all you need to know about
Mobile Telephone History
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GSM first stood for Groupe Speciale Mobile, after the study group that created the standard. It's now known as Global System for Mobile Communications, although the "C" isn't included in the abbreviation. In 1982 twenty-six European national phone companies began developing GSM. This Conference of European Postal and Telecommunications Administrations or CEPT, planned a uniform, European wide cellular system around 900 MHz. A rare triumph of European unity, GSM achievements became "one of the most convincing demonstrations of what co-operation throughout European industry can achieve on the global market." Planning began in earnest and continued for several years.
In the mid-1980s commercial mobile telephony took to the air. The North American terrestrial system or NATS was introduced by Airfone in 1984, the company soon bought out by GTE. The aeronautical public correspondence or APC service breaks down into two divisions. The first is the ground or terrestial based system (TAPC). That's where aircraft placed telephone calls go directly to a ground station. The satellite-based division, which came much later, places calls to a satellite which then relays the transmission to a ground station. AT&T soon established their own TAPC network after GTE.
In December 1988 Japan's Ministry of Posts and Telecommunications ended NTT's monopoly on mobile phone service. Although technically adept, NTT was also monolithic and bureaucratic, it developed a good cellular system but priced it beyond reach, and required customers to lease phones, not to buy them. With this atmosphere and without competition cellular growth in Japan had flatlined. With rivals cellular customers did increase but it was not until April,1994, when the market was completely deregulated, allowing price breaks and letting customers own their own phones, did Japanese cellular really take off.
In 1989 The European Telecommunication Standards Institute or ETSI took responsibility for further developing GSM. In 1990 the first recommendations were published. Pre-dating American PCS, the United Kingdom asked for and got a GSM plan for higher frequencies. The Digital Cellular System or DCS1800 works at 1.8 GHz, uses lower powered base stations and has greater capacity because more frequencies are available than on the continent. Aside from these "air interface" considerations, the system is pure GSM. The specs were published in 1991.
The late 1980s saw North American cellular becoming standardized as network growth and complexity accelerated. In 1988 the analog networking cellular standard called TIA-IS-41 was published. [Crowe] This Interim Standard is still evolving. IS-41 seeks to unify how network elements operate; the way various databases and mobile switches communicate with each other and with the regular landline telephone network. Despite ownership or location, all cellular systems across America need to act as one larger system. In this way roamers can travel from system to system without having a call dropped, calls can be validated to check against fraud, subscriber features can be supported in any location, and so on. All of these things rely on network elements cooperating in a uniform, timely manner.
In 1990 in-flight radio-telephone moved to digital. The FCC invited applications for and subsequently awarded new licences to operate digital terrestial aeronautical public correspondence or TAPC services in the US. GTE Airfone, AT&T Wireless Services (previously Claircom Communications), and InFlight Phone Inc. were awarded licenses. "[T]hese U.S. service providers now have TAPC networks covering the major part of North America. The FCC has not specified a common standard for TAPC services in the US, other than a basic protocol for allocating radio channel resources, and all three systems are mutually incompatible. Currently over 3000 aircraft are fitted with one of these three North American Telephone Systems (NATS). It is estimated that the potential market for TAPC services in North America is in excess of 4000 aircraft." [Capway]
North America goes digital: IS-54
In 1990 North American carriers faced the question -- how do we increase capacity? -- do we pick an analog or digital method? The answer was digital. 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 NAMPS, an analog scheme that increased capacity by cutting down voice channels from 30KHz to 10KHz. IS-54 on the other hand increased capacity by digital means: sampling, digitizing, and then multiplexing conversations, a technique called TDMA or time division multiple access. This method separates calls by time, placing parts of individual conversations on the same frequency, one after the next. It tripled call capacity.
Using IS-54, a cellular carrier could convert any of its systems' 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 happily 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. CANTEL got IS-54 going in Canada in 1992. IS-54 also supported authentication, a help in preventing fraud. IS-54, now rolled into IS-136, accounts for perhaps half of the cellular radio accounts in this country.
I should point out that no radio service can be judged on whether it is all digital or not. Other factors such as poorer voice quality must be considered. In America GSM systems usually operate at a higher frequency than it does in most of Europe. As we will see later, nearly twice as many base stations are required as on the continent, leaving gaps and holes in coverage that do not exist with lower frequency, conventional cellular. And data transfer remains no higher than 9.6 kbs, a fifth the speed of an ordinary landline modem. Tremendous potential exists but until networks are built out and other problems solved, that potential remains unfulfilled.
Meanwhile, back on the continent, commercial GSM networks started operating in mid-1991 in European countries. GSM developed later than conventional cellular and in many respects was better designed. Its North American counterpart is sometimes called PCS 1900, operating in a higher frequency band than the original European GSM. But be careful with marketing terms: in America a PCS service might use GSM or it might not. All GSM systems are TDMA based, but other PCS systems use what's known as IS-95, a CDMA based technology. Sometimes GSM at 1900Mhz is called PCS 1900, sometimes it is not. Arrgh.
Advanced Mobile Phone Service contended well with GSM and PCS at first, but it has since declined in market share. While it was still vibrant, David Crowe put it like this:
"The best known AMPS systems are in the US and Canada, but AMPS is also a de facto standard throughout Mexico, Central and South America, very common in the Pacific Rim and also found in Africa and the remains of the USSR. In summary, AMPS is on every continent except Europe and Antarctica. . . due to the high capacity allowed by the cellular concept, the lower power which enabled portable operation and its robust design, AMPS has been a stunning success. Today, more than half the cellular phones in the world operate according to AMPS standards . . . From its humble beginnings, AMPS has grown from its roots as an 800MHz analog standard, to accommodate TDMA and CDMA digital technology, narrowband (FDMA) analog operation (NAMPS), in-building and residential modifications."
"Most recently, operation in the 1800 Mhz (1.8-2.2 GHz) PCS frequency band has been added to standards for CDMA and TDMA. All of these additions have been done while maintaining an AMPS compatibility mode (known as BOA: Boring Old AMPS). It might be boring, but it works, and the AMPS compatibility makes advanced digital phones work everywhere, even if all their features are not available in analog mode."