Fourth generation cellular systems and smart antennas
This presentation is the property of its rightful owner.
Sponsored Links
1 / 34

Fourth Generation Cellular Systems and Smart Antennas PowerPoint PPT Presentation


  • 73 Views
  • Uploaded on
  • Presentation posted in: General

Fourth Generation Cellular Systems and Smart Antennas. Jack H. Winters. April 11, 2002 [email protected] Goal. Wireless communications, anywhere, in any form In any form: high-speed data (Internet) voice audio (music) video Anywhere: home buildings (office) pedestrian vehicles

Download Presentation

Fourth Generation Cellular Systems and Smart Antennas

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Fourth generation cellular systems and smart antennas

Fourth Generation Cellular Systems and Smart Antennas

Jack H. Winters

April 11, 2002

[email protected]


Fourth generation cellular systems and smart antennas

Goal

  • Wireless communications, anywhere, in any form

  • In any form:

    • high-speed data (Internet)

    • voice

    • audio (music)

    • video

  • Anywhere:

    • home

    • buildings (office)

    • pedestrian

    • vehicles

  • Secure wireless virtual office


Outline

OUTLINE

  • Current Systems

  • Current Trends

  • Strategy Proposal

  • Technical Issues


Current systems

$/Cell

$/Sub

$ 500,000

$ 1000

$ 100

$ 500

$ 100

$ 10

802.11a

5.5GHz Unlicensed

802.11b

2.4GHz Unlicensed

3G Wireless

~ 2GHz

Current Systems

Peak Data Rate

High performance/price

100 Mbps

10 Mbps

1 Mbps

BlueTooth

2.4GHz

100 kbps

High ubiquity and mobility

Range

10 feet

100 feet

1 mile

10 miles

Mobile Speed

60 mph

2 mph

10 mph

30 mph


Cellular data

Cellular Data

  • CDPD (US) < 10 kbps

  • GPRS = 30-40 kbps

  • EDGE = 80 kbps

  • WCDMA = 100 kbps (starting in Japan, but not for several years in US)


Fourth generation cellular systems and smart antennas

Barker

Barker

CCK

CCK

1 ms

11 chips

727 ns

8 chips

Key 802.11b Physical Layer Parameters:

Data rate:

  • 1, 2, 5.5, 11 Mbps

Modulation/Spreading:

  • Direct Sequence Spread Spectrum (DSSS)

  • DBPSK, DQPSK with 11-chip Barker code (1, 2 Mbps) (this mode stems from the original 802.11 standard)

  • 8-chip complementary code keying (CCK) (5.5, 11 Mbps)

  • optional: packet binary convolutional coding (PBCC), 64 state, rate 1/2 CC (BPSK 5.5 Mbps, QPSK 11 Mbps)

Transmission modes:(dynamic rate shifting)

Chip rate:

11 MHz

Frequency band:

Industrial, Scientific and Medical (ISM, unlicensed) 2.4 - 2.4835 GHz

Bandwidth:

22 MHz - TDD

Channel spacing:

5 MHz

Number of channels:

Total of 14 (but only the first 11 are used in the US), with only

3 nonoverlapping channels


Fourth generation cellular systems and smart antennas

3.2 ms

FFT

G

4 ms

52=48+4 tones

64 point FFT

Key 802.11a Physical Layer Parameters:

Data rate:

6, 9, 12, 18, 24, 36, 48, 54 Mbps

Modulation:

BPSK, QPSK, 16QAM, 64QAM

Coding rate:

1/2, 2/3, 3/4

User data rates (Mbps):

Subcarriers:

52

BPSK

QPSK

QAM16

QAM64

Pilot subcarriers:

4

R=1/2

6

12

24

FFT size:

64

R=2/3

48

4 ms

Symbol duration:

R=3/4

9

18

36

54

Guard interval:

800 ns

Subcarrier spacing:

312.5 kHz

Bandwidth:

16.56 MHz - TDD

Channel spacing:

20 MHz

Frequency band:

Unlicensed national infrastructure (U-NII), 5.5 GHz

Number of channels:

Total of 12 in three blocks between 5 and 6 GHz

:


Current trends

Current Trends

  • Business WLANs dominate, but home usage growing faster (8 million WLANs sold last year)

  • Spontaneous appearance of neighborhood/residential access sites via consumer broadband wire-line connections

  • Public WLAN offerings for enterprise and home users when they are away from the office or home

    • Players:

      • Wayport: Covers over 450 hotels & 9 airports US, Canada, UK

      • Aggregators:

        • Deep Blue Wireless (hotels and coffee houses)

        • Joltage

        • Sputnik

        • hereUare

        • Boingo Wireless/


Community 802 11b lans

North America

Bay Area Wireless User Group

Equip2rip (Oahu, HI)

Guerrilla.net (Boston)

Pdx Personal Telco

pdxwireless.org (Portland, Oregon)

SBAY.ORG Wireless Network (San Francisco Bay Area)

Seattle Wireless (Seattle)

Seattle Wireless Internet Project

SFLAN (San Francisco)

Xlan (Seattle)

Europe

Consume (London, UK)

Elektrosmog (Stockholm and Gothenburg)

Wlan.org.uk (UK)

Wireless France (France)

Wireless MediaPoli (Helsinki)

Australia

Community 802.11b LANs

Bay Area 802.11b Access Point Map


Possible strategies

Possible Strategies

  • Broadband Residential Access

    • Provide 802.11b’s to selected cable modem customers or pole locations for universal wireless high-speed data coverage (1 mile radius) with access to other homes in neighborhood

    • Since cable modem is at 1.5 Mbps and 802.11b is at 11 Mbps, provide fiber to these selected homes or poles (economical for selected homes)

  • Broadband Business Access

    • Fiber to building access points (e.g., floors)

    • Extend to residences for virtual offices


Fourth generation cellular systems and smart antennas

WLAN Overlay for Broadband Cable Infrastructure

HYBRID FIBER WIRELESS

  • Logical fit with cable infrastructure

  • Responds to ad-hoc and organized competition

  • Potential for higher data rate alternative to DOCSIS

  • Synergy with streaming digital media


Hybrid fiber wireless

Hybrid Fiber Wireless

  • Run fiber down streets (or to selected homes/businesses) to access points (1 mile apart) for universal coverage with one infrastructure)

    • Start with wireless data access (802.11b)

    • Extend range and migrate to:

      • Voice

      • Audio (music)

      • Video

      • Mobility

      • Higher data rates (54 Mbps - 802.11a and higher)

      • Virtual personal/office (remote workforce) environment


Technical issues

Technical Issues

  • Voice/Music streaming/Video streaming (802.11e)

  • Universal coverage (Internet roaming)

  • Range

  • Higher data rates

  • Capacity/Interference)

  • Key constraint: Stay within existing standards/standard evolution (enhance performance within standards and drive standards evolution)


Internet roaming

Internet Roaming

  • Seamless handoffs between WLAN and WAN

    • high-performance when possible

    • ubiquity with reduced throughput

  • management/brokering of consolidated WLAN and WAN access

  • adaptive or performance-aware applications

    • I-mobile, CC/PP, location based

  • Nokia GPRS/802.11b PCMCIA card

  • NTT DoCoMo WLAN/WCDMA trial

Cellular Wireless

Internet

Wireless LAN’s

Home

Enterprise

Public


Technical issues1

Technical Issues

  • Voice/Music streaming/Video streaming (802.11e)

  • Universal coverage (Internet roaming)

  • Range

  • Higher data rates

  • Capacity/Interference)

  • Key constraint: Stay within existing standards/standard evolution (enhance performance within standards and drive standards evolution)


Wireless system enhancements

$/Cell

$/Sub

$ 500,000

$ 1000

$ 100

$ 500

$ 100

$ 10

802.11a

5.5GHz Unlicensed

802.11b

2.4GHz Unlicensed

3G Wireless

~ 2GHz

Wireless System Enhancements

Peak Data Rate

High performance/price

100 Mbps

10 Mbps

Enhanced

1 Mbps

BlueTooth

2.4GHz

100 kbps

High ubiquity and mobility

Range

10 feet

100 feet

1 mile

10 miles

60 mph

Mobile Speed

2 mph

10 mph

30 mph


Enhancements

Enhancements

  • Smart Antennas (keeping within standards):

    • Range increase

    • Interference suppression

    • Capacity increase

    • Data rate increase using multiple transmit/receive antennas (MIMO)

  • Radio resource management techniques (using cellular techniques in WLANs):

    • Dynamic packet assignment

    • Power control

    • Adaptive coding/modulation/smart antennas

  • Modification of 802.11a/4G (a+) for one cellular/WLAN standard


Fourth generation cellular systems and smart antennas

SIGNAL

INTERFERENCE

BEAMFORMER WEIGHTS

INTERFERENCE

Smart Antennas

SIGNAL OUTPUT

  • Smart Antennas significantly improve performance:

  • Higher antenna gain with multipath mitigation (gain of M with M-fold diversity)  Range extension

  • Interference suppression (suppress M-1 interferers)  Quality and capacity improvement

  • With smart antennas at Tx/Rx  MIMO capacity increase(M-fold)


Fourth generation cellular systems and smart antennas

SIGNAL

SIGNAL

OUTPUT

INTERFERENCE

BEAMFORMER

WEIGHTS

BEAM

SELECT

SIGNAL

SIGNAL

OUTPUT

BEAMFORMER

INTERFERENCE

Smart Antennas for Cellular

  • Key enhancement technique to increase system capacity, extend coverage, and improve user experience in cellular (IS-136)

Uplink Adaptive Antenna

Downlink Switched Beam Antenna

In 1999, combining at base stations changed from MRC to MMSE for capacity increase


Multiple input multiple output mimo radio

Multiple-Input Multiple-Output (MIMO) Radio

  • With M transmit and M receive antennas, can provide M independent channels, to increase data rate M-fold with no increase in total transmit power (with sufficient multipath) – only an increase in DSP

    • Indoors – up to 150-fold increase in theory

    • Outdoors – 8-12-fold increase typical

  • AT&T measurements show 4x bit rates & capacity increase in all mobile & indoor/outdoor environments (4 Tx and 4 Rx antennas)

    • 216 Mbps 802.11a (4X 54 Mbps)

    • 1.5 Mbps EDGE

    • WCDMA


Fourth generation cellular systems and smart antennas

11.3 ft

Prototype Dual Antenna Handset

Rooftop Base Station Antennas

MIMO Channel Testing

MobileTransmitters

Test Bed Receivers with RooftopAntennas

W1

Tx

Rx

  • Perform timing recovery and symbol synchronization

  • Record 4x4 complex channel matrix

  • Evaluate capacity and channel correlation

W2

Rx

Tx

Rx

Tx

W3

Terminal Antennas on a Laptop

Rx

Tx

W4

Synchronous

test

sequences

LO

LO

Mobile Transmitters


Fourth generation cellular systems and smart antennas

DIVERSITY TYPES

  • Spatial: Separation – only ¼ wavelength needed at terminal

  • Polarization: Dual polarization (doubles number of antennas in one location

  • Pattern: Allows even closer than ¼ wavelength

  • 4 or more antennas on a PCMCIA card

  • 16 on a handset

  • Even more on a laptop


Fourth generation cellular systems and smart antennas

MIMO Antennas

Base Station Antennas

  • Antennas mounted on 60 foot tower on 5 story office building

  • Dual-polarized slant 45 1900 MHz sector antennas and fixed multibeam antenna with 4 - 30 beams

Laptop Prototype

  • 4 patch antennas at 1900 MHz separated by 3 inches (/2 wavelengths)

  • Laptop prototype made of brass with adjustable PCB lid


Fourth generation cellular systems and smart antennas

MIMO Field Test Results

  • Measured capacity distribution is close to the ideal for 4 transmit and 4 receive antennas


Fourth generation cellular systems and smart antennas

Smart

Antenna

Smart

Antenna

AP

AP

Smart Antennas for WLANs

Interference

Smart Antennas can significantly improve the performance of WLANs

  • TDD operation (only need smart antenna at access point or terminal for performance improvement in both directions)

  • Interference suppression  Improve system capacity and throughput

    • Supports aggressive frequency re-use for higher spectrum efficiency, robustness in the ISM band (microwave ovens, outdoor lights)

  • Higher antenna gain  Extend range (outdoor coverage)

  • Multipath diversity gain  Improve reliability

  • MIMO (multiple antennas at AP and laptop)  Increase data rates


Smart antennas

Smart Antennas

  • Adaptive MIMO

    • Adapt among:

      • antenna gain for range extension

      • interference suppression for capacity (with frequency reuse)

      • MIMO for data rate increase

  • With 4 antennas at access point and terminal, in 802.11a have the potential to provide up to 216 Mbps in 20 MHz bandwidth within the standard

  • In EDGE/GPRS, 4 antennas provide 4-fold data rate increase (to 1.5 Mbps in EDGE)

  • In WCDMA, BLAST techniques proposed by Lucent


Radio resource management

Radio Resource Management

  • Use cellular radio resource management techniques in WLANs: Adaptive coding/modulation, dynamic packet assignment, power control

    • Not available on market

      • Current system administrators and users unaware of capacity/coverage issues

      • Performance statistics generated in current WLANs, but interpretation difficult

    • Techniques:

      • Use software on controller PC for multiple access points to analyze data and control system

      • Power control to permit cell ‘breathing’ (for traffic spikes)

      • Dynamic AP channel assignment

    • Combination of radio resource management and smart antennas yields greater gains than sum of gains


Cell breathing in wlan systems

Cell Breathing in WLAN Systems

AP

AP

AP

AP

AP

AP

AP

AP

AP

AP

AP

AP

AP

AP

  • Measure traffic load for each access point

  • Shrink overloaded cell by reducing RF power

  • Expand others to cover abandoned areas


Adaptive channel assignment

Cochannel

interference

High traffic

load

Adaptive Channel Assignment

Initial Assignment

After one iteration

2

1

3

3

2

3

3

1

2

3

1

2

2

2

3

2

3

1

  • Assign channels to maximize capacity as traffic load changes


Standards evolution

$/Cell

$/Sub

$ 500,000

$ 1000

$ 100

$ 500

$ 100

$ 10

802.11a

5.5GHz Unlicensed

802.11b

2.4GHz Unlicensed

3G Wireless

~ 2GHz

Standards Evolution

Peak Data Rate

High performance/price

100 Mbps

10 Mbps

802.11a+

1 Mbps

BlueTooth

2.4GHz

100 kbps

High ubiquity and mobility

Range

10 feet

100 feet

1 mile

10 miles

60 mph

Mobile Speed

2 mph

10 mph

30 mph


Fourth generation cellular systems and smart antennas

3.2 ms

FFT

G

4 ms

52=48+4 tones

64 point FFT

Issues for 802.11a:

Data rate:

6, 9, 12, 18, 24, 36, 48, 54 Mbps

Modulation:

BPSK, QPSK, 16QAM, 64QAM

Coding rate:

1/2, 2/3, 3/4

Subcarriers:

52 - insufficient for high data rates in wide area

Pilots subcarriers:

4 - insufficient if number of subcarriers increased

FFT size:

64 - too small for number of carriers in crowded spectrum

4 ms - too short for efficient wide area operation

Symbol duration:

Guard interval:

800 ns - too short for wide area operation

Subcarrier spacing:

312.5 kHz - too large for narrow channels

Bandwidth:

16.56 MHz - too large for spectrum available

Channel spacing:

20 MHz

Carrier accuracy:

20 ppm - leads to too much carrier error

Carrier error @5.8GHz:

114 kHz - too much for narrower channel spacing,

even at 1.9 GHz


Fourth generation cellular systems and smart antennas

User data rates (Mbps):

BPSK

QPSK

QAM16

QAM64

R=1/2

1.66

3.33

6.66

R=2/3

13.33

R=3/4

2.5

5

10

15

204.8 ms

FFT

G

230.4 ms

832=768+64 tones

2048 point FFT

Changes for high-mobility operation:

Data rate:

1.66, 2.5, 3.33, 5, 6.66, 10, 13.33, 15 Mbps

Modulation:

BPSK, QPSK, 16QAM, 64QAM

Coding rate:

1/2, 2/3, 3/4

subcarriers:

832 = 52*16

Pilot subcarriers:

64 = 4*16

FFT size:

2048 = 64*32

230.4 ms = 3.2*64 + .8*32

Symbol duration:

25.6 ms = .8*32

Guard interval:

Subcarrier spacing:

4.833 kHz = 312.5/64

Bandwidth:

~5 MHz » 16.56/4

Channel spacing:

5 MHz » 20/4

Carrier accuracy:

.5 ppm for 5 GHz, 1 ppm for 2.4 GHz

Carrier error @5.8GHz:

2.9 kHz, 1.9 kHz @ 1.9 GHz


Fourth generation cellular systems and smart antennas

OFDM tradeoffs

DVB-T

2k mode

802.11a

4G

Data

rate

6, 9, 12, 18, 24,

36, 48, 54 Mb/s

2.56-8.96 Mb/s

4.98-31.67 Mb/s

Tone

modulation

BPSK, QPSK,

16QAM, 64QAM

QPSK, “16QAM,”

“64QAM”

QPSK,16QAM

Coding

rate

[1/2, 2/3, 3/4, 5/6,

7/8] + RS(204,88)

1/2, 2/3, 3/4

1/2, 2/3, 3/4, 7/8

Nt

52

640

1705

4 ms

200 ms

231-280 ms

tB

40 ms

7-56 ms

tB-tF

800 ns

ft

312.5 kHz

6.25 kHz

4.464 kHz

fB

16.56 MHz

4 MHz

7.6 MHz

fop

~5 GHz

~2 GHz

~500 MHz


Fourth generation cellular systems and smart antennas

Conclusions

  • We evolving toward our goal of universal high-speed wireless access, but technical challenges remain

  • These challenges can be overcome by the use of:

    • Smart antennas to reduce interference, extend range, increasedata rate, and improve quality, without standards changes

    • Radio resource management techniques, in combination with smart antennas – further enhanced by a standards evolution to 4G


  • Login