Transcript Wireless Data Services for Cellular Telephony

State and Future of Wireless
Communications and Networking
Ender Ayanoglu
UC Irvine EECS/CPCC/Calit2
11/14/2012
UCI EECS Colloquium
1
Slides Available from
My personal Web page
www.eng.uci.edu/~ayanoglu
Scroll down to the bottom of the page for
My EECS Colloquium Slides Fall 2012
2
Communications in the ’90s-’00s
Hot research, development, commercialization due
mainly to the introduction and popularity of
– Cellular voice wireless
– Internet
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Many New Products and Services
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Voiceband modems (V.34, V.90, V.92)
Digital subscriber line modems (DMT, CAP)
Cable TV and cable Internet access
100 Mb/s, 1 Gb/s Ethernet
2nd-4th Generation (digital) cellular voice
Optical amplifiers
Dense Wavelength Division Multiplexing for fiber
optic transmissions
• Smart phones, tablets
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Enabling Technologies:
Code Division Multiple Access (CDMA)
• Each user bit is expanded by the use of a code, unique to a
user and orthogonal among users
• Signal spectrum is expanded (spread)
• Sum of interference by all other users appears as additive
Gaussian noise to a particular user
• Receiver employs the same code as the transmitter and pulls
transmitted information from below all noise and interference
• Powerful technique for voice communication
• Used by cellular services of Sprint and Verizon in US, some
others worldwide
• Also used in 802.11b
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Enabling Technologies:
Orthogonal Frequency Division Multiplexing (OFDM)
• Employs IFFT and FFT to translate the transmitted
message into the frequency domain
• Estimates the frequency response of the channel and
equalizes the channel in the frequency domain
• Best technique for broadband frequency selective
channels
• Employed in 801.11a/g, ADSL, DAB, DVB, etc
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Enabling Technologies:
Multi-Input Multi-Output (MIMO)
• Multiple transmit and receive antennas to
– Increase transmission rate
– Improve BER vs SNR performance
• Part of 802.11n
• Under consideration in upcoming standards
• Single- and multi-user versions
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How Much Fading is There?
• Fading can cause 30-40 dB loss in received signal power!
• Power link budgets in wireless communications require
corresponding fading margins (assume received power can go
down by 103-104 times!)
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Wireless LANs: IEEE 802.11
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doc.: IEEE 802.11-10/0692r0
IEEE 802.11 Standards Pipeline
802.11mb
Maintenance
k+r+y
MAC
802.11aa
Video Transport
802.11s
Mesh
802.11u
WIEN
802.11r
Fast Roam
802.11V
Network
Management
802.11k
RRM
802.11Y
Smart Grid
802.11ae
QoS Mgmt Frm
FIA
S1G
802.11p
WAVE
802.11af
TVWS
802.11W
Management
Frame
Security
802.11ad
VHT 60GHz
PHY Submission
Study
groups
TG without draft
Contention
Based
Protocol
802.11n
High
Throughput
(>100 Mbps)
802.11ac
VHT 5GHz
Discussion
Topics
802.11 -2007
802.11z
TDLS
TG
Letter Ballot
Slide 10
Sponsor
Ballot
Published
Amendment
e
QoS
h
DFS & TPC
i
Security
f
Inter AP
a 54 Mbps
5GHz
g
54 Mbps
2.4GHz
802.11b (’99)
11 Mbps
2.4GHz
Published
Standard
Wireless LANs: IEEE 802.11
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New Standard: IEEE 802.11ac
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Currently under development which will provide high throughput in the 5 GHz band
Will enable multi-station WLAN throughput of at least 1 Gb/s and a maximum single link throughput
of at least 500 Mb/s.
Accomplished by extending the air interface concepts embraced by 802.11n: wider RF bandwidth (up
to 160 MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation
(up to 256 QAM)
Devices with the 802.11ac specification are expected to become common by 2015 with an estimated
one billion spread around the world
A number of companies already announced chips
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IEEE 802.11ac Features
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Only for the 5 GHz band
Wider channel bandwidths
– 80 MHz and 160 MHz channel bandwidths (vs. 40 MHz in 802.11n)
• 80 MHz mandatory for stations (STAs), 160 MHz optional
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More MIMO spatial streams
– Support for up to 8 spatial streams (vs. 4 in 802.11n)
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Multi-user MIMO (MU-MIMO)
– Multiple STAs, each with one or more antennas, transmit or receive independent data streams
simultaneously
• “Space Division Multiple Access” (SDMA): streams not separated by frequency, but instead resolved spatially,
analogous to 11n-style MIMO
– Downlink MU-MIMO (one transmitting device, multiple receiving devices) included as an optional mode
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Modulation
– 256-QAM, rate 3/4 and 5/6, added as optional modes (vs. 64-QAM, rate 5/6 maximum in 802.11n)
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Other elements/features
– Single sounding and feedback format for beamforming (vs. multiple in 802.11n)
– MAC modifications (mostly to support above changes)
– Coexistence mechanisms for 20/40/80/160 MHz channels, 11ac and 11a/n devices
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State of Wireless LANs
• Wireless LANs are a very successful area and will
remain so for many years
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Mobile Cellular Networking Generations
• First Generation (1G, Analog Voice)
– Analog System
– AMPS, NAMPS (US), NMT 450, NMT 900 (Eu), N-TACS (J)
• Second Generation (2G, Digital Voice)
– Digital System
– TDMA [IS-136], CDMA [IS-95] (US), GSM (Eu), PDC (J)
• 2.5G
– Evolution to 3G
– GPRS (Global Packet Radio Service), EDGE (Enhanced Data GSM
Environment)
• Third Generation (3G, Data Rides on Digital Voice)
– High-speed packetized voice and data
– IMT2000 req.: 144K vehicular, 384K pedestrian, 2M indoor
– WCDMA (GSM), CDMA2000 (IS-95), TD-SCDMA (C)
• Fourth Generation (4G, Everything Rides on Data Packets)
– WiMAX, LTE
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Cell-phone: The one device that everyone carries
Walkie-Talkie
Voice
PDA
Photo Album
Television
Camcorder
Glucometer
Camera
Wallet
FM Radio
Bar Scanner
Game Console
PC
MP3 Player
Newspaper
GPS Device
Rolodex
Pager
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Handset Sales Predictions
(Asia-Pacific)
• New and more powerful handsets every year,
customers will likely replace handsets every 2 years
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Evolution to 3G
GSM
TDMA
GSM/GPRS
GSM/GPRS/EDGE
WCDMA
PDC
cdmaOne
cdma2000
1x
cdma2000
1xEV-DV
cdma2000
1xEV-DO
TD-SCDMA
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2G Cellular Market Share
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2005: 3G is Being Rolled Out
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Verizon
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EV-DO (Evolution – Data Optimized)
400-700 kb/s down, 50-70 kb/s up
$60/mo. unlimited use
About 84 US markets, 426 US airports
Sprint
– EV-DO
– $40/mo. Up to 40 MB/mo., $60/mo. Unlimited use
– About 48 US markets
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Cingular (including AT&T Wireless)
– UMTS (WCDMA)
– 220-320 kb/s down, 400-700 after upgrade to HSDPA (Hi-Speed Downlink Pkt Acc.)
• CDMA well-suited for voice but not for data
• Another high-speed technology will likely be needed
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3G-4G Story
• Japanese service provider DoCoMo proposed W-CDMA as the 3G standard to
3GPP, accepted
• As demand increased newer techniques introduced GPRS, EDGE, HSDPA,
HSUPA
• 3GPP2 developed versions of EV-DO Rev 0, A-C
• As demand kept increasing, it was realized that CDMA-based technologies
would not suffice. DoCoMo suggested technology similar to what was
developed in WiMAX (802.16e)
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Source: WiMAX Forum 2009
Evolution to 4G
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3GPP Long Term Evolution (LTE)
3GPP Release 8 ratified as a standard, oriented towards 4G.
• Peak download 326.4 Mbit/s for 4x4 antennas, 172.8 Mbit/s for 2x2 antennas
for every 20 MHz
• Peak upload 86.4 Mbit/s for every 20 MHz
• At least 200 active users in every 5 MHz cell (i.e., 200 active data clients)
• Sub-5ms latency for small IP packets
• Spectrum slices as small as 1.4 MHz (and as large as 20 MHz) supported
• Optimal cell size of 5 km, 30 km w/ reasonable performance, up to 100 km
w/ acceptable performance
• Co-existence with legacy standards
• Supports MBSFN (Multicast Broadcast Single Frequency Network). Can
deliver services such as Mobile TV using the LTE infrastructure (competitor
for DVB-H)
• Transition from the existing UMTS circuit + packet switching combined
network, to an all-IP flat architecture
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LTE PHY Layer
• Methods to combat multipath
– OFDM
– MIMO
• New access method scheme
– OFDMA
– SC-FDMA (Single Carrier – Frequency Division Multiplexing)
OFDM breaks the bandwidth into
multiple narrower QAM-modulated
subcarriers. As a result, each
subcarrier faces a much less
distorted channel. This, and a number
of associated signal processing
techniques simplify equalizing the
channel substantially
OFDMA: Orthogonal Frequency Division Multiple Access
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Multiplexing scheme for LTE DL
A number of subcarriers are assigned to each user for a specific time
interval (Physical Resource Block) (time-frequency dimension)
PRB is the smallest element for
resource allocation. It contains 12
consecutive subcarriers for one
slot duration
Resource Element: One
subcarrier for each symbol
period
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LTE Reference signals are interspersed
among Resource Elements
2D Time and Frequency Grid
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Downlink Channel Mapping
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Uplink Channel Mapping
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Single Carrier Frequency Domain Equalization
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OFDM has a large Peak-to-Average Power ratio. This results in the use of power
amplifiers such that they are kept in their linear operating region, in an inefficient
mode. As a result, OFDM causes transmitters to be expensive. This is a problem on the
uplink.
There is a way to modify the OFDM transmitter and receivers such that this problem
disappears. The TX and RX are very similar to OFDM, with additional blocks. This
system keeps the equalization advantages of OFDM. LTE chose this solution for the TX
in the MS.
M>N
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Single Carrier Frequency Division Multiple Access
Example comparison with OFDMA
WiMAX uses OFDMA in both uplink and downlink. SC-FDMA can offer larger cell
coverage, OFDMA can provide higher throughput, with SC-FDMA being less expensive.
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Carrier Adoption of LTE
• Carriers supporting GSM or HSPA networks can be expected to
upgrade to LTE. However, several networks that don't use these
standards are also upgrading to LTE
• Alltell, Verizon, China Telecom/Unicom and Japan's KDDI. These
are CDMA carriers and have chosen to take the GSM evolution
path as opposed to the 3GPP2 CDMA evolution path UMB
• Verizon Wireless plans to begin LTE trials in 2008
• AT&T Mobility will upgrade to LTE as their 4G technology, but will
introduce HSUPA and HSPA+ as bridge standards
• T-Mobile, Vodafone, France Télécom, Telia Sonera and Telecom
Italia Mobile announced or talked publicly about their commitment
to LTE
• Bell Canada plans to start LTE deployment in 2009-2010
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Evolution of 3G Variants to LTE
Source: WiMAX Forum 2009
State of Mobile Cellular Networks
• Mobile cellular one of the most commercially successful
technology introductions ever
• 2.5G and 3G rolled out, we are now seeing 4G
• LTE emerging as the common standard
• Very active field, will continue to be for a long time
• New technologies (antenna arrays, etc) are needed and will
be introduced
• New modulation formats and increased bit rates are likely
• 4G is here, LTE-Advanced is very sophisticated
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Federal Communications Commission (FCC)
Ruling on White Space
-60
“White spaces”
dBm
-100
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470 MHz
Frequency
750 MHz
TV spectrum is large, many bands are unused
This is especially true at UHF
Fall ’10: FCC opened these bands to unlicensed use, contingent on
The ruling is expected to impact wireless transmission , possibly creating Super
Wi-Fi coverage (better transmission in these bands)
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IEEE 802 Wireless Space
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ZigBee Wireless Personal Area Network
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Likely Scenario for the Future of Wireless
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802.11 is very successful
2.5G-3G services proliferated beyond expectations
802.11 public access service commonplace
PDAs and laptops which integrate 802.11 and 2.5G-3G will be
commonplace
• Roaming between 802.11 and 2.5G-3G is next
• Very high data rate 802.11 via modern processing (802.11ac)
is next
• LTE major push
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Future of Moore’s Law
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Feature sizes
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90 nm today
65 nm in 2005-2007
45 nm in 2007-2010
32 nm in 2009-2013
22 nm in 2011-2016
Theoretically can shrink down to 4 nm (about 2023): Beyond which source and drain of a transistor
are so close, electrons can drift on their own; losing reliability.
– IBM announced a proof-of-concept transistor at 6 nm (20 Si atoms) in 2002
– However, before 4 nm, leakage current is a problem
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Ways to increase speed and reduce power consumption
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Multicore processor architectures (New software will be needed, hard!)
3D stacked integrated circuits
Low-power circuit design techniques, e.g., sleep-transistor technology
Tri-gate transistor: Reduction in leakage current and power consumption
Better dielectrics
Hybrid semiconductors with nanowires
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ITRS View:
Extrapolation (Although Slowing Down)
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Federico Faggin’s View:
Architect of the First Microprocessor (4004)
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Kurzweil’s Accelarating Returns Argument
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Evolution of computing has always occurred at exponential pace
Future developments will occur at exponential speed too
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If Exponential Development of
Computing Speed Continues
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A Conservative Outlook to
the Future of Moore’s Law
• Rate of doubling slowed down to about 3 years, maybe more
• Current leading edge feature size is about 22 nm
• Next generations may follow a route of about 3 more
generations until about 14 nm, 6-8 years
• Human ingenuity may take us further via a number of options
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What is the Future of Communications?
• Broadband: Higher speed to home and business
• Home networking, esp. distribution of video in home
• Convergence of PDAs, pagers, cell phones, laptops, always
on connectivity to the Internet and voice network
• “Wearable” computers
• Convergence of communications and computing
• IP will eventually carry more than best effort data
• VoIP will replace circuit-switched telephony
• Sensors everywhere
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What a Communication Processor
May Look Like in 15 Years
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Sample Research Topics in Communications
• Multi-Input Multi-Output (Smart Antennas)
– WLAN and cellular
– Very hot research area
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Ad-hoc networks
Mesh (multihop) networks
Optical packet switching
Wearable computing
User interface (big bottleneck)
– Speech and handwriting recognition, hard!
• Pervasive communications (machine-to-machine)
• Energy efficiency
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Slides Available from
My personal Web page
www.eng.uci.edu/~ayanoglu
Scroll down to the bottom of the page for
My EECS Colloquium Slides Fall 2012
51