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Emerging Wireless Standards
Wireless Summer School
June 4, 2008
Session A1
1:30-5:15 PM
James Neel
[email protected]
(540) 230-6012
www.crtwireless.com
Jeff Reed
[email protected]
(540) 231-2972
www.wireless.vt.edu
Presentation Overview
Theory
(32) OFDM and Antenna Array
Theory
Emerging Standards
(24) Cellular and WiMAX
(16) WLAN
(10) WPAN
(11) Cognitive Standards
( 7) Interoperability Standards
( 6) Summary and Trends
Break & Poster Session
2:45-3:30
http://www.wisoa.net/members_logos/mobile_in
ternet-big.jpg
Principles of Orthogonal
Frequency Division Multiplexing
and Multiple Input Multiple Output
Communications Systems
Intersymbol Interference
– Limits maximum throughput
• Solutions:
– Equalization (high complexity)
– Longer symbol periods (generally
means lower data rate)
BER Floor for various modulations
10-1
Coherent Detection
+ BPSK
QPSK
OQPSK Modulation
x MSK
Irreducible BER
• Occurs when symbol period (Ts)
is less than channel delay
spread, 
• ISI introduces an error floor to
BER
x
10-2
x
x
+
+
x
+
10-3
+
x
QPSK limit
+
10-4
10-2
10-1
delay spread
symbol period
=

100
T
J. C.-I. Chuang, "The Effects of Time Delay Spread on Portable Radio
Communications Channels with Digital Modulation," IEEE JSAC, June
1987
Multicarrier communications:
Longer period, same data rate
•Concept:
–Divide original data stream at
rate R into L lower rate (R/L)
streams on different carriers to
increase symbol time
•Long history
–KINEPLEX
–ANDEFT
–KATHRYN
•Effects
–High receiver complexity
J. Andrews, A. Ghosh, R. Muhamed,
Fundamentals of WiMAX, Prentice Hall, 2007
Hf
B/L
• separate receiver chain per carrier
–Bandwidth due to sidebands
–Each subcarrier experiences flat
fading
Bc
B
f
OFDM
• Much simpler to create multicarrier transmission using
iFFT
– Information carried in magnitude and phase of each bin
– Then can be recovered by using FFT at receiver
• Ideal inverse Fourier transform
of multicarrier would be infinite
duration sine waves
– Cut at Symbol duration Ts
– Rectangular windowing causes
sinc spectrum in frequency
domain with zeros at 1/Ts
– Orthogonal subcarriers
Magnitude
T0
Frequency
Guard intervals and intersymbol
interference
Guard interval
OFDM Symbol
Guard interval
OFDM Symbol
Delay Spread
OFDM Symbol
Delay Spread
• If we space OFDM symbols by gaps at
least as long as the delay spread, then
there will be no intersymbol interference
• However, there will still be interference
within the symbol (intrasymbol)
Equalization and the DFT
• While using longer symbol timing means OFDM can
avoid irreducible errors, still have interfering energy in
band from multipath
– Received signal is the (linear) convolution of channel impulse
response with transmitted signal
y  h* x
• DFT Circular Convolution Theorem
– Circular convolution of two discrete vectors in time domain
y  xh
– Is multiplication in the frequency domain
Yk  X k H k
• Implication: If we can make the system behave like a
circular convolution, equalization is trivial
– complex multiplication per FFT bin at the receiver
Cyclic Prefix
• Adding a cyclic
prefix at transmitter
leads to circular
convolution
• Note that
misaligned timing
still results in a
circular
convolution, just
time shifted
– Makes for phase
shifts in FFT bins
– Correct that in a
moment
J. Andrews, A. Ghosh, R. Muhamed,
Fundamentals of WiMAX, Prentice Hall, 2007
Comments on Cyclic Prefix
J. Andrews, A.
Ghosh, R.
Muhamed,
Fundamentals of
WiMAX, Prentice
Hall, 2007
•Permits low complexity
equalization for same data
rates
•Single carrier tap#
approximately bandwidth
delay product
–MAC
•OFDM, number subcarriers
grows with bandwidthdelay product, so
• We’re transmitting redundant
bits (no information transfer)
– Bandwidth penalty: L / (L + v)
– Power penalty: L / (L + v)
• Penalty becomes negligible as
L becomes large (but there are
tradeoffs! – more later)
• Power penalty generally more
important in practice where
systems are interference limited
• Penalty can be avoided with
zero prefix
– Nothing transmitted in guard band
(zero prefix)
– Receiver adds tail back to
beginning of symbol
– Used in WiMedia
Frequency Errors
• Primary sources of
frequency errors
– Doppler shift
– Clock mismatches
– Phase noise
• Effects
– Reduction in amplitude
(missampling sinc)
– Intercarrier
interference
O. Edfors, M. Sandell, J. van de Beek D. Landström, F. Sjöberg, “An
Introduction to Orthogonal Frequency Division Multiplexing,” Sep 98,
Available online: http://epubl.luth.se/avslutade/0347-0881/96-16/esb96rc.pdf
Effects of Frequency Errors
• Comments
– Impact greater for higher
SNR signals
– Note 5% estimation error
can lead to 5 dB effective
degradation at 64-QAM like
SNRs
– Big frequency impact is why
OFDM was originally for
fixed deployments
• Techniques
– Data aided
– Non data aided
– Cyclic prefix
O. Edfors, M. Sandell, J. van de
Beek D. Landström, F. Sjöberg,
“An Introduction to Orthogonal
Frequency Division Multiplexing,”
Sep 98, Available online:
http://epubl.luth.se/avslutade/0347
-0881/96-16/esb96rc.pdf
Fading Channel
AWGN
Channel Estimation
• Channel assumed static for duration of symbol, though
frequency/phase varying over bandwidth
• Solution, embed pilot symbols at regular intervals in the
symbol
– Used closest pilot
– Interpolate
Hf
From IEEE Std 802.16-2004
Peak-to-Average Power Ratio
Output Power
(dBm)
• Sum of large number of
(somewhat) independent
subcarriers leads to signal
distribution that is somewhat
Gaussian
• Implications
P1dB,out
Fu
nd
am
en
ta
l
1dB
MDS
1
1
Noise Floor
BDR
P1dB,in
Input Power (dBm)
– long tails for amplitude distribution PAPR CDF for Varying # Subcarriers
– Possibly large ratios of peak-topower ratios
10
10
– Introduces harmonics and
significant out-of-band spectral
energy
10
log(CDF)
• Long tails can drive amplifiers
into nonlinear region
10
0
(a )N=16
(b) N=32
(c) N=64
(d) N=128
(e) N=256
(f) N=1024
-1
-2
(a)
(b)
-3
(c)
10
(d)
-4
(e)
10
10
(f)
-5
-6
0
2
4
6
8
PAPR[dB]
10
12
14
16
Solution Techniques
Spectral Effects of Windowing and Clipping
• Clipping
– Eliminate signals above a certain
level or ratio
• Peak windowing
– Filter peaks
• Linear block code
– Select only those codewords with
small PAPR
– Can also provide error correction
• Peak Cancellation
– Subtract signals from high peaks
– Need to be similar bandwidth to
limit out-of-band interfernce
• Symbol Scrambling
Peak Cancellation, Clipping, PAPR = 4dB
Adaptive Modulation
• Different subcarriers
experience different
flat fades
• Means different SINR
• Adapting modulation
scheme of each
subcarrier to its SINR
allows the system to
approach Shannon
capacity
J. Andrews, A. Ghosh, R. Muhamed,
Fundamentals of WiMAX, Prentice Hall, 2007
Hf
B/L
B/L
Bc
B
f
OFDMA
• Multiple user access with
OFDM
• Lots of flexibility possible
when splitting up OFDM
symbols and frames
• Allocation algorithms
– Maximum Sum Rate
– Proportional fairness
– Proportional rates
constraints
– Assign different subcarriers
to different users
– Assign different time slots
to different users
– Vary modulation and
coding
– Vary powers
– More options available with
antenna arrays
J. Andrews, A. Ghosh, R. Muhamed,
Fundamentals of WiMAX, Prentice Hall, 2007
OFDM Summary
• OFDM overcomes even severe intersymbol
interference through the use of the IFFT and a
cyclic prefix.
• Limiting factor is frequency offset
– Correctable via simple algorithm when preambles
used
• Two key details of OFDM implementation are
synchronization and management of the peak-toaverage ratio.
• OFDMA provides a lot of flexibility to a system’s
resource allocation
– Permits exploitation of multi-user diversity
Antenna Array Algorithms and
MIMO
Antenna Array Principles
• Exploit multiple independent channels created
by multipath diversity
• Works with uncorrelated antennas
–Array gain
• Coherently combine energy from antennas
• Works even with perfectly correlated antennas
as received SNR increases linearly with the
number of receive antennas
10
Fading Envelopes [dB]
•The use of multiple antennas provide two
forms of diversity:
–Diversity gain
5
0
-5
-10
0
200
400
600
Samples
800
• Adding additional transceiver chains is expensive (SWAP and cost),
but can provide tremendous (though competing) gains
–
–
–
–
Increase the system reliability (decrease the bit or packet error rate)
Increase the achievable data rate and hence system capacity
Increase the coverage area
Decrease the required transmit power
1000
Receive Diversity
• Oldest and simplest diversity
technique
• Receiver leverages independence
of fades on antennas
– Selection Combining (SC)
– Equal Gain Combining (EGC)
• Weight signals by SINR
• Best performance (system SINR is
sum of antenna SINRs)
...
Comparator
Preset
Threshold
Short-Term
Average
Average SNR Improvements
MRC
SNR (dB)
– Maximum Ratio Combining (MRC)
Antenna
Receiver
• Choose antenna with maximum SINR
• Lowest complexity
• Phase align and sum signals across
antennas
Selection Diversity
EGC
SC
Antennas
Open Loop Transmit Diversity (1/2)
• Transmitter sends multiple
signals (possibly copies)
– These interfere at the receiver,
but if coded properly, the
receiver can recover the signal
• Simplest implementation is
orthogonal space time block
codes or Alamouti codes1
– Assumes flat constant channel
over two symbol periods (may
not be true for high mobility)
– Requires channel knowledge at
receiver
– No change in rate required
h1
TX
Encoder
h2
RX
Decoder
• Receiver Alamouti Operation
• Output SNR 2x1 Alamouti
1. S. M. Alamouti, “A simple transmit diversity technique for
wireless communications,” IEEE Journal on Selected Areas in
Communications, vol 16 pp.1451–1458, Oct 1998
Open Loop Transmit Diversity (2/2)
A 4x2 Stacked Alamouti System
• 2x2 STBC (same transmit
encoder) SINR
– Note number of h terms
maximized when Nt = Nr for a
fixed number of antennas
– Also full-diversity, orthogonal
STBCs exist only for certain
combinations of Nt and Nr.
• Can also use space-time
trellis codes for added 1-2
dB, but those have
exponential complexity order
J. Andrews, A. Ghosh, R. Muhamed, Fundamentals
of WiMAX, Prentice Hall, 2007
Comparison of STBC and MRC
Space-Time Trellis Coding
• Convolutional code applied to space and time domain
• Each antenna output is mapped into modulation symbol
• Maximum likelihood sequence estimator ( Viterbi algorithm)
Example) Delay Diversity (by Wittneben [4])
Encoder structure for two antennas
Modular-4
addition
Output to ANT1
g11
(u1,u2)
g12
Generator matrix form
g21 g31
g41
[a1 a2 a3 a4]
a1
a2
a3
g22 g32
a4
g42
QPSK mapping
Output to ANT2
Closed Loop Systems
•Transmit selection diversity
–Antenna(s) chosen which maximizes
SINR
–Equivalent to receiver selection diversity
–Not as good as beamforming
–Little bandwidth required
–Makes most sense in in deployments
with small bandwidths and small delay
spreads (low range)
• Linear diversity precoding
–Feedback channel state information to transmit encoder
–Transmit encoder then attempts to fine encoding matrix which
maximizes SNR at the receiver
–Higher SNR than STBC
–Typically use some sort of codebook to reduce feedback bandwidth
Beamforming Systems
Narrowband adaptive array or linear combiner
x1(t)
w1
x2(t)
w2
xM(t)
•
120
y(t)
150
wM
The weight vector is adjusted to improve the
reception of some desired signal
–
Angle of arrival
•
–
MUSIC, ESPRIT
Eigenbeamforming
•
•
•
...

90 1.5
60
1
No physical interpretation, but useful in multipath
environment
Minimize some cost function
Useful for interference rejection, multipath
fading mitigation, and increased antenna gain
interferer
30
0.5
180
0
desired
330 signal
210
240
270
300
Adaptive Beamforming
• Narrowband beamforming is equivalent to spatial
filtering
–By choosing appropriate sensor coefficients, it is
possible to steer the beam in the desired direction
–By varying the sensor coefficients (spatial filter taps)
adaptively, the interference is reduced
• Wideband beamforming requires joint space-time
processing
–Phase shift at the antennas is frequency dependent
–Frequency-dependent response is required (filter)
• Common algorithms
–Maximum Signal to Interference and Noise Ratio
(MSINR)
–Minimum Mean Squared Error
–Least Mean Squares
–Minimum Variance Distortionless Response (MVDR)
–Recursive Least Squares
–Similar to linear precoding, but may account for
interferers
Performance Comparison
• MRT refers to
maximum ratio
transmission
– the choice of antenna
weights that maximize
received SNR
• With optimal
eigenbeamformer,
canceling an interferer
is equivalent to
dropping an antenna
element
3 dB
Modified from: J. Andrews, A. Ghosh, R. Muhamed,
Fundamentals of WiMAX, Prentice Hall, 2007
Spatial Multiplexing
• In rich scattering environments, independent data signals
transmitted from different antennas can be uniquely decoded to yield
an increase in channel capacity
x1
Source
Modulation &
Coding
xM
h11
..
.
hN1
h1M
hNM
Channel
..
.
y1
Demodulation
& Decoding
xN
Sink
Spatial Multiplexing Techniques
•Open loop (Unknown channel)
–Maximum likelihood
• Little gain, except at low SNR
–Zero-forcing
•Closed loop (known channel)
–Singular Value Decomposition
• Computationally complex
• Capacity (assuming waterfilling)
• Evaluates pseudo-inverse of H
• Can dramatically increase noise power
–MMSE
• Minimizes distortion
• Like Zero-forcing at high SNR, but
without the instability at low SNR
–BLAST
• Layers & codes transmissions across
antennas
• Effectively linear receiver with
successive interference cancellation
• Receiver iterates through transmission
streams using MMSE or ZF
• Works better in lab than real-world due
to high SNR requirement
• For large SNR, capacity grows
linearly with rank of H,
approximately min{Nt, Nr}
–Approximations guided by
• information capacity,
• error probability
• detection MSE
• received SNR
–Can tradeoff multiplexing for
diversity
Relative Capacity as function of
Antenna Array Technique
• 19 BS, 3 sectors, spaced 2.8 km, mix of
users
• Proportional Fair scheduling
Source: WiMAX Forum
Correlation/Coupling Effects
• Spacing between antennas influence
correlation and coupling
• Multipath components can act like interference
for beamforming which reduces antenna gain
4x4, SNR = 20 dB, 30 AS
http://www.ngwnet.ac.uk/files/wspres/mimo2.thompson.pdf
Beamforming BER
[Ref. D. Figueiredo, WPMC’04]
Diversity vs. Beamforming
•
•
•
•
•
•
•
Diversity Combining
Combine signals from different
antenna elements using various
algorithms
Signal from each element is
processed separately
Signals have to be uncorrelated
for maximum performance
Mitigates fading
Increases gain
Can improve polarization match
No interference rejection
capabilities
Adaptive beamforming
• Focus the antenna’s gain in the
direction of the desired signal
– Achieved by manipulating the
weights associated with each
element
• Antenna elements have to be
separated by /2 to attain a
certain phase difference in the
signals
– Signals are correlated
• All advantages of diversity
combining
• Has interference rejection
capabilities
– Typically > 20 dB
MIMO Summary
• Spatial diversity offers incredible
improvements in reliability, comparable to
increasing the transmit power by a factor of
10–100.
• These diversity gains can be attained with
multiple receive antennas, multiple transmit
antennas, or a combination of both.
• Beamforming techniques are an alternative
to directly increase the desired signal energy
while suppressing, or nulling, interfering
signals.
• In contrast to diversity and beamforming,
spatial multiplexing allows multiple data
streams to be simultaneously transmitted
using sophisticated signal processing.
• Since multiple-antenna techniques require
channel knowledge, the MIMO-OFDM
channel can be estimated, and this channel
knowledge can be relayed to the transmitter
for even larger gains.
• It is possible to switch between diversity and
multiplexing modes to find a desirable
reliability-throughput operating point;
multiuser MIMO strategies can be harnessed
to transmit to multiple users simultaneously
over parallel spatial channels.
J. Andrews, A. Ghosh, R. Muhamed,
Fundamentals of WiMAX, Prentice Hall, 2007
Presentation Overview
Theory
(32) OFDM and Antenna Array
Theory
Emerging Standards
(24) Cellular and WiMAX
(16) WLAN
(10) WPAN
(11) Cognitive Standards
( 7) Interoperability Standards
( 6) Summary and Trends
Break & Poster Session
2:45-3:30
http://www.wisoa.net/members_logos/mobile_in
ternet-big.jpg
Cellular and WiMAX
LTE, UMB, TD-SCDMA, WiMAX
Cellular Overview
• Two primary competing approaches to 3G
– 3GPP Family
3GPP Declared IP
• GSM, GPRS, EDGE, WCDMA, TD-SCDMA
(WCDMA-TDD), HSCSD, HSPDA, LTE, LTE
Advanced
• Promotional www.gsmworld.com
• Standards
www.3gpp.org
– 3GPP2 Family
• CDMAOne (IS-95a,b), 1xRTT, 1xEVDO,
1xEVDV, UMB
• Promotional http://www.cdg.org
• Standards
www.3gpp2.org
– One vision
• Voice + high speed data + mobility
3GPP2 Declared IP
– One dominant IP holder (Qualcomm)
• New Entrant
– Mobile WiMAX and WiMAX II (802.16m)
– Standard http://wirelessman.org/
– Promotional http://www.wimaxforum.org
– Lower cost IP
• 350 companies own essential IP
• http://www.eetimes.eu/design/197007324
Source: “3G Cellular Standards and Patents”, David J.
Goodman and Robert A. Meyers
GSM Dominates the Landscape
http://www.coveragemaps.com/gsmposter_world.htm
• 3GPP (GSM/WCDMA) has most of the market (77% in 2005, 83% in
2006, 86.6% in 2008)
– Most of that lead is in GSM
• 3GPP2 (cdma2000) got a massive jump on 3GPP
– 418/431 million of CDMA is 3G (www.cdg.org)
– 3GPP2 = 11.4%, 3GPP = 5.6%
• WiMAX just cranking up but will be deploying years ahead of LTE
3GPP Technologies
•
Generic Access Network (UMA)
–
•
• High Speed Downlink Packet Access
• W-CDMA downlink
•
Packet Switched Handoffs
–
•
Supports handoffs between GSM
networks and 802.11 or Bluetooth
networks
Enables easier handoffs between
different 3GPP networks
Multimedia Broadcast/Multicast
Services
–
Simultaneous broadcast of data
streams to multiple recipients
•
–
–
–
–
8-10 Mbps (and 20 Mbps for MIMO systems)
over a
5MHz bandwidth
Adaptive Modulation and Coding (AMC),
MIMO (Release 6)
Hybrid ARQ
All IP core network
•
•
(Release 4)
Originally ATM
• High Speed Uplink Packet Access
(Enhanced UpLink)
– Similar technologies to HSDPA on uplink
– AT&T in 350 markets
•
•
Table from: http://www.umtsworld.com/technology/images/hsdpa.png
http://www.mobileburn.com/news.jsp?Id=466
0
Loosely coincides with launch of 3G iPhone
3GPP Long Term Evolution (LTE)
E-UTRA Air Interface
• Evolved Universal Terrestrial Radio Access
• Downlink: Adaptive multilink OFDM (AMLOFDM), which means different bandwidths
based on demand
Approximate Deployment Schedule
– Variable prefix size
• 4.7 ms to 16.7 ms
• Intent to support up to 120 km cells
– Called High Speed OFDM Packet Access or
HSOPA
•
•
•
•
•
•
•
•
Uplink: SC-FDMA (more later)
DL 100 Mbps in 20 MHz (5 bps/Hz)
UL 50 Mbps in 20 MHZ (2.5 bps/Hz)
Reduced transition time between states (such
as between idle and active states)
Variable bandwidth allocations: 1.25 MHz, 1.6
MHz, 2.5 MHz, 5 MHz, 10 MHz, 15 MHz and 20
MHz in both the uplink and downlink
At least 200 users/cell
Load sharing/policy across radio access
technologies
Support for antenna arrays
http://www.motorola.com/staticfiles/Business/Solutions/Industry
Solutions/Service Providers/Wireless
Operators/LTE/_Document/6993_MotDoc.pdf
All IP Core Network
– Beamforming, MIMO
– Space Division Multiple Access
http://hgmyung.googlepages.com/3gppLTE.pdf
More LTE Details
Frame Structure
http://www.motorola.com/staticfiles/Business/Solutions/Industr
y Solutions/Service Providers/Wireless
Operators/LTE/_Document/6993_MotDoc.pdf
http://en.wikipedia.org/wiki/SC-FDMA
• SC-FDMA (UL)
– Applies frequency domain equalization to
single-carrier system
– Like spread-OFDM
– Transmits serially (single-carrier)
– Better PAPR (single carrier)
– Less sensitivity to carrier offset
– Similar complexity for just equalization
– Subframes 0,5 must be DL
– Otherwise arbitrary TDD structure
• Other Features
– Interference Mitigation
– Extensions
• But extra steps to effect SC-FDMA
– Better battery life
– Possibly worse performance in fading
channels
http://www.motorola.com/staticfiles/Business/Solutions/Industry
Solutions/Service Providers/Wireless
Operators/LTE/_Document/6993_MotDoc.pdf
TD-SCDMA
• Time Division – Synchronous CDMA
– Synchronized uplink channels aided by
joint detection
– China’s 3G technology
• Core network is almost the same as
WCDMA
– Requires mature 2G (GSM) network for
implementation
• Part of the 3GPP (3rd Generation
Planning Partnership Project)
• Multiple chip rates
– LCR: 1.28 Mcps, 1.6 MHz BW
– HCR: 3.84 Mcps, 5 MHz BW
• 3GPP
LCR TDD
（R4）
LTE TDD
LCR TDD
（R5）
LCR TDD
(R6)
LCR TDD
(R7)
• CCSA
MC-CDMA
TDD
OFDMA
TDD
SC-FDMA
/OFDMA TDD
TD-SCDMA
Stage III
（R6/R7）
TD-SCDMA
Stage II
（R5）
TD-SCDMA
Stage I
（R4 2003/03）
N Frequency
Bands Cell
TD-SOFDMA
Multi-carrier
Current status
Short Term Evolution
2005
Long Term Evolution
2007
ZTE Corporation, “3GPP Specification Evolution”
• TDD link
– Does not use paired frequency bands
• Optimum for symmetric and asymmetric
data services
– 1.6 MHz bandwidth allows flexibly
spectrum allocation
• Partially motivated by avoiding paying
Qualcomm royalties
B. Li, D. Xie, S.Cheng, J. Chen, P. Zhang,
W.Zhu, B. Li; “Recent advances on TDSCDMA in China,” IEEE Comm. Mag, vol
43, pp 30-37, Jan 2005
TD-SCDMA Multiple Access Options
Significant Issues Deploying
• Standardized in 1999
• Was going to roll out in 2004
– http://www.commsdesign.com/news/marke
t_news/OEG20030102S0009
• Then 2005
– http://www.chinadaily.com.cn/english/doc/2
004-06/23/content_341749.htm
• Then 2006
– http://www.accessmylibrary.com/premium/
0286/0286-9623636.html
• Then 2007
– http://www.theage.com.au/news/Technolog
y/China-Mobile-to-launch-3G-mobileservicesend2007/2007/02/12/1171128898337.html
• Now will reportedly issues licenses in
2008
– http://news.zdnet.com/2110-1035_226207356.html
• Delays make Chinese state-owned
service providers unhappy
– Grumblings about forgoing TD-SCDMA
from ChinaMobile (primary deployer)
– http://www.forbes.com/markets/feeds/afx/2
006/01/31/afx2489964.html
• However, China has made it a point of
national pride to have the network
running for the 2008 Olympics
– http://www.highbeam.com/doc/1G1150687033.html
– Is already being tested in 10 cities
(includes the Olympic cities) but
nationwide licenses may not even be
issued by the Olympics
• http://www.thestandard.com.hk/news_detail.a
sp?pp_cat=1&art_id=54099&sid=15557306&c
on_type=1
– First commercial trials supposed to begin
April 1, 2008
• http://www.tdscdmaalliance.org/english/news/list.asp?id=4426
– First public demos in May went badly
• http://www.pcworld.com/businesscenter/articl
e/146128/china_shows_off_olympic_techsort
_of.html
• China won’t allow 3G or WiMAX until
TD-SCDMA takes off
• Developed a bad reputation
– http://homepage.mac.com/dwbmbeijing/ibl
og/SiHu/C520534961/E20060302210839/i
ndex.html
– Unnamed China Mobile engineer – “you
GIVE me a TD-SCDMA network, and I
wouldn't take it."
Older 3GPP2 Technologies
• cdma2000 1xRTT
– Packet-switched (always on)
– Maximum of 144kbps
• Typical 40-60 kbps
– 2G / 3G
• 1x EVDO
– CDMA EVolution Data Only
• Designed to support only data applications
– VOIP
• Also known as:
– CDMA 1x EV-DO
– CDMA EV-DO
• EVDO Rev A
– Wide deployment
• Verizon, Sprint, Kindle best known
– Features
•
•
•
•
Higher modulation uplink
Multi-user packets (time-slots)
Lower Latency
Couple new data rates downlink (changed
code rate)
• Promotional
– http://www.evdoinfo.com
– Can offer data rates of 384kbps - 2.4Mbps
• Does not mix voice traffic with data traffic
• Changes modulation, # timeslots
Verizon EVDO-Rev A Coverage Map
• EVDV (Voice + Data)
– Dead on arrival
• http://telephonyonline.com/mag/telecom_evdv
_dead/index.html
• Qualcomm halted work on the standard in
2005
– http://news.com.com/Cell+phone+makers
+to+adopt+Internet+calling/2100-7352_35618191.html
– Slow to field
http://www.verizonwireless.com
EVDO Rev B (TIA-856 RevB)
• Adds Multiple carriers – 2xEVDO, 3xEVDO,…
– Up to 15 1.25 MHz carriers within 20 MHz
• Adds support for 64-QAM modulation
• DL 73.5 Mbps
• UL 27 Mbps
• Dynamic non-contiguous carrier allocation
• Support for single carrier and multiple carrier subscribers
• Standardized 2006
• Trials mid-2007
• Software upgrade (at BTS) to Rev A
• Commercial deployments?
– No major announcements
EVDO Rev C (UMB)
•
Spec published Sep 24, 2007
–
http://www.cdg.org/news/press/2007/Sep24_07.asp
– 3GPP2 (UMB) beats 3GPP to market again
– Chipsets available nowish
•
•
Data rates, mobile with 20 MHz bandwidth
–
–
•
http://www.qualcomm.com/press/releases/2007/070327_complete_solution_ultra.html
DL: 288 Mbps
UL: 75 Mbps
Key technologies
– OFDMA, MIMO, beamforming
– Flexible spectrum allocation
–
–
Enhanced QoS
Support for multiple access technologies
– Reduced latency
•
Likely killed when Verizon went with LTE
–
http://www.phoneplusmag.com/hotnews/79h20122346.html
– Dead on Arrival
•
http://www.abiresearch.com/products/research_brief/Wireless_Infrastructure_Research_Briefs/112
– Qualcomm differs (ineffectually)
•
–
http://www.fiercebroadbandwireless.com/story/qualcomm-ceo-umb-not-dead-yet/2008-01-14
Alltel didn’t even say they had considered it (WiMAX vs LTE – chose LTE)
•
http://www.betanews.com/article/Report_Alltels_choice_of_LTE_a_big_loss_for_WiMAX_UMB/121095
6891
802.16 Family (WiMAX)
802.16
802.16a
802.16c
802.16d
802.16e
802.16f
Apr 2002
Apr 2003
Jan 2003
Oct 2004
Dec 2005
Dec 2005
LOS 10-66 GHz
2-11 GHz
2-11 GHz
Combined 802.16,a,c
Mobile WiMAX
Net Management
Database (MIB)
802.16g Spring 2007 Network
management plane
802.16h 2009
License-exempt
Coexistence
802.16i Fall 2008
Mobile Management
Information Base
802.16j 2009
Mobile Multihop Relay
802.16k Aug 2007
Network Management
802.16m 2010
4G
Projections based on data at
http://grouper.ieee.org/groups/802/16/published.html
Commercialization Roadmap
WiMAX Forum (2006): Mobile WiMAX – Part I: A Technical
Overview and Performance Evaluation.
Available at www.wimaxforum.org
802.16e (Mobile WiMAX, 802.162005)
• Ideally, 802.16 + mobility
PHY Spec Overview
– Really intended for nomadic or low
mobility
– Not backwards compatible with 802.162004
• http://www.unstrung.com/document.a
sp?doc_id=76862
• Direct competitor to 3G, 4G, 802.20
though WiMAX Forum once said
otherwise
• Numerous ongoing deployments and
working systems, particularly for
WiBRO
• PHY
– Scalable OFDM + Optional MIMO
– Convolutional turbo codes
– Optional block turbo codes, LDPC
WiMAX Forum (2006): Mobile WiMAX – Part I: A Technical Overview and
Performance Evaluation. Available at www.wimaxforum.org
Other Mobile WiMAX Features
•
•
•
•
•
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.
• Security
– AES for traffic and control data
– EAP
– Privacy and Key Management
Protocol Version 2 (PKMv2)
– 3-way handshake on handoffs
• IP Core Network (supports
Voice Over IP)
• Multicast Broadcast Services
– Like cellular multicast services
• WiBRO
– Defines a set of options for
Mobile WiMAX for Korean
deployment
WiMAX Spectrum
• WiMAX Spectrum Alliances
• Regulatory Database
– AT4 Wireless
– Launched November 2006
– http://www.wimaxforum.org/join/spectrum_d
emo/
• WiMAX Global Roaming Alliance
– 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
• 700 MHz band
– http://www.xchangemag.com/articles/501/79
h13917183935.html?cntwelcome=1
http://www.wimaxforum.org/news/downloads/supercomm_2005/
WF_Day_in_a_Life_with_WiMAX_Final.pdf
• Recent reports of interference with with
C-Band VSAT
– http://www.suirg.org/pdf/SUIRG_WiMaxFie
ldTestReport.pdf
• Officially declared 3G so 3G spectrum
– http://www.wirelessweek.com/WiMAX-is3G.aspx
Mobile WiMAX Deployments
• First Mobile WiMAX
products certified April
2008
– 2.3 GHz, 4 base, 4
subscriber
– POSDATA, Runcom
Technologies Ltd,
Samsung Electronics
Co., LTD and Sequans
Communications
– http://www.wimaxforum
.org/news/pr/view?item
_key=59390fb727bfa1
5b5b8d11bf9341b2b11
76099f8
802.16d + 802.16e + WiBRO
http://www.wimaxforum.org/technology/documents/wimax_networks_worldwide_11x17.pdf
• Success appears tied to
Sprint-Nextel / Clearwire effort
Clearwire/Sprint
Merged Company
Clearwire Coverage
• Fixed WiMAX based
wireline
replacement service
to home + portability
within coverage
area
• 2 Mbps data + voice
http://www.clearwire.com/
Sprint
• Mobile WiMAX
• Rapid deployment to major cities
– 10,000 sites in preparation
– 1750 base stations delivered in 2007, 20,000
antennas
• Incorporated into numerous devices
(cameras and televisions)
• Open Network (support Android)
• Federal government connectivity via WiMAX
– http://www.wimaxday.net/site/2007/06/05/sprint-planswimax-for-gov%e2%80%99t-services/
• http://www.clearwireconnections
.com/pr/pressreleases/050708.p
df
• Clearwire + Sprint WiMAX unit
– Called Clearwire
• Investors
– $3.2 Billion from Google (500 M),
Comcast (1.05B), Time-Warner
(550M), Bright House (100M),
Trilogy Equity (10M)
– Sprint owns 51%
– Clearwire owns 27%
– Investors own 22%
• Nationwide focus
– 120-140 million coverage by 2010
• Commercial agreements
– Intel will put WiMAX in chipsets
• Had been planning on that
– Google services to be carried
(and search provider)
– Support Android
– Sprint, Comcast, TimeWarner, and
Bright House will be wholesale
– Sprint contributes its 2.5 GHz
holdings
WiBro
•
Korean version of 802.16e
–
–
•
Korean spectrum allocated 2002
–
•
2.3 GHz (100 MHz)
Harmonization 802.16e/WiBro agreed Nov 2004
–
–
•
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
–
–
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 well ahead of SK
•http://www.wimax.com/commentary/blog/blog-2007/wibrosubscriber-numbers-korea-telecom-kt-far-ahead-of-sk-telecom
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 Nortel 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
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
IEEE 802.20
• Fill performance gap between “high data-rate,
low mobility 802 standards” and “high
mobility cellular networks”
• From QTDD/QFDD Proposal
• OFDMA data channel
• CDMA control channel
• Bandwidths
– 5 MHz – 20 MHz
• MIMO
– Single, multiple code word
– Pseudo- Eigen beamforming
• Space Division Multiple Access
– Separate mode from MIMO
• Data Rate 260 Mbps
– MIMO, 20 MHz
• Turbo coding
• Time-frequency hopping
• Supposed to support inter Radio Access
Technology handoffs
• Similar to UMB
– UMB is effectively an upgrade to MBFDD version
– IEEE C802.20-07/14
– Likely same fate (contributions way down)
• 802.20 Shenanigans
• Allegations of process abuse brought to a
screeching halt when standard suspended
in September
• Project Launched 2004
• Looked to be dead in the water
– Flarion leading proposal
– Qualcomm leading vote holder
• Turned around when Qualcomm bought
Flarion (Aug 05)
– http://www.dailywireless.org/modules.php?na
me=News&file=article&sid=4532
• Went to proposal downselection process
– Qualcomm (Flarion) TDD, FDD
– ETRI
– BEST-WINE (Kyocera)
• Reapproved in Dec 06
• First meeting Jan 2007
4G (IMT-Advanced)
•
•
Wireless community already
looking towards 4G
Requirements being formalized
–
–
–
–
•
1 Gbps fixed
100 Mbps mobile (end-to-end)
Support for heterogeneous nets
Global roaming
Several candidates already
emerging
– LTE-Advanced
– 802.16m
– NTT DoCoMo’s 5 Gbps prototype
3G Americas, “Defining 4G: Understanding the ITU Process for the
Next Generation of Wireless Technology,” July 2007 Available online:
http://3gamericas.com/PDFs/3G_Americas_Defining_4G_WP_July2007.pdf
• http://www.nttdocomo.com/pr/files/2
0070209_attachment02.pdf
– China’s home grown standard
• http://www.forbes.com/markets/fee
ds/afx/2007/09/25/afx4151478.html
•
Common techniques
– OFDMA, MIMO, small cell sizes
optimized for low speed, but
support for high speed, IP
backbone
http://www.nttdocomo.com/pr/files/20070209_attachment01.pdf
802.16m
Requirements
• TGm System Requirements
Document
– http://wirelessman.org/tgm/docs/8021
6m-07_002r4.pdf
– http://wirelessman.org/tgm/docs/8021
6m-07_003.pdf
• Key functionalities to be added (not
defined yet)
– Routing
– Self Organization
– Multi-Carrier
– Multi-Radio Coexistence
IEEE C802.16m-07/002r1
• 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
Cellular Summary
• Lots of decisions appear motivated by politics and IP costs
• UMB, 802.20 likely dead for different though related reasons
• Likely competing standards are LTE and WiMAX
– Very similar technologies though
– General trend of adopting successful technologies
• Success of Mobile WiMAX highly contingent on success of new
ClearWire entity
– Well funded
– If successful, will change cellular business models
• Applications finally driving networks (iPhone, Kindle)
• LTE is very slow out of the gate
– 3GPP still has not caught up with 3GPP2
– Will LTE be the same?
• 4G a ways out, but preparation is underway
Presentation Overview
Theory
(32) OFDM and Antenna Array
Theory
Emerging Standards
(24) Cellular and WiMAX
(16) WLAN
(10) WPAN
(11) Cognitive Standards
( 7) Interoperability Standards
( 6) Summary and Trends
Break & Poster Session
2:45-3:30
http://www.wisoa.net/members_logos/mobile_in
ternet-big.jpg
Wireless LANs
802.11
802.11 Alphabet Soup
Jun
Sep
Sep
Oct
Jun
Jun
Oct
Jun
Oct
Sep
May
May
Jun
Sep
Sep
Dec
Sep
Dec
Dec
Mar
May
May
1997
1999
1999
2001
2003
2003
2003
2004
2004
2005
2008
2008
2008
2008
2009
2009
2009
2009
2009
2010
2010
2011
802.11
802.11a
802.11b
802.11d
802.11f
802.11g
802.11h
802.11i
802.11j
802.11e
802.11k
802.11r
802.11y
802.11n
802.11w
802.11p
802.11z
802.11v
802.11t
802.11u
802.11s
802.11aa
2 Mbps ISM
54 Mbps UNII
11 Mbps ISM
global roaming
interoperability
54 Mbps ISM
spectrum management
security
Japanese spectrum
real time QoS
RRM measurements
fast roaming
US 3.65 GHz
100 Mbps
packet security
vehicular (5.9)
Direct Link Setup
network management
Testing
external networks
mesh networks
Video Transport Streams
Past dates are standards approval
dates.
Future dates from 802.11 working
group timelines
Letters are working group (WG)
designations.
Letters assigned alphabetically as
groups created.
No WG/ WG document
802.11c MAC Bridging
work incorporated into 802.1d
802.11l “typologically unsound”
802.11m doc maintenance
802.11o “typologically unsound”
802.11q too close to 802.1q
802.11x generic 802.11 standard
802.11t (test) will produce 802.11.2
http://grouper.ieee.org/groups/802/11/Reports/802.11_Timelines.htm
WiFi Alliance
•
Industrial consortium that promotes
802.11
Millions of WiFi Chipset Shipped
– www.wi-fi.org
•
•
•
•
•
•
Certifies interoperability between
vendors’ products
Certifies consistency with standards
Fills in the gap when 802.11 standards
process is too slow (draft n)
WiFi success owes significant debt to
WiFi Alliance
Line between 802.11 standards
community and WiFi Alliance has
gotten very blurry
Certifications
– 802.11a/b/g/n WiFi
– 802.11e Wireless Multimedia
– Draft 2.0 n
Wi-Fi Alliance, Introducing Wi-Fi Protected Setup™, January 3, 2007
Distributed Coordination Function
(DCF)
• Intended to combat “hidden
nodes” in an uncoordinated
network and generate fair
access to channel
• Basic components:
–After waiting DIFS after last
detected transmission, source
sends Request to Send (RTS)
–Destination replies with Clear to
Send (if OK)
–Data is then transferred and
ACKed
–If an error occurs (e.g., collision),
then station has to wait for DIFS +
random backoff.
• Random backoff grows with # of
collisions
• Network allocation vector
– Acts as virtual carrier sense
– Duration given in RTS/CTS
fields
• DIFS = DCF Interframe Space
• SIFS = Short Interframe Space
802.11 overhead
• Significant overhead involved
in 802.11
– RTS/CTS/ACK SIFS
– TCP, IP, MAC framing
– Real throughput is rarely come
close to PHY raw rate
http://www.cs.tut.fi/kurssit/TLT-6556/Slides/Lecture4.pdf
wireless.ictp.trieste.it/school_2002/lectures/ermanno/System_Performance.ppt
802.11n overview
• Adds MIMO to WLAN OFDM
• Operate in either UNII or ISM bands
• Status:
–In Ballot
–But held up by IP battles
Streaming Home Multimedia (HDTV)
• http://arstechnica.com/news.ars/post/2007
0924-dark-australian-patent-cloud-loomsover-802-11n-spec.html
• CSIRO (http://www.csiro.au/) holds some
key IP, hadn’t signed letter of assurance,
has history of WiFi lawsuits and sought
injunctions
– Got bought off
• Last freely available draft
–Enhanced Wireless Consortium
(merger of TGnSync and WWiSE)
–http://www.enhancedwirelessconsortiu
m.org/home/EWC_PHY_spec_V127.pd
f (PHY)
–http://www.enhancedwirelessconsortiu
m.org/home/EWC_MAC_spec_V124.pd
f (MAC)
Source: http://www.tgnsync.org/products
802.11n PHY (in 1 slide)
• MIMO evolution of 802.11 OFDM PHY
–Up to 4 antennas per device
• 20 and 40MHz channels
–Fully interoperable with legacy
802.11a/b/g
–288 Mbps in 20MHz and 600 Mbps in
40MHz (64 QAM, 4 spatial streams, 1/2
guard interval)
–Claim of 100 Mbps in real throughput
• Optional enhancements
–Transmit beamforming with negligible
overhead at the client
–Advanced channel coding techniques
(RS)
–Space Time Block Coding (Alamouti and
others)
–1/2 guard interval (i.e., 400ns instead of
800 ns)
–7/8 rate coding
http://www.enhancedwirelessconsortium.org/home/EWC_PHY_spec_V127.pdf
802.11n MAC Features
• Supports 802.11e (QoS)
• Frame aggregation
–Single and multiple destinations
• Bi-directional data flow
• Link adaptation with explicit feedback
and control of channel sounding
packets
• Protection mechanisms
–For seamless interoperability and
coexistence with legacy devices
• Channel management
–Including management of 20/40MHz
operating modes
–Channel estimation and feedback
• Power management for MIMO
receivers
• Data aggregation
Broadcom, “802.11n: Next-Generation Wireless
LAN Technology,” White Paper, April 06
802.11n Certification
• Wi-Fi Alliance
Key Certification Features
– Certifying to Draft 2.0
while draft is approved
– Certify to Ratified
Standard when
available
– 22 August 2007 Almost 70 products
certified for compliance
with Draft 2.0 of the
802.11n
• http://www.wifiplanet.com/news/article
.php/3578886
Wi-Fi CERTIFIED™ 802.11n draft 2.0: Longer-Range, Faster-Throughput,
Multimedia-Grade Wi-Fi® Networks
802.11p Operation
• “Dedicated Short Range
Communications” (DSRC)
– Started in IEEE 1609, spun into 802.11p
– Aka (WAVE) Wireless Access for
Vehicular Environment
• IEEE 802.11a adjusted for low
overhead operations
– 54 Mbps, <50 ms latency
– 5.850 to 5.925GHz band
• Spectrum divided into 7 bands
– 178 is control (safety)
– 2 edge channels are reserved for future
– The rest are service channels (not
application specific)
• Mix of roadside-to-vehicle and vehicleto-vehicle communications
• Questions on business model
– http://www.rita.dot.gov/press_room/pres
s_releases/index.html
D. Jiang, V. Taliwal, A. Meier, W. Holfelder, R. Herrtwich, “Design
of 5.9 ghz dsrc-based vehicular safety communication,“ IEEE
Wireless Comm, Oct 06, pp. 36-43
802.11p Applications
COLLISION
IMMINENT
IMMINENT
LEFT
~
~
FRONT
COLLISION
In-Vehicle
Displays and
Annunciations
~
~
Note 1: The OBU in the vehicle recognizing the threat
transmits a WARNING and COLLISION PREPARATION
MESSAGE with the location address of the threat vehicle.
Note 2: Only the OBU in the threatening vehicle processes
the message because only it matches the threat address.
~
~
• Emergency warning system for
vehicles
• Cooperative Adaptive Cruise
Control
• Cooperative Forward Collision
Warning
• Intersection collision avoidance
• Approaching emergency vehicle
warning (Blue Waves)
• Vehicle safety inspection
• Transit or emergency vehicle
signal priority
• Electronic parking payments
• Commercial vehicle clearance
and safety inspections
• In-vehicle signing
• Rollover warning
• Probe data collection
• Highway-rail intersection warning
up to
Note 3: COLLISION PREPARATION includes seat belt
tightening, side air bag deployment, side bumper
expansion, etc.
100 m
(328
ft)
Car NOT Stopping
Radar Threat Identification
Traffic Signal
Traffic Signal
OBUs on Control Ch
From: IEEE 802.11- 04/ 0121r0
Available:
http://www.npstc.org/meetings/Cash%20WAVE%20In
formation%20for%205.9%20GHz%20061404.pdf
802.11r overview
•
Fast BSS Roaming/Transition within IEEE WLAN networks
– Preserve security with handovers <50ms
•
Fast BSS Roaming is possible only within a certain area called the mobility
domain (MD), inter-MD cases are not covered
– Mobility Domain (MD): Set of BSS grouped together with the same 48bit MD
Identifier
– FT functionality seeks to provide handover performance for RT services
•
Key Issues
– Resource Reservations
– Security
•
Collapsed 5 step process down to 3
–
–
–
•
Scanning – active or passive for other APs in the area
Authentication with a (one or more) target AP
Re-association to establish connection at target AP
Released 2008
http://www.cs.tut.
fi/kurssit/TLT6556/Slides/Lect
ure4.pdf
Reduction in Roaming Time
S. Bangolae, C. Bell, E.Qi, “Performance study of fast BSS
transition using IEEE 802.11r,” International Conference On
Communications And Mobile Computing, 2006
http://www.networkcomputing.com/gallery/2007/0416/0416t
tb.jhtml;jsessionid=0CK4ZKR20HC5QQSNDLPCKHSCJU
NN2JVN
802.11s
• Modify 802.11 MAC to create
dynamic self-configuring
network of access points (AP)
called and Extended Service
Set (ESS) Mesh
• Automatic topology learning,
dynamic path selection
• Single administrator for 802.11i
(authentication)
• Support up to 32 AP
• Support higher layer
connections
• Allow alternate path selection
metrics
• Extend network merely by
introducing access point and
configuring SSID
1. http://standards.ieee.org/board/nes/projects/802-11s.pdf
IP or
Ethernet
802.11s
• Key Technologies
– Topology Formation
– Internetworking
– Routing
– Security
• Open 802.11s (Linux)
– http://www.open80211s.org/
• Numerous WiFi mesh products
– http://www.cs.wustl.edu/~jain/cse
574-06/ftp/j_jmesh/sld019.htm
Deployment Scenarios
http://ieee802.org/802_tutorials/nov06/802.11s_Tutorial_r5.pdf
J. Hauser, D. Shyy, M. Green, MCTSSA 802.11s Military Usage Case
WLAN Summary
• Significant overhead in baseline
• 802.11n slow to finalize standard
– WiFi Alliance certifying to Draft 2.0
• Most activities directed towards expanding
markets
– Better support for voice
– Vehicular networks
– Other spectrum opportunities
• 802.11j, 802.11h (later)
– Mesh networks (802.11s)
– Interoperability with cellular (later)
Presentation Overview
Theory
(32) OFDM and Antenna Array
Theory
Emerging Standards
(24) Cellular and WiMAX
(16) WLAN
(10) WPAN
(11) Cognitive Standards
( 7) Interoperability Standards
( 6) Summary and Trends
Break & Poster Session
2:45-3:30
http://www.wisoa.net/members_logos/mobile_in
ternet-big.jpg
Wireless Personal Area
Networks
Industry and Open Standards
802.15 Standards
802.15.1
802.15.2
802.15.3
802.15.3a
802.15.3b
802.15.3c
802.15.4
802.15.4a
802.15.4b
802.15.4c
802.15.4d
802.15.4e
802.15.5
802.15.6
IGThz
SGRFID
SGVLC
April 2002
Oct 2003
Jun 2003
May 2008
May 2003
March 2007
Sep 2006
Jan 2009
Mar 2009
Jan 2009?
• Proprietary / Industry
Bluetooth
Coexistence
High data rate
UWB (high rate)
Doc Maintenance
mm-wave PHY
zigbee (PHY/MAC)
UWB (low rate)
Updates 802.15.4 document
Chinese WPAN PHY
950 MHz in Japan
MAC for 802.15.4c
WPAN Mesh
Body Area Networks
Terahertz interest group (300 GHz+)
RFID Study Group
Visible Light
802.15.3a disbanded Jan 2006
MBOA technologies became WiMedia
High speed DS-UWB basically dead after
Freescale pulled out
– Zigbee (on 802.15.4)
• Zigbee Pro
–
–
–
–
–
–
–
–
Bluetooth (originally)
WiBree
WiMedia
Z-Wave
En-Ocean
Insteon
Keer
TransferJet
Emerging 802.15 Standards
• 802.15.4c (China)
–779-787 MHz band
–Two PHY Modulations: MPSK PHY and OQPSK
–Considering OFDM, beamforming
MPNC
• 802.15.4d (Japan)
• 802.15.5e
–Enhanced MAC for Industrial applications
–Modified MAC for 802.15.4c changes
• 802.15.5
–Mesh networking
• Terahertz study group
–300 GHz -> 3 THz
–http://www.ieee802.org/15/pub/IGthz.html
• TG6 – Body Area Networks
–http://www.ieee802.org/15/pub/TG6.html
–Just starting
• Visible Light Interest Group
–http://www.ieee802.org/15/pub/IGvlc.html
MPNC
MPNC
PN 3
MPNC
MPCN
Mesh
PN 1
PN 2
IEEE P802.15.5™/D0.01, July 2006
ZigBee
Standard
http://www.zigbee.org/en/spec_download/download_request.asp
Application
–
–
–
Customer
API
Security
•
32- / 64- / 128-bit encryption
Network
ZigBee
Alliance
IEEE
802.15.4
PHY
•
Silicon
Stack
App
Source: http://www.zigbee.org/en/resources/
• Open source implementations
•
Open-ZB
–
•
http://www.open-zb.net/
Meshnetics Open-MAC
–
http://www.meshnetics.com/opensource/mac/
•
868MHz/915MHz, 2.4 GHz
Band specific modulations
20-250 kbps
MAC
–
–
868MHz / 915MHz / 2.4GHz
“the hardware”
Physical & Media Access Control layers
PHY
–
–
–
Star / Mesh / Cluster-Tree
MAC
IEEE 802.15.4
–
–
•
the software
Network, Security & Application layers
Brand management
CSMA-CA channel access
Support for ad-hoc networks
Zigbee Pro (Industrial grade)
–
–
–
–
–
–
–
Network Scalability
Fragmentation
Frequency Agility
Automated Device Address Management
Group Addressing
Centralized Data Collection
Wireless Commissioning
WiMedia
• Industry alliance from MBOA 802.15.3a
• Standardized for US in Dec 2005 in ECMA-368 and 369
– http://www.ecma-international.org/publications/standards/Ecma-368.htm
– ECMA used specifically to avoid 802 standardization problems
• PHY
–
–
–
–
–
Multiband OFDM QPSK
53.3, 80, 106.7, 160, 200, 320, 400, 480 Mbps nominal data rates
Range of 10 m indoor
Data can be interleaved across 3 bands, 7 defined patterns (channels)
Mandatory support for band group 1
• MAC
–
–
–
–
–
Peer to Peer, Ad-hoc
AES 128
From Fig 28:
Support for Dynamic Channel Selection
Ranging via propagation delay measurements
Bluetooth-like information discovery
WiMedia Implementations
• Primarily marketed as cable
replacement
• Wireless USB out in Dec 2006
From:
http://www.wimedia.org/en/events/documents/02WiMedia_Overview_CES200
6.ppt
–Hub-spoke model
–Mandatory support for band group
1
–Mandatory rates of 53.3, 106.7,
200 Mbps
–Initial Belkin device didn’t live up to
the hype
• Data rate of 6.35 Mbits/s
• Reportedly not to WiMedia spec
• http://www.eetimes.com/news/latest/
showArticle.jhtml?articleID=1966021
48
• Now certified
– http://www.wimedia.org/imwp/idms/pop
ups/pop_download.asp?contentID=119
61
• Bluetooth 3.0 devices in
2008
– http://gizmodo.com/gadge
ts/wireless/nextgenbluetooth-30-on-the-way179684.php
• Wireless Firewire and IP
also supported over
WiMedia standard
•
Status
– Nokia sponsored initiative announced Oct 2006
– Specification work is currently being evaluated, targeted for availability second
quarter 2007
– Trial chips probably available late 2007
•
Public data: (from wibree.com (no more) and
http://www.theregister.co.uk/2006/10/06/wibree_analysis/ )
–
–
–
–
–
2.4 GHz ISM band
Range 10 meters
1 Mbps data rate
Targets low power/low cost market
From http://www.computerworld.com.au/index.php/id;992123146;fp;4;fpid;18
•
•
•
•
•
Up to 8 devices Master/Slave
Turns off frequency hopping
Expects different technology to serve as backbone between masters
Expects to share resources with full Bluetooth
Many reports mentioned WiBree as a competitor to Bluetooth
– Brought into Bluetooth fold as low power alternative
– “Bluetooth Low Energy”
– https://www.bluetooth.org/About/bluetooth_sig.htm#Bluetooth%20Wireless%20
Technology
– Now a competitor to Zigbee
Z-Wave
• Originally Zensys proprietary
– http://www.zen-sys.com/
Z-Wave Alliance
• Industry standard “Z-wave”
– http://www.z-wave.com
• Low power alternative to Zigbee
• PHY
– 9.6 kbps or 40 kbps
– GFSK
– 100 ft range
• 900 MHz ISM
• http://www.z-wavealliance.com/
• http://en.wikipedia.org/wiki/Z-Wave
http://www.z-wave.com/modules/AboutZWave/?id=21&chk=4ed024468cb3d7f9095aa54227ea1
97a
Other Proprietary Standards
• TransferJet (Sony)
•
– http://www.kleer.com
– Proprietary low power RF for
audio / video
–Features
• http://www.sony.net/SonyInfo/News/Pre
ss/200801/08-002E/index.html
• Electric induction field coupling
• 3 cm range
• 4.48 GHz center frequency
• 560 Mbps (Max) 375 Mbps (effective)
•
–Demonstrated shortly after
announced
• http://www.engadget.com/2008/01/06/vi
deo-sonys-transferjet-getsdemonstrated/
En-Ocean
– http://www.enocean.com/en/
– Best known as energy scavengers
– Runs a proprietary wireless mesh
protocol
– Adaptive modulation
• “Touch & Get: transfer by touching
devices together
• Some registration security
Kleer
•
Insteon
– Mixes power line comm with RF
comm
– Industry Alliance (15
manufacturers)
• http://www.insteon.net/allianceabout.html
• Wireless Valley is a member
– Open source
http://www.efundies.com/
WPAN Summary
• Greater reliance on industry standards than other classes
of waveforms
– Seems to work more smoothly
– Bluetooth, WiMedia, Z-wave
• Bifurcation into low power devices (e.g., Zigbee, Wibree)
and high-throughput devices
• Impulse UWB as a WPAN appears dead
• Heavy emphasis on mesh networks
• Possible trend to mix protocols at different mesh levels
• Possible later push by WiMAX (ClearWire / XOhm) into
market
Presentation Overview
Theory
(32) OFDM and Antenna Array
Theory
Emerging Standards
(24) Cellular and WiMAX
(16) WLAN
(10) WPAN
(11) Cognitive Standards
( 7) Interoperability Standards
Break & Poster Session
2:45-3:30
http://www.wisoa.net/members_logos/mobile_in
ternet-big.jpg
Emerging Cognitive Standards
Cognitive Radio
• An approach to wireless
engineering wherein the radio, radio
network, or wireless system is
endowed with the capacities to:
– acquire, classify, and organize
information (aware)
– retain information (aware)
– apply logic and analysis to information
(reason)
– make and implement choices (agency)
about operational aspects of the radio,
network, or wireless system in a
manner consistent with a purposeful
goal (intelligent).
– “Cognitive Radio Definitions and Nomenclature,”
Working Document SDRF-06-R-0009-V0.08
802.22
• Wireless Regional Area Networks (WRAN)
– First explicit cognitive radio standard
– Aimed at bringing broadband access in rural and remote areas
– Takes advantage of better propagation characteristics at VHF and
low-UHF
– Takes advantage of unused TV channels that exist in these sparsely
populated areas
– Still defining inter-cell coexistence
• Status (IEEE 802.22-06/0251r0)
– Resolving lots of comments
– Still developing
• 802.22.1
– Enhanced interference protection
• 802.22.2
– Best practices for deployment
Features of 802.22
•
•
•
•
Data Rates 5 Mbps – 70 Mbps
Point-to-multipoint TDD/FDD
DFS, TPC
Adaptive Modulation
– QPSK, 16, 64-QAM, Spread
QPSK
• OFDMA on uplink and downlink
• Use multiple contiguous TV
channels when available
• Fractional channels (adapting
around microphones)
• Space Time Block Codes
• Beam Forming
– No feedback for TDD (assumes
channel reciprocity)
• 802.16-like ranging
• 802.16 MAC plus the following
–Multiple channel support
–Coexistence
• Incumbents
• BS synchronization
• Dynamic resource sharing
–Clustering support
–Signal detection/classification
routines
• Security based on 802.16e
security
• Collaborative sensing
• Techniques in 802.22 will be
extended to other standards and to
other bands around the world
Unlicensed White Space Devices
• Concept:
–Allow unlicensed secondary users into unoccupied TV bands via DSA
–“WiFi on Steroids” http://news.cnet.com/8301-10784_3-9901747-7.html
–Only thing really defined is proposed methods for avoidance
• Detect and avoid
• Geolocate and avoid (perhaps helped by beacon)
– Google’s beacon white paper:
http://services.google.com/blog_resources/google_geolocation_white_paper.pdf
• Wireless Innovation Alliance (basically the White Space Coalition)
–http://www.wirelessinnovationalliance.com/index.cfm
–Key players
• Microsoft, Google, Dell, Motorola, Phillips
• 1.5 hr discussion with Larry Page
– http://www.newamerica.net/events/2008/google_unwired
• Lots of objections from TV broadcasters and wireless microphone
manufacturers / users
• Initial problems
–Microsoft device broken – DTV recovered signals Microsoft prototype didn’t detect
• http://crtwireless.com/blog/2007/08/02/fcc-report-on-tv-band-prototype-measurementsreleased/
–Motorola device false negatives with strong adjacent channels
• http://www.broadcastingcable.com/article/CA6560691.html
• FCC continuing to review submitted devices
–http://crtwireless.com/blog/2007/11/29/motorola-submits-new-white-space-device-forfcc-testing/
802.11h – Unintentionally Cognitive
•
Dynamic Frequency
Selection (DFS)
–
Avoid radars
•
–
•
Listens and discontinues
use of a channel if a radar is
present
Uniform channel utilization
Transmit Power Control
(TPC)
–
–
–
–
Interference reduction
Range control
Power consumption Savings
Bounded by local regulatory
conditions
802.11y
•
Ports 802.11a to 3.65 GHz – 3.7 GHz (US Only)
–
–
•
•
FCC opened up band in July 2005
Ready 2008
Intended to provide rural broadband access
Incumbents
– Band previously reserved for fixed satellite service (FSS) and radar installations –
including offshore
– Must protect 3650 MHz (radar)
– Not permitted within 80km of inband government radar
– Specialized requirements near Mexico/Canada and other incumbent users
•
Leverages other amendments
– Adds 5,10 MHz channelization
(802.11j)
– DFS for signaling for radar
avoidance (802.11h)
•
•
Working to improve channel
announcement signaling
Database of existing devices
– Access nodes register at
http://wireless.fcc.gov/uls
– Must check for existing devices at
same site
Source: IEEE 802.11-06/0YYYr0
802.16h
•
Draft1 to ballot Oct 06,
67% approve, resolving
comments)
•
•
Draft 6 to ballot May 2008
Improved Coexistence
Mechanisms for LicenseExempt Operation
Explicitly, 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.
IEEE 1900
• IEEE 1900 (aka Standards Coordinating Committee 41 –
Dynamic Spectrum Access Networks)
– http://www.scc41.org/
– 1900.1 – Terminology and Concepts
– 1900.2 - Recommended Practice for Interference and
Coexistence Analysis
• Approved
• http://crtwireless.com/blog/2008/04/02/19002-approved/
– 1900.3 – Conformance Evaluation for SDR modules
– 1900.4 – Architectural Building Blocks
• network resource managers
• device resource managers
• the information to be exchanged between the building blocks
– 1900.5 – Policy Languages
DARPA’s WNAN Program
• Objectives
– Reduced cost via intelligent
adaptation
– Greater node density
– Gains in throughput/scalability
WNaN Protocol Stack
Optimizing
Topology
• Leveraged programs
– Control Based MANET – low
Network
overhead protocols
– Microsystems Technology Office
– RFMEMS, Hermit, ASP
MAC
– xG – opportunistic use of
spectrum
– Mobile Network MIMO - MIMO
Physical
Wideband Network Waveform
– Connectionless Networks –
rapid link acquisition
– Disruption Tolerant Networks
(DTN) – network layer protocols
Legend
CBMANET
WNaN
CBMANET
WNaN
CBMANET
MIMO (MNM)
xG
COTS
MEMS (MTO)
Other
programs
WNaN
program
Cognitive Radio Summary
• Numerous new
applications enabled
– Opportunistic spectrum
utilization, collaborative
radio, link reliability,
advanced network
structures
• Commercial
implementations starting to
appear
– 802.22, 802.11h,y, 802.16h
– And may have been around
for a while (cordless phones
with DFS)
• Significant resistance from
incumbents
• Standards tend to be
highly focused
– Work in specific bands
• No real standard for white
space coalition
– Still trying to get blessing to
operate in-band
• DoD may emerge into
commercial market in the
near future
• Rolling out incrementally
Presentation Overview
Theory
(32) OFDM and Antenna Array
Theory
Emerging Standards
(24) Cellular and WiMAX
(16) WLAN
(10) WPAN
(11) Cognitive Standards
( 7) Interoperability Standards
( 6) Summary and Trends
Break & Poster Session
2:45-3:30
http://www.wisoa.net/members_logos/mobile_in
ternet-big.jpg
Interoperability Standards
802.21, UMA/GAN 802.11u
Industry Standards
802.21 (Media Independent
Handoffs)
• Key Services
– Triggers (state change, predictive, network initiated)
– Network Information (services, maps, list of avaialble networks)
– Handover commands (client or network initiated, vertical
handoffs)
• July 2008: Targeted publication
http://www.ieee802.org/802_tutorials/july06/802 21-IEEE-Tutorial.ppt
V. Gupta, “IEEE 802.21 MEDIA INDEPENDENT HANDOVER,”
IEEE 802.21 session #15 July 17, 2006
• UMA allows to access the mobile voice
and data services of the cellular network
over a Wireless LAN
• Subscribers are enabled to roam and
handover between cellular networks and
wireless networks
• Mobile devices access the Core Network
through Unlicensed Mobile Access
Network (UMAN).
• UMAN has 3 major entities
–Unlicensed wireless network
–IP access network
–UMA Network controller (UNC)
http://www.umatoday.com
• UNC authorizes and authenticates the Mobile
devices for accessing the Core Network
• Part of 3GPP now
–Generic Access Network (GAN)
• Products
– http://www.umatoday.com/mobileHandsets.php
http://www.umatoday.com
•
•
VCC
Addresses shortcomings in UMA’s Voice Call Continuity (VCC)
Status
–
–
–
•
Different technologies agree to virtual channel
–
•
Joint control impossible
Some argue inferior to UMA
–
•
Initiated within 3GPP in June 2005
2006 through requirements, has only fully completed the requirements stage
2008 being extended to IMS Service Continuity
http://www.kineto.com/products/downloads/kineto_wp_UMA_VCC_2007.pdf
Some argue better than UMA
–
http://www-hk.huawei.com/publications/view.do?id=1480&cid=2622&pid=127
http://www.kineto.com/products/downloads/kineto_wp_UMA_VCC_2007.pdf
802.11u (Interworking with External
Networks)
• Standard out in 2010
• Specifically addresses handoffs where user not
preauthorized (generally because from another
network)
• Major Topics
–
–
–
–
Network Selection
Emergency Call support
Authorization from Subscriber Network,
Media Independent Handover Support
• Supporting information and control messages of 802.21
Other Cellular + WiFi
•
Seamless Converged Communication Across
Network (SCCAN)
–
–
•
Mobile Integrated Go-to-Market Network IP
Telephony Experience (Mobile IGNITE)
–
–
•
Mobile IGNITE
Vendor driven solution
http://www.bridgeportnetworks.com/partners/mobileignite.html
Wireless Wireline Convergence Working Group
–
–
•
Motorola, Proxim, Avaya – Enterprise solutions
http://www.sccan.org/
Alcatel, Cisco (International Packet
Communications Consortium)
http://www.packetcomm.org/index.shtml
Bottom line
–
–
Even for standard convergence type activities
there’s many different emerging standards.
Need for special radios to navigate standards?
http://www.spectralink.com/products/image
s/NL-01.gif
Interoperability Summary
•
•
•
Proliferation of standards + lack of
silver bullet standard means that
optimal access technology will
vary
Supporting growth in use of VoIP
will make networks less
dependent on particular access
technologies
Biggest issues are:
– Getting industries to agree
(Herding cats)
– Managing security across
heterogeneous networks
– Harmonizing handoff routines
•
•
802.21 is the standard that ties
together the vertical handoff
standards
Heavy focus on WiFi + Cellular
Rapid growth ?
Mobile voice traffic
Fixed voice traffic
VoIP traffic
-92 -93 -94 -95 -96 -97 -98 -99 -00 -01 -02 -03 -04 -05 -06 -07 -08
e e
e e
Source: Nokia 13.6.2005
Technology used to terminate the call
Presentation Overview
Theory
(32) OFDM and Antenna Array
Theory
Emerging Standards
(24) Cellular and WiMAX
(16) WLAN
(10) WPAN
(11) Cognitive Standards
( 7) Interoperability Standards
( 6) Summary and Trends
Break & Poster Session
2:45-3:30
http://www.wisoa.net/members_logos/mobile_in
ternet-big.jpg
Summary and Future Trends
Convergence of Approaches
• WiMAX becoming more like
cellular, cellular becoming
more like WiMAX
• Cellular like waveforms
converging to mix of OFDMA
+ MIMO optimized for low
speeds with small cell sizes
Source: http://www.wimaxforum.org/technology/downloads/
WiMAX_and_ IMT_2000.pdf
• Recognition of this convergence is leading to WiMAX being treated
like a cellular technology
– Sprint’s XOhm network (now ClearWire!)
– WiMAX classified as 3G
• WiMAX out of the gate first
– Nokia, Motorola, Samsung
– http://www.reuters.com/article/technology-media-telco-SPA/idUSSP31345620070904
• Because 3G took so long to deploy, WiMAX will steal a march
Breeding Successful Technologies
• Mobile WiMAX will be a MIMO standard, but
so will LTE
– Transition of technologies can significantly
extend useful lifetime of deployments
• Enhanced EDGE
• WCDMA + MIMO may steal LTE’s market
– 802.11n predates mobile WiMAX
• 802.22 techniques opening up legacy
spectrum for other standards
– White Space Coalition
– 802.16m
• Standards can expect to continue to evolve
even post-deployment
– Need for SDR
• May make for smoother transition to 4G
Erik Dahlman, Hannes Ekström, Anders Furuskär, Ylva
Jading, Jonas Karlsson, Magnus Lundevall, Stefan Parkvall,
“The 3G Long-Term Evolution – Radio Interface Concepts
and Performance Evaluation,” VTC 06
Take Aways (1/2)
• High data rate systems migrating to OFDM + Antenna
Array Processing PHY
– OFDM – WiMedia, 802.11a,g, 802.16, 802.20, 802.22, UMB,
LTE
– OFDM + MIMO – 802.11n, 802.16e, 802.20, UMB, LTE
• More responsive/adaptive resource management (early
cognitive radio)
– Multiple QoS levels – 802.11e; 802.16e; 802.20; UMB, LTE,
EVDO,
– Dynamic channel selection – WiMedia; 802.11h,y; 802.16h;
802.22
– Distributed sensing – 802.22
• Coexistence given increasing interest
– Vertical handoffs – 802.21, 802.11u
– Legacy systems – 802.22, 802.11h,y, 802.16h
• New bands opening up for old techs
– 802.15.4d, 802.11j,p,y
Take-Always (2/2)
• Some spectral harmonization
– 5 GHz for WiMAX
• China pushing own standards
– 802.15.4c, TD-SCDMA, TD-SOFDMA
• Emergence of Advanced Networking
– 802.11s, 802.15.5, 802.16j
• Increasing # of technologies
– Legacy systems not quickly fading and large # of new ones
• Convergence on AES for security
– 802.11i, WiMedia, Mobile WiMAX
• Convergence on all IP Backbone
– Mobile WiMAX, UMB, LTE
Useful Websites (News,
Promotional, Forums, Standards)
WLAN
www.wi-fi.org
www.wi-fiplanet.com/
http://grouper.ieee.org/groups/802/11/
802.15
www.bluetooth.com
https://www.bluetooth.org/
www.wimedia.org
http://www.zigbee.org/en/
http://www.uwbforum.org/
www.wibree.org
http://www.multibandofdm.org/
http://grouper.ieee.org/groups/802/15/
802.16
www.wimaxforum.org
http://wimaxxed.com
http://wimax.com
http://grouper.ieee.org/groups/802/16/
3GPP Family
www.gsmworld.com
www.umtsworld.com
www.gsacom.com
www.3gpp.org
http://www.tdscdma-forum.org/
3GPP2 Family
www.cdg.org
www.3gpp2.org
802.20
http://grouper.ieee.org/groups/802/20/
802.21
http://www.ieee802.org/21/
www.umatechnology.org
802.22
http://grouper.ieee.org/groups/802/22/
E2R “Requirements and scenario definition,”
Available online:
http://e2r.motlabs.com/Deliverables/E
2R_WP4_D4.1_040725.pdf