Wireless local loop 26 june

26 June 2007 Dr IZHAR-UL-HAQCIIT, Islamabad


wireless local loop

By

Dr.Izhar-ul-Hq

ICT, ISLAMABAD


What is WLL WLL stands for Wireless Local Loop

and it is basically the use of radio to providea 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.


Basic WLL communication system


Copper versus Wireless: The Cost of the Last Mile


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 subscribers—without the expense of burying tons of copper wire. Later on in this document the economics of WLL will further be delved into.


• 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.


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.


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.


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


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


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.


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.


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.


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.


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.


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.


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.


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.


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.


WLL encoding

• Safety

• Security

• Minimum of errors

• Most efficient data transfer


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.


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.


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.


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


• 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


CDMA: One of Multi-Access TechnologyCDMA: One of Multi-Access Technology

User 1 User 2 User 3

User 1

User 2

User 3

Time

Frequency

Time

Time

Frequency

Frequency

Code

Service Channels are allocated to different users at different bands, for example: TACS system

Service channels are allocated to different users at different times, for example: GSM

All users obtain service channel at the same time and within the same frequency bandFDMA

TDMA

CDMA

User 3

User 2

User 1


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.

Overview: What is CDMA?Overview: What is CDMA?


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

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

2.1GHz800MHz450MHz 800MHz 1900MHz 2100MHz


CDMA System architecture introduceCDMA System architecture introduce

MSC/VLR

Mobile IN SMSC/MMSC

GMSCPDSN/FA

HA

AAA/AN-AAA

OMC

Data ServicePlatform

HLR

Internet

BSC/PCF/IWF

iSite/SoftSite

IndoorMacro BTS

SoftSite

PSTN

SoftSite

Fixed TerminalHandset

OutdoorMacro BTS

Packet domain ArchitectureCircuit domain Architecture


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

WLL: Wireless Local Loop WLL: Wireless Local Loop


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.

Wireless Local Loop is booming Wireless Local Loop is booming


What Problems PTCL Meet for Seamless CoverageWhat Problems PTCL Meet for Seamless Coverage

C.O

C.O

C.O

C.O

High investment•Transmit cable expense•Land rent

Long deployment delays•Can’t meet increasing market

No mobility

Last mile access - Trouble in fixed networkLast mile access - Trouble in fixed network


• 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）

Service provision Difficulty in rural areasService provision Difficulty in rural areas

Convenient Telecom will stimulate Economy

Fact: Low telecom penetration in Rural Area!


WLL is The Best SolutionWLL is The Best Solution

BTS2

BTS1

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


CDMA450 WLL, an Excellent but Affordable OfferingCDMA450 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


CDMA450: Better choice for Broadband AccessCDMA450: 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;


Summary of CDMA WLL FeatureSummary of CDMA WLL Feature

Frequencymultiple choice: 450M, 800M and 1900M

Maturitywidely application, more than 250 M subs over the world

CostThe lowest cost per subbroad coverage(30km for 450Mhz)high integrationhigh spectral efficiency

Capacity1 CDMA frequency bandwidth = 4 time GSM /4 time Analog /20

time DECT / 30 time PHSService:

max. Data rate 153.6kbps, Voice service, circuit data service, packet service

Evolutionevolve to 1xEV- DO or 1xEV-DV smoothly


System Feature: Larger Coverage, Lower CostSystem Feature: Larger Coverage, Lower Cost

GSM conventional coverage GSM extended coverage

GSM with high efficiency technology

CDMA450 conventional coverage CDMA450 extended coverage

10km 30kmCoverage

Voi

ce C

apac

ity

in 5

MH

z

01

2345

6

k subs

1km

Cell radius (km) Cell area (km2) Relative Cell Count

450 48.9 7521 1

850950

29.4 2712 2.8

26.9 2269 3.3

1800 14.0 618 12.2

13.3 553 13.6

2100 12.0 449 16.2

Frequency(MHz)

1900

450MHz has the best radio propagation

WC

DM

A21

00


System feature: System feature: Multiple Transmission ModesMultiple Transmission Modes

BSC/PCF

E1/T1

Satellite

iSiteCSDH622/

SDH2.5G

Softsite

Softsite

Optical fiber

HDSL

Microwave

E1/T1

Optical fiber

HDSL

Microwave

Satellite


Projected WLL Subscribers by Region


CDMA: popular technologies in worldCDMA: popular technologies in world

CDMA surpasses 212 Million global subscribers

SOURCE: WWW.CDG.ORG


Asia Pacific CDMA Subscriber Growth History:December 1997 through June 2004Percent of total: 41.8%Percent growth:41% by year

Asia Pacific CDMA Subscriber Growth History:December 1997 through June 2004Percent of total: 41.8%Percent growth:41% by year

North America CDMA Subscriber Growth History:December 1997 through June 2004Percent of total:40.3%Percent growth: 18% by year

North America CDMA Subscriber Growth History:December 1997 through June 2004Percent of total:40.3%Percent growth: 18% by year

subscribers in Asia Pacific and North America subscribers in Asia Pacific and North America

SOURCE: WWW.CDG.ORG


One Year Period June 2003 through June 2004and Second Quarter 2004: April, May, June

Worldwide Growth

One Year 2nd Quarter 2004

Region Jun-04 SubscribersJun 03 - Jun

04Percent 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%

CDMA Worldwide Subscriber Growth Analysis:CDMA Worldwide Subscriber Growth Analysis:

SOURCE: WWW.CDG.ORG


CDMA 450 worldwide deployment CDMA 450 worldwide deployment


EVOLUTION OF CDMA2000

• IT EMERGED FROM EIA/TIA IS-95 STANDARD

• IMPROVED UPON REVERSE LINK

• INTRODUCED ADVANCED VOCODING SERVICES

• IMPROVED POWER CONTROL FUNCTIONS


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


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,MULTI-MODE HANDSETS AVAILABLE• INHERRENT VOICE SECURITY-2^41 LENGTH PN SEQUENCE• DATA INTEGRITY-ADVANCED ENCRYPTION TECHNIQUES


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……..


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


VOICE CAPACITY ADVANTAGES


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






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


HANDSET/FWT AVAILABILITY

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


Handset

– Model similar to mobile phones viz. Huawei ETS388


FWT

–Model similar to regular phone Huawei ETS2000





WLL Technologies by Market Segment

Documents

Wireless local loop 26 june