Dr IZHAR-UL-HAQ

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wireless local loop

• By
• Dr.Izhar-ul-Hq
• ICT, ISLAMABAD

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What is WLL

• WLL stands for Wireless Local Loop
• and it is basically the use of radio to provide
• a telephone connection to the home.
• It is sometimes called radio in the loop (RITL)
  or fixed-radio access (FRA).
• When WLL connects subscribers to the public
  switched telephone network (PSTN), radio signals
  are used as a substitute for copper for all or
  part of the connection between the subscriber and
  the switch. Included in this is cordless access
  systems, proprietary fixed radio access, and
  fixed cellular systems.

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Basic WLL communication system
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Copper versus Wireless The Cost of the Last Mile
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Overview

• Throughout the world of telecommunications
  professionals there has been a dramatic rise in
  interest in the WLL technology. In the late 20th
  century, industry analysts predicted that the
  global WLL market would reach millions of
  subscribers by the year 2000. An article in Red
  Herring magazine in 1997 predicted that, the
  WLL market is expected to grow from 563 million
  in 1996 to at least 6.3 billion in 2002. Much
  of this growth is occurring in emerging economies
  where half the world's population lacks plain old
  telephone service (POTS). Developing nations like
  China, India, Brazil, Russia, and Indonesia are
  looking to WLL technology as an efficient way to
  deploy POTS for millions of subscriberswithout
  the expense of burying tons of copper wire. Later
  on in this document the economics of WLL will
  further be delved into.

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• One of the best economic contributions WLL makes
  in developed economies is that it helps to unlock
  competition in the local loop, this enables new
  operators to bypass existing wireline networks to
  deliver POTS and data access. It will be shown
  throughout that the question isn't will the
  local loop go wireless?, but, when and where?.
  The aim of this Lecture is to discuss the history
  and basics of WLL, and look at the impact in
  Pakistan and the world. It will also examine the
  markets both past and present, and attempt to
  judge the future for this technology.

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History of WLL

• Wireless access first started to become a
  possibility in the 1950s and 1960s as simple
  radio technology reduced in price. For some
  remote communities in isolated parts of the
  country, the most effective manner of providing
  communication was to provide a radio, kept in a
  central part of the community. By the end of the
  1970s, communities linked by radio often had
  dedicated radio links to each house, the links
  connected into the switch such that they were
  used in the same manner as normal twisted-pair
  links. The widespread deployment of the cellular
  base station into switching sites helped with
  cost reduction. Similar access using
  point-to-point microwave links still continues to
  be widely used today.

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• During the reunification of West and East
  Germany, much funding was put into increasing the
  teledensity in East Germany. The installation of
  twisted-pair access throughout would have been a
  slow process. In the interim, cellular radio was
  seen to offer a stop-gap measure to provide rapid
  telecommunications capability. So in East Germany
  a number of cellular networks, based upon the
  analog Nordic Mobile Telephone (NMT) standard,
  were deployed in the 800 MHz frequency range. The
  key difference was that subscribers had fixed
  unit mounted to the sides of their houses to
  increase the signal strength and hence allow the
  networks to be constructed with larger cells for
  lower costs.
• Thus, we see the first WLL network was born.

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Historical Path

• Early 1950s.
• Single-channel VHF subscriber equipment was
  purchased from Motorola, but the maintenance
  costs were too high as a result of the valve
  technology used and the power consumption too
  high. The trial was discontinued and the
  subscribers were connected by wire

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Mid-1950s.

• Raytheon was given seed funds to develop 6 GHz
  band equipment, which would have a better
  reliability and a lower power consumption. The
  designers failed to achieve those goals and the
  system still proved too expensive

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Late 1950s.

• Some equipment capable of providing mobile
  service to rural communities was put on trial.
  Users were prepared to pay a premium for mobile
  use, but the system still proved to be too
  expensive in a fixed application for which users
  were not prepared to pay a premium.

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Early 1960s

• Systems able to operate on a number of radio
  channels were developed, eliminating the need for
  each user to share a specific channel and thus
  increase capacity. The general lack of channels
  and high cost, however, made these systems
  unattractive.

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Early 1970s.

• A Canadian manufacturer developed equipment
  operating at 150 MHz that proved successful in
  serving fixed subscribers on the Island of Lake
  Superior. The lack of frequencies in the band,
  however, precluded its widespread use.

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1970s Late.

• The radio equipment from several US
  manufacturers was linked to provide service to
  isolated Puerto Rican villages. The service was
  possible only because the geographical location
  allowed the use of additional channels, providing
  greater capacity than would have been possible
  elsewhere.

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Early 1980s.

• Communication satellites were examined for rural
  applications but were rejected as being too
  expensive.
• 1985. Trials of a point-to-multipoint radio
  system using digital modulation promised
  sufficient capacity and reliability to make WLL
  look promising.

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Four different flavours of WLL systems

• Cellular-based systems consisting of a
  network of base stations. The older systems are
  usually based on analogue technology, which is
  well proven and low-cost, but provides reduced
  speech quality, limited data capacity and low
  security. Examples include NMT 450/900, AMPS,
  TACS, N-AMPS. The newer digital systems offer
  better spectrum usage and are cost-effective for
  voice but are less standardised and still provide
  only limited fax/data throughput. Examples
  include GSM, DCS1800/PCS1900, IS-136/D-AMPS,
• IS-95 800/1900.

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• Cordless-based systems. These provide efficient
  spectrum usage in high densities but with limited
  range, making high infrastructure costs for
  smaller cell sizes.
• Examples include
• DECT, CT-2, PHS.

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• Proprietary systems. These are usually
  custom-designed for the application and provide
  high quality voice and data services, and other
  enhanced services. While many of these systems
  provide superior service to the cordless and
  digital cellular standards, they must overcome
  the inertia created by the high installed base of
  the older technologies. These include FDMA, TDMA,
  CDMA systems, such as the products made by
  Qualcomm and Granger.

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• Satellite-based systems, as described above,
  are also proprietary and are mainly focussed on
  the mobile market, but fixed line access is also
  envisaged in a few years. These provide global
  coverage in virtually all environments, but
  currently have very high usage costs and there
  are still unresolved domestic control issues.
  Examples include Iridium and Globalstar.

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WLL encoding

• Safety
•         Security
•         Minimum of errors
•         Most efficient data transfer

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Speech encoding

• In digital radio systems it is necessary to
  turn voice signals, which analog into a digital
  data stream. Speech encoding is a highly complex
  topic and a full treatment is well beyond the
  bounds of this talk. The simplest speech encoders
  are essentially analog-to-digital converters. The
  analog speech waveform is sampled periodically,
  and the instantaneous voltage level associated
  with the speech is converted into a digital
  level. The two main parameters are how
  frequently the speech is sampled "sample rate"
  and how many different bits are used to describe
  the voltage level.

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Error-correction coding and interleaving

• Information transmitted via a radio channel
  is liable to be corrupted. Interference, fading
  and random noise cause errors to be received, the
  level of which depends on the severity of the
  interference. Error correction is widely deployed
  in mobile radio, where fast fading is almost
  universally present. It is less critical in WLL,
  where the LOS path results in less severe
  problems. Nevertheless it is still necessary,
  especially for computer data transfer.
  Error-correction systems work by adding
  redundancy to the transmitted signal. The
  receiver checks that the redundant data is as
  expected if it is not, the receiver can make
  error correction decisions. Error-correction
  methodologies fall into two categories, block
  coding or convolutional coding. Both are highly
  involved and mathematical and are beyond the
  scope of this talk.

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Ciphering

• Almost all modern radio systems rely on some
  form of ciphering to provide secure transmission.
  The use of such security techniques both
  reassures the user that the conversation cannot
  be overheard and allows the operator to
  authenticate the user. Most ciphering schemes are
  relatively straightforward. The base station and
  the subscriber unit agree on a "mask" on a
  call-by-call basis. To the covert listener, who
  does not know the mask, the data is
  incomprehensible.

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Multiple access

• WLL technologies have differed over the years
  in the multiple access technologies that they
  use. A decision about which technology to adopt
  will depend upon the application. Each operator
  has a given amount of radio spectrum to divide
  among its users. There are broadly three main
  ways to do this

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• Frequency Division Multiple Access (FDMA),
• in which the frequency is divided into a
  number of slots and each user access a particular
  slot for a length of a call
• Time Division Multiple Access (TDMA),
• in which each user access all the frequency
  but for only a short period of time
• Code Division Multiple Access (CDMA),
• in which each user access all the frequency
  for all the time but distinguishes the
  transmission through the use of a particular code
•  

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CDMA One of Multi-Access Technology
Time
CDMA
Code
User 3
User 2
TDMA
All users obtain service channel at the same time
and within the same frequency band
User 1
Time
Frequency
User 3
User 2
FDMA
User 1
Time
Service channels are allocated to different users
at different times, for example GSM
User 1
User 2
User 3
Frequency
Service Channels are allocated to different users
at different bands, for example TACS system
Frequency
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Overview What is CDMA?

• CDMA stands for "Code Division Multiple Access
• CDMA is a 3G-based technologies and can works in
  multi frequency band(450MHz, 800MHz, 1900MHz,
  2.1G) .CDMA includes a family of standards
  developed by 3GPP2 CDMA2000 1X, CDMA2000 1xEV-DO
  and CDMA2000 1xEV-DV.
• It is a popular technology and growing rapidly in
  both mobile and WLL environment Currently, Over
  212 Millions subscribers adopt CDMA technologies.

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What is CDMA450?
-----Multiple Working Frequency Band

• CDMA450 is a CDMA2000 system deployed in 450 MHz
• CDMA450 is the best choice for WLL with best
  coverage performance
• Massive CDMA450 Successful cases both in
  developing and developed country

F-Band Up link Down link
1 450MHz 450 457.5 460 467.5
2 800MHz 824 849 869 894
3 1900MHz 1850 1910 1930 1990
4 2100MHz 1920 1980 2110 2170
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CDMA System architecture introduce
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WLL Wireless Local Loop

• Wireless is now accepted as an alternative local
  loop technology and its use has increased
  dramatically by incumbents and new entrants
  throughout the world.
• WLL involves the final connection between the
  existing telecom infrastructure and a
  subscriber's home by wireless technologies rather
  than cable
• CDMA WLL technology, which is wireless based, is
  ideally suited for urban regions of Pakistan as
  well as congested rural areas where it is
  extremely difficult to lay the cables
• CDMA WLL an affordable alternative for wire line
  voice and internet access services

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Wireless Local Loop is booming

• In low telecom penetration countries, there is
  tremendous demand for new business and
  residential telephone service. More and more
  operators are looking to wireless technologies to
  rapidly provide thousands of new subscribers with
  high-quality telephone service at a reasonable
  price.
• Existing landline operators can extend their
  network with WLL
• Cellular operators can capitalize on their
  current network to deliver residential service
  with WLL
• New service providers can quickly deploy
  non-traditional WLL solutions to rapidly meet a
  community's telephony needs
• The unique features and benefits of CDMA make it
  an excellent technology choice for fixed
  wireless telephone systems.

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What Problems PTCL Meet for Seamless Coverage
Last mile access - Trouble in fixed network
C.O

• High investment
• Transmit cable expense
• Land rent
• Long deployment delays
• Cant meet increasing market
• No mobility

C.O
C.O
C.O
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Service provision Difficulty in rural areas
Convenient Telecom will stimulate Economy Fact
Low telecom penetration in Rural Area!

• Fixed Line
• High investment, Hard for maintenance
• Higher Density area is far away from C.O. or ONU
• Tough terrain Mountains, Rivers, Lakes,
  Deserts, Gobi and Grassland, etc.
• Lack of infrastructure transmission...
• Low productiveness
• Low population density with broad area
• Less traffic per user
• Maintenance cost might be higher than revenue
• Satellite Transmission
• High cost, unbearable for public

Subscribers Penetration
Fixed line 234,000 9.24
Rural 13,000 0.5
Mobile 279,000 10.54
Internet 33,000 1.3
(example Tibet rural service situation)
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WLL is The Best Solution

• Low investment
• Transmission in the air, no cable cost
• few infrastructure expense
• Quick deployment
• attract more sub., especially high-end sub.
• Flexible network, easy adjustment
• Meet the need of increasing market
• Wide coverage, attract new sub.
• Remote area
• Provide limited mobility

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CDMA450 WLL, an Excellent but Affordable Offering

• 450MHz has the best radio propagation for broader
  coverage Lower frequencies are the key to
  reducing cost
• Especially suitable for broad, low-density
  coverage, due to long-range propagation ( up to
  30 km )
• Excellent ability to provide urban coverage due
  to good line of sight propagation
  characteristics
• CDMA450 system is a cost-effective 3G solution
• CDMA2000 1X, up to 153.6kbps data rate ( in
  average of 80 Kbps ),
• CDMA2000 1xEV-DO, up to 2.4 Mbps data rate ( in
  average of 800 Kbps )
• Lower infrastructure cost results from broad
  coverage
• Low initial investment, then scale capital
  investment with the subscriber growth
• The 450 MHz range has multiple bands available in
  many countries

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CDMA450 Better choice for Broadband Access

• It is particularly significant in rural areas
  where currently Internet access is slow dial-up
• Remote education, telemedicine, agricultural and
  industrial support and government services are
  always accompanied by high data speed internet
  access requirements
• CDMA450 is prettily suitable for broad coverage
  with lower cost vs. other expensive data access
  solutions
• Enjoy roaming and always on service
• Excellent feature of urban better coverage,
  results from the better radio propagation
• Today 153 Kbps peak value of high-speed data
  service available, in average of around 70 Kbps,
  and late in EV-DO, provide 2.4 Mbps peak data
  rates service, in average of 800 Kbps

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Summary of CDMA WLL Feature

• Frequency
• multiple choice 450M, 800M and 1900M
• Maturity
• widely application, more than 250 M subs over the
  world
• Cost
• The lowest cost per sub
• broad coverage(30km for 450Mhz)
• high integration
• high spectral efficiency
• Capacity
• 1 CDMA frequency bandwidth 4 time GSM /4 time
  Analog /20 time DECT / 30 time PHS
• Service
• max. Data rate 153.6kbps,
• Voice service, circuit data service, packet
  service
• Evolution
• evolve to 1xEV- DO or 1xEV-DV smoothly

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System Feature Larger Coverage, Lower Cost
k subs
6
CDMA450 conventional coverage
CDMA450 extended coverage
5
4
Voice Capacity in 5MHz
GSM with high efficiency technology
3
WCDMA2100
2
GSM conventional coverage
GSM extended coverage
1
0
10km
1km
30km
Coverage
450MHz has the best radio propagation
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System feature Multiple Transmission Modes

• E1/T1
• Optical fiber
• HDSL
• Microwave
• Satellite

Satellite
BSC/PCF
E1/T1
SDH622/
iSiteC
HDSL
SDH2.5G
Softsite
Optical fiber
Microwave
Softsite
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Projected WLL Subscribers by Region
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CDMA popular technologies in world
CDMA surpasses 212 Million global subscribers
SOURCE WWW.CDG.ORG
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subscribers in Asia Pacific and North America
Asia Pacific CDMA Subscriber Growth
HistoryDecember 1997 through June 2004 Percent
of total 41.8 Percent growth41 by year
SOURCE WWW.CDG.ORG
North America CDMA Subscriber Growth
HistoryDecember 1997 through June 2004 Percent
of total40.3 Percent growth 18 by year
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CDMA Worldwide Subscriber Growth Analysis
SOURCE WWW.CDG.ORG
One Year Period June 2003 through June 2004and
Second Quarter 2004 April, May, June
    Worldwide Growth Worldwide Growth Worldwide Growth Worldwide Growth
    One Year One Year 2nd Quarter 2004 2nd Quarter 2004
Region Jun-04 Subscribers Jun 03 - Jun 04 Percent Growth Mar 04- Jun 04 Percent Growth
Asia Pacific 88,800,000 25,710,000 41 4,400,000 5
North America 85,600,000 16,725,000 24 4,200,000 5
Caribbean Latin America 34,800,000 5,250,000 18 1,800,000 5
Europe, Middle East Africa 3,320,000 740,000 29 70,000 2
Total 212,520,000 48,425,000 30 10,470,000 5
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CDMA 450 worldwide deployment
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EVOLUTION OF CDMA2000

• IT EMERGED FROM EIA/TIA IS-95 STANDARD
• IMPROVED UPON REVERSE LINK
• INTRODUCED ADVANCED VOCODING SERVICES
• IMPROVED POWER CONTROL FUNCTIONS

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TECHNICAL SUPERIORITY OF CDMA

• LINE OF SIGHT IS NOT REQUIRED AS IN HIGHER
  FREQUENCY SYSTEMS
• RANGE OF TRANSMISSION IS HIGHER THAN DECT/PHS
  SYSTEMS
• BETTER COVERAGE, CAPACITY AND HIGHER DATA RATE
  AVAILABLE COMPARED TO AMPS, GSM ETC
• LOWER PRICE COMPARED TO PROPERIETSRY SYSTEMS

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COMPETETIVE ADVANTAGE

• GREATER SPECTRAL EFFICIENCY-MORE THAN 35 USERS
  PER SECTOR PER 1.25MHz
• SUPERIOR VOICE QUALITY-13 Kbps QCELP, 8 Kbps
  QCELP, EVRC, SMV
• FEWER DROPPED CALLS-SOFT AND SOFTER HAND-OFF,
  CELL BREATHING
• LOWER TRANSMISSION POWER-LONGER BATTERY LIFE-TIME
• HIGHER DATA THROUGHPUT RATES-153 Kbps with
  release 0, 307.2Kbps with Release A
• ENHANCED GLOBAL ROAMING CAPABILITY-MULTI-BAND,MULT
  I-MODE HANDSETS AVAILABLE
• INHERRENT VOICE SECURITY-241 LENGTH PN SEQUENCE
• DATA INTEGRITY-ADVANCED ENCRYPTION TECHNIQUES

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COVERAGE ADVANTAGE

• 450 AND 800 MHz SYSTEMS OFFER MORE COVERAGE
• IN TRADITIONAL TDMA SYSTEMS SYNCHRONIZATION
  BETWEEN BTS AND SUBSCRIBER TERMINAL ARRISE BUT IN
  CDMA SYSTEMS..

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VOICE CAPACITY ADVANTAGES

• MORE THAN 45 ERLANGS OF VOICE CAPACITY PER SECTOR
  PER 1.25MHz CARRIER
• 3-5 TIMES MORE CAPACITY THAN THAT OFFERED BY GSM
• DOUBLE THAT OF IS-95

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VOICE CAPACITY ADVANTAGES
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DATA CAPACITY ADVANTAGES

• SYSTEMS WITH FREQUENCIES HIGHER THAN 2.4 GHz
  REQUIRE MORE COSTLY INFRASTRUCTURE AND CUSTOMER
  PREMISES EQUIPMENT
• DECT AND PHS HAVE TO SACRIFY VOICE FOR 64-128
  Kbps DATA RATES

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DATA CAPACITY ADVANTAGES
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DATA CAPACITY ADVANTAGES
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3-G SERVICES

• COLOURED LCD PHONE AND FIXED WIRELESS DEVICES
  AVAILABLE
• CAMERA PHONES
• CAMCORDER PHONES
• VoD PHONES
• GPS PHONES
• PUSH TO TALK PHONES
• MULTIMESDIA DEVICES FOR FULL TO LIMITED MOBILITY
• SYNTHESIZED SOUNDS
• MP3
• USB CONNECTIVITY
• SMS, EMS AND MMS
• INTERNET BROWSING

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HANDSET/FWT AVAILABILITY

• FWTs MADE BY AUDIOVOX, AXESSTEL, HUAWEI,
  HYUNDAI-KURITEL, MOTOROLLA, LG etc
  etc.

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Handset

• Model similar to mobile phones viz. Huawei
  ETS388

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FWT

• Model similar to regular phone Huawei ETS2000

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THANK YOU
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WLL Technologies by Market Segment