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State and Future of WirelessCommunications and Networking

Ender Ayanoglu UC Irvine EECS/CPCC/Calit2

11/14/2012UCI EECS Colloquium

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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

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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

• 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

doc.: IEEE 802.11-10/0692r0

Submission Slide 10

IEEE 802.11 Standards Pipeline

PHY

SponsorBallot

MAC

Study groups

802.11kRRM

802.11rFast Roam

802.11b (’99)11 Mbps2.4GHz

PublishedStandard

a 54 Mbps5GHz

g54 Mbps2.4GHz

eQoS

iSecurity

f Inter AP

hDFS & TPC

802.11VNetwork

Management

802.11sMesh

802.11uWIEN

802.11YContention

BasedProtocol

TG Letter Ballot

802.11 -2007802.11mbMaintenance

k+r+y802.11aa

Video Transport

802.11acVHT 5GHz

802.11adVHT 60GHz

TG without draftDiscussion Topics

PublishedAmendment

802.11aeQoS Mgmt Frm

802.11nHigh

Throughput(>100 Mbps)

802.11WManagement

Frame Security

802.11zTDLS

802.11pWAVE

802.11afTVWS

Smart Grid

FIA

S1G

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Wireless LANs: IEEE 802.11

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New Standard: IEEE 802.11ac

• 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• 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

• More MIMO spatial streams– Support for up to 8 spatial streams (vs. 4 in 802.11n)

• 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

• Modulation– 256-QAM, rate 3/4 and 5/6, added as optional modes (vs. 64-QAM, rate 5/6 maximum in 802.11n)

• 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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Wallet

MP3 Player

Game Console

FM Radio

PDAVoice

PagerPC

Bar Scanner

CamcorderWalkie-TalkieTelevision

Newspaper Rolodex

Glucometer

GPS Device

Photo Album

Camera

Cell-phone: The one device that everyone carries

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Handset Sales Predictions

• New and more powerful handsets every year, customers will likely replace handsets every 2 years

(Asia-Pacific)

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Evolution to 3G

cdma2000 1x

GSM

TDMA GSM/GPRS GSM/GPRS/EDGE WCDMA

cdmaOne cdma2000 1xEV-DV

cdma2000 1xEV-DO

TD-SCDMA

PDC

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2G Cellular Market Share

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• Verizon– 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

• 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

2005: 3G is Being Rolled Out

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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)

Source: WiMAX Forum 2009

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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

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

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OFDMA: Orthogonal Frequency Division Multiple Access

• 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

LTE Reference signals are interspersed

among Resource Elements

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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

• 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

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.

Example comparison with OFDMA

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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

Evolution of 3G Variants to LTE

Source: WiMAX Forum 2009

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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

• 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)

dBm

Frequency

-60

-100

“White spaces”

470 MHz 750 MHz

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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

• 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

• Feature sizes– 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

• Ways to increase speed and reduce power consumption– 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

• 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 tothe 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

• 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