMO feedback
Enhanced Profiles
Downlink, Ped B
Downlink, Ped A
Enhance Profile Summary
5% & 10% Data Rate, Band AMC, Ped B (1,1,3)
• Fifth and tenth percentile DL data rates are not improved by
increasing either transmit or receive diversity order.
• Implies that transmit diversity with antennas in DL is not sufficient to
improve the cell-edge data rate in the case of (1,1,3) reuse
• Closed loop (4x2) however, provides significant
• (1,1,3) frequency reuse will not be able to provide carrier-grade
reliability and guaranteed data rate unless closed-loop MIMO
features are used.
System Performance Comments
• Frequency planning
– (1,1,3) gives highest per-sector
• But unequal distribution – cell edge performs poorly
– (1,3,3) gives good cell edge performance
• But requires additional spectrum
– (1,1,3) with segmentation is a compromise solution
• Scheduling algorithms w/ multi-user diversity can significantly
improve cell throughput – up to 25%
• Diversity (receiver more so than transmitter) gives significant gain in
average throughput – 50-80%
– Cell-edge behavior still bad enough that (1,1,3) is hard to justify
– Needs closed-loop MIMO
• Closed loop MIMO gives big gains
• Overall spectral efficiency (throughput/sector/total deployment
bandwidth)
– Open loop MIMO 1.7 Mbps/Hz
– Closed loop pedestrian 3.9 Mbps/Hz
Interference Patterns with Reuse = 1
http://www.wimaxforum.org/technol
ogy/downloads/mobile_wimax_depl
oyment_alternatives.pdf
Relative Capacity as function of
• 19 BS, 3 sectors,
spaced 2.8 km, mix of
users
• Proportional Fair
scheduling
WiMAX Performance
Comparisons
Technology Comparison
WiMAX Forum (2006): Mobile WiMAX – Part
II: Competitive Analysis. Available at
www.wimaxforum.org
Performance Comparisons with
Existing 3G, 3G+
WiMAX Forum (2006): Mobile WiMAX – Part II: Competitive Analysis. Available at www.wimaxforum.org
Performance Comparisons
Mobile WiMAX: The Best Personal
Broadband Experience!
June 2006, Available at
www.wimaxforum.org
Cost Comparison
•
•
•
•
Fewer base stations to provide same level of service with Mobile WiMAX
than HSPA or EVDO RevB
Less cost tied up in IP royalties (~2-3% vs 10-15%)
New spectrum costs
http://www.wimaxforum.org/technology/faq/
– The second generation of Subscriber Equipment is expected to be priced from
$200 - $300 in 2008.
– The third-generation CPEs will be integrated into laptops and other portable
devices and are expected to initially cost approximately $100 and be available in
2nd half 2008.
Mobile WiMAX: The
Best Personal
Broadband Experience!
June 2006, Available at
www.wimaxforum.org
Summary of comparisons
• Mobile WiMAX is most directly comparable not to
existing 3G or 3G+ standards, but to ones coming out
in a few years
– LTE
– EVDO, Rev C (UMB)
• Similar performance comes from similar technologies
– OFDMA, MIMO, MBS, HARQ, Turbo codes, Adaptive
modulations, bandwidths, IP core, VOIP
• So some convergence in technologies (at last!)
– Yet these “converged” standards have a huge number of
options available, so will be difficult for a single ASIC solution
– Likely need for SDR
Mobile WiMAX Deployments
and Availability
Certification, Chipsets, Products,
Spectrum, Deployments
WiMAX Certification Schedule
•
The WiMAX Forum plans to have
five certification test labs located
in the U.S., Europe, China, Korea
and Taiwan by end of 2007.
– http://www.wimax.com/commentar
y/news/wimax_industry_news/wim
ax-forumae-designates-first-northamerican-based-certification-lab
•
Certification Waves
– (.16-2004) Wave 1 enables a
simple air link
– (.16-2004) Wave 2 adds QoS,
security, and advanced radio
features for outdoor CPEs
– (.16-2004) Wave 3, adds indoor
CPEs and PCMCIA cards for fixed
and nomadic networks
– (.16e) Wave 4, adds hand-offs
and simple mobile for 802.16e or
mobile WiMax
– (.16e) Wave 5 adds full mobility
Source:
http://www.wimaxforum.org/technology/downloads/W
iMAX_and_IMT_2000.pdf
WiMAX Certification Labs
•
AT4 Wireless
Parque Tecnologico de Andalucia
Calle Severo Ochoa 2
29590 Campanillas, Málaga
Spain
•
Telecommunications Technology
Association
267-2 Seohyun-dong
Bundang-gu
Seongnam-City
Gyeonggi-do
463-824 Korea
•
China Academy of
Telecommunication Research
52 Hua Yuan Bei Lu
Haidian District
Beijing 100083
China
•
•
31 certified products
http://www.wimaxforum.org/kshow
case/view/catalog_search
Chipsets (1/4)
•
Beceem Communications (BCS2000)
–
–
–
–
•
Fujitsu MB86K21 SoC is Wave 2
–
–
–
–
•
Wave 2, SIMO, MIMO,
baseband IC + RFIC (all PHY, MAC, RF)
2.x and 3.x GHz bands
http://www.beceem.com/products/ms120.shtml
Wave 2 SOC
2-11 GHz, 802.16e compliant
Either base or subscriber
http://www.fujitsu.com/downloads/MICRO/fma/pdf/wimax_mobilefs.pdf
Sequans Communications (3 mobile products)
– SQN2110
• 3 FPGA chipset for base stations
• Wave 2,
– SQN1130 SOC
• Baseband PHY, MAC
• Wave 2
– SQN 1110
• Like 1130, but for Wave 1
• http://www.sequans.com/site/products.html
Chipsets (2/4)
•
Wavesat Umobile SOC
–
–
–
–
–
•
Wave 2
Programmable PHY, MAC
2x2 MIMO
Support for 802.11a/g
www.wavesat.com
Runcom Technologies Ltd
–
RNA 200
•
•
•
–
Others:
•
•
•
802.16e-2005
Full PHY/MAC (no RF)
http://www.runcom.com/upload/infocenter/info_images/28012007194733RNA200%20ASIC.pdf
RNF2000 is FPGA version
RNA2000 ASIC version
TeleCIS Wireless
–
–
–
–
–
–
TCW 1620 Portable 802.16-2004 implementation
Lowest power SoC
PHY/MAC
MAC supports Wave 2 and Wave 3
2x2 MIMO
Built in PCI interface
Chipsets (3/4)
•
Comsys Mobile
– CM1100
•
•
•
•
Mobile WiMA baseband
Wave 2 compliant
High speed support
http://www.comsysmobile.com/commaxcm1100.html
– CM1125
•
•
•
•
•
GSM/EDGE + Mobile WiMAX
Baseband PHY/MAC
Class-12 E/GPRS mobile
http://www.comsysmobile.com/commaxcm1125.html.
Altair Semiconductor
– ALT2150
• Mobile WiMAX SOC
• Wave 2 Handset
• http://www.ccpu.com/
•
ApaceWave Technologies
– APW-2000 SoC
– Wave 2 MIMO A,B
– http://www.apacewave.com/
Chipsets (4/4)
• picoChip
– WiMAX Reference Designs
– http://www.picochip.com/solutions/wimax
– PC8520 802.16-2004 base station
– PC8530 Mobile WiMAX base station
– PC6530 Femtocell base station
– PC8532 Wave2 Basestation PHY
– All software upgradable
Intel
• Chipsets still in the works, but…
• Service providers already have expressed a
preference for Intel
– http://www.digitimes.com/systems/a20070831PD215.
html
– Nokia already ordered
• http://www.wimaxday.net/site/2007/09/27/nokia-orders-intelchips-intel/
– Microsoft working on WiMAX drivers
• http://www.wimaxday.net/site/2006/11/07/runcom-signs-dealwith-microsoft/
– Apple rumored to want Intel chips
• http://www.macnn.com/articles/05/06/01/apple.and.wimax/
More Intel
• Already secured deals for use of WiMAX chips in laptops
–
–
–
–
–
Hoping to repeat Centrino success
2008 "Montevina" both Wi-Fi networking and WiMAX
Deals: Lenovo, Acer, Asus, Panasonic and Toshiba
No Deals: Dell, HP
Part of a planned “WiMAX Inside” Marketing campaign
• http://www.wimaxday.net/site/2007/08/03/intel-plans-%e2%80%9cwimaxinside%e2%80%9d-marketing
• Investing in WiMAX service providers
– Bulgaria with Nexcom Bulgaria
• http://www.wimax.com/commentary/news/wimax_industry_news/intelcapital-and-mci-have-invested-in-bulgarian-wimax-operator-nexcom
– Japan with KDDI
• http://www.wimax.com/commentary/news/wimax_industry_news/intelcapital-and-mci-have-invested-in-bulgarian-wimax-operator-nexcom
More 802.16e equipment
• Adaptix
– SDR OFDMA/TDD
platform
– Salvaged technology
from Broadstorm
• Alvarion
– Devices support
802.16-2004 and e
•
ArrayComm
–
–
–
•
OFDM + smart antennas
Uses IntelliCell beamforming
technology
Applied to other standards
Navini
–
–
–
–
Adds smart antennas to
nomadic OFDM
Wireless broadband Georgia –
BellSouth August 05
Multicarrier Synchronous
Beam Forming
Adaptive modulation QPSK –
64 QAM
Other Product Vendors
• From
http://www.wimaxforum.org/kshowcase/view
– Redline, Selex, Nokia-Siemens, ET Industries,
Axxcelera, Aperto Netwrosk, Alvarion, Airspan,
Siemens, SR Telecom, Telsima
WiMax Frequency Allocation
http://www.wimaxforum.org/news/downloads/supercomm_2005/WF_Day_in_a_Life_with_WiMAX_Final.pdf
3.5 GHz is the international band for WiMAX
Other WiMAX Spectrum
Opportunities
• 700 MHz band
– http://www.xchangemag.com/articles/501/79h139171
83935.html?cntwelcome=1
– Needs to support public safety in the nationwide band
– No plan for WiMAX certification profile unless band
becomes global
• 3G Spectrum
– Push to be included as a 3G standard
• http://www.livemint.com/2007/09/06000634/India-backsWimax-techon-3G-n.html
WiMAX Spectrum Alliances
•
Regulatory Database
–
–
–
•
WiMAX Global Roaming Alliance
–
–
–
–
•
AT4 Wireless
Launched November 2006
http://www.wimaxforum.org/join/spectrum_demo/
Brought together unlicensed providers to promote global roaming
Now defunct
Will probably come back in some form
http://www.theregister.co.uk/2006/09/29/oz_wimax_roaming_alliance/
WiMAX Spectrum Owners' Alliance
–
–
–
–
http://www.wisoa.com/
Promotes roaming agreements
Participants:
Unwired Australia, Network Plus Mauritius, UK Broadband, Irish Broadband,
Austar Australia/Liberty Group, Telecom New Zealand, WiMAX Telecom
Group, Enertel and Woosh Telecom
WiMAX Trials
M. Giles, “Wireless Broadband,” EDUCAUSE 2006, October 9, 2006
150 Fixed WiMAX trials are underway around the world.
Technology Deployment
Timeline
• 2006
– Mobile WiMAX Trials
– Fixed WiMAX Ramp
– >150 WiMAX Trials/Networks Planned
• 2007
– Mobile WiMAX (MIMO) Trials
– Mobile WiMAX (SISO) Ramp
• 2008
– Dual-Mode & Multi-Mode Handhelds
– Mobile WiMAX (MIMO) Ramp
• Source: M. Giles, “Wireless Broadband,”
EDUCAUSE 2006, October 9, 2006.
Clearwire Coverage
• Provides Fixed
WiMAX based
wireline
replacement
service to home +
portability within
coverage area
• 2 Mbps data +
voice
http://www.clearwire.com/
• Founded in October 2003 by Craig O. McCaw
Fixed WiMAX for AT&T
• Fixed WiMAX services as DSL/cable
competitor (like ClearWire)
– Launch in 2Q 2008 for the US South in old
BellSouth spectrum
– 2.3 GHz band
– Already trialing system in Alaska
– http://www.unstrung.com/document.asp?doc_i
d=133853&f_src=unstrung_gnews
Fixed WiMAX Deployments
•
WiMAX I – IEEE 802.16 – 2004
–
–
–
–
–
•
Equipment
–
–
•
(Intel) Alvarion Ltd., Aperto Networks Inc., Proxim Corp., Redline
Communications Inc., Siemens AG, and China's Huawei Technologies Co.
and ZTE Corp
Other: Picochip, WaveSat
Current Deployments
–
–
•
IEEE Standard issued
WiMAX Forum specification
Fixed point-to-point/point-to-multipoint
First WiMAX certified products end of year
Certified in 3.5 GHz band
$1.4 billion in revenue in 2004 (Marvedis)
Altitude (France) voice over pre-WiMAX
Trial Deployments
–
–
–
Seattle - Sprint
http://www.wimaxxed.com/wimaxxed_news/sprint_motorol.html
London (2006)
http://www.wimaxxed.com/wimaxxed_news/london_councils.html
Xbox360? http://wimax.com/commentary/spotlight/wimax-xbox
Sprint XOhm
•
Mobile WiMAX focus of next generation
Sprint cellular network XOhm
–
•
– Precommercial launch in two
markets by end of 2007
– Multi-market launch in early
2008
– 10,000 sites in preparation
– 1750 base stations delivered
in 2007, 20,000 antennas
– 2010 coverage
http://www.wimax.com/commentary/spotligh
t/zoom-on-xohm-2013-an-update-from-thesprint-technology-summit
Sprint device expectations
– Sprint partners (Motorola, Intel,
Samsung) have said embed 50 million
units by 2010 in the US. These will be
mainly laptops and PDAs. Sprint
alluded that it expects chipset cost to
go down to $5-$15
– WiMAX incorporated in cameras and
televisions, household appliances,
and security systems, as well as over
50 million hand-held devices
Fast extensive rollout planned
– http://www.wimaxday.net/site/2007
/09/28/sprint-dominates-andtantilises-wimax-world-usa-withxohm/
http://www.xohm.com/latestnews.html
Expects $2-2.5 billion in revenue by 2010,
of which 80% comes from new revenue
and 20% is from cannibalization. Assuming
an ARPU of $30 per month ($360/year),
that means 6.2 million subscribers by 2010
–
•
•
•
•
48 million homes, 4.5 million offices,
130 million consumer electronic devices
Open network
– “As long as the device is WiMAX
certified, it will work on Sprint’s
network after provisioning. Sprint
wants to sell services, not
devices.”
More Sprint
• Partnering with ClearWire to accelerate WiMAX
deployment
– Roam between networks and exchange spectrum
– http://www.xohm.com/news_071907.html
• Going to provide federal government connectivity via
WiMAX
– http://www.wimaxday.net/site/2007/06/05/sprint-plans-wimax-forgov%e2%80%99t-services/
• Partnering with Google to provide services
– Aiming for the “digital lifestyle”
– Gmail, social networking tools, location-based services and
multi-media services.
– http://www.wimaxday.net/site/2007/07/27/sprint-and-google-willpartner-for-mobile-wimax-services/
Motorola
• Focusing on being an infrastructure vendor
• Lots of test trials
• 2.5 GHz band in Chicago for Sprint
– http://www.wimaxday.net/site/2007/09/26/it-worksmotorola-takes-wimax-out-of-the-lab-and-into-the-city/
• 25 other trials around the world
– http://www.wimaxday.net/site/2007/03/28/motorola-in25-wimax-trials/
First WiBRO Deployment
• Nov 15, 2005 – Launch of KT’s personal
broadband service
• “To prove its mobility, KT delivered two-way
video, Internet and messaging broadband
services, a range of devices that were located in
a traveling shuttle bus that allowed conference
attendees to experience mobile broadband.”
• Given Mobile WiMAX certification in late 2006.
– http://www.wimaxforum.org/news/press_releases/AP
EC_release_111505_FINAL_FINAL1.pdf
Additional Deployments of Mobile
WiMAX
• Arialink with Samsung products (rural Michigan)
– http://www.3g.co.uk/PR/April2006/2948.htm
• Islanet (Puerto Rico)
– http://www.techweb.com/wire/networking/193402237
• Wateen in Pakistan (Motorola)
– http://news.com.com/2100-1039_3-6075684.html
• AT&T (Soma) in Nevada
– http://telephonyonline.com/wimax/marketing/att_mobile_wimax_111606/
• Taiwan (Far Eastone)
– http://www.wimaxday.net/site/2007/09/28/far-eastone-plans-wimax-rollout/
• Telecom (Bahrain)
– http://www.gulf-dailynews.com/Story.asp?Article=194068&Sn=BUSI&IssueID=30181
Projected Market Breakdown
http://www.wisoa.net/members_logos/ecosystem-2-big.jpg
Further amendments
802.16h, 802.16j, 802.16m
802.16h
•
•
•
Improved Coexistence
Mechanisms for
License-Exempt
Operation
Basically, a cognitive
radio standard
Incorporates many of
the hot topics in
cognitive radio
– Token based
negotiation
– Interference
avoidance
– Network collaboration
– RRM databases
•
Coexistence with non
802.16h systems
– Regular quiet times
for other systems to
transmit
From: M. Goldhamer, “Main concepts of IEEE P802.16h / D1,” Document Number:
IEEE C802.16h-06/121r1, November 13-16, 2006.
General Cognitive Radio Policies in
802.16h
• Must detect and avoid radar and other higher
priority systems
• All BS synchronized to a GPS clock
• All BS maintain a radio environment map (not
their name)
• BS form an interference community to resolve
interference differences
• All BS attempt to find unoccupied channels first
before negotiating for free spectrum
– Separation in frequency, then separation in time
DFS in 802.16h
• Adds a generic
algorithm for
performing
Dynamic
Frequency
Selection in license
exempt bands
• Moves systems
onto unoccupied
channels based on
observations
Generic DFS Operation Figure h1
(fuzziness in original)
Adaptive Channel
Selection
• Used when BS turns on
• First – attempt to find a
vacant channel
– Passive scan
– Candidate Channel
Determination
– Messaging with Neighbors
• Second – attempt to
coordinate for an
exclusive channel
• If unable to find an empty
channel, then BS
attempts to join the
interference community
on the channel it detected
the least interference
Figure h37: IEEE 802.16h-06/010 Draft IEEE Standard for Local and
metropolitan area networks Part 16: Air Interface for Fixed Broadband
Wireless Access Systems Amendment for Improved Coexistence
Mechanisms for License-Exempt Operation, 2006-03-29
Collaboration
• BS can request interfering
systems to back off transmit
power
• Master BS can assign transmit
timings
– Intended to support up to 3
systems (Goldhammer)
• Slave BS in an interference
community can “bid” for
interference free times via
tokens.
• Master BS can advertise
spectrum for “rent” to other
Master BS
– Bid by tokens
• Collaboration supported via
Base Station Identification
Servers, messages, and RRM
databases
• Interferer identification by
finding power, angle of arrival,
and spectral density of
OFDM/OFDMA preambles
• Every BS maintains a
database or RRM information
which can be queried by other
BS
– This can also be hosted
remotely
802.16h Status
• Currently in letter ballot
– Draft 2c (password protected):
http://www.ieee802.org/16/private/drafts/le/P8
0216h_D2c.zip
802.16j Mobile Multi-hop Relay
• Expand coverage, capacity by
adding relay stations
• Intended for licensed operation
• Not intended as a mesh network
– Actually a tree
• Support mobile units
•
•
Relays controlled from base
stations
Fixed Relay
– Permanent installation
– Useful for coverage holes
•
Nomadic Relay
– Temporary fixed installation
– Extra capacity for special
events (military SDR
conferences)
•
Mobile Relay
– Placed on mobile platform to
support users on the platform
– Useful for public transport
(buses, trains)
Modified from Fig 1 in IEEE 802.16mmr-05/032
802.16j Requirements
• Backwards compatible frame structure supporting both
relay frames and legacy frames
• Definition of RF requirements including the relay link
frequency, duplexing and channel B/W
• Relay shall support network entry for the mobile station
QoS and HARQ shall be supported by relay as defined
in legacy 16e systems
• Relay supports mobile station handover
• The specification shall support relay mobility
• The use of multiple antennas to enhance the spectral
efficiency of the relay link
• The support of more than one relay hop between MMRBS and MS
– http://www.ieee802.org/16/relay/docs/80216j-06_016r1.pdf
802.16j Status
• Failed letter ballot 9-25-07
– 67% (needed 75%)
http://ieee802.org/16/ballots/ballot28/report28.
html
• Last open draft
– http://www.ieee802.org/16/relay/docs/80216j06_026r4.zip
Mesh in 802.16-2004
• Mesh protocols not fully specified in 802.16-2004
– Network Entry supported, some neighbor services
– Routing? Congestion?
• 802.16-2004.3 (WirelessMAN OFDM) PHY includes
frames for Mesh operation between subscribers
• SkyPilot is developing a layer for Mesh operation that
sits atop 802.16-2004.3
– Targeted for Public safety applications in 4.9 GHz band
– http://www.wi-fiplanet.com/news/article.php/3549846
• 802.16f should aid creation of fixed mesh networks
• 802.16i may help for mobile devices
• If market demand exists, would likely be an
amendment that specifies mechanisms for mesh as
802.11s did for 802.11’s ad-hoc mode
802.16m
• Intended to be 4G (satisfy requirements of IMT-Advanced)
• http://www.ieee802.org/16/tgm/
• Requirements still being defined
–
–
–
–
–
–
–
–
–
–
–
http://www.ieee802.org/16/tgm/docs/80216m-07_002r1.pdf
Backwards compatible with 802.16j
Support MMR (802.16j), though not specifically part of the standard
Will define new profile WirelessMAN-OFDMA/2008
Support interoperability with other systems
Bands under 6 GHz
Bandwidths of 5-20 MHz (others may be used based on ITU and
operator requirements)
TDD and FDD
Support MIMO and beamforming
Mobile expected to have 1 transmit and 2 receive antennas
Support E-911 services
IEEE C802.16m-07/002r1
More Draft 802.16m requirements
•
Minimum Peak Rate
– Downlink 6.5 bps/Hz
– Uplink 2.8 bps/Hz
•
•
Latency less than 802.16e
Radio Resource Management
– Reporting, interference management
– Multicast broadcast service
– “High-resolution” location determination
•
Internetworking with:
– 802.11 3GPP, 3GPP2
•
•
•
•
•
Coverage optimized for 5 km, functional to 30-100 km
Optimized for low mobility (<15kph), maintain connection up to 350 kph
Optimized for contiguous spectrum but support discontiguous
Reuse/share bandwidth with legacy systems
Direct migration from 802.16e
IEEE C802.16m-07/002r1
802.16m Usage models
• High data rates and improved
performance in legacy cell sizes
• Very high data rates in smaller cells
• High mobility support
• Deployment with MMR
• Co-deployment with other networks
• Collocation/coexistence with
PAN/LAN/WAN
WiMAX Summary
Points to Remember
• Very flexible standard
– Modulation, subcarriers, coding, antenna arrays
• Big performance gain from Turbo codes and closed-loop
MIMO
• Different scheduling/subcarrier allocation algorithms
work better in different environments
• WiMAX receiving massive commercial interest at the
moment
– Sprint is way out in front with XOhm in the US
– WiBRO has been doing well in Korea for a while
• Intel is a little late, but will likely dominate
– “WiMAX Inside” push on laptops
– Backing service providers, so they’ve doubled their bet
Points to Remember
• People are already looking towards
802.16m
• WiMAX is emerging primarily as a cellular
competitor
– Previously viewed as more of a backhaul
• Lots of software radio based
implementations coming out
– picoChip,
Useful WiMAX Resources
• WiMAX Standards
– http://ieee802.org/16/pubs/80216-2004.html
– http://www.ieee802.org/16/pubs/80216e.html
• Mobile System Profile Rev 1.4 (May 2007)
– http://www.wimaxforum.org/technology/documents/wi
max_forum_mobile_system_profile_v1_40.pdf
• WiMAX News
– http://www.ieee802.org/16/relay/docs/80216j06_026r4.zip
• WiMAX Forum:
– http://www.wimaxforum.org/home