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Wireless Local Loop (WLL). By: Panos Tzanos Vladimeros Vladimerou Derek Starr. Presentation Outline. What is WLL? Differences with mobile cellular systems Why WLL? System Analysis examples The future of WLL. Definition. What is WLL?

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wireless local loop wll
Wireless Local Loop (WLL)

By:

Panos Tzanos

Vladimeros Vladimerou

Derek Starr

presentation outline
Presentation Outline
  • What is WLL?
  • Differences with mobile cellular systems
    • Why WLL?
  • System Analysis
    • examples
  • The future of WLL
definition
Definition
  • What is WLL?

- WLL is a system that connects subscribers to the local telephone station wirelessly.

  • Systems WLL is based on:
    • Cellular
    • Satellite (specific and adjunct)
    • Microcellular
  • Other names
    • Radio In The Loop (RITL)
    • Fixed-Radio Access (FRA).
wll services
WLL services
  • Desirable:
    • Wireless feature should be transparent
    • Wireline Custom features
  • Other:
    • Business related
      • Hunt groups,
      • Call transfers
      • Conference calling
    • Calling cards, coin phones
    • V.29 (9600bps)
    • ISDN (64kbps)
wll should provide
WLL should provide…
  • Toll-quality service
  • Expand from a central office to about 5 miles
  • Low license cost
  • Subscriber costs equivalent or better than copper
ideas for u s market
Ideas for U.S. market
  • Supplement Copper Lines
    • Easier third telephone line
    • Data service
  • Fixed Mobile Users
    • Take phone wherever you want / charged on 2 levels
    • “home” could mean neighborhood
    • Charged regular mobile rate if you’re on the road
cost considerations
Cost Considerations
  • Wireless cost is constant over distance for WLL
  • Wireline depends on distance AND terrain
situations made for wll
Situations “made” for WLL
  • Environments where 3rd line is degraded might be cheaper to go wireless
  • Where it’s impossible to lay copper (3rd world, small islands)
  • Business parks, industrial areas
  • Speedy deployment, stop gap application till wireline is in
    • 90-120 days for activation
developed vs developing
Developed vs. Developing
  • Developed: Wireline service
    • Firmly established, cellular penetration is relatively high
    • Incumbent operator would use it to install 2nd, 3rd lines, coverage to rural areas
    • 2nd or 3rd competitive operator deploy it for fast & cost effective deployment
    • Quick way to establish market presence
    • cellular complement to their offerings
developed vs developing11
Developed vs. Developing
  • Developing
    • Quick & easy to deploy in countries with little copper line service, so as to accommodate people on enormous waiting lists for basic service
    • Low maintenance costs
    • Allows more competition in provider market
examples
Examples
  • UK
    • 150 PTOs have licenses for wireless
    • Focus on regional networks
    • WLL Commercial services
      • Ionica, Atlantic Telecom, Scottish Telecom
  • Poland
    • Most exciting market in eastern Europe
    • Local loop is the bottleneck
    • 150,000 WLL lines since 1996 (15% of new)
    • Ericsson, Motorola contracts
connection setup
Connection Setup

UWLL

WANU

WASU

Transceiver

Air

Interface

TWLL

Trunk

WLL

Controller

AM

HLR

PSTN

Switch

function

  • Wireless Access Network Unit(WANU)
    • Interface between underlying telephone network and wireless link
    • consists of
      • Base Station Transceivers (BTS)
      • Radio Controller(RPCU)
      • Access Manager(AM)
      • Home Location Register(HLR)

Wireless Access Subscriber Unit(WASU)

  • located at the subscriber
  • translates wireless link into a traditional telephone connection
important results of fixed to fixed propagation in wlls
Important Results of Fixed to Fixed Propagation in WLLs
  • Signal channel is not a Rayleigh fading channel:
    • Power control algorithms are simpler and can be utilized more effectively
  • Channel Randomness is lost:
    • Makes analysis difficult
  • Pathloss exponent is considerably smaller (Why?):
    • 20dB/dec compared to 40dB/dec
    • Decreases cell capacity
    • Allows for larger coverage area
fixed to fixed propagation cont d
Fixed to Fixed Propagation(cont’d)
  • No handoffs necessary:
    • Decreases hardware costs and system complexity
    • Increases quality of service through accurate traffic predictions
  • Allows usage of directional antennas:
    • Can greatly reduce interference and increase cell capacity

30dB

10dB

-30dB

-40dB

0o

60o

0o

120o

180o

BS antenna

Subscriber antenna

in cell interference cdma
In-Cell Interference (CDMA)
  • I = (Nh – 1)aS  NhaS

a = voice activity factor

Nh = total # of houses

S = power received at cell site from every house

out of cell interference
Out-of-Cell Interference
  • Pathloss: 20dB/dec as opposed to 40dB/dec

 need to take in account more tiers

  • Only from houses whose antennas are directed at the center cell base station
interference from another cell
Interference from Another Cell
  • Blue area is region of interferers for C
  • It is Not a perfect pie shape
  • If w = (1/2)*(antenna width)

(in radians)

  • W = w+2sin-1((R/D)sin(w/2))
  • If w<<1 and R<<D:

W = w (1+(R/D))

is the “pie” arc length

per tier interference
Per-Tier Interference
  • Integration over W and all the cells at tier n yields:

In = [aNhSw/(3sqrt(3))][1/n]

for n>4

  • Interference is proportional to antenna width w and inversely proportional to the tier number.
  • Decreasing the antenna width can greatly reduce interference.
  • As the number of tiers approaches infinity, so does the total interference. Therefore, system capacity is a function of the total number of tiers in the system.
examples of services provided
Examples of services provided
  • Marconi WipLL (wireless IP local loop)
    • Based on Frequency hopping CDMA
    • Internet Protocol 64kbps to 2.4Mbps rates Committed Information Rate or best effort service
  • Lucent WSS (wireless subscriber system)
    • 800 to 5000 subscribers per switch
    • Uses FDMA/FDD 12 Km to 40Km coverage
  • GoodWin WLL
    • DECT standards
    • 9.6 kbps rate
    • Specified conditions -5°С...+55°С, 20...75% humidity
future of wll overview
Future of WLL / Overview
  • Depends on
    • economic development
    • existing infrastructure of a region
  • Offers
    • market competition
    • quick deployment
    • relatively reliable service at low costs
forecasts
Forecasts

800M projected new lines by 2002

685M in developing countries

questions
Questions?

Basie station

references
References

http://www.tenet.res.in/Papers/wll/iete1.html

http://bicsi.org/Wireless2/index.htm

http://sss-mag.com/wlltutor.html

http://www.cdg.org/

http://www.voicendata.com/may98/will.html

http://www.cdg.org/tech/wll.asp

http://www.motorola.com/NSS/Press/press_archive_1997/19970826a.html

http://www.mobilemark.com/WLL_antennas.html

http://www.atdi.co.uk/t_wll.htm

http://www.lucent.com/wireless/

http://www.art-telecom.fr/communiques/pressrelease/98-13a.htm

http://www.fcr.fr/en/savoirfaire/blr.htm

http://www.citi.columbia.edu/wireless/col_1096.htm

http://www.telecomresearch.com/tutorials.html

http://www.kyocera.co.jp/frame/product/telecom/english/wll/index.htm

http://www.americasnetwork.com/issues/96issues/961101/110196_wll.html

http://208.220.133.42/issues/199803/tci/bout.html

references27
References

http://www.smartrunk.com/WLL/SSIWLL.html

http://www.amd.pl/products/cpd/prodover/wllsol.html

http://www.biz.uiowa.edu/class/6K251_park/Student-Reports/ymao/index.html

http://ieeexplore.ieee.org/iel3/5002/13722/00632520.pdf

http://www.ece.queensu.ca/dept/vpoor.pdf

http://www.mprg.ee.vt.edu/tech_xfer/ppt/EmergingTechnology.pdf

http://www.carlsontech.com/manual15.html

http://www.corporateinformation.com/data/statusa/china/chinavsat.html

http://www.hindubusinessline.com/2001/01/09/stories/14096802.htm

http://www.tradeport.org/ts/countries/brazil/mrr/mark0115.html

http://www.atdi.com/99/p_wll.htm

http://www.marconi.com/html/news/libertywlltrials.htm

http://citeseer.nj.nec.com/359563.html

http://www.corporateinformation.com

http://www.stanford.edu/class/ee359/

http://www.alcatel.com/telecom/asd/products/groups/access/wireless/wllacc1.htm

http://www.goodwin.ru:8086/products/wll/

http://www.goodwin.ru:8086/dect.html (DECT standard)

references28
References

Wideband CDMA personal communications system featuring IDSN compatibility

Reed Fisher, Henri Suyderhoud, Toshiro Kato, Atushi Fukasawa and Takuro Sato

©1997 IEEE

Performance Analysis of WCDMA WLL Protocol

Seong Won Shum, Sang Hwan Lee, Minsoo Suk, Hang Gu Bahk

Hyundai Electronics ICCT’98 Beijing, China

Capacity of a Wireless Local Loop Network based on GSM

Thomas Klingenbrunn, Preben Mogensen

Center for Person Kommukation, Aalborg University

© 1998 IEEE

Network Management Applications for wireless local loop

Jelena Vucetic Paul Kline

Dynamic Telecomminications, Inc. 1998

references29
References

Implementation of code acquisition and code tracking loop for CDMA wireless local

loop system

Jae-Wook Chung, Jin-Su Kim, Young-Gyun Jeong, Jeong-Suk Ha

Electronics and Telecommincations Research Institute, Yusong, Taejon, Korea

©1998 IEEE

Implementation of Base Station Receiver for CDMA Wireless Local Loop System

Jae W. Chung, Jin S. Kim, Y. G. Jeong, J. S. Ha

Electronics and Telecommincations Research Institute, Yusong, Taejon, Korea

©1997 IEEE

Wireless Local Loop – Propagation Environment Measurements and analysis

Levin M., Katz E., Gil A., Freedman A., Matityahu I., Dilmon D.

Wireless Systems Tadiran Telecommunications, Israel

1996 IEEE

Issues and challenges of implementing a wireless local loop based telephone

access network

T.Minero, T. Babji NEC cororation, JAPAN

© 1997 IEEE

references30
References

Wireless local loop: why the slow take up?

Andrian May, Electronics Communication Engineering Journal 1998

A Wideband CDMA based Wireless Local Loop Protocol

Mehmet Ulema and Young Ki Yoon

Daewoo Telecom R&D Center © 1999 IEEE

An Implementation of Wireless Local Loop fixed Station

Sang Sik Lim, Mobile Telecommunication Division

Electronics and Telecommunications Research Institute, Taejon, Korea

© 1998 IEEE

A comparison of wireless local loop with competing access technologies

W. Webb, Electronics & Communication Engineering Journal 1998

Estimate of Uplink in Overlaid Macrocell/Multi-Microcell CDMA WLL Systems

J. S. Roh, S. Y. Kim, S. J. Cho, S. C. Son, S. E. Cho H. J. Kang

references31
References

Wireless Local Loop Made For the USA?

David Kopf, Peter Meade, America’s Network November 1996

The Performance of DS-CDMA For Wireless Local Loop

Q. Bi, D.R. Pulley

1996 IEEE

Wireless Local Loop: Architecture, Technologies and Services

Anthony R. Noeprel, Hughes Network Systems, Yi-Bing Lin

CSIE/NCTU 1998 IEEE