Advanced Mobile Phone System or AMPS is the Analog Mobile Phone System Standard

8/3/2019 Advanced Mobile Phone System or AMPS is the Analog Mobile Phone System Standard

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Cellular Mobile Communication Technologies

A cellphone is a mobile electronic telecommunications device that use radio waves to allow

people the communicate dialing and receiving phone calls trough a wireless cellular network.

The cellular network interconnected to the public phone system and is based on several telecomcells, called base station (cell sites) where the phones can connect. The cell bases have a tower

with antennas with a zone of coverage (usually from 0.8 to 13 kilometres), and the mobilephones connect to the nearest base to make and receive calls. In a cellular network, cells aregenerally organized in groups of seven to form a cluster. There is a cell site or base station

at the centre of each cell, which houses the transmitter/receiver antennae and switching

equipment. The size of a cell depends on the density of subscribers in an area: for instance, in adensely populated area, the capacity of the network can be improved by reducing the size of a

cell or by adding more overlapping cells. This increases the number of channels available

without increasing the actual number of frequencies being used. All base stations of each cell

are connected to a central point, called the Mobile Switching Office (MSO), either by fixed linesor microwave. The MSO is generally connected to the PSTN (Public Switched Telephone

Network): Cellular technology allows the hand-off of subscribers from one cell to another as

they travel around. This is the key feature which allows the mobility of users. A computerconstantly tracks mobile subscribers of units within a cell, and when a user reaches the border of

a call, the computer automatically hands-off the call and the call is assigned a new channel in a

different cell.

International roaming arrangements govern the subscribers ability to make and receive calls the

home networks coverage area.

Mobile Phone Generations

Mobile phone development over the last twenty years is commonly split into generations.

0G0G refers to pre-cellphone mobile telephony technology, such as radio telephones that some had

in cars before the advent of cellphones.

One such technology is the Autoradiopuhelin (ARP) launched in 1971 in Finland as the country's

first public commercial mobile phone network.

1G1G (or 1-G) is short for first-generation wireless telephone technology, cellphones. These are the

analog cellphone standards that were introduced in the 80's and continued until being replaced by2G digital cellphones.

One such standard is NMT (Nordic Mobile Telephone), used in Nordic countries, Eastern

Europe and Russia. Another is AMPS (Advanced Mobile Phone System) used in the United

States.

Anticedant to 1G technology is the mobile radio telephone, or 0G.
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UMTS (Universal Mobile Telephone System), based on W-CDMA technology, is the solution

generally preferred by countries that used GSM, centered in Europe. UMTS is managed by the3GPP organization also responsible for GSM, GPRS and EDGE.

FOMA, launched by Japan's NTT DoCoMo in 2001, is generally regarded as the world's firstcommercial 3G service. However, while based on W-CDMA, it is not generally compatible with

UMTS (although there are steps currently under way to remedy the situation).

CDMA2000The other significant 3G standard is CDMA2000, which is an outgrowth of the earlier 2G

CDMA standard IS-95. CDMA2000's primary proponents are outside the GSM zone in the

Americas, Japan and Korea. CDMA2000 is managed by 3GPP2, which is separate andindependent from UMTS's 3GPP.

TD-SCDMAA less well known standard is TD-SCDMA which is being developed in the People's Republic ofChina by the companies Datang and Siemens. They are predicting an operational system for

2005.

AMPS

Advanced Mobile Phone System or AMPS is the analog mobile phone system standard,introduced in the Americas during the early 1980s. Though analog is no longer considered

advanced at all, the relatively seamless cellular switching technology AMPS introduced was

what made the original mobile radiotelephone practical, and was considered quite advanced at

the time.

TechnologyIt was a first-generation technology, using FDMA which meant each cell site would transmit ondifferent frequencies, allowing many cell sites to be build near each other. However it had thedisadvantage that each site did not have much capacity for carrying calls. It also had a poor

security system which allowed people to steal a phone's serial code to use for making illegal

calls. It was later replaced by the newer Digital TDMA system which brought improved securityas well as increased capacity.

Frequency bandsFor each market area, there were to be two licensee (networks). Each network is authorized touse 416 channels in the 800 MHz band. Each channel is composed of 2 frequencies. 416 of these

are in the 824~849 MHz range for transmissions from mobile stations to the base stations, paired

with 416 frequencies in the 869~894 MHz range for transmissions from base stations to themobile stations. Each cell site will use a subset of these channels, and must use a different set

than neighboring cells to avoid interference. This significantly reduces the number of channels

available at each site in real-world systems. Each AMPS frequency is 30kHz wide.

The AMPS band was taken from the same 806~890 MHz frequency band which was originally

UHF TV channels 70~83. This meant that these UHF channels could not be used for UHF TV

transmission as these frequencies were to be used for AMPS transmission.


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Introduction of digital TDMALater, many AMPS networks were partially converted to what became (incorrectly) known asTDMA, a digital, TDMA, based 2G standard used mainly by Cingular Wireless (who has

purchased AT&T Wireless in October 2004) and US Cellular. TDMA networks were backward

compatiable with AMPS. The mis-use of the term TDMA (which is a type of channel sharingscheme) to refer to a particular access protocol has caused some confusion. The first version of

the TDMA standard was known as IS-54 and was supplanted by IS-136.

Introduction of GSM and CDMAAMPS and TDMA are now being phased out in favor of either CDMA and GSM which allow

for higher capacity data transfers which open for gateway services over WAP and i-mode,

Multimedia Messaging Services (MMS), and wireless Internet Access. The major differencebetween the two options is that many CDMA phones can fall-back on to AMPS networks if the

phone can not get a CDMA signal but can get a AMPS signal. CDMA phones can not use

TDMA, only AMPS. GSM phones, being designed by Europeans who had never intended that

GSM be used in America, do not normally support this feature. However there are some phonescapable of supporting AMPS, TDMA and GSM all in one phone. However AMPS/CDMA

phones supports seamless handoffs between CDMA and AMPS/TDMA while GSM phones cannot.

Analog system in EuropeTotal Access Communication System or TACS is the European version of AMPS. ETACS wasan extended version of TACS with more channels. TACS and ETACS are now obsolete in

Europe, having been replaced by the more scalable and all-digital GSM system.

Companies using AMPSTelecom New Zealand - Telecom customers are in the process of migrating over to the new

CDMA service. The old AMPS/D-AMPS system is due to be phased out in 2007. Since the

establishment of the AMPS service in 1987 the network had always had the largest coverage ofany network in New Zealand. However in recent times Digital GSM and CDMA coverage has

matured enough to match or exceed AMPS coverage in many areas.

Verizon Wireless - Although most Verizon customers use digital services, the backup AMPS

network is the largest in the United States.Bell Mobility, Telus Mobility and Rogers Wireless all operate AMPS networks in Canada,

though they have since been overlaid with digital services.


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GSM (Global System for Mobile Communications, originally Groupe Spcial Mobile)

GSM is a cellular network, which means that mobile phones connect to it by searching for cellsin the immediate vicinity. There are five different cell sizes in a GSM networkmacro,micro,

pico, femto and umbrella cells. The coverage area of each cell varies according to the

implementation environment. Macro cells can be regarded as cells where thebase stationantennais installed on a mast or a building above average roof top level. Micro cells are cells whose

antenna height is under average roof top level; they are typically used in urban areas. Picocells

are small cells whose coverage diameter is a few dozen metres; they are mainly used indoors.

Femtocells are cells designed for use in residential or small business environments and connectto the service providers network via a broadband internet connection. Umbrella cells are used to

cover shadowed regions of smaller cells and fill in gaps in coverage between those cells.

Cell horizontal radius varies depending on antenna height, antenna gain and propagationconditions from a couple of hundred meters to several tens of kilometres. The longest distance

the GSM specification supports in practical use is 35 kilometres (22 mi). There are also several

implementations of the concept of an extended cell,[7] where the cell radius could be double oreven more, depending on the antenna system, the type of terrain and the timing advance.

Indoor coverage is also supported by GSM and may be achieved by using an indoor picocell base

station, or an indoor repeaterwith distributed indoor antennas fed through power splitters, todeliver the radio signals from an antenna outdoors to the separate indoor distributed antenna

system. These are typically deployed when a lot of call capacity is needed indoors; for example,in shopping centers or airports. However, this is not a prerequisite, since indoor coverage is also

provided by in-building penetration of the radio signals from any nearby cell.The modulation used in GSM is Gaussian minimum-shift keying (GMSK), a kind of continuous-

phase frequency shift keying. In GMSK, the signal to be modulated onto the carrier is first

smoothed with a Gaussian low-pass filter prior to being fed to a frequency modulator, whichgreatly reduces the interference to neighboring channels (adjacent-channel interference).

GSM carrier frequenciesGSM networks operate in a number of different carrier frequency ranges (separated into GSM

frequency ranges for 2G and UMTS frequency bands for 3G), with most 2G GSM networksoperating in the 900 MHz or 1800 MHz bands. Where these bands were already allocated, the

850 MHz and 1900 MHz bands were used instead (for example in Canada and the UnitedStates). In rare cases the 400 and 450 MHz frequency bands are assigned in some countriesbecause they were previously used for first-generation systems.

Most 3G networks in Europe operate in the 2100 MHz frequency band.

Regardless of the frequency selected by an operator, it is divided into timeslots for individual

phones to use. This allows eight full-rate or sixteen half-rate speech channels per radiofrequency. These eight radio timeslots (or eight burst periods) are grouped into a TDMA frame.

Half rate channels use alternate frames in the same timeslot. The channel data rate for all 8

channels is 270.833 kbit/s, and the frame duration is 4.615 ms.The transmission power in the handset is limited to a maximum of 2 watts in GSM850/900 and 1

watt in GSM1800/1900.

General Packet Radio Service (GPRS)GPRS is a packet oriented Mobile Data Service available to users of the 2G cellular

communication systems Global System for Mobile Communications (GSM), as well as in the 3G

systems. In the 2G systems, GPRS provides data rates from 56 up to 114 kbit/s.

GPRS data transfer is typically charged per megabyte of traffic transferred, while data

communication via traditional circuit switching is billed per minute of connection time,independent of whether the user actually is using the capacity or is in an idle state. GPRS is a

best-effort packet switched service, as opposed to circuit switching, where a certain Quality of

Service (QoS) is guaranteed during the connection for non-mobile users.
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2G cellular systems combined with GPRS are often described as "2.5G", that is, a technologybetween the second (2G) and third (3G) generations of mobile telephony. It provides moderate

speed data transfer, by using unused Time division multiple access (TDMA) channels in, for

example, the GSM system. Originally there was some thought to extend GPRS to cover otherstandards, but instead those networks are being converted to use the GSM standard, so that GSM

is the only kind of network where GPRS is in use. GPRS is integrated into GSM Release 97 and

newer releases. It was originally standardized by European Telecommunications Standards

Institute (ETSI), but now by the 3rd Generation Partnership Project (3GPP).

A GPRS connection is established by reference to its Access Point Name (APN). The APN

defines the services such as Wireless Application Protocol (WAP) access, Short Message Service(SMS), Multimedia Messaging Service (MMS), and forInternet communication services such as

email and World Wide Web access.

Overview of GSM, GPRS, and UMTSGeneral Packet Radio

ServiceOverview of GSM, GPRS, and UMTSGeneral Packet Radio Service The general packet radiosystem (GPRS) provides packet radio access for mobile Global System for Mobile

Communications (GSM) and time-division multiple access (TDMA) users. In addition toproviding new services for today's mobile user, GPRS is important as a migration step towardthird-generation (3G) networks. GPRS allows network operators to implement an IP-based core

architecture for data applications, which will continue to be used and expanded for 3G services

for integrated voice and data applications. The GPRS specifications are written by the EuropeanTelecommunications Standard Institute (ETSI), the European counterpart of the American

National Standard Institute (ANSI).

GPRS is the first step toward an end-to-end wireless infrastructure and has the following goals:

Open architecture

Consistent IP servicesSame infrastructure for different air interfaces

Integrated telephony and Internet infrastructure

Leverage industry investment in IPService innovation independent of infrastructure

Benefits of GPRSThe GPRS provides the following benefits:

Overlays on the existing GSM network to provide high-speed data service

Always on, reducing the time spent setting up and taking down connections

Designed to support bursty applications such as e-mail, traffic telematics, telemetry, broadcastservices, and web browsing that do not require detected connection.

By implementing Cisco GPRS products and related solutions, mobile service providers can

optimize their networks to deploy high quality mobile voice and data services. They can also

benefit from new operating efficiencies, peer-to-peer IP-based architecture for scalability, and IPstandard interfaces to billing and customer support.

GPRS ApplicationsGPRS enables a variety of new and unique services to the mobile wireless subscriber. Thesemobile services have unique characteristics that provide enhanced value to customers. These
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alert the user on the device of their choice when messages are received.

Value Added Services

Value-added services refer to the content provided by network operators to increase the value of

services to their subscribers. Two terms that are frequently used to describe delivery of dataapplications arepush andpull, as defined below.

Push describes the transmission of data at a predetermined time or under predetermined

conditions. It also refers to the unsolicited supply of advertising (for example, delivery of newsas it occurs or stock values when they fall below a preset value).Pulldescribes the request for data in real time by the user (for example, checking stock quotes or

daily news headlines).To be valuable to subscribers, this content must possess several characteristics:

Personalized information that is tailored to the user (for example, a stock ticker that focusses onkey quotes and news or an e-commerce application that knows a user's profile)

Localized content that is based on a user's current location and includes maps, hotel finders, or

restaurant reviewsMenu screens that are intuitive and easy to navigate

Security for e-commerce sites for the exchange of financial or other personal informationSeveral value-added services are outlined in the following sections.

E-commerce

E-commerce is defined as business conducted on the Internet or data service. This includes

applications in which a contract is established for the purchase of goods and services and onlinebanking applications. These applications require user authentication and secure transmission of

sensitive data over the data connection.

Banking

The banking industry is interested in promoting electronic banking because electronic

transactions are less costly to conduct than personal transactions in a bank. Specific bankingfunctions that can be accomplished over a wireless connection include balance checking, moneytransfers between accounts, bill payment, and overdraft alert.

Financial TradingThe immediacy of transactions over the Internet and the requirement for up-to-the-minute

information has made the purchasing of stocks online a popular application. By coupling push

services with the ability to make secure transactions from the mobile terminal, a service that isunique to the mobile environment can be provided.

Location-Based Services and Telematics

Location-based services provide the ability to link push or pull information services with a user'slocation. Examples include hotel and restaurant finders, roadside assistance, and city-specific

news and information. This technology also has vertical applications. These allow, for example,

tracking vehicles in a fleet or managing the operations of a large workforce.

Vertical Applications

In the mobile environment, vertical applications apply to systems using mobile architectures to

support the specific tasks within a company. Examples of vertical applications include:

Sales supportConfiguring stock and product information for sales staff, integrating

appointment details, and placing orders remotelyDispatchingCommunicating job details such as location and scheduling and permitting


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information queries to support the job

Fleet managementControlling a fleet of delivery or service staff and vehicle, monitoring theirlocations, and scheduling their work

Parcel deliveryTracking the locations of packages for customers and monitoring the

performance of the delivery system

Advertising

Advertising services are offered as a push information service. Advertising may be offered to

customers to subsidize the cost of voice or other information services. Advertising may be

location sensitive. For example, a user entering a mall can receive advertisements specific to thestores in that mall.

GPRS ArchitectureGPRS is a data network that overlays a second-generation GSM network. This data overlay

network provides packet data transport at rates from 9.6 to 171 kbps. Additionally, multiple users

can share the same air-interface resources simultaneously.

GPRS attempts to reuse the existing GSM network elements as much as possible, but to

effectively build a packet-based mobile cellular network, some new network elements,interfaces, and protocols for handling packet traffic are required. Therefore, GPRS requires

modifications to numerous network elements as summarized

Enhanced Data rates for GSM Evolution (EDGE)Enhanced Data rates for GSM Evolution (EDGE), Enhanced GPRS (EGPRS), orIMTSingle Carrier (IMT-SC) is a backward-compatible digital mobile phone technology that

allows improved data transmission rates, as an extension on top of standard GSM. EDGE can beconsidered a 3G radio technology and is part ofITU's 3G definition,but is most frequently

referred to as 2.75G. EDGE was deployed on GSM networks beginning in 2003 initially by

Cingular(now AT&T) in the United States.

EDGE is standardized by 3GPP as part of the GSM family, and it is an upgrade that provides a

potential three-fold increase in capacity of GSM/GPRS networks. The specification achieveshigher data-rates by switching to more sophisticated methods of coding, within existing GSMtimeslots. Introducing 8PSKencoding, EDGE is capable of delivering higher bit-rates per radio

channel in good conditions.

EDGE can be used for anypacket switched application, such as an Internet connection. High-

speed data applications such as video services and other multimedia benefit from EGPRS'

increased data capacity. EDGE Circuit Switched is a possible future development[citation

needed].

Evolved EDGE was added in Release 7 of the 3GPP standard. This is a further extension on top

of EDGE, providing reduced latency and potential speeds of 1Mbit/s by using even morecomplex coding functions than the 8PSK originally introduced with EDGE.

Technology

EDGE/EGPRS is implemented as abolt-on enhancement for2G and 2.5G GSM and GPRSnetworks, making it easier for existing GSM carriers to upgrade to it. EDGE/EGPRS is a

superset to GPRS and can function on any network with GPRS deployed on it, provided the

carrier implements the necessary upgrade.

Although EDGE requires no hardware or software changes to be made in GSM core networks,

base stations must be modified. EDGE compatible transceiver units must be installed and the
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base station subsystem needs to be upgraded to support EDGE. If the operator already has this in

place, which is often the case today, the network can be upgraded to EDGE by activating anoptional software feature. Today EDGE is supported by all major chip vendors forGSM. New

mobile terminal hardware and software is also required to decode/encode the new modulation

and coding schemes and carry the higher user data rates to implement new services.

Transmission techniques

In addition to Gaussian minimum-shift keying (GMSK), EDGE uses higher-order PSK/8 phaseshift keying (8PSK) for the upper five of its nine modulation and coding schemes. EDGE

produces a 3-bit word for every change in carrier phase. This effectively triples the gross data

rate offered by GSM. EDGE, like GPRS, uses a rate adaptation algorithm that adapts themodulation and coding scheme (MCS) according to the quality of the radio channel, and thus the

bit rate and robustness of data transmission. It introduces a new technology not found in GPRS,

Incremental Redundancy, which, instead of retransmitting disturbed packets, sends moreredundancy information to be combined in the receiver. This increases the probability of correct

decoding.

EDGE can carry data speeds up to 236.8 kbit/s (with end-to-end latency of less than 150 ms) for

4 timeslots (theoretical maximum is 473.6 kbit/s for 8 timeslots) in packet mode. This means itcan handle four times as much traffic as standard GPRS. EDGE will therefore meets the

International Telecommunications Union's requirement for a 3G network, and has been acceptedby the ITU as part of the IMT-2000 family of3G standards. It also enhances the circuit data

mode called HSCSD, increasing the data rate of this service.

EGPRS modulation and coding scheme (MCS) In good radio conditions, EDGE can be four

times as efficient as GSM. GSM use four coding schemes (CS-1 to 4) while EDGE provides nine

Modulation and Coding Schemes (MCS-1 to 9).

Coding and modulation

scheme (MCS) Speed(kbit/s/slot) Modulation MCS-1 8.80 GMSK MCS-2 11.2 GMSK MCS-3 14.8 GMSK MCS-417.6 GMSK MCS-5 22.4 8-PSK MCS-6 29.6 8-PSK MCS-7 44.8 8-PSK MCS-8 54.4 8-PSK

MCS-9 59.2 8-PSK

Classification EDGE is part of ITU's 3G definition and is considered a 3G radio technology.

EDGE Evolution EDGE Evolution improves on EDGE in a number of ways. Latencies arereduced by lowering the Transmission Time Interval by half (from 20 ms to 10 ms). Bit rates are

increased up to 1 MBit/s peak speed and latencies down to 100 ms using dual carriers, higher

symbol rate and higher-order modulation (32QAM and 16QAM instead of 8-PSK), and turbo

codes to improve error correction. And finally signal quality is improved using dual antennasimproving average bit-rates and spectrum efficiency. EDGE Evolution can be gradually

introduced as software upgrades, taking advantage of the installed base. With EDGE Evolution,

end-users will be able to experience mobile internet connections corresponding to a 500 kbit/sADSL service.

Networks The Global mobile Suppliers Association (GSA) states that,as of May 2008, therewere 313 commercial GSM/EDGE networks in 147 countries, from a total of 363 mobile

network operator commitments in 165 countries.

GPRS coding
http://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/Gaussian_minimum-shift_keyinghttp://en.wikipedia.org/wiki/Phase_shift_keying#Higher-order_PSK.2F8_phase_shift_keyinghttp://en.wikipedia.org/wiki/Phase_shift_keying#Higher-order_PSK.2F8_phase_shift_keyinghttp://en.wikipedia.org/wiki/GPRShttp://en.wikipedia.org/wiki/Hybrid_ARQhttp://en.wikipedia.org/wiki/Timeslothttp://en.wikipedia.org/wiki/GPRShttp://en.wikipedia.org/wiki/International_Telecommunications_Unionhttp://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/ITUhttp://en.wikipedia.org/wiki/IMT-2000http://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/HSCSDhttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Evolved_EDGEhttp://en.wikipedia.org/wiki/Turbo_codehttp://en.wikipedia.org/wiki/Turbo_codehttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/Gaussian_minimum-shift_keyinghttp://en.wikipedia.org/wiki/Phase_shift_keying#Higher-order_PSK.2F8_phase_shift_keyinghttp://en.wikipedia.org/wiki/Phase_shift_keying#Higher-order_PSK.2F8_phase_shift_keyinghttp://en.wikipedia.org/wiki/GPRShttp://en.wikipedia.org/wiki/Hybrid_ARQhttp://en.wikipedia.org/wiki/Timeslothttp://en.wikipedia.org/wiki/GPRShttp://en.wikipedia.org/wiki/International_Telecommunications_Unionhttp://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/ITUhttp://en.wikipedia.org/wiki/IMT-2000http://en.wikipedia.org/wiki/3Ghttp://en.wikipedia.org/wiki/HSCSDhttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Modulationhttp://en.wikipedia.org/wiki/Evolved_EDGEhttp://en.wikipedia.org/wiki/Turbo_codehttp://en.wikipedia.org/wiki/Turbo_code


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GPRS offers a number of coding schemes with different levels of error detection and correction.

These are used dependent upon the radio frequency signal conditions and the requirements forthe data being sent. These are given labels CS-1 to CS-4:

1. CS-1: - This applies the highest level of error detection and correction. It is used in

scenarios when interference levels are high or signal levels are low. By applying highlevels of detection and correction, this prevents the data having to be re-sent too often.

Although it is acceptable for many types of data to be delayed, for others there is a more

critical time element. This level of detection and coding results in a half code rate, i.e. for

every 12 bits that enter the coder, 24 bits result. It results in a throughput of 9.05 kbpsactual throughput data rate.

2. CS-2: - This error detection and coding scheme is for better channels. It effectively uses a2/3 encoder and results in a real data throughput of 13.4 kbps which includes the

RLC/MAC header etc.

3. CS-3: - This effectively uses a 3/4 coder and results in a data throughput of 15.6 kbps.

4. CS-4: - This scheme is used when the signal is high and interference levels are low. Nocorrection is applied to the signal allowing for a maximum throughput of 21.4 kbps. If all

eight slots were used then this would enable a data throughput of 171.2 kbps to beachieved.

In addition to the error detection and coding schemes, GPRS also employs interleavingtechniques to ensure the effects of interference and spurious noise are reduced to a minimum. It

allows the error correction techniques to be more effective as interleaving helps reduce the total

corruption if a section of data is lost.As blocks of 20 ms data are carried over four bursts, with a total of 456 bits of information, a

total of either 181, 268, 312, or 428 bits of payload data are carried dependent upon the error

detection and coding scheme chosen, i.e. from CS-1 to CS-4, respectively.GPRS classes and coding schemes

In a GPRS network there are four coding schemes:-Channel Coding

SchemeCS-1 CS-2 CS-3 CS-4

Pre-cod. USF 3 6 6 12

Infobits without

USF181 268 312 428

Parity bits BC 40 16 16 16

Tail bits 4 4 4 -

Output conv

encoder

456 588 676 456

Punctured bits 0 132 220 -

Code rate 1/2 ~2/3 ~3/4 1

Data rate kbit/s 9.05 13.4 15.6 21.4

Maximum data

speed with 8 time-

slots

72.4 kb/s 107.2 kb/s 124.8 kb/s 171.2 kb/s

The choice of coding scheme depends on the condition of the channel provided by the cellular

network (quality of the radio link between cell phone and base station). If the channel is very


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noisy, the network may use CS-1 to ensure higher reliability; in this case the data transfer rate is

only 9.05 kbit/s per GSM time slot used. If the channel is providing a good condition, thenetwork could use CS-3 or CS-4 to obtain optimum speed, and would then have up to 21.4 kbit/s

per GSM time slot.

The multislot classes are as follows:-

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Class Download UploadMax.

slots

1 1 1 2

2 2 1 3

3 2 2 3

4 3 1 4

5 2 2 4

6 3 2 4

7 3 3 5

8 4 1 5

9 3 2 510 4 2 5

11 4 3 5

12 4 4 5

13 3 3 unlimited

14 4 4 unlimited

15 5 5 unlimited

16 6 6 unlimited

17 7 7 unlimited

18 8 8 unlimited

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26 8 4 unlimited27 8 4 unlimited

28 8 6 unlimited

29
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WAP Wireless Application ProtocolWAP is a global standard developed by the WAP Forum for wireless devices to access theInternet and telephony services. WAP can also be used to access data from corporate intranets

through public or private IP networks. Figure A shows the WAP services that are currently

offered.

WAP specifications

WAP is an open specification that defines a set of protocols in application, session, transaction,security, and transport layers. To leverage existing programming and development skills, it is

based on existing standards and protocols such as XML, HTTP, UDP, HTML, and JavaScript.

The key elements of the WAP specification include:

A well-known applications development framework. The WAP transport model is

analogous to the Internet model, except for the gateway that is inserted between the Web

server and the client. This familiar model leverages the existing development skills ofWWW programming.

WML (Wireless Markup Language) as the standard markup language.

A browser inside WAP devices that parses WML and WMLScript.

A framework to support advanced telephony services, like WWW to mobile messaging,

call forwarding, mobile to telefax access, and address book access.

Figure B compares a protocol stack based on the Internet model to WAP. As you can see,

numerous networks are included in WAP, with the ultimate goal of targeting multiple networks.

How WAP works

A typical WAP network consists of the following components:

User with WAP-enabled device

Gateway

Application server

The application server can be located in either a public or private IP network. The gateway

normally is located in telecom networks, but it can be set up by a company using its own

computer systems. To get an idea of how these components work together, lets look at a typicalscenario using WAP technology:

1. A user with a WAP device requests content from the application server.

2. The request reaches the gateway first, which does the protocol translation from WAP to

HTTP and routes the HTTP request to the destination server.3. The server returns WML output and adds HTTP headers to the gateway, depending upon

whether dynamic or static pages are requested.

4. The gateway converts WML and HTTP to binary form to conserve bandwidth and returns

a WAP response to the user.5. The browser inside the WAP device interprets the WML and shows the contents.

WAP limitations

Compared to PCs, wireless devices are limited in terms of processing power, memory, battery

life, and display size. Other issues of low bandwidth, latency, and connection stability motivated

the forum to come up with a new set of WAP standards. They have reused many of the existingstandards while creating new extensions to address the above-mentioned problems. The new

WAP specifications leverage the existing investment in hardware, software, applications, and

development skills.


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The WAP marketplace

The drive toward WAP-enabled devices is gathering momentum. The WAP Forum, a consortium

of 90 percent of the world's key handset manufacturers, has announced the upcoming release of

WAPcompatible handsets. According to the forum, in less than two years, all new digitalhandheld devices will be WAP-enabled. Business technology advisorGartnerpredicts that the

mobile phone will become the most widely used Internet access device in the world, with the

number of installed mobile phones topping 1 billion after 2003.

Online applications and services that do not transfer a large amount of information across a

network will fuel most of WAPs success. Services such as stock quotes, news, weather, and

sports are already operational. As mobile commerce (m-commerce) becomes a faster, moresecure channel, services such as banking, retail coupons, wireless ticketing, and sales notification

will become commonplace. Look for this technology to change the way we interact with the

Internet.

Access Technologies

There are three main cellular technologies: Older Analog/FDMA,Modern TDMA, NewerCDMA

TDMA is the leading digital technology in cellular phones today.

Time Division Multiple Access (TDMA) is one of several technologies used in digital wirelesstransmissions that increases the efficiency of the network by allowing a greater number of

simultaneous transmissions. Networks using TDMA assign 6 timeslots for each frequency

channel. Devices using the wireless network send bursts of information that are reassembled at

the receiving end.

TDMA builds on FDMA (Frequency Division Multiple Access) by dividing conversations byfrequency and time. Since digital compression allows voice to be sent under 10 kilobits per

second (equivalent to 10 kHz), TDMA can fit three digital conversations into a FDMA/Analog

channel (which is 30 kHz). By sampling a persons voice for, say 30 milliseconds, thentransmitting it in 10 milliseconds; the system is able to offer 3 timeslots per channel in a round-

robin fashion. This technique allows compatibility with FDMA while enabling digital services

and easily boosting the system by 3 times capacity. This leads to increase calls, more users onthe network and better cellular quality.

Compared to analog FDMA transmissions, TDMA offers a cellular carriers a efficient bandwidth

option. TDMA is more secure, and has better quality of voice transmissions over longer and

shorter distances. The newer CDMA(Code Division Multiple Access) technology is moreadvanced than basic FDMA. Due to lower cost savings compared to CDMA, TDMA is the

digital transmission of choice in today's cellular world. TDMA is more popular with cellular

carriers and manufactures and is the adopted digital standard for most phones. TDMA can beviewed as modern technology, FDMA/Analog as older technology.

Spread Spectrum Technology
http://www.wapforum.org/http://gartner12.gartnerweb.com/public/static/wireless/mobile_wire.htmlhttp://www.cellphonecarriers.com/analog-fdma.htmlhttp://www.cellphonecarriers.com/tdma-cell-phone.htmlhttp://www.cellphonecarriers.com/cdma-wireless-phone.htmlhttp://www.cellphonecarriers.com/cdma-wireless-phone.htmlhttp://www.cellphonecarriers.com/analog-fdma.htmlhttp://www.cellphonecarriers.com/cdma-wireless-phone.htmlhttp://www.wapforum.org/http://gartner12.gartnerweb.com/public/static/wireless/mobile_wire.htmlhttp://www.cellphonecarriers.com/analog-fdma.htmlhttp://www.cellphonecarriers.com/tdma-cell-phone.htmlhttp://www.cellphonecarriers.com/cdma-wireless-phone.htmlhttp://www.cellphonecarriers.com/cdma-wireless-phone.htmlhttp://www.cellphonecarriers.com/analog-fdma.htmlhttp://www.cellphonecarriers.com/cdma-wireless-phone.html

Documents

Advanced Mobile Phone System or AMPS is the Analog Mobile Phone System Standard