IS-54 and IS-136 are second-generation (2G) mobile phone systems, known as Digital AMPS (D-AMPS). It is used throughout the Americas, particularly in the United States and Canada. D-AMPS is considered end-of-life, and existing networks are in the process of being replaced by GSM/GPRS and CDMA2000 technologies. 0G refers to pre-cellular mobile telephony technology. ... Push-to-Talk (PTT), also known as Press-to-Transmit, is a method of conversing on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode. ... The Mobile Telephone System (MTS) was one of the earliest mobile telephone standards. ... The Improved Mobile Telephone Service (IMTS) is a pre-cellular VHF/UHF radio system that links to the PSTN. IMTS was the radiotelephone equivalent of land dial phone service. ... The Advanced Mobile Telephone System was a 0G method of radio communication, mainly used in Japanese portable radio systems. ... OLT (Norwegian for Offentlig Landmobil Telefoni, Public Land Mobile Telephony), was the first land mobile telephone network in Norway. ... MTD (Swedish abbreviation for Mobilelefonisystem D, or Mobile telephony system D) was a manual mobile phone system for the 450 MHz frequency band. ... Autotel (also called PALM, or Public Automated Land Mobile) is a radiotelephone service which was the missing link between earlier MTS/IMTS and later cellular telephone services. ... ARP (Autoradiopuhelin, Car Radio Phone in English) was the first commercially operated public mobile phone network in Finland. ... 1G (or 1-G) is short for first-generation wireless telephone technology, cellphones. ... For other meanings of the abbreviation, see: NMT. NMT (Nordisk MobilTelefoni or Nordiska MobilTelefoni-gruppen, Nordic Mobile Telephone in English) is a mobile phone system that was specified by the Nordic telecommunications administrations (PTTs) starting in 1970, and opened for service in 1981 as a response to the increasing congestion... Advanced Mobile Phone System (AMPS) is the analog mobile phone system standard developed by Bell Labs, and officially introduced in the Americas in 1983[1][2] It was the primary analog mobile phone system in North America (and other locales) through the 1980s and into the 2000s, and is still... hicap is a mobile techonology which has a consumer interface with a wide variety of industry references. ... Cellular Digital Packet Data (CDPD) uses unused bandwidth normally used by AMPS mobile phones between 800 and 900 MHz to transfer data. ... Cingular Interactive Truck at Ground Zero on 9/11/2001 Mobitex Network Design Mobitex is an OSI based open standard, national public access wireless data network first introduced in 1991 by carriers RAM Mobile Data and in Canada 1990 by Rogers Cantel. ... DataTac is a wireless data network technology originally developed by Motorola and deployed in the United States as the ARDIS network. ... This article or section does not cite its references or sources. ... The Global System for Mobile Communications, GSM (original acronym: Groupe Spécial Mobile) is the most popular standard for mobile phones in the world. ... Iden is also a village in East sussex, England iDEN Base Radio at a Cell Site Integrated Digital Enhanced Network (iDEN) is a mobile telecommunications technology, it is known to eat little children, developed by Motorola, which provides its users the benefits of a trunked radio and a cellular telephone. ... Interim Standard 95 (IS-95), is the first CDMA-based digital cellular standard pioneered by Qualcomm. ... Personal Digital Cellular (PDC) is a 2G mobile phone standard developed and used exclusively in Japan. ... Circuit Switched Data, often known as CSD, is the original form of data transmission developed for the GSM mobile phone system. ... The Personal Handy-phone System (PHS), also marketed as the Personal Access System (PAS), is a mobile network system operating in the 1880-1930 MHz frequency band. ... General Packet Radio Service (GPRS) is a mobile data service available to users of GSM and IS-136 mobile phones. ... High-Speed Circuit-Switched Data (HSCSD), is a development of Circuit Switched Data, the original data transmission mechanism of the GSM mobile phone system. ... Wideband Integrated Dispatch Enhanced Network, or WiDEN, is a software upgrade developed by Motorola for its iDEN enhanced specialized mobile radio (or ESMR) wireless telephony protocol. ... CDMA2000 is a family of third-generation (3G) mobile telecommunications standards that use CDMA, a multiple access scheme for digital radio, to send voice, data, and signalling data (such as a dialed telephone number) between mobile phones and cell sites. ... Enhanced Data rates for GSM Evolution (EDGE) or Enhanced GPRS (EGPRS), is a digital mobile phone technology that allows for increased data transmission rate and improved data transmission reliability. ... 3G is short for third-generation technology in the context of mobile phone standards. ... W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network. ... Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile phone technologies. ... FOMA, officially short for Freedom of Mobile Multimedia Access, is the brand name for the 3G services being offered by Japanese mobile phone operator NTT DoCoMo. ... UMTS-TDD is a mobile data network standard built upon the UMTS 3G cellular mobile phone standard, using a TD-CDMA, TD-SCDMA, or other 3GPP-approved, air interface that uses Time Division Duplexing to duplex spectrum between the up-link and down-link. ... Evolution-Data Optimized, abbreviated as EV-DO or EVDO and often EV, is a wireless radio broadband data standard adopted by many CDMA mobile phone service providers in United States, Canada, Mexico, Europe, Asia, Russia, Brazil, and Australia. ... TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) is a 3G mobile telecommunications standard, being pursued in the Peoples Republic of China by the Chinese Academy of Telecommunications Technology (CATT), Datang and Siemens AG, in an attempt to develop home-grown technology and not be dependent on Western... The Generic Access Network (GAN) was formerly known as Unlicensed Mobile Access (UMA), until it was adopted by the 3GPP in April 2005. ... High-Speed Packet Access (HSPA) is a collection of mobile telephony protocols that extend and improve the performance of existing UMTS protocols. ... High-Speed Downlink Packet Access (HSDPA) (Sometimes known as High-Speed Downlink Protocol Access) is a 3G mobile telephony protocol in the HSPA family, which provides a smooth evolutionary path for UMTS-based networks allowing for higher data transfer speeds. ... High-Speed Uplink Packet Access (HSUPA) is a 3G mobile telephony protocol in the HSPA family with up-link speeds up to 5. ... HSPA+ (or HSPA Evolution) is a 3G mobile telephony protocol defined in 3GPP release 7 (expected in 2007). ... High Speed OFDM Packet Access (HSOPA) is a proposed part of 3GPPs Long Term Evolution (LTE) upgrade path for UMTS systems. ... This article is about the mobile phone standard. ... Ultra Mobile Broadband is the brand name to describe the advanced technologies and services that will be supported by the CDMA2000 1xEV-DO Revision C (Rev. ... 3GPP LTE (Long Term Evolution) is the name given to a project within the Third Generation Partnership Programme to improve the UMTS mobile phone standard to cope with future requirements. ... It has been suggested that this article or section be merged with IEEE 802. ... Cellular frequencies - the general term which unites radio frequencies utilized by cellular networks to provide service to their subscribers. ... The Specialized Mobile Radio system (SMR) is a conventional two-way radio system, or trunked radio system, operated by a service in the 800 or 900 Mhz bands. ... Cellular frequencies - the general term which unites radio frequencies utilized by cellular networks to provide service to their subscribers. ... Personal Communications Service or PCS is the name for the 1900-MHz radio band used for digital mobile phone services in Canada and the United States. ... This article or section does not cite its references or sources. ... World map showing the Americas CIA political map of the Americas The Americas are the lands of the Western hemisphere or New World consisting of the continents of North America[1] and South America with their associated islands and regions. ... Not to be confused with Get Some Mates The Global System for Mobile Communications (GSM) is the most popular standard for mobile phones in the world. ... General Packet Radio Service (GPRS) is a mobile data service available to users of GSM mobile phones. ... CDMA2000 is a family of third-generation (3G) mobile telecommunications standards that use CDMA, a multiple access scheme for digital radio, to send voice, data, and signalling data (such as a dialed telephone number) between mobile phones and cell sites. ...

Although this system is most often referred to as TDMA, this name is based on the acronym for time division multiple access, a common multiple access technique which is used by multiple protocols, including GSM, as well as in IS-54 and IS-136. The two different uses of this term can be confusing. TDMA (the technique) is also used in the GSM standard. However, TDMA (the standard, i.e. IS-136) has been competing against GSM and systems based on Code division multiple access (CDMA) for adoption by the network carriers, although it is now being phased out in favor of GSM technology. Time division multiple access (TDMA) is a channel access method for shared medium (usually radio) networks. ... Time division multiple access (TDMA) is a channel access method for shared medium (usually radio) networks. ... Code division multiple access (CDMA) is a form of multiplexing and a method of multiple access that divides up a radio channel not by time (as in time division multiple access), nor by frequency (as in frequency-division multiple access), but instead by using different pseudo-random code sequences for...

D-AMPS uses existing AMPS channels and allows for smooth transition between digital and analog systems in the same area. Capacity was increased over the preceding analog design by dividing each 30 kHz channel pair into three time slots (hence time division) and digitally compressing the voice data, yielding three times the call capacity in a single cell. A digital system also made calls more secure because analog scanners could not access digital signals. Calls were encrypted, although the algorithm used (CMEA) was later found to be weak. [1] Advanced Mobile Phone System or AMPS is the analog mobile phone system standard, introduced in the Americas during the early 1980s. ... In cryptography, the Cellular Message Encryption Algorithm (CMEA) is a block cipher which was used for securing mobile phones in the United States. ...

IS-136 added a number of features to the original IS-54 specification, including text messaging, circuit switched data (CSD), and an improved compression protocol. SMS and CSD were both available as part of the GSM protocol, and IS-136 implemented them in a nearly identical fashion. “SMS” redirects here. ... In telecommunications, a circuit switching network is one that establishes a dedicated circuit (or channel) between nodes and terminals before the users may communicate. ...

Large IS-136 networks include Cingular Wireless and U.S. Cellular in the United States, and Rogers Wireless in Canada. Cingular (who purchased AT&T Wireless in October 2004) and Rogers Wireless have upgraded their existing IS-136 networks to GSM/GPRS, while US Cellular is migrating most of their network to CDMA2000. Rogers Wireless removed all 1900 MHz IS-136 in 2003, and is slowly doing the same with their 800 MHz spectrum as the equipment fails. It is not unusual for a Rogers D-AMPS customer to have coverage in a specific location one day, and then none in that same area the next.^{[citation needed]} Rogers will deactivate their IS-136 network (along with AMPS) in May 2007. “AT&T Wireless” redirects here. ... U.S. Cellular (NYSE: USM) is a super-regional cellular telephone provider, serving 5. ... Rogers AT&T Wireless logo when Rogers wireless division was in partnership with AT&T Rogers Wireless, formerly known as Rogers AT&T Wireless, is a wholly owned subsidiary of Rogers Communications. ... AT&T Wireless Services, Inc. ... 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... CDMA2000 is a family of third-generation (3G) mobile telecommunications standards that use CDMA, a multiple access scheme for digital radio, to send voice, data, and signalling data (such as a dialed telephone number) between mobile phones and cell sites. ... 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ...

IS-54 is the first mobile communication system which had provision for security, and the first to employ TDMA technology.[2]

Introduction

IS-54 stands for Interim Standard-54, which is a mobile communication standard employing digital technology. Standards, in general establish the compatibility and performance requirements for technology. Standards assist manufacturers, service providers, and end users to build, buy, and use products that provide mutually agreed upon features, functionality, and performance. Standards also facilitate the interoperability of products built by different manufacturers. With standards, the service provider and end user have more choices in products than would otherwise be available, and likewise manufacturers have greater access to market than otherwise.

IS-54 was standardized by Electronic Industries Alliance (EIA) and Telecommunications Industry Association (TIA) together. It later became an American National Standard when it got approved by the American National Standards Institute (ANSI). When an interim standard becomes an American National Standard, the IS designator is dropped. The ANSI designation of IS-54 is ANSI/TIA/EIA-627, but this standard is still popularly referred to as IS-54. The Electronic Industries Alliance (EIA, until 1997 Electronic Industries Association) is a trade organization for electronics manufacturers in the United States. ... The Telecommunications Industry Association (TIA) is the leading trade association for the information and communications technology (ICT) industry, with 600 member companies that manufacture or supply the products and services used in global communications across all technology platforms. ... The American National Standards Institute or ANSI (IPA pronunciation: ) is a private nonprofit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. ... The American National Standards Institute or ANSI (pronounced an-see) is a nonprofit organization that oversees the development of standards for products, services, processes and systems in the United States. ...

IS-54 maintains compatibility with Advanced Mobile Phone System (AMPS) in many ways. It is a digital extension of AMPS and so it is also quite widely known as Digital AMPS (D-AMPS). Another name for IS-54 is United States Digital Cellular (USDC). But sometimes D-AMPS and USDC also refers to the other prominent interim standard IS-136. Advanced Mobile Phone System (AMPS) is the analog mobile phone system standard developed by Bell Labs, and officially introduced in the Americas in 1983[1][2] It was the primary analog mobile phone system in North America (and other locales) through the 1980s and into the 2000s, and is still...

History

The evolution of mobile communication has been almost wholly in 3 different geographic regions. The standards that were born in these regions were quite independent. The 3 regions are North America, Europe and Japan. The earlier mobile or wireless technologies were wholly analog and are collectively known as 1st Generation (1G) technologies. In Japan, the 1G standards were Nippon Telegraph and Telephone (NTT) and the high capacity version of it (Hicap). The European systems were not common and the ‘European Union’ viewpoint that is visible in the later technologies was absent. Various 1G standards that were in use in Europe include C-Netz (in Germany and Austria), Comviq (in Sweden), Nordic Mobile Telephones/450 (NMT450) and NMT900 (both in Nordic countries), NMT-F (French version of NMT900), Radiocom 2000 (RC2000) (in France), and Total Access Communication System(TACS) (in the United Kingdom). North American standards were Advanced Mobile Phone System (AMPS) and Narrow-band AMPS (N-AMPS). Mobile phones from various years Several mobile phones A mobile or cellular telephone is a long-range, portable electronic device for personal telecommunications over long distances. ... World map showing North America A satellite composite image of North America. ... World map showing the location of Europe. ... 1G (or 1-G) is short for first-generation wireless telephone technology, cellphones. ... Nippon Telegraph and Telephone (日本電信電話 Nippon Denshin Denwa) is a telephone company that dominates the telecommunication market in Japan. ... hicap is a mobile techonology which has a consumer interface with a wide variety of industry references. ... For other meanings of the abbreviation, see: NMT. NMT (Nordisk MobilTelefoni or Nordiska MobilTelefoni-gruppen, Nordic Mobile Telephone in English) is a mobile phone system that was specified by the Nordic telecommunications administrations (PTTs) starting in 1970, and opened for service in 1981 as a response to the increasing congestion... Advanced Mobile Phone System or AMPS is the analog mobile phone system standard, introduced in the Americas during the early 1980s. ... Advanced Mobile Phone System (AMPS) is the analog mobile phone system standard developed by Bell Labs, and officially introduced in the Americas in 1983[1][2] It was the primary analog mobile phone system in North America (and other locales) through the 1980s and into the 2000s, and is still...

Out of the 1G standards, the most successful was the AMPS system^{[citation needed]}. Despite the Nordic countries' cooperation, European engineering efforts were divided among the various standards, and the Japanese standards didn’t get much attention. Developed by Bell Labs in the 1970s and first used commercially in the United States in 1983, AMPS operates in the 800 MHz band in the United States and is the most widely distributed analog cellular standard. (The 1900 MHz PCS band, established in 1994, is for digital operation only.) The success of AMPS kick-started the mobile age in the North America. Political map of the Nordic countries and associated territories. ... Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. ... The 1970s decade refers to the years from 1970 to 1979, inclusive. ... 1983 (MCMLXXXIII) was a common year starting on Saturday of the Gregorian calendar. ... A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... PCS can stand for: Personal Communications Service Permanent Change of Station Public and Commercial Services Union See also: Personal Computers This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... 1994 (MCMXCIV) was a common year starting on Saturday of the Gregorian calendar, and was designated as the International Year of the Family and the International Year of the Sport and the Olympic Ideal by United Nations. ...

The market showed an increasing demand because it had higher capacity and mobility than the then existing mobile communication standards. For instance, the Bell Labs system in the 1970s could carry only 12 calls at a time throughout all of New York City. AMPS used Frequency Division Multiple Access FDMA which meant each cell site would transmit on different frequencies, allowing many cell sites to be built near each other. New York, NY redirects here. ... FDMA, or frequency-division multiple access, is the oldest and most important of the three main ways for multiple radio transmitters to share the radio spectrum. ...

However, AMPS had many disadvantages too. Primarily, it didn’t have the potential to support the increasing demand for mobile communication usage. Each cell site did not have much capacity for carrying higher numbers of calls. It also had a poor security system which allowed people to steal a phone's serial code to use for making illegal calls. All of these triggered the search for a more capable system.

The quest resulted in IS-54, the first American 2G standard. In March 1990, the North American cellular network incorporated the IS-54B standard, the first North American dual mode digital cellular standard. This standard won over Motorola's Narrowband AMPS or N-AMPS, an analog scheme that increased capacity by cutting down voice channels from 30 kHz to 10 kHz. IS-54, on the other hand, increased capacity by digital means using TDMA protocols. This method separates calls by time, placing parts of individual conversations on the same frequency, one after the next. TDMA tripled call capacity. Motorola (NYSE: MOT) is an American multinational communications company based in Schaumburg, Illinois, a Chicago suburb. ... Time division multiple access (TDMA) is a channel access method for shared medium (usually radio) networks. ...

Using IS-54, a cellular carrier could convert any of its system's analog voice channels to digital. A dual mode phone uses digital channels where available and defaults to regular AMPS where they are not. IS-54 was, in fact, backward compatible with analog cellular and indeed co-exists on the same radio channels as AMPS. No analog customers were left behind; they simply couldn't access IS-54's new features. IS-54 also supported authentication, a help in preventing fraud. Analog electronics are those electronic systems with a continuously variable signal. ... A digital system is one that uses discrete values (often electrical voltages), especially those representable as binary numbers, or non-numeric symbols such as letters or icons, for input, processing, transmission, storage, or display, rather than a continuous spectrum of values (ie, as in an analog system). ... In technology (especially computing), backward compatibility has several related but differing meanings: A system is backward compatible if it is compatible with earlier versions of itself, or sometimes other earlier systems, particularly systems it intends to supplant. ... Authentication (Greek: αυθεντικός = real or genuine, from authentes = author ) is the act of establishing or confirming something (or someone) as authentic, that is, that claims made by or about the thing are true. ...

Technology specifications

IS-54 employs the same 30 kHz channel spacing and frequency bands (824-849 and 869-894 MHz) as AMPS. Capacity was increased over the preceding analog design by dividing each 30 kHz channel pair into three time slots and digitally compressing the voice data, yielding three times the call capacity in a single cell. A digital system also made calls more secure because analog scanners could not access digital signals.

The IS-54 standard specifies 84 control channels, 42 of which are shared with AMPS. To maintain compatibility with the existing AMPS cellular telephone system, the primary forward and reverse control channels in IS-54 cellular systems use the same signaling techniques and modulation scheme (binary FSK) as AMPS. An AMPS/IS-54 infrastructure can support use of either analog AMPS phones or D-AMPS phones.

The access method used for IS-54 is Time Division Multiple Access (TDMA), which was the first U.S. digital standard to be developed. It was adopted by the TIA in 1992. TDMA subdivides each of the 30 kHz AMPS channels into 3 full-rate TDMA channels, each of which is capable of supporting a single voice call. Later, each of these full-rate channels was further sub-divided into two half-rate channels, each of which, with the necessary coding and compression, could also support a voice call. Thus, TDMA could provide 3 to 6 times the capacity of AMPS traffic channels. Time Division Multiple Access or TDMA was initially defined by the IS-54 standard and is now specified in the IS-13x series of specifications of the EIA/TIA.

The channel transmission bit rate for digitally modulating the carrier is 48.6 kbit/s. Each frame has six time slots of 6.67-ms duration. Each time slot carries 324 bits of information, of which 260 bits are for the 13-kbit/s full-rate traffic data. The other 64 bits are overhead; 28 of these are for synchronization, and they contain a specific bit sequence known by all receivers to establish frame alignment. Also, as with GSM, the known sequence acts as a training pattern to initialize an adaptive equalizer.

The IS-54 system has different synchronization sequences for each of the six time slots making up the frame, thereby allowing each receiver to synchronize to its own preassigned time slots. An additional 12 bits in every time slot are for the SACCH (i.e., system control information). The digital verification color code (DVCC) is the equivalent of the supervisory audio tone used in the AMPS system. There are 256 different 8-bit color codes, which are protected by a (12, 8, 3) Hamming code. Each base station has its own preassigned color code, so any incoming interfering signals from distant cells can be ignored.

The modulation scheme for IS-54 is 7C/4 differential quaternary phase shift keying (DQPSK), otherwise known as differential 7t/4 4-PSK or π/4 DQPSK. This technique allows a bit rate of 48.6 kbit/s with 30 kHz channel spacing, to give a bandwidth efficiency of 1.62 bps/Hz. This value is 20% better than GSM. The major disadvantage with this type of linear modulation method is the power inefficiency, which translates into a heavier hand-held portable and, even more inconvenient, a shorter time between battery recharges.

IS-54 security features is also a matter of interest as it was the first standard to specify some security measures. IS-54 uses the CAVE (Cellular Authentication, Voice Privacy and Encryption) algorithm for authentication and the CMEA (Cellular Message Encryption Algorithm) for encryption.

The technical specifications can be summarized as below:

Call processing

A conversation's data bits makes up the DATA field. Six slots make up a complete IS-54 frame. DATA in slots 1 and 4, 2 and 5, and 3 and 6 make up a voice circuit. DVCC stands for digital verification color code, arcane terminology for a unique 8-bit code value assigned to each cell. G means guard time, the period between each time slot. RSVD stands for reserved. SYNC represents synchronization, a critical TDMA data field. Each slot in every frame must be synchronized against all others and a master clock for everything to work.

Time slots for the mobile-to-base direction are constructed differently from the base-to-mobile direction. They essentially carry the same information but are arranged differently. Notice that the mobile-to-base direction has a 6-bit ramp time to enable its transmitter time to get up to full power, and a 6-bit guard band during which nothing is transmitted. These 12 extra bits in the base-to-mobile direction are reserved for future use.

Once a call comes in the mobile switches to a different pair of frequencies; a voice radio channel which the system carrier has made analog or digital. This pair carries the call. If an IS-54 signal is detected it gets assigned a digital traffic channel if one is available. The fast associated channel or FACCH performs handoffs during the call, with no need for the mobile to go back to the control channel. In case of high noise FACCH, embedded within the digital traffic channel overrides the voice payload, degrading speech quality to convey control information. The purpose is to maintain connectivity. The slow associated control channel or SACCH does not perform handoffs but conveys things like signal strength information to the base station.

The IS-54 speech coder uses the technique called vector sum excited linear prediction (VSELP) coding. This is a special type of speech coder within a large class known as code-excited linear prediction (CELP) coders. The speech coding rate of 7.95 kbit/s achieves a reconstructed speech quality similar to that of the analog AMPS system using frequency modulation. The 7.95-kbit/s signal is then passed through a channel coder that loads the bit rate up to 13 kbit/s. The new half-rate coding standard reduces the overall bit rate for each call to 6.5 kbit/s, and should provide comparable quality to the 13-kbit/s rate. This half-rate gives a channel capacity six times that of analog AMPS. Vector Sum Excited Linear Prediction (VSELP) is a speech coding method used in the IS-54 standard. ... CELP stands for Code Excited Linear Prediction and is a speech coding algorithm originally proposed by M.R. Schroeder and B.S. Atal in 1984. ...

System example

The discussion of a communication system won’t be complete without the explanation of a system example. A dual-mode cellular phone as specified by the IS-54 standard is explained. A dual-mode phone is capable of operating in an analog-only cell or a dual-mode cell. Both the transmitter and the receiver support both analog FM and digital time division multiple access (TDMA) schemes. Digital transmission is preferred, so when a cellular system has digital capability, the mobile unit is assigned a digital channel first. If no digital channels are available, the cellular system will assign an analog channel. The transmitter converts the audio signal to a radio frequency (RF), and the receiver converts an RF signal to an audio signal. The antenna focuses and converts RF energy for reception and transmission into free space. The control panel serves as an input/output mechanism for the end user; it supports a keypad, a display, a microphone, and a speaker. The coordinator synchronizes the transmission and receives functions of the mobile unit. A dual-mode cellular phone consists of the following:

• Transmitter
• Antenna assembly
• Receiver
• Control panel
• Coordinator

Successor technologies

By 1993 American cellular was again running out of capacity, despite a wide movement to IS-54. The American cellular business continued booming. Subscribers grew from one and a half million customers in 1988 to more than thirteen million subscribers in 1993. Room existed for other technologies to cater to the growing market. The technologies that followed IS-54 stuck to the digital backbone laid down by it.

IS-136

A pragmatic effort was launched to improve IS-54 that eventually added an extra channel to the IS-54 hybrid design. Unlike IS-54, IS-136 utilizes time division multiplexing for both voice and control channel transmissions. Digital control channel allows residential and in-building coverage, dramatically increased battery standby time, several messaging applications, over the air activation and expanded data applications. IS-136 systems needed to support millions of AMPS phones, most of which were designed and manufactured before IS-54 and IS-136 were considered. IS-136 added a number of features to the original IS-54 specification, including text messaging, circuit switched data (CSD), and an improved compression protocol. IS-136 TDMA traffic channels use π/4-DQPSK modulation at a 24.3-kbaud channel rate and gives an effective 48.6 kbit/s data rate across the six time slots comprising one frame in the 30 kHz channel.

Sunset for D-AMPS in the US

Cingular Wireless, the largest US carrier to support D-AMPS (which it refers to as "TDMA"), has announced the first 19 wireless markets where it will turn down its existing network in order to release the spectrum to its GSM and UMTS platforms. [3] [4] According to the announcement, the first markets to officially go offline will do so on May 30, 2007, with other areas following in June and July. Cingular has indicated they expect to turn down the remaining markets at the same time that they decommission AMPS service, beginning in mid-February 2008. Cingular Wireless is the largest United States mobile phone company, with headquarters in Atlanta, Georgia, United States. ... Universal Mobile Telecommunications System (UMTS) is one of the third-generation (3G) mobile phone technologies. ...

References

• History of mobile communication:1990's
• Paper on CMEA
• Cingular Wireless: "TDMA Service Sunset"
• Edge Wireless: "TDMA Network Changing to GSM/GPRS"

External links

• Timeslot structure for IS-136 and IS-54